Derivative Instruments [Abstract] Derivative Instruments [Abstract] Derivative Instruments, Gain (Loss) by Hedging Relationship, by Income Statement Location, by Derivative Instrument Risk [Table] Derivative Instruments, Gain (Loss) [Table] Derivative Instrument Risk [Axis] Derivative Instrument [Axis] Derivative Contract Type [Domain] Derivative Contract [Domain] Interest Rate Swap [Member] Commodity Option [Member] Derivative Instruments, Gain (Loss) [Line Items] Derivative Instruments, Gain (Loss) [Line Items] Summary of Derivative Instruments by Risk Exposure [Abstract] Power contracts included in operating revenues Power contracts included in operating revenues Power contracts included in operating revenues Natural gas contracts included in fuel and purchased energy expense Natural gas contracts included in fuel and purchased energy expense Natural gas contracts included in fuel and purchased energy expense Interest rate swaps included in interest expense Interest rate swaps included in interest expense Interest rate swaps included in interest expense Gain (Loss) on Derivative Instruments, Net, Pretax Gain (Loss) on Derivative Instruments, Net, Pretax Gain (Loss) on Sale of Derivatives Gain (Loss) on Sale of Derivatives Mark-to-market gain (loss) Unrealized Gain (Loss) on Derivatives Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Hedging Designation [Axis] Hedging Designation [Axis] Hedging Designation [Domain] Hedging Designation [Domain] Designated as Hedging Instrument [Member] Not Designated as Hedging Instrument [Member] Derivatives, Fair Value [Line Items] Derivatives, Fair Value [Line Items] Derivative assets, current Derivative Asset, Current Derivative Assets, Noncurrent Derivative Asset, Noncurrent Total derivative assets Derivative Asset, Fair Value, Gross Asset Current derivative liabilities Derivative Liability, Current Derivative Liabilities, Noncurrent Derivative Liability, Noncurrent Total derivative liabilities Derivative Liability, Fair Value, Gross Liability Net derivative assets (liabilities) Derivative, Fair Value, Net Debt Disclosure [Abstract] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] First Lien Term Loans 2018 [Member] First Lien Term Loans 2018 [Member] First Lien Term Loans 2018 [Member] First Lien Term Loan 2019 [Member] First Lien Term Loan 2019 [Member] First Lien Term Loan 2019 [Member] 2020 First Lien Term Loan [Member] 2020 First Lien Term Loan [Member] 2020 First Lien Term Loan [Member] First Lien Term Loans [Member] Loans Payable [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Long-term Debt Long-term Debt Business Combinations [Abstract] Six Power Plants To be disposed of [Table Text Block] Six Power Plants To be disposed of [Table Text Block] Six Power Plants To be disposed of [Table Text Block] Disclosure of Long Lived Assets Held-for-sale [Table Text Block] Disclosure of Long Lived Assets Held-for-sale [Table Text Block] Derivative Instruments Derivative Instruments and Hedging Activities Disclosure [Text Block] Segment Reporting [Abstract] Schedule of Financial Data for Segments Schedule of Segment Reporting Information, by Segment [Table Text Block] Schedule of Revenues from External Customers and Long-Lived Assets [Table] Schedule of Revenues from External Customers and Long-Lived Assets [Table] Geographical [Axis] Geographical [Axis] Segment, Geographical [Domain] Geographical [Domain] West [Member] West Member Texas [Member] TEXAS North [Member] North Member Southeast [Member] Southeast Member Intersegment Elimination [Member] Intersegment Eliminations [Member] Revenues from External Customers and Long-Lived Assets [Line Items] Revenues from External Customers and Long-Lived Assets [Line Items] Revenue from External Customer Revenue from External Customer Revenue from External Customer Intersegment revenue Intersegment revenue Intersegment revenue Operating revenues Revenues Commodity Margin Commodity Margin Commodity Margin Add: Mark-to-market commodity activity, net and other Mark-to-Market Commodity Activity, Net and Other Revenue Mark-to-Market Commodity Activity, Net and Other Revenue Plant operating expense Operating Costs and Expenses Depreciation and amortization expense Depreciation, Depletion and Amortization, Nonproduction Sales, general and other administrative expense Selling, General and Administrative Expense Other operating expenses Other Cost and Expense, Operating (Income) loss from unconsolidated investments in power plants Income (Loss) from Equity Method Investments Income from operations Operating Income (Loss) Interest expense, net of interest income Interest Revenue (Expense), Net Debt extinguishment costs and other (income) expense, net Debt Extinguishment Costs and Other (Income) Expense, Net Debt Extinguishment Costs and Other (Income) Expense, Net Income (loss) before income taxes Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest Commodity Margin for Six Southeast Power Plants Sold Commodity Margin for Six Southeast Power Plants Sold Commodity Margin for Six Southeast Power Plants Sold Lease levelization Lease levelization LeaseLevelization Contract amortization Contract amortization Contract amortization CCFC Term Loan B-2 [Member] CCFC Term Loan B-2 [Member] CCFC Term Loan B-2 [Member] Incremental CCFC Term Loans [Member] Incremental CCFC Term Loans [Member] Incremental CCFC Term Loans [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] Debt Instrument, Redemption, Period [Axis] Debt Instrument, Redemption, Period [Axis] Debt Instrument, Redemption, Period [Domain] Debt Instrument, Redemption, Period [Domain] Debt Instrument, Face Amount Debt Instrument, Face Amount Long Term Debt net of Original Issuance Disount Long Term Debt net of Original Issuance Disount Long Term Debt net of Original Issuance Disount Earnings (Loss) per Share [Abstract] Earnings (Loss) per Share [Abstract] Schedule of Weighted Average Number of Shares [Table Text Block] Schedule of Weighted Average Number of Shares [Table Text Block] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Use of Collateral [Abstract] Use of Collateral Abstract Schedule of Collateral Collateral [Table Text Block] Collateral table text block Earnings (Loss) per Share Earnings Per Share [Text Block] Accounting Policies [Abstract] Accounting Policies [Table] Accounting Policies [Table] Accounting Policies [Table] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Geothermal Properties, Gross [Member] Geothermal Properties, Gross [Member] Geothermal Properties, Gross [Member] Property, Plant and Equipment, Other Types [Member] Property, Plant and Equipment, Other Types [Member] Building, Machinery and Equipment, Gross [Member] Building, Machinery and Equipment, Gross [Member] Building, Machinery and Equipment, Gross [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum [Member] Minimum [Member] Maximum [Member] Maximum [Member] Equity Method Investee, Name [Axis] Investment, Name [Axis] Equity Method Investee, Name [Domain] Investment, Name [Domain] Greenfield [Member] Greenfield [Member] Greenfield member Whitby [Member] Whitby [Member] Whitby member Restricted Cash and Cash Equivalents [Axis] Restricted Cash and Cash Equivalents [Axis] Cash and Cash Equivalents [Domain] Cash and Cash Equivalents [Domain] Debt Service Debt Service [Member] Debt service member Rent Reserve Rent Reserve [Member] Rent Reserve member Construction Major Maintenance Construction Major Maintenance [Member] Construction major maintenance member Security Project Insurance Security Project Insurance [Member] Security project insurance member Other Other Restricted Cash [Member] Other restricted cash member Accounting Policies [Line Items] Accounting Policies [Line Items] [Line Items] for Accounting Policies [Table] Current Restricted Cash and Cash Equivalents, Current Non-current Restricted Cash and Cash Equivalents, Noncurrent Total Restricted Cash and Cash Equivalents Property, Plant and Equipment, Estimated Useful Lives Property, Plant and Equipment, Useful Life Cash and cash equivalents subject to project finance facilities and lease agreements Cash and cash equivalents subject to project finance facilities and lease agreements Interest Costs Capitalized Interest Costs Capitalized Treasury Stock, Value, Acquired, Cost Method Treasury Stock, Value, Acquired, Cost Method Adjustments Related to Tax Withholding for Share-based Compensation Adjustments Related to Tax Withholding for Share-based Compensation 2022 First Lien Notes [Member] 2022 First Lien Notes [Member] 2022 First Lien Notes [Member] Statement of Financial Position [Abstract] ASSETS Assets [Abstract] Current assets: Assets, Current [Abstract] Cash and cash equivalents ($136 and $242 attributable to VIEs) Cash and Cash Equivalents, at Carrying Value Accounts receivable, net of allowance of $7 and $5 Accounts Receivable, Net, Current Inventories Inventory, Net Margin deposits and other prepaid expense Margin deposits and Other Prepaid Expenses Margin deposits and Other Prepaid Expenses Restricted cash, current ($122 and $100 attributable to VIEs) Current assets held for sale Assets Held-for-sale, Current Other current assets Other Assets, Current Total current assets Assets, Current Property, plant and equipment, net ($4,542 and $4,191 attributable to VIEs) Property, Plant and Equipment, Net Restricted cash, net of current portion ($66 and $68 attributable to VIEs) Investments in power plants Equity Method Investments Long-term derivative assets Other assets ($196 and $195 attributable to VIEs) Other Assets, Noncurrent Total assets Assets LIABILITIES & STOCKHOLDERS’ EQUITY Liabilities and Equity [Abstract] Current liabilities: Liabilities, Current [Abstract] Accounts payable Accounts Payable, Current Accrued interest payable Interest Payable, Current Debt, current portion ($134 and $140 attributable to VIEs) Debt, Current Derivative liabilities, current Current liabilities held for sale Liabilities of Assets Held-for-sale Other current liabilities Other Liabilities, Current Total current liabilities Liabilities, Current Debt, net of current portion ($3,303 and $2,923 attributable to VIEs) Long-term Debt, Excluding Current Maturities Long-term derivative liabilities Other long-term liabilities Other Liabilities, Noncurrent Total liabilities Liabilities Commitments and contingencies (see Note 12) Commitments and Contingencies Stockholders’ equity: Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Preferred stock, $0.001 par value per share; authorized 100,000,000 shares, none issued and outstanding Preferred Stock, Value, Issued Common stock, $0.001 par value per share; authorized 1,400,000,000 shares, 500,563,630 and 497,841,056 shares issued, respectively, and 417,133,226 and 429,038,988 shares outstanding, respectively Common Stock, Value, Issued Treasury stock, at cost, 83,430,404 and 68,802,068 shares, respectively Treasury Stock, Value Additional paid-in capital Additional Paid in Capital, Common Stock Accumulated deficit Retained Earnings (Accumulated Deficit) Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Total Calpine stockholders’ equity Stockholders' Equity Attributable to Parent Noncontrolling interest Stockholders' Equity Attributable to Noncontrolling Interest Total stockholders’ equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Total liabilities and stockholders’ equity Liabilities and Equity Financial Instrument [Axis] Financial Instrument [Axis] Financial Instruments [Domain] Financial Instruments [Domain] Gains (Loss) Recognized in OCI (Effective Portion) Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net Gain (Loss) Reclassified from AOCI into Income (EffectivePortion) Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net Line of Credit Facility [Table] Line of Credit Facility [Table] Lender Name [Axis] Lender Name [Axis] Line of Credit Facility, Lender [Domain] Line of Credit Facility, Lender [Domain] Corporate Revolving Facility [Member] Corporate Revolving Facility [Member] Corporate Revolving Facility Member CDH [Member] CDH [Member] Calpine Development Holdings Member Various Project Financing Facilities [Member] Various Project Financing Facilities [Member] Various project financing facilities member Line of Credit Facility [Line Items] Line of Credit Facility [Line Items] Letters of Credit Outstanding, Amount Letters of Credit Outstanding, Amount Schedule of Long-term Debt Instruments Schedule of Long-term Debt Instruments [Table Text Block] First Lien Notes First Lien Notes [Table Text Block] First lien notes table text block First Lien Term Loans First Lien Term Loans [Table Text Block] First Lien Term Loans [Table Text Block] Schedule of Line of Credit Facilities Schedule of Line of Credit Facilities [Table Text Block] Schedule of Carrying Values and Estimated Fair Values of Debt Instruments Schedule of Carrying Values and Estimated Fair Values of Debt Instruments [Table Text Block] Variable Interest Entities and Unconsolidated Investments [Abstract] Variable Interest Entities and Unconsolidated Investments Abstract Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Line Items] Equity Method Investment, Ownership Percentage Equity Method Investment, Ownership Percentage Shareholder Transaction [Abstract] Shareholder Transaction [Abstract] Statement [Table] Statement [Table] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event [Member] Subsequent Event [Member] Statement [Line Items] Statement [Line Items] Shareholder Ownership Percentage Shareholder Ownership Percentage Shareholder Ownership Percentage Common Stock Purchased from Shareholder Common Stock Purchased from Shareholder Common Stock Purchased from Shareholder Purchase Price of Common Stock Purchased from Shareholder Purchase Price of Common Stock Purchased from Shareholder Purchase Price of Common Stock Purchased from Shareholder Mergers, Acquisitions and Dispositions Disclosures [Text Block] Mergers, Acquisitions and Dispositions Disclosures [Text Block] Use of Collateral [Text Block] Use of Collateral [Text Block] Use of Collateral [Text Block] Fair Value Disclosures [Abstract] Derivative Instruments Subject to Master Netting Arrangement [Table] Derivative Instruments Subject to Master Netting Arrangement [Table] Derivative Instruments Subject to Master Netting Arrangement [Table] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Fair Value, Inputs, Level 3 [Member] Fair Value, Inputs, Level 3 [Member] Commodity Exchange Traded Futures and Swaps Contracts [Member] Commodity Exchange Traded Futures and Swaps Contracts [Member] Commodity Exchange Traded Futures and Swaps Contracts [Member] Commodity Forward Contract [Member] Commodity Forward Contract [Member] Commodity Forward Contract [Member] Interest Rate Swap [Member] Asset Class [Axis] Asset Class [Axis] Fair Value by Asset Class [Domain] Asset Class [Domain] Derivative Instruments Subject to Master Netting Arrangement [Line Items] Derivative Instruments Subject to Master Netting Arrangement [Line Items] [Line Items] for Derivative Instruments Subject to Master Netting Arrangement [Table] Derivative, Fair Value, Gross Amount Not Offset Against Collateral, Net Derivative Fair Value, Amount Not Offset Against Collateral, Net Derivative Fair Value, Amount Not Offset Against Collateral, Net Derivative Fair Value, Amount Not Offset Against Collateral, Net Derivative Asset, Fair Value, Amount Offset Against Collateral Derivative Asset, Fair Value, Amount Offset Against Collateral Derivative Asset, Fair Value, Gross Asset Derivative Asset, Fair Value, Amount Not Offset Against Collateral Derivative Asset, Fair Value, Amount Not Offset Against Collateral Derivative Liability, Fair Value, Gross Liability Derivative Liability, Fair Value, Amount Not Offset Against Collateral Derivative Liability, Fair Value, Amount Not Offset Against Collateral Margin/Cash (Received) Posted Subject to Master Netting Arrangement Derivative, Collateral, Right to Reclaim Cash, Net Derivative, Collateral, Right to Reclaim Cash, Net Derivative Liability, Fair Value, Amount Offset Against Collateral Derivative Liability, Fair Value, Amount Offset Against Collateral Derivative, Fair Value, Amount Offset Against Collateral, Net Derivative, Fair Value, Amount Offset Against Collateral, Net Derivative, Collateral, Right to Reclaim Cash Derivative, Collateral, Right to Reclaim Cash Derivative, Collateral, Obligation to Return Cash Derivative, Collateral, Obligation to Return Cash Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Schedule of Share-based Compensation, Activity [Table Text Block] Schedule of Share-based Compensation, Activity [Table Text Block] Schedule of Non-Qualified Stock Option Activity Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block] Schedule of Assumptions Used to Estimate Fair Value for Options Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Schedule of Restricted Stock and Restricted Stock Unit Activity Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block] Variable Interest Entities and Unconsolidated Investments in Power Plants Variable Interest Entities and Unconsolidated Investments [Text Block] Variable Interest Entities and Unconsolidated Investments 2024 First Lien Notes [Member] 2024 First Lien Notes [Member] 2024 First Lien Notes [Member] Derivative, Nonmonetary Notional Amount, Energy Measure Derivative, Nonmonetary Notional Amount, Energy Measure Nonmonetary Notional Amount of Price Risk Derivatives Natural Gas Nonmonetary Notional Amount of Price Risk Derivatives Natural Gas Nonmonetary Notional Amount of Price Risk Derivatives Natural Gas Derivative, Nonmonetary Notional Amount, Mass Derivative, Nonmonetary Notional Amount, Mass Price Risk Derivatives [Abstract] Derivative, Notional Amount Derivative, Notional Amount Summary of Significant Accounting Policies Basis of Presentation and Significant Accounting Policies [Text Block] Debt Debt Disclosure [Text Block] Fair Value Measurements [Abstract] Fair Value Measurements [Abstract] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 2 [Member] Fair Value, Inputs, Level 2 [Member] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Cash equivalents Cash and Cash Equivalents, Fair Value Disclosure Margin deposits Margin Deposit Assets Commodity futures contracts Commodity Futures Contracts Assets, Fair Value Disclosure Commodity Futures Contracts Assets, Fair Value Disclosure Commodity forward contracts Commodity Forward Contracts Assets, Fair Value Disclosure Commodity Forward Contracts Assets, Fair Value Disclosure Interest Rate Swap Assets, Fair Value Disclosure Interest Rate Swap Assets, Fair Value Disclosure Interest Rate Swap Assets, Fair Value Disclosure Total assets Assets, Fair Value Disclosure Margin deposits held by us posted by our counterparties Security Deposit Liability Commodity futures contracts Commodity Futures Contracts Liabilities, Fair Value Disclosure Commodity Futures Contracts Liabilities, Fair Value Disclosure Commodity forward contracts Commodity Forward Contracts Liabilities, Fair Value Disclosure Commodity Forward Contracts Liabilities, Fair Value Disclosure Interest rate swaps Interest Rate Swap Liabilities, Fair Value Disclosure Interest Rate Swap Liabilities, Fair Value Disclosure Liabilities, Fair Value Disclosure Financial and Nonfinancial Liabilities, Fair Value Disclosure First Lien Notes 2019 [Member] First Lien Notes 2019 [Member] 2019 First Lien Notes Member First Lien Notes 2020 [Member] First Lien Notes 2020 [Member] 2020 First Lien Notes Member First Lien Notes 2021 [Member] First Lien Notes 2021 [Member] 2021 First Lien Notes Member First Lien Notes 2023 [Member] First Lien Notes 2023 [Member] 2023 First Lien Notes Member Corporate Debt Securities [Member] Corporate Debt Securities [Member] Income (Loss) From Unconsolidated Investments in Power Plants Income (Loss) From Unconsolidated Investments in Power Plants and Distributions [Table Text Block] Income (Loss) From Unconsolidated Investments in Power Plants and Distributions. Schedule of Equity Method Investments Equity Method Investments [Table Text Block] Income Tax Disclosure [Abstract] Schedule of Components of Income Tax Expense (Benefit) Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Basis of Presentation and Summary of Significant Accounting Principles [Abstract] Basis of Presentation and Summary of Significant Accounting Principles [Abstract] Schedule of Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Buildings, machinery and equipment Buildings, Machinery and Equipment, Gross Buildings, machinery and equipment, gross Geothermal properties Geothermal Properties, Gross Geothermal Properties, Gross Other Property, Plant and Equipment, Other, Gross Property, Plant and Equipment, Gross Property, Plant and Equipment, Gross Less: Accumulated depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Property, Plant and Equipment, Gross, Less Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Property, Plant and Equipment, Gross, Less Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Property, Plant and Equipment, Gross, Less Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Land Land Construction in progress Construction in Progress, Gross Property, plant and equipment, net Income Tax Contingency [Table] Income Tax Contingency [Table] Income Tax Authority [Axis] Income Tax Authority [Axis] Income Tax Authority [Domain] Income Tax Authority [Domain] Income Tax Contingency [Line Items] Income Tax Contingency [Line Items] Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Estimated Range of Change, Upper Bound Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Estimated Range of Change, Upper Bound Income tax (expense) benefit Income Tax Expense (Benefit) Effective Income Tax Rate, Continuing Operations Effective Income Tax Rate Reconciliation, Percent Unrecognized Tax Benefits Unrecognized Tax Benefits Unrecognized Tax Benefits that Would Impact Effective Tax Rate Unrecognized Tax Benefits that Would Impact Effective Tax Rate Unrecognized Tax Benefits Resulting in Net Operating Loss Carryforward Unrecognized Tax Benefits Resulting in Net Operating Loss Carryforward Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Estimated Range of Change, Lower Bound Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Estimated Range of Change, Lower Bound Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Disposal Group Name [Axis] Power Plant [Axis] Power Plant [Axis] Power Plant [Domain] Power Plant [Domain] [Domain] for Power Plant [Axis] Oneta Energy Center [Member] Oneta Energy Center [Member] Oneta Energy Center [Member] Carville Energy Center [Member] Carville Energy Center [Member] Carville Energy Center [Member] Decatur Energy Center [Member] Decatur Energy Center [Member] Decatur Energy Center [Member] Hog Bayou Energy Center [Member] Hog Bayou Energy Center [Member] Hog Bayou Energy Center [Member] Santa Rosa Energy Center [Member] Santa Rosa Energy Center [Member] Santa Rosa Energy Center [Member] Columbia Energy Center [Member] Columbia Energy Center [Member] Columbia Energy Center [Member] Six Power Plants [Member] Six Power Plants [Member] Six Power Plants [Member] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Guadalupe Energy Center [Member] Guadalupe Energy Center [Member] Guadalupe Energy Center [Member] Guadalupe Expansion Capacity [Member] Guadalupe Expansion Capacity [Member] Guadalupe Expansion Capacity [Member] Business Acquisition [Line Items] Business Acquisition [Line Items] Other Assets Held-for-sale, Current Other Assets Held-for-sale, Current Current assets held for sale Number of power plants to be disposed of Number of power plants to be disposed of Number of power plants to be disposed of Ownership percentage before divestiture of business Ownership percentage before divestiture of business Ownership percentage before divestiture of business Proceeds from Sale of Productive Assets Proceeds from Sale of Productive Assets Working Capital Adjustment to Sale price Working Capital Adjustment to Sale price Working Capital Adjustment to Sale price Business Combination, Contingent Consideration, Liability Business Combination, Contingent Consideration, Liability Power generation capacity Power generation capacity Power generation capacity Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net Number of 525 MW generation blocks to be acquired in the Guadalupe acquisition Number of 525 MW generation blocks to be acquired in the Guadalupe acquisition Number of 525 MW generation blocks to be acquired in the Guadalupe acquisition Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property Assets Held-for-sale, Property, Plant and Equipment Assets Held-for-sale, Property, Plant and Equipment Assets Held-for-sale, Other, Noncurrent Assets Held-for-sale, Other, Noncurrent Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Measurement Basis [Axis] Measurement Basis [Axis] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Portion at Fair Value Measurement [Member] Portion at Fair Value Measurement [Member] Reported Value Measurement [Member] Reported Value Measurement [Member] Loans Payable [Member] Secured Debt [Member] Secured Debt [Member] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Notes Payable, Fair Value Disclosure Notes Payable, Fair Value Disclosure Loans Payable, Fair Value Disclosure Loans Payable, Fair Value Disclosure Notes Payable, Other Payables, Disclosure Notes Payable, Other Payables, Disclosure Notes Payable, Other Payables, Disclosure Subsidiaries Term Loan Subsidiaries Term Loan Subsidiaries Term Loan Debt Excluding Capital Leases Debt Excluding Capital Leases Debt Excluding Capital Leases Natural gas and power prepayments Natural gas and power prepayments Natural gas and power prepayments Total margin deposits and natural gas and power prepayments with our counterparties Derivative Collateral Right To Reclaim Cash And Natural Gas And Power Prepayments Total Derivative Collateral Right To Reclaim Cash And Natural Gas And Power Prepayments Total Letters of credit issued Letters of credit issued Letters of credit issued First priority liens under power and natural gas agreements First priority liens under power and natural gas agreements First priority liens under power and natural gas agreements First priority liens under interest rate swap agreements First priority liens under interest rate swap agreements First priority liens under interest rate swap agreements Total letters of credit and first priority liens with our counterparties Letters of Credit Issued and First Priority Liens Under Power Natural Gas And Interest Rate Swap Agreements Letters of Credit Issued and First Priority Liens Under Power Natural Gas And Interest Rate Swap Agreements Letters of credit posted with us by our counterparties Letters Of Credit Posted By Counterparties Letters Of Credit Posted By Counterparties Total margin deposits and letters of credit posted with us by our counterparties Derivative Collateral Obligation To Return Cash And Letters Of Credit Posted By Counterparties Derivative Collateral Obligation To Return Cash And Letters Of Credit Posted By Counterparties Use of Collateral (Textuals) [Abstract] Use of Collateral Textuals Abstract Margin And Prepayment Amounts Included In Other Assets Margin And Prepayment Amounts Included In Other Assets Margin And Prepayment Amounts Included In Other Assets Margin And Prepayment Amounts Included In Margin Deposits And Other Prepaid Expenses Margin And Prepayment Amounts Included In Margin Deposits And Other Prepaid Expenses Margin And Prepayment Amounts Included In Margin Deposits And Other Prepaid Expenses Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Balance, beginning of period Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value Included in net income: Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings [Abstract] Included in operating revenues Fair Value, Assets Measured with Unobservable Inputs on Recurring Basis, Gain (Loss) Included in Operating Revenue Fair Value, Assets Measured with Unobservable Inputs on Recurring Basis, Gain (Loss) Included in Operating Revenue Fair Value, Assets Measured with Unobservable Inputs on Recurring Basis, Gain (Loss) Included In Fuel And Purchased Energy Expense Fair Value, Assets Measured with Unobservable Inputs on Recurring Basis, Gain (Loss) Included In Fuel And Purchased Energy Expense Fair Value, Assets Measured with Unobservable Inputs on Recurring Basis, Gain (Loss) Included In Fuel And Purchased Energy Expense Purchases, issuances and settlements: Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases, (Sales), Issuances, (Settlements) [Abstract] Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Issuances Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Issuances Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements Fair Value, Liabilities, Level 2 to Level 1 Transfers, Amount Fair Value, Liabilities, Level 2 to Level 1 Transfers, Amount Fair Value, Liabilities, Level 1 to Level 2 Transfers, Amount Fair Value, Liabilities, Level 1 to Level 2 Transfers, Amount Transfers into level 3 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 Transfers out of Level 3 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 Balance, end of period Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Assets and Liabilities with Recurring Fair Value Measurements (Textuals) [Abstract] Assets and Liabilities with Recurring Fair Value Measurements Textuals Abstract Cash Equivalents Included In Cash And Cash Equivalents, Fair Value Disclosure Cash Equivalents Included In Cash And Cash Equivalents, Fair Value Disclosure Cash Equivalents Included In Restricted Cash, Fair Value Disclosure Cash Equivalents Included In Restricted Cash, Fair Value Disclosure Cash Equivalents Included In Restricted Cash, Fair Value Disclosure Income Taxes Income Tax Disclosure [Text Block] Document and Entity Information [Abstract] Document and Entity Information [Abstract] Entities [Table] Entities [Table] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Entity Information [Line Items] Entity Information [Line Items] Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Document Type Document Type Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Amendment Flag Amendment Flag Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Segment Information Segment Reporting Disclosure [Text Block] Assets and Liabilities with Recurring Fair Value Measurements Fair Value Disclosures [Text Block] Schedule of Derivatives Instruments Statements of Financial Performance and Financial Position, Location [Table Text Block] Schedule of Derivatives Instruments Statements of Financial Performance and Financial Position, Location [Table Text Block] Schedule of Notional Amounts of Outstanding Derivative Positions Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block] Schedule of Derivative Instruments in Statement of Financial Position, Fair Value Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Derivative Instruments Subject to Master Netting Arrangements [Table Text Block] Offsetting Assets [Table Text Block] Realized Unrealized Gain Loss by Instrument Realized Unrealized Gain Loss by Instrument [Table Text Block] Realized Unrealized Gain Loss by Instrument Table Text Block Schedule of Other Derivatives Not Designated as Hedging Instruments, Statements of Financial Performance and Financial Position, Location Schedule of Other Derivatives Not Designated as Hedging Instruments, Statements of Financial Performance and Financial Position, Location [Table Text Block] Derivatives Designated as Hedges Derivative Instruments, Gain (Loss) [Table Text Block] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] Award Type [Axis] Award Type [Axis] Award Type [Domain] Equity Award [Domain] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Options, Outstanding Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Options, Outstanding, Weighted Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Options, Outstanding, Weighted Average Remaining Contractual Term Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term Options, Outstanding, Intrinsic Value Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value Options, Grants in Period, Gross Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross Options, Grants in Period, Weighted Average Exercise Price Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Options, Exercises in Period Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Options, Exercises in Period, Weighted Average Exercise Price Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Options, Forfeitures in Period Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period Options, Forfeitures in Period, Weighted Average Exercise Price Share-based Compensation Arrangements by Share-based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price Options, Expirations in Period Share-based Compensation Arrangement by Share-based Payment Award, Options, Expirations in Period Options, Expirations in Period, Weighted Average Exercise Price Share-based Compensation Arrangements by Share-based Payment Award, Options, Expirations in Period, Weighted Average Exercise Price Options, Exercisable Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number Options, Exercisable, Weighted Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price Options, Exercisable, Weighted Average Remaining Contractual Term Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term Options, Exercisable, Intrinsic Value Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value Options, Vested and Expected to Vest, Outstanding Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value Schedule of Components of Restricted Cash Schedule of Restricted Cash and Cash Equivalents [Table Text Block] Schedule of Property, Plant and Equipment Property, Plant and Equipment [Table Text Block] Statement of Cash Flows [Abstract] Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Net income (loss) Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization expense(1) Depreciation, Depletion and Amortization Debt extinguishment costs Non Cash Gains Losses On Extinguishment Of Debt Non Cash Gains Losses On Extinguishment Of Debt Deferred income taxes Increase (Decrease) in Deferred Income Taxes Mark-to-market activity, net (Income) from unconsolidated investments in power plants Return on unconsolidated investments in power plants Proceeds from Equity Method Investment, Dividends or Distributions Stock-based compensation expense Share-based Compensation Other Other Noncash Income (Expense) Change in operating assets and liabilities: Increase (Decrease) in Operating Assets [Abstract] Accounts receivable Increase (Decrease) in Accounts Receivable Derivative instruments, net Increase (Decrease) in Derivative Assets and Liabilities Other assets Increase (Decrease) in Other Operating Assets Accounts payable and accrued expenses Increase (Decrease) in Accounts Payable and Accrued Liabilities Other liabilities Increase (Decrease) in Other Accounts Payable Net cash provided by (used in) operating activities Net Cash Provided by (Used in) Operating Activities Cash flows from investing activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Purchases of property, plant and equipment Payments to Acquire Property, Plant, and Equipment Purchase of Guadalupe Energy Center, net of cash Payments to Acquire Businesses, Net of Cash Acquired Decrease in restricted cash Increase (Decrease) in Restricted Cash Other Payments for (Proceeds from) Other Investing Activities Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Cash flows from financing activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Borrowings under CCFC Term Loans Borrowings from CCFC Term Loans Borrowings from CCFC Term Loans Repayment of CCFC Term Loans, CCFC Notes and First Lien Term Loans Repayments of Debt Borrowings from project financing, notes payable and other Proceeds from Issuance of Long-term Debt Repayments of project financing, notes payable and other Repayments of Long-term Debt Financing costs Payments of Financing Costs Stock repurchases Payments for Repurchase of Common Stock Proceeds from exercises of stock options Proceeds from Stock Options Exercised Other Proceeds from (Payments for) Other Financing Activities Net cash provided by (used in) financing activities Net Cash Provided by (Used in) Financing Activities Net decrease in cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents, beginning of period Cash and cash equivalents, end of period Cash paid during the period for: Cash paid during the period for Title for required cash payments as presented on the Statement of Cash Flows Interest, net of amounts capitalized Interest Paid, Net Income taxes Income Taxes Paid Supplemental disclosure of non-cash investing activities: Noncash Investing and Financing Items [Abstract] Change in capital expenditures included in accounts payable Capital Expenditures Incurred but Not yet Paid New Accounting Pronouncements, Policy [Policy Text Block] New Accounting Pronouncements, Policy [Policy Text Block] Basis of Interim Presentation Basis of Accounting, Policy [Policy Text Block] Use of Estimates in Preparation of Financial Statements Use of Estimates, Policy [Policy Text Block] Reclassifications Reclassification, Policy [Policy Text Block] Cash and Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Restricted Cash Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block] Derivatives Derivatives, Policy [Policy Text Block] Commitments and Contingencies Commitments and Contingencies, Policy [Policy Text Block] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Antidilutive Securities [Axis] Antidilutive Securities [Axis] Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Share-based awards Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Statement of Comprehensive Income [Abstract] Net income (loss) Cash flow hedging activities: Cash Flow Hedges Derivative Instruments at Fair Value, Net [Abstract] Gain (loss) on cash flow hedges before reclassification adjustment for cash flow hedges realized in net income (loss) Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax Reclassification adjustment for loss on cash flow hedges realized in net income (loss) Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax Foreign currency translation gain (loss) Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss), before Reclassification and Tax Income tax benefit Other Comprehensive Income (Loss), Tax Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax Comprehensive income (loss) Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Comprehensive (income) attributable to the noncontrolling interest Comprehensive (Income) Loss, Net of Tax, Attributable to Noncontrolling Interest Comprehensive income (loss) attributable to Calpine Comprehensive Income (Loss), Net of Tax, Attributable to Parent (Income) from unconsolidated investments in power plants Variable Interest Entities [Axis] Variable Interest Entities [Axis] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Primary Beneficiary [Member] Variable Interest Entity, Primary Beneficiary [Member] Allowance for Doubtful Accounts Receivable, Current Allowance for Doubtful Accounts Receivable, Current Preferred Stock, Par or Stated Value Per Share Preferred Stock, Par or Stated Value Per Share Preferred Stock, Shares Authorized Preferred Stock, Shares Authorized Preferred Stock, Shares Issued Preferred Stock, Shares Issued Preferred Stock, Shares Outstanding Preferred Stock, Shares Outstanding Common Stock, Par or Stated Value Per Share Common Stock, Par or Stated Value Per Share Common Stock, Shares Authorized Common Stock, Shares Authorized Common Stock, Shares, Issued Common Stock, Shares, Issued Common Stock, Shares, Outstanding Common Stock, Shares, Outstanding Treasury Stock, Shares Treasury Stock, Shares Fair Value, Measurement Inputs, Disclosure Fair Value, Assets Measured on Recurring Basis [Table Text Block] Fair Value Inputs, Assets, Quantitative Information Fair Value Inputs, Assets, Quantitative Information [Table Text Block] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Director Plan [Member] Director Plan [Member] Director Plan [Member] Equity Plan [Member] Equity Plan [Member] Equity Plan [Member] Stock Options [Member] Employee Stock Option [Member] Restricted Stock [Member] Restricted Stock [Member] Restricted Stock Units (RSUs) [Member] Restricted Stock Units (RSUs) [Member] Performance Shares [Member] Performance Shares [Member] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Vesting period for graded and cliff vesting options - minimum Vesting period for graded and cliff vesting options - minimum Vesting period for graded and cliff vesting options - minimum Vesting period for graded and cliff vesting options - maximum Vesting period for graded and cliff vesting options - maximum Vesting period for graded and cliff vesting options - maximum Share-based Compensation Arrangement by Share-based Payment Award, Award Expiration Minimum Range Share-based Compensation Arrangement by Share-based Payment Award, Award Expiration Minimum Range Share-based Compensation Arrangement by Share-based Payment Award, Award Expiration Minimum Range Share-based Compensation Arrangement by Share-based Payment Award, Award Expiration Maximum Range Share-based Compensation Arrangement by Share-based Payment Award, Award Expiration Maximum Range Share-based Compensation Arrangement by Share-based Payment Award, Expiration Maximum Range Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized Common Stock, Capital Shares Reserved for Future Issuance Common Stock, Capital Shares Reserved for Future Issuance Percentage of sub-grants representing the total Percentage of sub-grants representing the total Percentage of sub-grants representing the total grant Vest Term of First Sub Grant Vest Term of First Sub Grant Vesting Term of First Sub Grant Vest Term of the Second Sub-Grant Vest Term of the Second Sub-Grant Vesting Term of the Second Sub-Grant Vest Term of the Third Sub-Grant Vest Term of the Third Sub-Grant Vesting Term of the Third Sub-Grant Grants in Option Grants with Three Year Cliff Vesting Grants in Option Grants with Three Year Cliff Vesting Number of Grants in Option Grants with Three Year Cliff Vesting Vesting term of option grants with three year cliff vesting Vesting term of option grants with three year cliff vesting Vesting term of option grants with three year cliff vesting Allocated Share-based Compensation Expense Allocated Share-based Compensation Expense Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value Employee Service Share-based Compensation, Cash Received from Exercise of Stock Options Employee Service Share-based Compensation, Cash Received from Exercise of Stock Options Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value Allocated Share Based Compensation Expense Liability Classified Share-Based Awards Allocated Share Based Compensation Expense Liability Classified Share-Based Awards Allocated Share Based Compensation Expense Liability Classified Share-Based Awards Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Notes Payable, Other Payables [Member] Notes Payable, Other Payables [Member] Capital Lease Obligations [Member] Capital Lease Obligations [Member] Debt, Current Long-term Debt, Excluding Current Maturities Fair Value Inputs, Assets, Quantitative Information [Table] Fair Value Inputs, Assets, Quantitative Information [Table] Liability Class [Axis] Liability Class [Axis] Fair Value by Liability Class [Domain] Fair Value by Liability Class [Domain] Power Contracts [Member] Physical Power [Member] Physical Power [Member] Power Congestion Products [Member] Power Congestion Products [Member] Power Congestion Products [Member] Asset Class [Domain] Valuation Technique [Axis] Valuation Technique [Axis] Valuation Technique [Domain] Valuation Technique [Domain] Fair Value Hierarchy [Domain] Fair Value Inputs, Assets, Quantitative Information [Line Items] Fair Value Inputs, Assets, Quantitative Information [Line Items] Fair Value Inputs Quantitative Information Power Fair Value Inputs Quantitative Information Power Fair Value Inputs Quantitative Information Power Income Statement [Abstract] Operating revenues: Revenues [Abstract] Commodity revenue Sales Revenue from Energy Commodities and Services Mark to Market Gain (Loss) Mark to Market Gain Loss on Derivatives included in Operating Revenues Mark to Market Gain Loss on Derivatives included in Operating Revenues Other revenue Other Operating Income Operating expenses: Cost of Revenue [Abstract] Commodity expense Cost of Goods and Services, Energy Commodities and Services Mark to Market (Gain) Loss Mark to Market Gain Loss on Derivatives Included in Fuel and Purchased Energy Expense Mark to Market Gain Loss on Derivatives Included in Fuel and Purchased Energy Expense Fuel and purchased energy expense Cost of Revenue Total operating expenses Costs and Expenses Interest expense Interest Expense Interest (income) Investment Income, Interest Debt extinguishment costs Gains (Losses) on Extinguishment of Debt Other (income) expense, net Other Nonoperating Income (Expense) Income tax expense (benefit) Net income (loss) Net income attributable to the noncontrolling interest Net Income (Loss) Attributable to Noncontrolling Interest Net income (loss) attributable to Calpine Net Income (Loss) Attributable to Parent Basic earnings (loss) per common share attributable to Calpine: Earnings Per Share, Basic [Abstract] Weighted average shares of common stock outstanding (in thousands) Weighted Average Number of Shares Outstanding, Basic Net income (loss) per common share attributable to Calpine — basic Earnings Per Share, Basic Diluted earnings (loss) per common share attributable to Calpine: Earnings Per Share, Diluted [Abstract] Weighted average shares of common stock outstanding (in thousands) Weighted Average Number of Shares Outstanding, Diluted Net income (loss) per common share attributable to Calpine — diluted Earnings Per Share, Diluted Reconciliation of Basic to Diluted Weighted Average Shares [Abstract] Reconciliation of Basic to Diluted Weighted Average Shares [Abstract] Weighted Average Number Diluted Shares Outstanding Adjustment Weighted Average Number Diluted Shares Outstanding Adjustment Weighted average shares of common stock outstanding (in thousands) Organization, Consolidation and Presentation of Financial Statements [Abstract] Schedule of Variable Interest Entities [Table] Schedule of Variable Interest Entities [Table] Inland Empire Energy Center [Member] Inland Empire Energy Center [Member] Inland Empire Energy Center member Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] Variable Interest Entity, Financial or Other Support, Amount Variable Interest Entity, Financial or Other Support, Amount Equity Method Investment, Summarized Financial Information, Debt Equity Method Investment, Summarized Financial Information, Debt Equity Method Investment, Summarized Financial Information, Debt Prorata Share of Equity Method Investment, Summarized Financial Information, Debt Prorata Share of Equity Method Investment, Summarized Financial Information, Debt Prorata Share of Equity Method Investment, Summarized Financial Information, Debt Distribution from equity method investee Distribution from equity method investee Distribution from equity method investee Call Option Exercise Period Call Option Exercise Period Call Option Exercise Period Put Option Exercise Period Put Option Exercise Period Put Option Exercise Period Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Parent [Member] Parent [Member] Noncontrolling Interest [Member] Noncontrolling Interest [Member] Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Tax Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Tax Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax Derivative Instruments (Textuals) [Abstract] Derivative Instruments Textuals Abstract Maximum length of time hedging using interest rate derivative instruments Maximum Length of Time Hedged in Interest Rate Cash Flow Hedge Derivative, Net Liability Position, Aggregate Fair Value Derivative, Net Liability Position, Aggregate Fair Value Collateral Already Posted, Aggregate Fair Value Collateral Already Posted, Aggregate Fair Value Additional Collateral, Aggregate Fair Value Additional Collateral, Aggregate Fair Value (Gain) Loss on Discontinuation of Cash Flow Hedge Due to Forecasted Transaction Probable of Not Occurring, Net Gain (Loss) on Discontinuation of Cash Flow Hedge Due to Forecasted Transaction Probable of Not Occurring, Net Cash Flow Hedge (Gain) Loss to be Reclassified within Twelve Months Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months Interest Rate Derivative Liabilities, Fair Value on Settlement Date [Line Items] Interest Rate Derivative Liabilities, Fair Value on Settlement Date [Abstract] Interest Rate Derivative Liabilities, Fair Value on Settlement Date [Abstract] Early Tender Amount [Member] Early Tender Amount [Member] Early Tender Amount [Member] Interest Periods [Axis] Interest Periods Axis Interest Periods [Domain] Interest Periods Domain Line of Credit Facility, Increase (Decrease), Net Line of Credit Facility, Increase (Decrease), Net Debt Instrument, Interest Rate, Effective Percentage Debt Instrument, Interest Rate, Effective Percentage Line of Credit Facility, Maximum Borrowing Capacity Line of Credit Facility, Maximum Borrowing Capacity Shareholder Transaction Shareholder Transaction Disclosure [Text Block] Shareholder Transaction Disclosure [Text Block] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Scenario, Forecast [Member] Scenario, Forecast [Member] 2019, 2020 and 2021 First Lien Notes [Member] 2019, 2020 and 2021 First Lien Notes [Member] 2019, 2020 and 2021 First Lien Notes [Member] Senior Unsecured Notes 2025 [Member] Senior Unsecured Notes 2025 [Member] Senior Unsecured Notes 2025 [Member] Senior Unsecured Notes 2023 [Member] Senior Unsecured Notes 2023 [Member] Senior Unsecured Notes 2023 [Member] Debt Instrument, Interest Rate, Stated Percentage Debt Instrument, Interest Rate, Stated Percentage Deferred Finance Costs, Net Deferred Finance Costs, Net Debt Extinguishment costs Stock-Based Compensation Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Award Date [Axis] Award Date [Axis] Award Date [Domain] Award Date [Domain] Equity Award [Domain] Vesting [Axis] Vesting [Axis] Vesting [Domain] Vesting [Domain]