Receivables [Abstract] Schedule of Financing Receivable, Allowance for Credit Losses [Table] Schedule of Financing Receivable, Allowance for Credit Losses [Table] Financing Receivable Information by Portfolio Segment [Axis] Class of Financing Receivable [Axis] Financing Receivable Allowance [Domain] Class of Financing Receivable [Domain] Federally insured loans [Member] Federally insured student loans [Member] Federally insured student loans [Member] Non-federally insured loans [Member] Non-federally insured student loans [Member] Non-federally insured student loans [Member] Financing Receivable, Allowance for Credit Losses [Line Items] Financing Receivable, Allowance for Credit Losses [Line Items] Financing Receivable, Allowance for Credit Losses [Roll Forward] Financing Receivable, Allowance for Credit Losses [Roll Forward] Allowance for loan losses - balance Financing Receivable, Allowance for Credit Losses Provision for loan losses Provision for Loan, Lease, and Other Losses Charge-offs Financing Receivable, Allowance for Credit Losses, Write-downs Recoveries - non-federally insured loans Financing Receivable, Allowance for Credit Losses, Recovery Purchase (sale) of federally insured loans and other, net Purchase or Sale of Financing Receivables Purchase/Sale of Financing Receivables Transfer from repurchase obligation related to non-federally insured loans purchased, net Transfer from the Repurchase Obligation Related to Loans Sold or Purchased and other, net Transfer from the Repurchase Obligation Related to Loans Sold or Purchased and other, net Allowance for loan losses - balance Related Party Transactions [Abstract] Related Party Transactions Related Party Transactions Disclosure [Text Block] Organization, Consolidation and Presentation of Financial Statements [Abstract] Basis of Financial Reporting Basis of Accounting [Text Block] Derivative Financial Instruments [Abstract] Derivative Financial Instruments [Abstract] Derivative Instruments, Gain (Loss) by Hedging Relationship, by Income Statement Location, by Derivative Instrument Risk [Table] Derivative Instruments, Gain (Loss) [Table] Derivative Instruments, Gain (Loss) by Income Statement Location [Axis] Income Statement Location [Axis] Income Statement and Other Comprehensive Income (Loss) Location [Domain] Income Statement Location [Domain] 1:3 basis swaps [Member] One Month to Three Month LIBOR Basis Swap [Member] One Month to Three Month LIBOR Basis Swap [Member] Interest rate swaps - floor income hedges [Member] Fixed Rate Floor Income Interest Rate Swap [Member] Fixed Rate Floor Income Interest Rate Swap [Member] Interest rate swaps - hybrid debt hedges [Member] Hybrid Debt interest Rate Swap [Member] Hybrid Debt interest Rate Swap [Member] Cross-currency interest rate swaps [Member] Currency Swap [Member] Other [Member] Other Contract [Member] Derivative Instruments, Gain (Loss) [Line Items] Derivative Instruments, Gain (Loss) [Line Items] Derivative settlements, net derivative settlements derivative settlements Change in fair value Derivative, Gain (Loss) on Derivative, Net Re-measurement of Euro Notes (foreign currency transaction adjustment) - income (expense) Foreign Currency Transaction Gain (Loss), before Tax Derivative market value and foreign currency adjustments and derivative settlements - income (expense) Gain (Loss) on Derivative Instruments, Net, Pretax Debt Disclosure [Abstract] Bonds and Notes Payable Debt Disclosure [Text Block] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Discount Axis [Axis] Discount Axis [Axis] Discount Axis [Axis] Discount Axis [Domain] Discount Axis [Domain] [Domain] for Discount Axis [Axis] Non-accretable discount [Member] Non-Accretable Discount [Member] Non-Accretable Discount [Member] Investment Type [Axis] Investment Type [Axis] Investment Type Categorization [Domain] Investments [Domain] held for investment [Member] held for investment [Member] held for investment [Member] Federally Insured Student Loans [Axis] Federally Insured Student Loans [Axis] Federally Insured Student Loans [Axis] Federally Insured Student Loans [Domain] Federally Insured Student Loans [Domain] [Domain] for Federally Insured Student Loans [Axis] Stafford and Other [Member] Stafford and Other [Member] Stafford and Other [Member] Consolidation Loans [Member] Consolidation Loans [Member] Consolidation Loans [Member] Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Student loans receivable, gross Financing Receivable, Gross Loan discount, net of unamortized loan premiums and deferred origination costs Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums, Other Allowance for loan losses Student loans receivable Financing Receivable, Net Goodwill and Intangible Assets Disclosure [Abstract] Goodwill Disclosure [Text Block] Goodwill Disclosure [Text Block] Bonds and Notes Payable [Abstract] Bonds and Notes Payable [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] Class A [Member] Class A [Member] Class A [Member] Class B [Member] Class B [Member] Class B [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] 2014-1 Securitization [Member] 2014-1 Securitization [Member] 2014-1 Securitization [Member] 2014-2 Securitization [Member] 2014-2 Securitization [Member] 2014-2 Securitization [Member] 2014-3 Securitization [Member] 2014-3 Securitization [Member] 2014-3 Securitization [Member] 2014-4 Securitization [Member] [Domain] 2014-4 Securitization [Member] [Domain] 2014-4 Securitization [Member] [Domain] 2014-5 Securitization [Member] [Domain] 2014-5 Securitization [Member] [Domain] 2014-5 Securitization [Member] 2014-2 Securitization [Axis] 2014-2 Securitization [Axis] 2014-2 Securitization [Axis] 2014-2 Securitization [Domain] 2014-2 Securitization [Domain] [Domain] for 2014-2 Securitization [Axis] 2014-2 Securitization Class A-1 [Member] 2014-2 Securitization Class A-1 [Member] 2014-2 Securitization Class A-1 [Member] 2014-2 Securitization Class A-2 [Member] 2014-2 Securitization Class A-2 [Member] 2014-2 Securitization Class A-2 [Member] 2014-2 Securitization Class A-3 [Member] 2014-2 Securitization Class A-3 [Member] 2014-2 Securitization Class A-3 [Member] 2014-4 Securitization [Axis] 2014-4 Securitization [Axis] 2014-4 Securitization [Axis] 2014-4 Securitization [Domain] 2014-4 Securitization [Domain] [Domain] for 2014-4 Securitization [Axis] 2014-4 Securitization Class A-1 [Member] 2014-4 Securitization Class A-1 [Member] 2014-4 Securitization Class A-1 2014-4 Securitization Class A-2 [Member] 2014-4 Securitization Class A-2 [Member] 2014-4 Securitization Class A-2 [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Debt Instrument, Variable Rate Basis Debt Instrument, Interest Rate Terms Debt Instrument, Basis Spread on Variable Rate Basis Debt Instrument, Basis Spread on Variable Rate Asset-backed securitization issuance, Unamortized Discount Debt Instrument, Unamortized Discount Asset-backed securitization, issuance date Debt Instrument, Issuance Date Asset-backed securitization issuance, Face Amount Debt Instrument, Face Amount Long-term Debt, Fair Value Long-term Debt, Fair Value Debt Instrument, Maturity Date Range, End Debt Instrument, Maturity Date Range, End Earnings Per Share [Abstract] Earnings Per Common Share Earnings Per Share [Text Block] Statement of Financial Position [Abstract] Statement [Table] Statement [Table] 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] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Common Class A [Member] Common Class A [Member] Common Class B [Member] Common Class B [Member] Statement [Line Items] Statement [Line Items] Assets: Assets [Abstract] Student loans receivable (net of allowance for loan losses) Cash and cash equivalents: Cash and Cash Equivalents [Abstract] Cash and cash equivalents - not held at a related party Cash and cash equivalents not held at related party Cash and cash equivalents - not held at a related party Cash and cash equivalents - held at a related party Cash and cash equivalents related party Cash and cash equivalents - held at a related party. Total cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Investments Investments Restricted cash and investments Restricted Cash and Investments Restricted cash - due to customers Restricted cash - due to customers Restricted cash - due to customers Accrued interest receivable Interest Receivable Accounts receivable (net of allowance for doubtful accounts) Accounts Receivable, Net Goodwill Goodwill Intangible assets, net Intangible Assets, Net (Excluding Goodwill) Property and equipment, net Property, Plant and Equipment, Net Other assets Other Assets Fair value of derivative instruments Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value Total assets Assets Liabilities: Liabilities [Abstract] Bonds and notes payable Debt and Capital Lease Obligations Accrued interest payable Interest Payable Other liabilities Other Liabilities Due to customers Payables to Customers Fair value of derivative instruments Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value Total liabilities Liabilities Equity: Equity [Abstract] Nelnet, Inc. shareholders' equity: Stockholders' Equity Attributable to Parent [Abstract] Preferred stock Preferred Stock, Value, Issued Common stock: Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract] Common stock Common Stock, Value, Issued Additional paid-in capital Additional Paid in Capital Retained earnings Retained Earnings (Accumulated Deficit) Accumulated other comprehensive earnings Accumulated Other Comprehensive Income (Loss), Net of Tax Total Nelnet, Inc. shareholders' equity Stockholders' Equity Attributable to Parent Noncontrolling interest Stockholders' Equity Attributable to Noncontrolling Interest Total equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Commitments and contingencies Liabilities and Equity [Abstract] Total liabilities and equity Liabilities and Equity Net assets of consolidated variable interest entities Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net Subsequent Event [Abstract] Subsequent Event [Abstract] Subsequent Event [Table] Subsequent Event [Table] Lender Name [Axis] Lender Name [Axis] Line of Credit Facility, Lender [Domain] Line of Credit Facility, Lender [Domain] FFELP Warehouse Total [Member] FFELP Warehouse Total [Member] FFELP Warehouse Total [Member] 2014 Securitization [Member] 2014 Securitization [Member] 2014 Securitization [Member] Receivable Type [Axis] Receivable Type [Axis] Receivable Type [Domain] Receivable [Domain] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Extraordinary Item [Axis] Extraordinary Item [Axis] Extraordinary Item [Domain] Extraordinary Item [Domain] Subsequent Event [Line Items] Subsequent Event [Line Items] Debt and Capital Lease Obligations Long-term Debt, Fair Value Line of Credit Facility, Amount Outstanding Line of Credit Facility, Amount Outstanding Line of Credit Facility, Remaining Borrowing Capacity Line of Credit Facility, Remaining Borrowing Capacity Investments, Debt and Equity Securities [Abstract] Schedule of Gain (Loss) on Investments [Table] Schedule of Gain (Loss) on Investments [Table] Investments by Category [Axis] Investments by Category [Axis] Gain (Loss) on Investments, Including Marketable Securities and Investments Held at Cost, Categories of Investments [Domain] Marketable Securities and Investments Held at Cost [Domain] Available-for-sale Securities [Member] Available-for-sale Securities [Member] Gain (Loss) on Investments [Line Items] Gain (Loss) on Investments [Line Items] Other income Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax Income tax expense Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax Net Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax Income Statement [Abstract] Statement, Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Interest income: Interest income: [Abstract] Loan interest Loan interest Student loan interest. Investment interest Investment Income, Interest Total interest income Interest and Dividend Income, Operating Interest expense: Interest Expense [Abstract] Interest on bonds and notes payable Interest Expense Net interest income Interest Income (Expense), Net Less provision for loan losses Net interest income after provision for loan losses Interest Income (Expense), after Provision for Loan Loss Other income (expense): Other Income and Expenses [Abstract] Loan and guaranty servicing revenue Bank Servicing Fees Tuition payment processing and campus commerce revenue Tuition payment processing and campus commerce revenue Tuition payment processing and campus commerce revenue. Enrollment services revenue Enrollment services revenue Enrollment services revenue Other income Other Income Gain on sale of loans and debt repurchases Gain on sale of loans and debt repurchases net Gains on sale of student loans and debt repurchases, net. Derivative market value and foreign currency adjustments and derivative settlements, net Derivative Market Value And Foreign Currency Adjustments And Derivative Settlements Net Derivative market value and foreign currency adjustments and derivative settlements, net. Total other income (expense) Noninterest Income Operating expenses: Operating Expenses [Abstract] Salaries and benefits Labor and Related Expense Cost to provide enrollment services Cost to provide enrollment services Costs to provide enrollment services. Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Other Other Expenses Total operating expenses Operating Expenses Income before income taxes Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest Income tax expense Income Tax Expense (Benefit) Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net income attributable to noncontrolling interest Net Income (Loss) Attributable to Noncontrolling Interest Net income attributable to Nelnet, Inc. Net Income (Loss) Attributable to Parent Earnings per common share: Net income attributable to Nelnet, Inc. shareholders - basic and diluted Earnings Per Share, Basic and Diluted Weighted average common shares outstanding - basic and diluted Weighted Average Number of Shares Outstanding, Basic and Diluted Segment Reporting [Abstract] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Business Segments [Axis] Segments [Axis] Segment [Domain] Segments [Domain] Student Loan and Guaranty Servicing [Member] Student Loan and Guaranty Servicing [Member] Student Loan and Guaranty Servicing [Member] Tuition Payment Processing and Campus Commerce [Member] Tuition Payment Processing and Campus Commerce [Member] Tuition Payment Processing and Campus Commerce [Member] Enrollment Services [Member] Enrollment Services [Member] Enrollment Services [Member] Total Fee-Based [Member] Total Fee Based [Member] Total Fee Based [Member] Asset Generation and Management [Member] Asset Generation and Management [Member] Asset Generation and Management [Member] Corporate and Other [Member] Corporate and Other [Member] Intersegment Eliminations [Member] Intersegment Eliminations [Member] Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Total interest income Interest expense Net interest income Less provision for loan losses Net interest income after provision for loan losses Other income (expense): Other income (expense): [Abstract] Intersegment servicing revenue Revenues Derivative market value and foreign currency adjustments, net Derivative Market Value and Foreign Currency Adjustment Derivative Market Value and Foreign Currency Adjustment Total other income (expense) Intersegment expenses, net intersegment expenses intersegment expenses Total operating expenses Income (loss) before income taxes and corporate overhead allocation Income (loss) before income taxes and corporate overhead allocation Income (loss) before income taxes and corporate overhead allocation Corporate overhead allocation Corporate Overhead Allocation Corporate Overhead Allocation Income (loss) before income taxes Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest Income tax (expense) benefit Net income (loss) Net income (loss) attributable to Nelnet, Inc. Line of Credit Facility [Table] Line of Credit Facility [Table] amendment to maturity date of liquidity provisions [Member] amendment to expiration date of liquidity provisions [Member] amendment to expiration date [Member] amendment to maturity date [Member] amendment to maturity date [Member] amendment to maturity date [Member] Date of line of credit amendment [Axis] Date of line of credit amendment [Axis] Date of line of credit amendment [Axis] Date of line of credit amendment [Domain] Date of line of credit amendment [Domain] [Domain] for Date of line of credit amendment [Axis] Line of Credit Facility [Axis] NHELP-II Warehouse [Member] NHELP-II Warehouse [Member] NHELP-II Warehouse [Member] NFSLW-I Warehouse [Member] NFSLW-I Warehouse [Member] NFSLW-I Warehouse [Member] NHELP-III Warehouse [Member] NHELP-III Warehouse [Member] NHELP-III Warehouse [Member] FFELP Warehouse Total [Member] Warehouse Agreement Borrowings [Member] Line of Credit [Member] Line of Credit [Member] Line of Credit Facility [Line Items] Line of Credit Facility [Line Items] Maximum financing amount Line of Credit Facility, Maximum Borrowing Capacity Amount outstanding Amount available Expiration of liquidity provisions expiration of liquidity provisions expiration of liquidity provisions Line of credit facility, termination date Line of credit facility, termination date Line of credit facility, termination date Maximum Advance Rates - range minimum Maximum Advance Rates - range minimum Maximum Advance Rates - range minimum Maximum advance rates - range maximum Maximum Advance Rates - range maximum Maximum Advance Rates - range maximum Minimum Advance Rates - range minimum Minimum Advance Rates - range minimum Minimum Advance Rates - range minimum Minimum advance rates - range maximum Minimum Advance Rates - range maximum Minimum Advance Rates - range maximum Advanced as equity support FFELP warehouse facility equity support FFELP warehouse facility equity support Line of Credit Facility, Increase (Decrease), Net Line of Credit Facility, Increase (Decrease), Net Business Combinations [Abstract] Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill Goodwill, Acquired During Period Goodwill, Acquired During Period Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net Asset-backed Securities [Member] Asset-backed Securities [Member] Extinguishment of Debt, Amount Extinguishment of Debt, Amount Gain from debt repurchases Gain (Loss) on Repurchase of Debt Instrument Schedule of Debt Schedule of Debt [Table Text Block] Schedule of Line of Credit Facilities Schedule of Line of Credit Facilities [Table Text Block] Schedule of asset-backed securitizations [Table Text Block] Schedule of asset-backed securitizations [Table Text Block] Schedule of asset-backed securitizations [Table Text Block] Fair Value Disclosures [Abstract] Fair Value Fair Value Disclosures [Text Block] Derivative, by Nature [Axis] Derivative, by Nature [Axis] Derivative, Name [Domain] Derivative, Name [Domain] Fixed Rate Floor Income Interest Rate Swap [Member] Student loan Asset Backed Securities Euro Notes [Axis] Student loan Asset Backed Securities Euro Notes [Axis] Student loan Asset Backed Securities Euro Notes [Axis] Student Loan Asset Backed Securities Euro Note [Domain] Student Loan Asset Backed Securities Euro Note [Domain] Student Loan Asset Backed Securities Euro Note [Domain] Currency Swap [Member] Cross-currency interest rate swap 1 [Member] Euro Note Interest Rate Swap 1 - Euro Value [Member] Euro Note Interest Rate Swap 1 - Euro Value [Member] Cross currency interest rate swap 2 [Member] Euro Note Interest Rate Swap 2 - Euro Value [Member] Euro Note Interest Rate Swap 2 - Euro Value [Member] Derivative, Average Fixed Interest Rate Derivative, Average Fixed Interest Rate Re-measurement of Euro Notes Change in fair value of cross currency interest rate swaps Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net Total impact to statements of income - income (expense) Derivative, Notional Amount Derivative, Notional Amount Derivative Instruments and Hedging Activities Disclosure [Abstract] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Derivative Instrument Risk [Axis] Derivative Instrument [Axis] Derivative Contract Type [Domain] Derivative Contract [Domain] Derivatives, Fair Value [Line Items] Derivatives, Fair Value [Line Items] Fair value of derivative instruments, asset Fair value of derivative instruments, liability Derivatives subject to enforceable master netting arrangement, asset Derivative Asset, Fair Value, Amount Offset Against Collateral Derivatives subject to enforceable master netting arrangement, liability Derivative Liability, Fair Value, Amount Offset Against Collateral Cash collateral received Derivative, Collateral, Obligation to Return Cash Cash collateral pledged Derivative, Collateral, Right to Reclaim Cash Fair value of derivative instruments, asset, net Derivative Assets Not Designated As Hedging Instruments, Net Derivative Assets Not Designated As Hedging Instruments, Net Fair value of derivative instruments, liability, net Derivative Liabilities Not Designated As Hedging Instruments, Net Derivative Liabilities Not Designated As Hedging Instruments, Net Pro forma financial information [Abstract] Pro forma financial information [Abstract] Finite-Lived Intangible Assets Acquired as Part of Business Combination [Table] Finite-Lived Intangible Assets Acquired as Part of Business Combination [Table] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Trade Names [Member] Trade Names [Member] Computer Software, Intangible Asset [Member] Computer Software, Intangible Asset [Member] Covenants not to compete [Member] Noncompete Agreements [Member] Customer Relationships [Member] Customer Relationships [Member] Acquired Finite-Lived Intangible Assets [Line Items] Acquired Finite-Lived Intangible Assets [Line Items] Business Acquisition, Percentage of Voting Interests Acquired Business Acquisition, Percentage of Voting Interests Acquired Business Acquisition, Goodwill, Expected Tax Deductible Amount Business Acquisition, Goodwill, Expected Tax Deductible Amount Acquired Finite-lived Intangible Assets, Weighted Average Useful Life Finite-lived Intangible Assets Acquired Business Combination, Consideration Transferred Business Combination, Consideration Transferred Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, Low Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, Low Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High Business Combination, Contingent Consideration, Liability Business Combination, Contingent Consideration, Liability Statement of Cash Flows [Abstract] Net income Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization, including debt discounts and student loan premiums and deferred origination costs Depreciation, Depletion and Amortization Student loan discount accretion Student loan discount accretion Student loan discount accretion Derivative market value adjustment Derivative market value adjustment Gain/Loss included in earnings for the period from the change in fair value of derivative instruments not designated as hedging instruments. Foreign currency transaction adjustment Foreign Currency Transaction Gain (Loss), Unrealized Payments to terminate and/or amend derivative instruments, net of proceeds Payments to terminate and/or amend derivative instruments Payments to terminate and/or amend derivative instruments (not designated as hedging). Gain on sale of loans Gain on Sale of Financing Receivables Gain on Sale of Financing Receivables Gain from debt repurchases Gain from sales of available-for-sale securities, net Available-for-sale Securities, Gross Realized Gain (Loss) Deferred income tax expense (benefit) Deferred Income Tax Expense (Benefit) Non-cash compensation expense Share-based Compensation Other Other Noncash Income (Expense) (Increase) decrease in accrued interest receivable Increase (Decrease) in Accrued Interest Receivable, Net Increase in accounts receivable Increase (Decrease) in Accounts Receivable (Increase) decrease in other assets Increase (Decrease) in Other Operating Assets Increase (decrease) in accrued interest payable Increase (Decrease) in Interest Payable, Net Decrease in other liabilities Increase (Decrease) in Other Operating Liabilities Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Cash flows from investing activities, net of acquisitions: Net Cash Provided by (Used in) Investing Activities [Abstract] Purchases of student loans and student loan residual interests Payments to Acquire Finance Receivables Purchases Of Student Loans From Related Party Purchases Of Student Loans From Related Party Purchases of student loans, including loan premiums, from a related party. Net proceeds from student loan repayments, claims, capitalized interest, participations, and other Proceeds from Collection of Finance Receivables Proceeds from sale of student loans Proceeds from Sale of Finance Receivables Purchases of available-for-sale securities Payments to Acquire Available-for-sale Securities Proceeds from sales of available-for-sale securities Proceeds from Sale of Available-for-sale Securities Purchases of other investments, net Payments for (Proceeds from) Other Investing Activities Repayments of notes and other receivables Proceeds from Collection of Other Receivables Purchases of property and equipment, net Payments to Acquire Property, Plant, and Equipment Decrease (increase) in restricted cash Increase (Decrease) in Restricted Cash and Investments Business acquisition, net of cash acquired Payments to Acquire Businesses, Net of Cash Acquired Net cash (used in) provided by investing activities Net Cash Provided by (Used in) Investing Activities Cash flows from financing activities, net of borrowings assumed: Net Cash Provided by (Used in) Financing Activities [Abstract] Payments on bonds and notes payable Repayments of Debt and Capital Lease Obligations Proceeds from issuance of bonds and notes payable Proceeds from Issuance of Debt Payments of debt issuance costs Payments of Debt Issuance Costs Dividends paid Payments of Dividends Repurchases of common stock Payments for Repurchase of Common Stock Proceeds from issuance of common stock Proceeds from Issuance of Common Stock Issuance of noncontrolling interest Proceeds from Noncontrolling Interests Distribution to noncontrolling interest Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Net cash (used in) provided by financing activities Net Cash Provided by (Used in) Financing Activities Net increase 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 Supplemental disclosures of cash flow information: Supplemental Cash Flow Information [Abstract] Interest paid Interest Paid Income taxes paid, net of refunds Income Taxes Paid, Net Noncash activity: Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Investing activity - student loans and other assets acquired Noncash or Part Noncash Acquisition, Value of Assets Acquired Financing activity - borrowings and other liabilities assumed in acquisition of student loans Noncash or Part Noncash Acquisition, Value of Liabilities Assumed Basis of Financial Reporting Basis of Financial Reporting [Policy Text Block] Basis of Financial Reporting [Policy Text Block] Business Acquisition, Pro Forma Revenue Business Acquisition, Pro Forma Revenue Business Acquisition, Pro Forma Net Income (Loss) Business Acquisition, Pro Forma Net Income (Loss) Business Acquisition, Pro Forma Earnings Per Share, Basic Business Acquisition, Pro Forma Earnings Per Share, Basic Risks and Uncertainties [Abstract] Concentration Risk Disclosure [Text Block] Concentration Risk Disclosure [Text Block] Concentration Risk [Table] Concentration Risk [Table] Concentration Risk Type [Axis] Concentration Risk Type [Axis] Concentration Risk Type [Domain] Concentration Risk Type [Domain] Concentration Risk Dollar Value [Member] Concentration Risk Dollar Value [Member] Concentration Risk Dollar Value [Member] Concentration Risk [Line Items] Concentration Risk [Line Items] Concentration Risk, Customer Concentration Risk, Customer Loan and guaranty servicing revenue Loan and guaranty servicing revenue Loan and guaranty servicing revenue. Subsequent Events [Abstract] Dividends [Axis] Dividends [Axis] Dividends [Domain] Dividends [Domain] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Litigation Status [Axis] Litigation Status [Axis] Litigation Status [Domain] Litigation Status [Domain] Litigation Case [Axis] Litigation Case [Axis] Litigation Case Type [Domain] Litigation Case [Domain] Disposal Group Name [Axis] Disposal Group Name [Axis] Disposal Groups, Including Discontinued Operations, Name [Domain] Disposal Groups, Including Discontinued Operations, Name [Domain] Proceeds to terminate and or amend derivative instruments Proceeds to terminate and or amend derivative instruments Proceeds to terminate and/or amend derivative instruments (not designated as hedging). Fair value of derivative instruments, liability Cash collateral received Payments to terminate and/or amend derivative instruments Commitments and Contingencies Disclosure [Abstract] Loss Contingencies [Table] Loss Contingencies [Table] Bais Yaakov of Spring Valley v. Peterson's Nelnet, LLC [Member] Bais Yaakov of Spring Valley v. Peterson's Nelnet, LLC [Member] Bais Yaakov of Spring Valley v. Peterson's Nelnet, LLC [Member] Than Zaw v. Nelnet, Inc. [Member] Than Zaw v. Nelnet, Inc. [Member] Than Zaw v. Nelnet, Inc. [Member] Grant Keating v. Peterson's Nelnet, LLC et al [Member] Grant Keating v. Peterson's Nelnet, LLC et al [Member] Grant Keating v. Peterson's Nelnet, LLC et al [Member] Loss Contingencies by party involved [Axis] Loss Contingencies by party involved [Axis] Loss Contingencies by party involved [Axis] Loss contingencies by party involved [Domain] Loss contingencies by party involved [Domain] Loss contingencies by party involved [Domain] Named plaintiff [Member] Named plaintiff [Member] Named plaintiff [Member] Class action members [Member] Class action members [Member] Class action members [Member] Loss Contingencies by Nature of Contingency [Axis] Loss Contingency Nature [Axis] Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] Pending or Threatened Litigation [Member] Pending Litigation [Member] Loss Contingencies [Line Items] Loss Contingencies [Line Items] Advertising faxes Advertising faxes Advertising faxes Loss Contingency, Damages Sought, Value, Per Violation Loss Contingency, Damages Sought, Value, Per Violation Loss Contingency, Damages Sought, Value, Per Violation Loss contingency, damages sought, value Loss Contingency, Damages Sought, Value Loss contingency, damages sought, value if trebled Loss Contingency, Damages Sought, Value if Trebled Loss Contingency, Damages Sought, Value if Trebled Loss contingency, actions taken by court, arbitrator or mediator Loss Contingency, Actions Taken by Court, Arbitrator or Mediator Loss contingency, inestimable loss Loss Contingency, Inestimable Loss Legal Proceedings Legal Matters and Contingencies [Text Block] Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Fair Value, by Balance Sheet Grouping Fair Value, by Balance Sheet Grouping [Table Text Block] Statement of Stockholders' Equity [Abstract] Dividends paid per common share Common Stock, Dividends, Per Share, Cash Paid Investments [Abstract] Investments Investment Holdings [Text Block] Fair Value, by Balance Sheet Grouping [Table Text Block] Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Related Party [Axis] Related Party [Axis] Related Party [Domain] Related Party [Domain] Union Bank and Trust Company [Member] Union Bank and Trust Company [Member] Union Bank and Trust Company [Member] Related Party Transaction [Line Items] Related Party Transaction [Line Items] Amount of Participation Amount of Participation Amount of Participation Contractual Obligation Contractual Obligation basis points earned on outstanding balance basis points earned on outstanding balance basis points earned on outstanding balance Financing Receivables [Text Block] Financing Receivables [Text Block] Consolidated Balance Sheets Parenthetical [Abstract] Consolidated Balance Sheets Parenthetical [Abstract] Allowance for doubtful accounts Allowance for Doubtful Accounts Receivable Preferred stock, par value (in dollars per share) Preferred Stock, Par or Stated Value Per Share Preferred stock, authorized shares Preferred Stock, Shares Authorized Preferred stock, issued shares Preferred Stock, Shares Issued Preferred stock, outstanding shares Preferred Stock, Shares Outstanding Par Value (in dollars per share) Common Stock, Par or Stated Value Per Share Shares Authorized Common Stock, Shares Authorized Shares Issued Common Stock, Shares, Issued Shares Outstanding Common Stock, Shares, Outstanding Repurchase Obligation [Table] Repurchase Obligation [Table] Repurchase Obligation [Table] repurchase obligaion [Axis] Repurchase Obligation [Axis] Repurchase Obligation [Axis] Repurchase Obligation [Domain] Repurchase Obligation [Domain] Repurchase Obligation [Domain] Cumulative non-federally insured loans participated subject to repurchase agreement [Member] Loans Participated [Member] Loans Participated [Member] Non-federally insured loans sold subject to repurchase agreement [Member] Non-Federally Insured Loans Sold Subject to Repurchase Agreement [Member] Non-Federally Insured Loans Sold Subject to Repurchase Agreement [Member] Repurchase Obligation [Line Items] Repurchase Obligation [Line Items] Repurchase Obligation [Line Items] Cumulative amount of participated non-federally insured student loans Cumulative Amount of Participate Non-Federally Insured Student Loans Cumulative Amount of Participate Non-Federally Insured Student Loans Days delinquent to trigger repurchase range, minimum Days Past Due to Trigger Repurchase - Range Minimum Days past due to trigger repurchase - range minimum Days delinquent to trigger repurchase range, maximum Days Past Due To Trigger Repurchase Range Maximum Days Past Due To Trigger Repurchase Range Maximum Proceeds from sale of non-federally insured student loans subject to repurchase agreements Proceeds from Sale of Non-Federally Insured Student Loans Subject to Repurchase Agreements Proceeds from Sale of Non-Federally Insured Student Loans Subject to Repurchase Agreements Percent of par value of non-federally insured student loans subject to repurchase agreements Percent of Par Value of Non-Federally Insured Loans Subject to Repurchase Agreements Percent of Par Value of Non-Federally Insured Loans Subject to Repurchase Agreements Days delinquent to trigger repurchase Days Past Due to Trigger Repurchase Days Past Due to Trigger Repurchase Change in Repurchase Obligation [Roll Forward] Change in Repurchase Obligation [Roll Forward] Change in Repurchase Obligation Beginning balance Repurchase Obligation Repurchase Obligation Transfer to the Allowance for Loan Losses Related to Loans Sold or Purchased and other, net Transfer to the Allowance for Loan Losses Related to Loans Sold or Purchased and other, net Transfer to/from the Repurchase Obligation Related to Loans Sold/Purchased and other, net Ending balance Business Combination [Abstract] Business Combination [Abstract] Business Combination Disclosure [Text Block] Business Combination Disclosure [Text Block] Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract] Amortization of Intangible Assets Amortization of Intangible Assets Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year Finite-Lived Intangible Assets, Amortization Expense, Year Two Finite-Lived Intangible Assets, Amortization Expense, Year Two Finite-Lived Intangible Assets, Amortization Expense, Year Three Finite-Lived Intangible Assets, Amortization Expense, Year Three Finite-Lived Intangible Assets, Amortization Expense, Year Four Finite-Lived Intangible Assets, Amortization Expense, Year Four Finite-Lived Intangible Assets, Amortization Expense, Year Five Finite-Lived Intangible Assets, Amortization Expense, Year Five Finite-Lived Intangible Assets, Amortization Expense, after Year Five Finite-Lived Intangible Assets, Amortization Expense, after Year Five Amortization of Intangible Assets Finite-Lived Intangible Assets, Net Investment Holdings [Table] Investment Holdings [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] Estimate of Fair Value Measurement [Member] Estimate of Fair Value Measurement [Member] Investment [Axis] Investment [Axis] Investment [Domain] Investment [Domain] Investments [Member] Investments [Member] Available-for-sale investments [Member] Trading investments [Member] Trading Securities [Member] Schedule of Available-for-sale Securities, Major Types of Debt and Equity Securities [Axis] Major Types of Debt and Equity Securities [Axis] Major Types of Debt and Equity Securities [Domain] Major Types of Debt and Equity Securities [Domain] Student Loan Asset-Backed and Other Debt Securities [Member] Debt Securities [Member] Equity securities [Member] Equity Securities [Member] Investment Holdings [Line Items] Investment Holdings [Line Items] Amortized cost Available-for-sale Securities, Amortized Cost Basis Gross unrealized gains Available-for-sale Securities, Gross Unrealized Gain Gross unrealized losses Available-for-sale Securities, Gross Unrealized Loss Available-for-sale Securities Available-for-sale Securities Investments, Fair Value Disclosure Investments, Fair Value Disclosure Restricted Investments Restricted Investments Guaranteed investment contracts - held-to-maturity Restricted Investments, at Fair Value Schedule of Debt and Capital Lease Obligations [Table] Schedule of Debt and Capital Lease Obligations [Table] [Table] Schedule of Debt and Capital Lease Obligations [Table] [Table] Variable-rate bonds and notes [Member] Variable-rate bonds and notes [Member] Variable-rate bonds and notes [Member] Bonds and notes based on indices [Member] Bonds and notes based on indicies [Member] Bonds and notes based on indicies [Member] Bonds and notes based on auction or remarketing [Member] Bonds and notes based on auction or remarketing [Member] Bonds and notes based on auction or remarketing [Member] FFELP warehouse facilities [Member] Junior Subordinated Debt [Member] Junior Subordinated Debt [Member] Other borrowings [Member] Notes Payable, Other Payables [Member] Bonds and notes payable, gross [Member] Debt [Member] Discount on bonds and notes payable [Member] Discount on bonds and notes payable [Member] Discount on bonds and notes payable [Member] Debt Instrument, Maturity Date Range, Start Debt Instrument, Maturity Date Range, Start Debt Instrument, Maturity Date Range, End Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum Schedule of Goodwill [Table Text Block] Schedule of Goodwill [Table Text Block] Schedule of Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Table] Schedule of Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Table] Antidilutive Securities [Axis] Antidilutive Securities [Axis] Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Common shareholders [Member] Common shareholders [Member] Common shareholders [Member] Unvested restricted stock shareholders [Member] Unvested restricted stock shareholders [Member] Unvested restricted stock shareholders [Member] Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items] Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items] Net income attributable to Nelnet, Inc. Earnings per share - basic and diluted Antidilutive securities excluded from computation of earnings per share Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Receivable [Domain] Purchase of residual interest [Member] Purchase of residual interest [Member] Purchase of residual interest [Member] Financing Receivable, Significant Purchases Financing Receivable, Significant Purchases Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums, Other Interest Rate Swaps - 1:3 Basis swaps Interest Rate Swaps - One month to Three Month LIBOR [Table Text Block] Interest Rate Swaps - 1 month to Three Month LIBOR [Table Text Block] Interest Rate Swaps - Floor Income Hedges Interest Rate Swaps - Floor Income Hedges [Table Text Block] Interest Rate Swaps - Floor Income Hedges [Table Text Block] Interest Rate Swaps - Unsecured Debt Hedges Interest Rate Swaps - Unsecured Debt Hedge [Table Text Block] Interest Rate Swaps - Unsecured Debt Hedge [Table Text Block] Impact of Foreign Exchange Contracts on the Statement of Income Impact of Foreign Exchange Contracts on the Statement of Income [Table Text Block] Impact of Foreign Exchange Contracts on the Statement of Income [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] Schedule of Derivative Instruments [Table Text Block] Schedule of Derivative Instruments [Table Text Block] Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance Derivative Instruments, Gain (Loss) [Table Text Block] Schedule of Segment Reporting Information, by Segment Schedule of Segment Reporting Information, by Segment [Table Text Block] Schedule of Financing Receivables Recorded Investment Credit Quality Indicator [Table] Schedule of Financing Receivable, Recorded Investment, Credit Quality Indicator [Table] Internal Credit Assessment [Axis] Internal Credit Assessment [Axis] Internal Credit Assessment [Domain] Internal Credit Assessment [Domain] Federally insured loans, excluding rehabiliation loans [Member] Federally insured loans, excluding rehabiliation loans [Member] Federally insured loans, excluding rehabiliation loans [Member] Financing Receivable, Recorded Investment, Past Due [Line Items] Financing Receivable, Recorded Investment, Past Due [Line Items] Loans Delinquent 31 Days or Greater in Percentage Loans Delinquent 31 Days or Greater in Percentage Loans Delinquent 31 Days or Greater in Percentage Loans in-school/grace/deferment Loans in School Grace and Deferment Loans in School Grace and Deferment Loans in forbearance Loans in Forbearance Loans in Forbearance Student loans receivable, gross Loans in repayment status: Loans in Repayment Status [Abstract] Loans in Repayment Status [Abstract] Loans current Financing Receivable, Recorded Investment, Current Loans current, percentage Loans in Repayment - Current, in Percentage Loans in Repayment, Current, in Percentage Loans delinquent 31-60 days Financing Receivable, Recorded Investment, 30 to 59 Days Past Due Loans delinquent 31-60 days, percentage Loans Delinquent 31 to 60 days in Percentage Loans Delinquent 31 to 60 days in Percentage Loans delinquent 61-90 days Financing Receivable, Recorded Investment, 60 to 89 Days Past Due Loans delinquent 61-90 days, percentage Loans Delinquent 61 to 90 Days in Percentage Loans Delinquent 61 to 90 Days in Percentage Loans delinquent 91-120 days Loans delinquent 91-120 days Loans delinquent 91-120 days Loans delinquent 91-120 days, percentage Loans delinquent 91-120 days, percentage Loans delinquent 91-120 days, percentage Loans delinquent 121-270 days Loans delinquent 121-270 days Loans delinquent 121-270 days Loans delinquent 121-270 days, percentage Loans delinquent 121-270 days, percentage Loans delinquent 121-270 days, percentage Loans Delinquent Greater than 271 Days Past Due Loans Delinquent Greater than 271 Days Past Due Loans Delinquent Greater than 271 Days Past Due Loans delinquent 271 days or greater, percentage Loans Delinquent 271 Days or Greater in Percentage Loans Delinquent 271 Days or Greater in Percentage Total loans in repayment Total Loans in Repayment Total Loans in Repayment Total loans in repayment, percentage Total Loans in Repayment in Percentage Total Loans in Repayment in Percentage Statement, Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Additional paid-in capital [Member] Additional Paid-in Capital [Member] Retained earnings [Member] Retained Earnings [Member] Accumulated other comprehensive earnings [Member] Accumulated Other Comprehensive Income (Loss) [Member] Noncontrolling interest [Member] Noncontrolling Interest [Member] Preferred Stock [Member] Preferred Stock [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Balance (in Shares) Shares, Issued Balance Noncontrolling Interest, Increase from Sale of Parent Equity Interest Noncontrolling Interest, Increase from Sale of Parent Equity Interest Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax Cash dividend on Class A and Class B common stock Dividends, Common Stock, Cash Issuance of common stock, net of forfeitures Stock Issued During Period, Value, New Issues Issuance of common stock, net of forfeitures (in Shares) Stock Issued During Period, Shares, New Issues Compensation expense for stock based awards Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Repurchase of common stock Stock Repurchased During Period, Value Conversion of Common Stock, Shares Converted Conversion of Stock, Shares Converted Conversion of Common Stock, Amount Converted Conversion of Stock, Amount Converted Repurchase of common stock (in Shares) Stock Repurchased During Period, Shares Balance (in Shares) Balance Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping, Disclosure Item Amounts [Axis] Fair value [Member] Carrying value [Member] Reported Value Measurement [Member] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Level 1 [Member] Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 2 [Member] Fair Value, Inputs, Level 2 [Member] Level 3 [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Assets, Fair Value Disclosure [Abstract] Assets, Fair Value Disclosure [Abstract] Cash and cash equivalents Restricted cash Restricted Cash Fair Value Restricted Cash Fair Value Restricted investments Derivative instruments Liabilities, Fair Value Disclosure [Abstract] Liabilities, Fair Value Disclosure [Abstract] Derivative instruments Statement of Comprehensive Income [Abstract] Other comprehensive income: Other Comprehensive Income (Loss), Net of Tax [Abstract] Available-for-sale securities: Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Tax, [Abstract] Unrealized holding gains (losses) arising during period, net Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, before Tax Less reclassification adjustment for gains recognized in net income, net Income tax effect Other Comprehensive Income (Loss), Tax Total other comprehensive income (loss) Comprehensive income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Comprehensive income attributable to noncontrolling interest Comprehensive (Income) Loss, Net of Tax, Attributable to Noncontrolling Interest Comprehensive income attributable to Nelnet, Inc. Comprehensive Income (Loss), Net of Tax, Attributable to Parent Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value by Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair Value, Measurements, Recurring [Member] Fair Value, Measurements, Recurring [Member] Student loan asset-backed securities [Member] Debt securities [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] Investments Fair value of derivative instruments Derivative Asset Total assets Assets, Fair Value Disclosure Fair value of derivative instruments Derivative Liability Total liabilities Financial and Nonfinancial Liabilities, Fair Value Disclosure Finite-Lived Intangible Assets, Net [Abstract] Schedule of Finite-Lived Intangible Assets [Table Text Block] Schedule of Finite-Lived Intangible Assets [Table Text Block] Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Derivative Financial Instruments Derivative Instruments and Hedging Activities Disclosure [Text Block] Derivative [Table] Derivative [Table] Fixed Rate Floor Income Interest Rate Swap [Member] One Month to Three Month LIBOR Basis Swaps [Axis] One Month to Three Month LIBOR Basis Swaps [Axis] One Month to Three Month LIBOR Basis Swaps [Axis] One Month to Three Month LIBOR Swaps [Domain] One Month to Three Month LIBOR Swaps [Domain] One Month to Three Month LIBOR Swaps [Domain] Maturity 2021 [Member] One Month to Three Month Basis Swap Outstancing 1 [Member] One Month to Three Month Basis Swap Outstancing 1 [Member] Maturity 2022 [Member] Maturity 2022 [Member] Maturity 2022 [Member] Maturity 2023 [Member] One Month to Three Month Basis Swap Outstanding 2 [Member] One Month to Three Month Basis Swap Outstanding 2 [Member] Maturity 2024 [Member] One Month to Three Month Basis Swap Outstanding 3 [Member] One Month to Three Month Basis Swap Outstanding 3 [Member] Maturity 2026 [Member] One Month to Three Month Basis Swap Oustanding 4 [Member] One Month to Three Month Basis Swap Oustanding 4 [Member] Maturity 2028 [Member] One Month to Three Month Basis Swap Outstanding 5 [Member] One Month to Three Month Basis Swap Outstanding 5 [Member] Maturity 2036 [Member] One Month to Three Month Basis Swap Outstanding 6 [Member] One Month to Three Month Basis Swap Outstanding 6 [Member] Maturity 2039 [Member] One Month to Three Month Basis Swap Outstanding 7 [Member] One Month to Three Month Basis Swap Outstanding 7 [Member] Maturity 2040 [Member] One Month to Three Month Basis Swap Outstanding 8 [Member] One Month to Three Month Basis Swap Outstanding 8 [Member] interest rate index [Axis] interest rate index [Axis] Interest rate index [Axis] Interest rate index [Domain] Interest rate index [Domain] Interest rate index [Domain] Fixed Rate Floor Income Interest Rate Swap [Axis] Fixed Rate Floor Income Interest Rate Swap [Axis] Fixed Rate Floor Income Interest Rate Swap [Axis] Fixed Rate Floor Income Interest Rate Swap [Domain] Fixed Rate Floor Income Interest Rate Swap [Domain] Fixed Rate Floor Income Interest Rate Swap [Domain] Maturity 2014 [Member] Fixed Rate Floor Income Interest Rate Swap 2 [Member] Fixed Rate Floor Income Interest Rate Swap 2 [Member] Maturity 2015 [Member] Fixed Rate Floor Income Interest Rate Swap 3 [Member] Fixed Rate Floor Income Interest Rate Swap 3 [Member] Maturity 2016 [Member] Fixed Rate Floor Income Interest Rate Swap 4 [Member] Fixed Rate Floor Income Interest Rate Swap 4 [Member] Maturity 2017 [Member] Fixed Rate Floor Income Interest Rate Swap 5 [Member] Fixed Rate Floor Income Interest Rate Swap 5 [Member] Junior Subordinated Hybrid Securities [Member] Unsecured Debt Interest Rate Swaps [Axis] Unsecured Debt Interest Rate Swaps [Axis] Unsecured Debt Interest Rate Swaps [Axis] Unsecured Debt Interest Rate Swaps [Domain] Unsecured Debt Interest Rate Swaps [Domain] Unsecured Debt Interest Rate Swaps [Domain] Unsecured Debt Interest Rate Swaps 1 [Member] Unsecured Debt Interest Rate Swaps 1 [Member] Unsecured Debt Interest Rate Swaps 1 [Member] Derivative [Line Items] Derivative [Line Items] Derivative, Type of Interest Rate Paid on Swap Derivative, Type of Interest Rate Paid on Swap Weighted average basis spread on variable rate Derivative, Basis Spread on Variable Rate Segment Reporting Segment Reporting Disclosure [Text Block] Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Asset, Useful Life Finite-Lived Intangible Asset, Useful Life Finite-Lived Intangible Assets, Net Finite-Lived Intangible Assets, Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization Schedule of Goodwill [Table] Schedule of Goodwill [Table] Segments [Axis] Segments [Domain] Goodwill [Line Items] Goodwill [Line Items] Goodwill, Period Start Goodwill, Period End Schedule of Earnings Per Share, Basic and Diluted Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Business Combinations Policy [Policy Text Block] Business Combinations Policy [Policy Text Block] Intangible Assets, Net (Excluding Goodwill) [Abstract] Intangible Assets Disclosure [Text Block] Intangible Assets Disclosure [Text Block] Summary Investment Holdings Summary Investment Holdings [Table Text Block] Realized Gain (Loss) on Investments [Table Text Block] Realized Gain (Loss) on Investments [Table Text Block] DEI non-printing [Abstract] DEI non-printing [Abstract] Document Information [Table] Document Information [Table] Document Information, Document [Axis] Document Information, Document [Axis] Document [Domain] Document [Domain] Document Information [Line Items] Document Information [Line Items] Entity Registrant Name Entity Registrant Name Document Type Document Type Current Fiscal Year End Date Current Fiscal Year End Date Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Entity Public Float Entity Public Float Amendment Flag Amendment Flag Entity Central Index Key Entity Central Index Key Entity Current Reporting Status Entity Current Reporting Status Entity Voluntary Filers Entity Voluntary Filers Entity Filer Category Entity Filer Category Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Schedule of Accounts, Notes, Loans and Financing Receivable Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Allowance for Credit Losses on Financing Receivables Allowance for Credit Losses on Financing Receivables [Table Text Block] Accrual Related to Repurchase Obligation Rollforward Accrual Related to Repurchase Obligation Rollforward [Table Text Block] Accrual related to repurchase obligation rol forward [Table Text Block] Financing Receivable Credit Quality Indicators Financing Receivable Credit Quality Indicators [Table Text Block]