v3.24.3
Fair Value of Financial Instruments - Significant Unobservable Inputs (Details) - Level 3 - Fair Value, Recurring
$ in Millions
Sep. 30, 2024
USD ($)
$ / BTU
$ / MWh
MWh
Low | Measurement Input, Commodity Forward Price | Valuation Technique, Option Model  
Fair Value Measurement Inputs and Valuation Techniques [Line Items]  
Derivative asset/liability measurement input | $ / BTU 2.31
High | Measurement Input, Commodity Forward Price | Valuation Technique, Option Model  
Fair Value Measurement Inputs and Valuation Techniques [Line Items]  
Derivative asset/liability measurement input | $ / BTU 12.52
Weighted Average | Measurement Input, Commodity Forward Price | Valuation Technique, Option Model  
Fair Value Measurement Inputs and Valuation Techniques [Line Items]  
Derivative asset/liability measurement input | $ / BTU 5.73
Long-term Power Commodity Contracts | Valuation Technique, Discounted Cash Flow  
Fair Value Measurement Inputs and Valuation Techniques [Line Items]  
Assets | $ $ 0
Liabilities | $ $ 326
Long-term Power Commodity Contracts | Low | Measurement Input, Commodity Forward Price | Valuation Technique, Discounted Cash Flow  
Fair Value Measurement Inputs and Valuation Techniques [Line Items]  
Derivative asset/liability measurement input | $ / MWh 19.67
Long-term Power Commodity Contracts | High | Measurement Input, Commodity Forward Price | Valuation Technique, Discounted Cash Flow  
Fair Value Measurement Inputs and Valuation Techniques [Line Items]  
Derivative asset/liability measurement input | $ / MWh 69.48
Long-term Power Commodity Contracts | Weighted Average | Measurement Input, Commodity Forward Price | Valuation Technique, Discounted Cash Flow  
Fair Value Measurement Inputs and Valuation Techniques [Line Items]  
Derivative asset/liability measurement input | $ / MWh 41.94
Heat Rate Call Option Commodity Contracts | Measurement Input, Commodity Forward Price | Valuation Technique, Option Model  
Fair Value Measurement Inputs and Valuation Techniques [Line Items]  
Assets | $ $ 7
Liabilities | $ $ 0
Heat Rate Call Option Commodity Contracts | Low | Measurement Input, Commodity Forward Price | Valuation Technique, Option Model  
Fair Value Measurement Inputs and Valuation Techniques [Line Items]  
Derivative asset/liability measurement input | $ / MWh (33.90)
Heat Rate Call Option Commodity Contracts | High | Measurement Input, Commodity Forward Price | Valuation Technique, Option Model  
Fair Value Measurement Inputs and Valuation Techniques [Line Items]  
Derivative asset/liability measurement input | $ / MWh 1,083.78
Heat Rate Call Option Commodity Contracts | Weighted Average | Measurement Input, Commodity Forward Price | Valuation Technique, Option Model  
Fair Value Measurement Inputs and Valuation Techniques [Line Items]  
Derivative asset/liability measurement input | $ / MWh 56.23
Other Financial Instruments | Valuation Technique, Discounted Cash Flow  
Fair Value Measurement Inputs and Valuation Techniques [Line Items]  
Assets | $ $ 10
Liabilities | $ $ 0
Other Financial Instruments | Low | Measurement Input, Commodity Forward Price | Valuation Technique, Discounted Cash Flow  
Fair Value Measurement Inputs and Valuation Techniques [Line Items]  
Derivative asset/liability measurement input | MWh 59,425
Other Financial Instruments | High | Measurement Input, Commodity Forward Price | Valuation Technique, Discounted Cash Flow  
Fair Value Measurement Inputs and Valuation Techniques [Line Items]  
Derivative asset/liability measurement input | MWh 118,850
Other Financial Instruments | Weighted Average | Measurement Input, Commodity Forward Price | Valuation Technique, Discounted Cash Flow  
Fair Value Measurement Inputs and Valuation Techniques [Line Items]  
Derivative asset/liability measurement input | MWh 111,091