Fair Value Measurements - Unobservable Inputs for Level 3 Natural Gas Supply Contracts (Details) - Natural gas supply contracts	Sep. 30, 2025 $ / MMBTU
Forward natural gas price per MMBtu(a) \| Minimum \| Discounted cash flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative, measurement input	1.62
Forward natural gas price per MMBtu(a) \| Maximum \| Discounted cash flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative, measurement input	5.34
Forward natural gas price per MMBtu(a) \| Arithmetic average \| Discounted cash flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative, measurement input	3.47
Volatility \| Minimum \| Option pricing model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative, measurement input	0.231
Volatility \| Maximum \| Option pricing model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative, measurement input	0.886
Volatility \| Arithmetic average \| Option pricing model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative, measurement input	0.305

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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