Financial Instruments (Narrative) (Details) Bcf in Billions	3 Months Ended	9 Months Ended	12 Months Ended	36 Months Ended
	Jun. 30, 2024 USD ($) counterparty Bcf	Jun. 30, 2024 USD ($) counterparty Bcf	Dec. 31, 2023 USD ($)	Dec. 31, 2025 USD ($) payment	Sep. 30, 2023 USD ($)	Jun. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
Foreign Currency Forward Contract Hedge Duration		7 years
After tax net hedging gains in accumulated other comprehensive income (loss)	$ 64,700,000	$ 64,700,000
After Tax Net Hedging Gains Reclassified Within Twelve Months		43,100,000
Fair market value of derivative liability with a credit-risk related contingency	0	0
Hedging Collateral Deposits	0	0			$ 0	$ 0	$ 91,670,000
California Asset Sale | Forecast
Derivative Instruments, Gain (Loss) [Line Items]
Maximum Annual Contingent Payment				$ 10,000,000
Amount of Each Incremental Contingency Payment				1,000,000
Incremental price, exceeding ICE Brent Average Price (in dollars per barrel)				1
California Asset Sale | Present Value of Contingent Consideration
Derivative Instruments, Gain (Loss) [Line Items]
Value of Contingent Consideration Received from Sale of Assets	2,400,000	2,400,000			$ 7,300,000
California Asset Sale | Mark to Market of Contingent Consideration
Derivative Instruments, Gain (Loss) [Line Items]
Mark-to-Market Adjustment for Contingent Consideration	$ (1,200,000)	$ (4,900,000)
California Asset Sale | Minimum
Derivative Instruments, Gain (Loss) [Line Items]
ICE Brent Average (in dollars per barrel)			$ 95
California Asset Sale | Minimum | Forecast
Derivative Instruments, Gain (Loss) [Line Items]
ICE Brent Average (in dollars per barrel)				$ 95
California Asset Sale | Maximum | Forecast
Derivative Instruments, Gain (Loss) [Line Items]
Number Of Annual Contingent Payments | payment				3
ICE Brent Average (in dollars per barrel)				$ 105
Cash Flow Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Hedge Duration		5 years
Over the Counter Swaps, No Cost Collars and Foreign Currency Forward Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Number of counterparties in which the company holds over-the-counter swap positions | counterparty	19	19
Number of counterparties in net gain position | counterparty	18	18
Credit risk exposure per counterparty	$ 5,400,000	$ 5,400,000
Maximum Credit Risk Exposure Per Counterparty		21,200,000
Collateral Received by the Company	$ 0	$ 0
Number of counterparties with a common credit-risk related contingency | counterparty	16	16
Hedging Collateral Deposits	$ 0	$ 0
Natural Gas Bcf | Cash Flow Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Nonmonetary notional amount of price risk cash flow hedge derivatives, natural gas | Bcf	334.0	334.0
Foreign Currency Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Hedging Notional Amount of Forecasted Transportation Costs	$ 54,400,000	$ 54,400,000