Financial Instruments (Narrative) (Details) Bcf in Billions	3 Months Ended	12 Months Ended	36 Months Ended
	Dec. 31, 2023 USD ($) counterparty Bcf	Dec. 31, 2023 USD ($) counterparty Bcf	Dec. 31, 2025 USD ($) payment	Sep. 30, 2023 USD ($)	Dec. 31, 2022 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)	$ 127,100,000	$ 127,100,000
After Tax Net Hedging Gains Reclassified Within Twelve Months	92,300,000
Fair market value of derivative liability with a credit-risk related contingency	0	0
Hedging Collateral Deposits	0	0		$ 0	$ 1,600,000	$ 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	3,100,000	3,100,000		$ 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	$ (4,200,000)
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	19	19
Credit risk exposure per counterparty	$ 9,600,000	$ 9,600,000
Maximum Credit Risk Exposure Per Counterparty	35,600,000
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	380.2	380.2
Foreign Currency Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Hedging Notional Amount of Forecasted Transportation Costs	$ 53,700,000	$ 53,700,000