Financial Instruments (Narrative) (Details) $ in Millions, Bcf in Billions	3 Months Ended
	Dec. 31, 2025 USD ($) counterparty Bcf
Derivative Instruments, Gain (Loss) [Line Items]
After tax net hedging gains in accumulated other comprehensive income (loss)	$ 46.2
After tax net hedging gains reclassified within twelve months	45.9
Fair market value of derivative liability with a credit-risk related contingency	0.2
Hedging Collateral Deposits	0.0
Foreign Currency Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Hedging notional amount of forecasted transportation costs	$ 41.0
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	17
Number of counterparties in net gain position | counterparty	16
Credit risk exposure per counterparty	$ 4.3
Maximum credit risk exposure per counterparty	10.8
Collateral received by the company	$ 0.0
Cash Flow Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Hedge duration	5 years
Cash Flow Hedges | Natural Gas Bcf
Derivative Instruments, Gain (Loss) [Line Items]
Nonmonetary notional amount of price risk cash flow hedge derivatives, natural gas | Bcf	403.1