Debt and Credit Agreements - Narrative (Details)	3 Months Ended		6 Months Ended		12 Months Ended
	Mar. 31, 2025 USD ($) swap	Jun. 30, 2024 USD ($)	Jun. 30, 2025 USD ($) swap	Jun. 30, 2024 USD ($)	Dec. 31, 2023 swap	Dec. 31, 2022 swap	Dec. 31, 2024 USD ($)
Line of Credit Facility
Other operating activities			$ (50,000,000)	$ (19,000,000)
Commercial Paper
Line of Credit Facility
Maximum borrowing capacity of credit facility			1,000,000,000.0
Borrowings outstanding			$ 75,000,000
Weighted average interest rate			4.62%
Commercial Paper | Minimum
Line of Credit Facility
Commercial paper term			7 days
Commercial Paper | Maximum
Line of Credit Facility
Commercial paper term			14 days
Two Separate Fixed-to-Floating Interest Rate Swaps Due 2055 | Fair Value Hedging
Line of Credit Facility
Derivative, number of fair value hedges | swap	2
Derivative, term of contract (in years)	10 years
Two Separate Fixed-to-Floating Interest Rate Swaps Due 2055 | Fair Value Hedging | Designated as Hedging Instrument
Line of Credit Facility
Interest rate fair value hedge asset at fair value			$ 10,000,000
Seven Fixed-to-Floating Interest Rate Swaps | Fair Value Hedging
Line of Credit Facility
Derivative, number of fair value hedges | swap			7
Derivative, term of contract (in years)			10 years
Two Separate Fixed-to-Floating Interest Rate Swaps | Fair Value Hedging
Line of Credit Facility
Derivative, number of fair value hedges | swap					2
Five Separate Fixed-to-Floating Interest Rate Swaps | Fair Value Hedging
Line of Credit Facility
Derivative, number of fair value hedges | swap						5
Five Separate Fixed-to-Floating Interest Rate Swaps | Fair Value Hedging | Designated as Hedging Instrument
Line of Credit Facility
Fair value hedge derivative instrument liabilities at fair value			$ 92,000,000				$ 123,000,000
2023 Fixed-to-Floating Interest Rate Swaps | Fair Value Hedging | Designated as Hedging Instrument
Line of Credit Facility
Interest rate fair value hedge asset at fair value			15,000,000				7,000,000
Interest Rate Swap | Cash Flow Hedge | Designated as Hedging Instrument
Line of Credit Facility
Asset value of the forward interest rate swap			500,000,000
Derivative asset, notional amount settled		$ 114,000,000		$ 114,000,000
Other operating activities		$ 52,000,000
Derivative asset, unsettled notional amount			0				$ 0
5.05% Notes Due 2035
Line of Credit Facility
Debt issued	$ 600,000,000
Debt interest rate	5.05%
Two Separate Fixed-to-Floating Interest Rate Swaps Due 2055
Line of Credit Facility
Debt issued	$ 250,000,000
Seven Fixed-to-Floating Interest Rate Swaps
Line of Credit Facility
Debt issued			1,100,000,000
3.25% Notes Due 2027
Line of Credit Facility
Debt issued			$ 850,000,000
Debt interest rate			3.25%
Unsecured Revolving Credit Facility Due 2028 | Credit Facility
Line of Credit Facility
Maximum borrowing capacity of credit facility			$ 1,200,000,000
Borrowings outstanding			$ 0