Debt and Credit Agreements - Narrative (Details)	3 Months Ended								6 Months Ended	9 Months Ended				12 Months Ended
	Jun. 30, 2024 USD ($)	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($) swap	Sep. 30, 2023 USD ($)	Jun. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Mar. 31, 2022 USD ($) swap	Jun. 30, 2023 USD ($)	Sep. 30, 2024 USD ($)		Sep. 30, 2023 USD ($)		Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Sep. 18, 2024 USD ($)
Line of Credit Facility
Other operating activities		$ (16,000,000)				$ (35,000,000)			$ 18,000,000	$ (35,000,000)	[1]	$ 67,000,000	[1]	$ (7,000,000)	$ (16,000,000)
Commercial Paper
Line of Credit Facility
Maximum borrowing capacity of credit facility										1,000,000,000.0
Borrowings outstanding										0
4.900% Notes Due 2055
Line of Credit Facility
Debt issued																$ 550,000,000
Debt interest rate																4.90%
Fixed Rate Notes Due 2033
Line of Credit Facility
Debt issued			$ 250,000,000											250,000,000
Fixed Rate Notes Due Between 2036 and 2040
Line of Credit Facility
Debt issued			$ 1,050,000,000					$ 800,000,000		1,050,000,000				1,050,000,000
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
Two Separate Fixed-to-Floating Interest Rate Swaps | 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 | Designated as Hedging Instrument | Fair Value Hedging
Line of Credit Facility
Interest rate fair value hedge asset at fair value			$ 19,000,000							21,000,000				19,000,000
Fixed-to-Floating Interest Rate Swap | Fair Value Hedging
Line of Credit Facility
Derivative, number of fair value hedges | swap								5
Derivative, term of contract (in years)								10 years
Fixed-to-Floating Interest Rate Swap | Designated as Hedging Instrument | Fair Value Hedging
Line of Credit Facility
Fair value hedge derivative instrument liabilities at fair value			107,000,000							99,000,000				107,000,000
Interest Rate Swap | Designated as Hedging Instrument | Cash Flow Hedge
Line of Credit Facility
Aggregate notional value of interest forward interest rate swap			114,000,000							500,000,000				114,000,000
Cash flow hedge derivative instrument assets at fair value			$ 48,000,000											$ 48,000,000
Derivative asset, notional amount settled	$ 114,000,000			$ 113,000,000	$ 113,000,000		$ 160,000,000		$ 113,000,000			$ 113,000,000			$ 160,000,000
Other operating activities	$ 52,000,000			$ 51,000,000	$ 44,000,000		$ 52,000,000
Derivative asset, unsettled notional amount										$ 0

[1] See Note 11, Revision of Prior Period Financial Statements.