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Contractual interest rate for funds borrowed, under the debt agreement.

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Nominal or face amount used to calculate payment on derivative.

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Gross amount of debt extinguished.

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Long-Term Debt and Short-Term Borrowings - Long-Term Debt Maturities and Extinguishments (Details) - USD ($)	1 Months Ended	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2021	Sep. 30, 2021
Interest rate contracts
Debt instrument
Derivative notional amount			$ 800,000,000
Fixed rate medium term note due 2022
Debt instrument
Debt redeemed	$ 450,000,000
Interest rate, stated percentage (as a percent)	2.75%	2.75%
Loss on early debt extinguishment		$ 11,000,000
Floating rate registered note due 2049
Debt instrument
Principal amount			500,000,000
Floating rate registered note due 2049 \| LIBOR
Debt instrument
Principal amount			500,000,000
Floating rate registered note due 2050 \| LIBOR
Debt instrument
Principal amount			$ 300,000,000
Fixed rate registered note due 2049
Debt instrument
Principal amount	$ 1,000,000,000	1,000,000,000
Fixed rate registered note due 2050
Debt instrument
Principal amount	$ 650,000,000	$ 650,000,000