Debt and Credit Facilities (Narrative) (Details)	1 Months Ended	12 Months Ended
	Oct. 31, 2021 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Mar. 31, 2022 USD ($)	Sep. 30, 2021 USD ($)	Mar. 31, 2021 USD ($)
Line of Credit Facility [Line Items]
Commercial paper		$ 0
Interest expense, debt		337,000,000	$ 315,000,000	$ 287,000,000
Credit Agreement | Revolving Credit Facility
Line of Credit Facility [Line Items]
Increase in line of credit facility, maximum borrowing capacity	$ 750,000,000
Maximum borrowing capacity	$ 2,250,000,000
Leverage ratio	3.75
Commercial Paper
Line of Credit Facility [Line Items]
Maximum borrowing capacity		$ 1,500,000,000
Maturities of time deposits		397 days
Commercial Paper | Subsequent Event
Line of Credit Facility [Line Items]
Maximum borrowing capacity					$ 2,250,000,000
Senior Unsecured Notes 2.625% due 2021
Line of Credit Facility [Line Items]
Debt instrument, repurchased face amount							$ 750,000,000
Stated interest rate		2.625%					2.625%
Senior Unsecured Notes, 1.125% Due 2021
Line of Credit Facility [Line Items]
Debt instrument, repurchased face amount						$ 400,000,000