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Debt (Narrative) (Details) - USD ($)				1 Months Ended
Debt (Narrative) (Details) - USD ($)	Apr. 15, 2021	Apr. 02, 2021	Apr. 01, 2021	Dec. 31, 2021	Mar. 31, 2022	Apr. 09, 2021	Apr. 08, 2021
Debt Instrument [Line Items]
Commercial paper outstanding					$ 825,000,000
Other Debt Facilities
Debt Instrument [Line Items]
Long-term line of credit				$ 0	0
Debt instrument, unused borrowing capacity				$ 508,000,000	$ 483,000,000
2.375% Senior Debt Obligations Due 2031
Debt Instrument [Line Items]
Interest rate				2.375%	2.375%
2.90% Senior Debt Obligations Due 2051
Debt Instrument [Line Items]
Interest rate				2.90%	2.90%
2.75% Senior Debt Obligations Due January 2022
Debt Instrument [Line Items]
Interest rate				2.75%
Repayments of debt				$ 500,000,000
Commercial Paper
Debt Instrument [Line Items]
Short-term debt				0	$ 825,000,000	$ 2,000,000,000	$ 1,500,000,000
Effective interest rate (percent)					0.91%
Revolving Credit Facility \| New Facility
Debt Instrument [Line Items]
Debt facilities, maximum borrowing capacity		$ 2,800,000,000
Term of debt		5 years
Long-term line of credit					$ 0
Revolving Credit Facility \| Old Facility
Debt Instrument [Line Items]
Debt facilities, maximum borrowing capacity			$ 1,800,000,000
Term of debt			5 years
Revolving Credit Facility \| 364-day Facility
Debt Instrument [Line Items]
Debt facilities, maximum borrowing capacity			$ 1,000,000,000
Term of debt			364 days
Senior Notes
Debt Instrument [Line Items]
Repayments of debt	$ 500,000,000
Senior Notes \| 2.375% Senior Debt Obligations Due 2031
Debt Instrument [Line Items]
Debt instrument face amount				400,000,000
Senior Notes \| 2.90% Senior Debt Obligations Due 2051
Debt Instrument [Line Items]
Debt instrument face amount				$ 350,000,000