Debt - Summary (Details) - USD ($)	Dec. 31, 2021	Sep. 30, 2021	Dec. 31, 2020	Aug. 13, 2020	Nov. 26, 2019
Debt Instrument [Line Items]
Long-term debt	$ 4,114,000,000		$ 4,110,000,000
Annual long term debt maturity year 2026	0
Senior Notes | 4.0% Senior Notes, due 2025
Debt Instrument [Line Items]
Total debt	696,000,000		695,000,000
Unamortized debt discount and issuance costs	$ 4,000,000
Interest rate (as a percent)	4.00%
Senior Notes | 2.95% Senior Notes, due 2027
Debt Instrument [Line Items]
Total debt			495,000,000
Unamortized debt discount and issuance costs	$ 4,000,000
Interest rate (as a percent)	2.95%
Annual long term debt maturity year 2026	$ 496,000,000
Senior Notes | 2.5% Senior Notes, due 2029
Debt Instrument [Line Items]
Total debt	496,000,000		495,000,000
Unamortized debt discount and issuance costs	$ 4,000,000
Interest rate (as a percent)	2.50%				2.50%
Senior Notes | 1.25% Senior Notes, due 2030
Debt Instrument [Line Items]
Total debt	$ 593,000,000		592,000,000
Unamortized debt discount and issuance costs	$ 7,000,000
Interest rate (as a percent)	1.25%			1.25%
Senior Notes | 6.55% Senior Notes, due 2037
Debt Instrument [Line Items]
Total debt	$ 290,000,000		$ 290,000,000
Unamortized debt discount and issuance costs	$ 3,000,000
Interest rate (as a percent)	6.55%	6.55%	6.55%
Senior Notes | 4.5% Senior Notes, due 2048
Debt Instrument [Line Items]
Total debt	$ 273,000,000		$ 273,000,000
Unamortized debt discount and issuance costs	$ 10,000,000
Interest rate (as a percent)	4.50%	4.50%
Senior Notes | 3.25% Senior Notes, due 2049
Debt Instrument [Line Items]
Total debt	$ 589,000,000		589,000,000
Unamortized debt discount and issuance costs	$ 11,000,000
Interest rate (as a percent)	3.25%				3.25%
Senior Notes | 2.3% Senior Notes, due 2060
Debt Instrument [Line Items]
Total debt	$ 681,000,000		$ 681,000,000
Unamortized debt discount and issuance costs	$ 19,000,000
Interest rate (as a percent)	2.30%			2.30%