Credit Facilities and Long-Term Debt (Summary of Debt Outstanding) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Jun. 26, 2020	Oct. 11, 2016	Sep. 20, 2011
Credit Facilities and Long-Term Debt :
Debt issuance costs and unamortized discount	$ (24)	$ (28)
Total debt	2,440	3,084
Less: short-term borrowings and current maturities of long-term debt	0	600
Long-term debt, net	$ 2,440	2,484
4.875% Senior Notes Due 2021
Credit Facilities and Long-Term Debt :
Interest rate	4.875%				4.875%
Outstanding balances	$ 0	600
2.250% Senior Notes Due 2023
Credit Facilities and Long-Term Debt :
Interest rate	2.25%
Outstanding balances	$ 564	612
Debt fair value	$ 577	640
3.250% Senior Notes Due 2026
Credit Facilities and Long-Term Debt :
Interest rate	3.25%			3.25%
Outstanding balances	$ 500	500
Debt fair value	$ 537	563
Senior Notes Due Twenty Twenty Eight
Credit Facilities and Long-Term Debt :
Interest rate	1.95%		1.95%
Outstanding balances	$ 500	500
Senior Notes Due Twenty Thirty One
Credit Facilities and Long-Term Debt :
Interest rate	2.25%		2.25%
Outstanding balances	$ 500	500
4.375% Senior Notes Due 2046
Credit Facilities and Long-Term Debt :
Interest rate	4.375%			4.375%
Outstanding balances	$ 400	400
Debt fair value	481	496
Level 1 | 4.875% Senior Notes Due 2021
Credit Facilities and Long-Term Debt :
Debt fair value	0	620
Level 1 | Senior Notes Due Twenty Twenty Eight
Credit Facilities and Long-Term Debt :
Debt fair value	497	529
Level 1 | Senior Notes Due Twenty Thirty One
Credit Facilities and Long-Term Debt :
Debt fair value	$ 496	$ 527