Stockholders' Equity (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Aug. 31, 2018	Nov. 20, 2015	Nov. 30, 2014
Class of Stock [Line Items]
Dividends, Common Stock, Cash	$ 137	$ 132	$ 120
Common Stock, Voting Rights, Number of Votes Per Share	one
Stock repurchase program, authorized amount				$ 150	$ 150	$ 250
Stock Repurchase Program, Shares Repurchased, Gross	7,075,720
Treasury Stock Purchase Price, Repurchase Program	$ 419
Ordinary Dividend [Member]
Class of Stock [Line Items]
Dividends, Common Stock, Cash	$ 137	$ 132	$ 120
Treasury Stock [Member]
Class of Stock [Line Items]
Stock repurchased 2014 program, shares repurchase	995,529	517,712	1,368,881