Shareholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
	Dec. 10, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Feb. 28, 2015
Stockholders Equity Note [Line Items]
Shares of common stock repurchased (in shares)		0	400,000
Aggregate cost of shares repurchased			$ 36	$ 45
Share of common stock available for repurchase (in shares)		5,100,000
Dividends paid		$ 389	$ 353	$ 319
Dividends declared per common share (USD per share)	$ 0.55	$ 2.20	$ 2.00	$ 1.82
Maximum
Stockholders Equity Note [Line Items]
Shares available under the program to purchase outstanding common stock (in shares)					10,000,000
DRIP
Stockholders Equity Note [Line Items]
Shares available for grant (in shares)		4,200,000