Shareholders' Equity - Common Stock (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Apr. 01, 2021	Jan. 31, 2021	Jun. 30, 2019
Equity, Class of Treasury Stock [Line Items]
Amount of common stock authorized for repurchase						$ 475,000,000	$ 2,000,000,000.0
Subsequent Event
Equity, Class of Treasury Stock [Line Items]
Amount of common stock authorized for repurchase					$ 425,000,000
2019 Program
Equity, Class of Treasury Stock [Line Items]
Common stock repurchased	$ 475,000,000	$ 500,000,000	$ 500,000,000	$ 500,000,000