Stockholders' Equity - Capital Stock and Share Repurchases (Details) - USD ($)	3 Months Ended		6 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Nov. 08, 2018	Apr. 03, 2017
Equity [Abstract]
Initial authorization						$ 2,000,000,000.0
Additional authorization					$ 2,000,000,000.0
Equity, Class of Treasury Stock [Line Items]
Number of shares repurchased (in shares)	6,220,190	7,359,609	0	13,579,799
Average price per share (in dollars per share)	$ 40.18	$ 54.35		$ 47.86
Amount	$ 250,000,000	$ 400,000,000		$ 650,000,000
Open market purchases
Equity, Class of Treasury Stock [Line Items]
Number of shares repurchased (in shares)	4,414,840	5,510,415
Average price per share (in dollars per share)	$ 33.96	$ 54.44
Amount	$ 150,000,000	$ 300,000,000
Accelerated stock repurchases
Equity, Class of Treasury Stock [Line Items]
Number of shares repurchased (in shares)	1,805,350	1,849,194
Average price per share (in dollars per share)	$ 55.39	$ 54.08
Amount	$ 100,000,000	$ 100,000,000