Segment Information (Net Revenue By Geographic Area) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue from External Customer [Line Items]
Net revenue	$ 1,151	$ 1,348	$ 2,610	$ 2,557
North America
Revenue from External Customer [Line Items]
Net revenue	578	531	1,205	1,021
International
Revenue from External Customer [Line Items]
Net revenue	$ 573	$ 817	$ 1,405	$ 1,536