Segment Information (Net Revenue By Timing Recognition) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting, Revenue Reconciling Item
Net revenue	$ 1,151	$ 1,348	$ 2,610	$ 2,557
Recognized at a point in time
Segment Reporting, Revenue Reconciling Item
Net revenue	337	629	779	877
Recognized over time
Segment Reporting, Revenue Reconciling Item
Net revenue	$ 814	$ 719	$ 1,831	$ 1,680