Segment Information - Reconciliation of Reportable Segment Profit to Consolidated (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Segment profit	$ 283	$ 529	$ 473	$ 1,181
Interest income	25	67	48	97
Interest expense	(96)	(104)	(202)	(195)
Restructuring costs	(265)	(32)	(337)	(174)
Transaction, separation and integration-related costs	(101)	(53)	(211)	(158)
Amortization of acquired intangible assets	(152)	(151)	(300)	(289)
Pension and OPEB actuarial and settlement losses	0	0	(2)	0
Goodwill impairment losses	0	(2,887)	0	(2,887)
Gain on arbitration award	0	632	0	632
Loss before income taxes	(306)	(1,999)	(531)	(1,793)
Operating segments
Segment Reporting Information [Line Items]
Segment profit	353	602	591	1,308
All Other
Segment Reporting Information [Line Items]
Segment profit	$ (70)	$ (73)	$ (118)	$ (127)