Segment Information - Reconciliation of Reportable Segment Profit to Consolidated (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Segment profit	$ 300	$ 528	$ 773	$ 1,709
Interest income	28	33	76	130
Interest expense	(82)	(93)	(284)	(288)
Restructuring costs	(104)	(74)	(441)	(248)
Transaction, separation and integration-related costs	(96)	(68)	(307)	(226)
Amortization of acquired intangible assets	(114)	(146)	(414)	(435)
Gain on disposition of businesses	2,046	0	2,046	0
Pension and OPEB actuarial and settlement losses	0	0	(2)	0
Goodwill impairment losses	0	(53)	0	(2,940)
Gain on arbitration award	0	0	0	632
Income (loss) before income taxes	1,978	127	1,447	(1,666)
Operating segments
Segment Reporting Information [Line Items]
Segment profit	361	585	952	1,893
All Other
Segment Reporting Information [Line Items]
Segment profit	$ (61)	$ (57)	$ (179)	$ (184)