Segment Information - Segment Measures (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]
Revenues	$ 4,288	$ 5,021	$ 13,344	$ 14,762
Segment profit	300	528	773	1,709
Depreciation and amortization	361	333	1,078	981
Amortization of acquired intangible assets	114	146	414	435
Operating segments
Segment Reporting Information [Line Items]
Revenues	4,288	5,021	13,344	14,762
Segment profit	361	585	952	1,893
Depreciation and amortization	334	305	1,001	899
Operating segments | GBS
Segment Reporting Information [Line Items]
Revenues	1,921	2,359	6,337	6,803
Segment profit	273	353	805	1,078
Depreciation and amortization	53	61	162	128
Operating segments | GIS
Segment Reporting Information [Line Items]
Revenues	2,367	2,662	7,007	7,959
Segment profit	88	232	147	815
Depreciation and amortization	281	244	839	771
All Other
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Segment profit	(61)	(57)	(179)	(184)
Depreciation and amortization	$ 27	$ 28	$ 77	$ 82