Segment Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenues	$ 5,178	$ 5,460	$ 15,473	$ 16,149
Segment profit	840	797	2,442	2,107
Depreciation and amortization	374	306	1,062	875
Amortization of acquired intangible assets	134	134	401	389
Reconciliation of Consolidated Operating Income to Income Before Taxes [Abstract]
Segment profit	840	797	2,442	2,107
Interest income	27	27	92	59
Interest expense	(81)	(73)	(249)	(220)
Restructuring costs	(76)	(210)	(418)	(585)
Transaction, separation and integration-related costs	(107)	(83)	(305)	(273)
Amortization of acquired intangible assets	(134)	(134)	(401)	(389)
Pension and OPEB actuarial and settlement gains	0	17	0	17
Income from continuing operations before income taxes	469	341	1,161	716
Operating segments
Segment Reporting Information [Line Items]
Revenues	5,178	5,460	15,473	16,149
Segment profit	923	873	2,673	2,237
Depreciation and amortization	347	281	969	803
Reconciliation of Consolidated Operating Income to Income Before Taxes [Abstract]
Segment profit	923	873	2,673	2,237
Operating segments | GBS
Segment Reporting Information [Line Items]
Revenues	2,169	2,315	6,493	6,893
Segment profit	395	423	1,198	1,066
Depreciation and amortization	23	16	59	67
Reconciliation of Consolidated Operating Income to Income Before Taxes [Abstract]
Segment profit	395	423	1,198	1,066
Operating segments | GIS
Segment Reporting Information [Line Items]
Revenues	3,009	3,145	8,980	9,256
Segment profit	528	450	1,475	1,171
Depreciation and amortization	324	265	910	736
Reconciliation of Consolidated Operating Income to Income Before Taxes [Abstract]
Segment profit	528	450	1,475	1,171
All Other
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Segment profit	(83)	(76)	(231)	(130)
Depreciation and amortization	27	25	93	72
Reconciliation of Consolidated Operating Income to Income Before Taxes [Abstract]
Segment profit	$ (83)	$ (76)	$ (231)	$ (130)