Segment Information (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Dec. 31, 2017	Dec. 30, 2016	Dec. 31, 2017	Dec. 30, 2016
Segment Reporting Information [Line Items]
Revenues	$ 6,186	$ 1,917	$ 18,262	$ 5,718
Segment profit	927	176	2,482	402
Depreciation and amortization	332	141	941	438
Amortization of acquired intangible assets	149	20	438	56
Reconciliation of Consolidated Operating Income to Income Before Taxes [Abstract]
Profit	927	176	2,482	402
Interest income	27	8	59	26
Interest expense	(77)	(33)	(231)	(87)
Restructuring costs	(213)	(3)	(595)	(85)
Pension and OPEB actuarial and settlement gains	17	0	17	0
Amortization of acquired intangible assets	(149)	(20)	(438)	(56)
Transaction and integration-related costs	(94)	(78)	(284)	(187)
Income before income taxes	438	50	1,010	13
Operating segments
Segment Reporting Information [Line Items]
Revenues	6,186	1,917	18,262	5,718
Segment profit	1,004	218	2,611	550
Depreciation and amortization	305	125	865	390
Reconciliation of Consolidated Operating Income to Income Before Taxes [Abstract]
Profit	1,004	218	2,611	550
Operating segments \| GBS
Segment Reporting Information [Line Items]
Revenues	2,315	1,046	6,893	3,130
Segment profit	431	134	1,093	349
Depreciation and amortization	16	25	67	81
Reconciliation of Consolidated Operating Income to Income Before Taxes [Abstract]
Profit	431	134	1,093	349
Operating segments \| GIS
Segment Reporting Information [Line Items]
Revenues	3,145	871	9,256	2,588
Segment profit	463	84	1,222	201
Depreciation and amortization	269	100	743	309
Reconciliation of Consolidated Operating Income to Income Before Taxes [Abstract]
Profit	463	84	1,222	201
Operating segments \| USPS
Segment Reporting Information [Line Items]
Revenues	726	0	2,113	0
Segment profit	110	0	296	0
Depreciation and amortization	20	0	55	0
Reconciliation of Consolidated Operating Income to Income Before Taxes [Abstract]
Profit	110	0	296	0
All Other
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Segment profit	(77)	(42)	(129)	(148)
Depreciation and amortization	27	16	76	48
Reconciliation of Consolidated Operating Income to Income Before Taxes [Abstract]
Profit	$ (77)	$ (42)	$ (129)	$ (148)

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