Restructuring Costs - Expense by Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2017	Jul. 01, 2016
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 190	$ 57
GBS
Restructuring Cost and Reserve [Line Items]
Restructuring costs	77	20
GIS
Restructuring Cost and Reserve [Line Items]
Restructuring costs	106	37
USPS
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 7	$ 0