Segment and Geographic Information 3 (Details) $ in Millions	12 Months Ended
	Mar. 31, 2017 Customer	Mar. 31, 2016 Customer	Mar. 31, 2015 USD ($) Customer
Segment Reporting Information, Additional Information [Abstract]
Number of customers accounting for 10% or more of total revenue | Customer	0	0	0
Mainframe Solutions | Fiscal 2015 Severance Actions
Segment Reporting Information [Line Items]
Severance costs			$ 17
Enterprise Solutions | Fiscal 2015 Severance Actions
Segment Reporting Information [Line Items]
Severance costs			15
Services | Fiscal 2015 Severance Actions
Segment Reporting Information [Line Items]
Severance costs			$ 8