Severance and Exit Costs 1 (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Accrued severance and exit costs activity
Accrued beginning balance	$ 19	$ 49	$ 84
Accrued ending balance	12	19	49
Severance Charges
Accrued severance and exit costs activity
Accrued beginning balance	3	28	55
Expense	0	0	60
Change in estimate	(1)	(3)	(7)
Payments	(1)	(22)	(77)
Accretion and other	0	0	(3)
Accrued ending balance	1	3	28
Facility Exit Charges
Accrued severance and exit costs activity
Accrued beginning balance	16	21	29
Expense	0	0	0
Change in estimate	0	0	0
Payments	(4)	(5)	(9)
Accretion and other	(1)	0	1
Accrued ending balance	$ 11	$ 16	$ 21