Severance and Exit Costs 1 (Details) (USD $) In Millions, unless otherwise specified					6 Months Ended
	Sep. 30, 2013	Mar. 31, 2013	Sep. 30, 2012	Mar. 31, 2012	Sep. 30, 2013 Severance Charges [Member]	Sep. 30, 2012 Severance Charges [Member]	Sep. 30, 2013 Facility Exit Charges [Member]	Sep. 30, 2012 Facility Exit Charges [Member]
Severance and exit costs activity
Accrued beginning balance	$ 85	$ 39	$ 35	$ 53	$ 16	$ 13	$ 23	$ 40
Expense					111	0	19	0
Change in estimate					(9)	(3)	0	0
Payments					(69)	(7)	(6)	(5)
Accretion and other					3	0	(3)	(3)
Accrued ending balance	$ 85	$ 39	$ 35	$ 53	$ 52	$ 3	$ 33	$ 32