Severance and Exit Costs 1 (Details) (USD $) In Millions, unless otherwise specified					12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2010	Mar. 31, 2013 Severance [Member]	Mar. 31, 2012 Severance [Member]	Mar. 31, 2011 Severance [Member]	Mar. 31, 2013 Facilities Abandonment [Member]	Mar. 31, 2012 Facilities Abandonment [Member]	Mar. 31, 2011 Facilities Abandonment [Member]
Severance and exit costs activity
Accrued beginning balance	$ 39	$ 53	$ 55	$ 116	$ 13	$ 8	$ 54	$ 40	$ 47	$ 62
Expense					18	49	0	0	0	0
Change in estimate					(6)	(8)	(3)	0	0	1
Payments					(9)	(36)	(42)	(13)	(11)	(19)
Accretion and other					0	0	(1)	(4)	4	3
Accrued ending balance	$ 39	$ 53	$ 55	$ 116	$ 16	$ 13	$ 8	$ 23	$ 40	$ 47