Severance and Exit Costs 1 (Details) (USD $) In Millions, unless otherwise specified					6 Months Ended
	Sep. 30, 2012	Mar. 31, 2012	Sep. 30, 2011	Mar. 31, 2011	Sep. 30, 2012 Severance [Member]	Sep. 30, 2011 Severance [Member]	Sep. 30, 2012 Facility Abandonment [Member]	Sep. 30, 2011 Facility Abandonment [Member]
Restructuring Reserve [Roll Forward]
Accrued beginning balance	$ 35	$ 53	$ 79	$ 55	$ 13	$ 8	$ 40	$ 47
Expense					0	44	0	0
Change in Estimate					(3)	0	0	0
Payments					(7)	(15)	(5)	(6)
Accretion and Other					0	0	(3)	1
Accrued ending balance	$ 35	$ 53	$ 79	$ 55	$ 3	$ 37	$ 32	$ 42