Other Income, Net (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2010
Other Income, Net [Abstract]
Business combination cost reimbursement	$ 0	$ 16	$ 0
Percentage of equity interest sold			50.00%
Pre-tax gain on sale of equity investments			17
After-tax gain on sale of equity investment			$ 14