Goodwill and Intangible Assets, Net (Narrative - Intangible Assets) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization Expense of Intangible Assets	$ 215	$ 191	$ 132
Annual Amortization Expense, 2014	284
Annual Amortization Expense, 2015	262
Annual Amortization Expense, 2016	228
Annual Amortization Expense, 2017	202
Annual Amortization Expense, 2018	184
Annual Amortization Expense, After 2018	$ 1,110