Goodwill and Intangible Assets, Net (Narrative) (Details) (USD $) In Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Goodwill and Intangible Assets, Net
Amortization expense of intangible assets	$ 49	$ 28	$ 97	$ 56
Annual amortization expense, 2012			193
Annual amortization expense, 2013			177
Annual amortization expense, 2014			163
Annual amortization expense, 2015			143
Annual amortization expense, 2016			119
Annual amortization expense, after 2016			$ 685