Condensed Consolidated Statements of Comprehensive Loss (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011
Net Loss	$ (45)	$ (205)	$ (225)	$ (324)
Other comprehensive loss, net of tax:
Change in unrealized gains on available-for-sale securities	(9)	(72)	(34)	(16)
Reclassification adjustment for realized gains on available-for-sale securities	(15)	0	(15)	(1)
Change in unrealized losses on derivative instruments	(2)	(1)	(4)	(2)
Reclassification adjustment for realized losses on derivative instruments	1	1	2	3
Foreign currency translation adjustments	(5)	4	(3)	(13)
Total other comprehensive loss, net of tax	(30)	(68)	(54)	(29)
Total comprehensive loss	$ (75)	$ (273)	$ (279)	$ (353)