Condensed Consolidated Statements of Comprehensive Loss (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Net loss	$ (273)	$ (381)	$ (51)	$ (180)
Other comprehensive income (loss), net of tax:
Change in unrealized gains and losses on available-for-sale securities	1	17	0	(25)
Change in unrealized losses on derivative instruments	(9)	(3)	(11)	(2)
Reclassification adjustment for realized losses on derivative instruments	0	1	2	1
Foreign currency translation adjustments	14	19	2	2
Total other comprehensive income (loss), net of tax	6	34	(7)	(24)
Total comprehensive loss	$ (267)	$ (347)	$ (58)	$ (204)