Consolidated Statements of Other Comprehensive Income (Loss) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Mar. 31, 2013
Net income $ 875 $ 8 $ 98
Other comprehensive income (loss), net of tax:      
Change in unrealized net gains and losses on available-for-sale securities 1 0 (46)
Reclassification adjustment for net realized gains on available-for-sale securities 0 0 (41)
Change in unrealized net gains and losses on derivative instruments 20 (19) (2)
Reclassification adjustment for net realized gains and losses on derivative instruments 11 9 4
Foreign currency translation adjustments (67) (22) (19)
Total other comprehensive loss, net of tax (35) (32) (104)
Total comprehensive income (loss) $ 840 $ (24) $ (6)