Income Taxes (Deferred Tax Assets And Liabilities) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Income Tax Disclosure [Abstract]
Accruals, reserves and other expenses	$ 163	$ 179
Tax credit carryforwards	462	214
Stock-based compensation	43	46
Net operating loss & capital loss carryforwards	199	286
Total	867	725
Valuation allowance	(675)	(510)
Deferred tax assets, net of valuation allowance	192	215
Depreciation	(12)	(16)
State effect on federal taxes	(63)	(56)
Amortization	(28)	(34)
Prepaids and other liabilities	(9)	(11)
Total	(112)	(117)
Deferred tax assets, net of valuation allowance and deferred tax liabilities	$ 80	$ 98