Income Taxes (Components Of Provision For Income Taxes Related To Continuing Operations) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Income Tax Disclosure [Abstract]
Federal	$ 453us-gaap_CurrentFederalTaxExpenseBenefit	$ 484us-gaap_CurrentFederalTaxExpenseBenefit	$ (84)us-gaap_CurrentFederalTaxExpenseBenefit
State	90	64	14
Foreign	101us-gaap_CurrentForeignTaxExpenseBenefit	193us-gaap_CurrentForeignTaxExpenseBenefit	46us-gaap_CurrentForeignTaxExpenseBenefit
Total current	644us-gaap_CurrentIncomeTaxExpenseBenefit	741us-gaap_CurrentIncomeTaxExpenseBenefit	(24)us-gaap_CurrentIncomeTaxExpenseBenefit
Federal	195	24	538
State	53	10	80
Foreign	(77)	(18)	(7)
Total deferred	171us-gaap_DeferredIncomeTaxExpenseBenefit	16us-gaap_DeferredIncomeTaxExpenseBenefit	611us-gaap_DeferredIncomeTaxExpenseBenefit
Income tax expense	$ 815us-gaap_IncomeTaxExpenseBenefit	$ 757us-gaap_IncomeTaxExpenseBenefit	$ 587us-gaap_IncomeTaxExpenseBenefit

Amount of current federal tax expense (benefit) pertaining to income (loss) from continuing operations.

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