Stockholders' Equity (Changes in Accumulated Other Comprehensive Income (Loss) by Component) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Beginning balance			$ (3)
Other comprehensive income (loss), net of tax	(671)	102	(573)	49
Ending balance	(425)		(425)
Foreign Currency Translation Adjustments, Net of Tax
Beginning balance			168
Other comprehensive income (loss) before reclassifications			(418)
Amounts reclassified to earnings and other			(10)
Other comprehensive income (loss), net of tax			(428)
Ending balance	(260)		(260)
Unrealized Losses on Cash Flow Hedges, Net of Tax
Beginning balance			(11)
Other comprehensive income (loss) before reclassifications			(2)
Amounts reclassified to earnings and other			0
Other comprehensive income (loss), net of tax			(2)
Ending balance	(13)		(13)
Unrealized Net Loss and Other Components of Benefit Plans, Net of Tax
Beginning balance			(160)
Other comprehensive income (loss) before reclassifications			0
Amounts reclassified to earnings and other			8
Other comprehensive income (loss), net of tax			8
Ending balance	(152)		(152)
Parent Company [Member]
Beginning balance			(3)
Other comprehensive income (loss) before reclassifications			(420)
Amounts reclassified to earnings and other			(2)
Other comprehensive income (loss), net of tax			(422)
Ending balance	$ (425)		$ (425)