Stockholders' Equity Stockholders' Equity (Other Comprehensive Income (Loss), Net of Tax) (Parentheticals) (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
Equity [Abstract]
Foreign currency translation adjustments arising during period, net of income tax benefit of nil, $2, nil and nil (1)	$ 0	$ 2	$ 0	$ 0
Reclassified to income statement, net of income tax expense of nil, $24, nil and $24(2)	0	24	0	24
Unrealized losses on cash flow hedges arising during period, net of income tax expense of nil, nil, nil and nil	0	0	0	0
Amortization of actuarial loss, prior service cost and transition obligation, net of income tax expense of $2, $2, $3 and $6 (3)	2	2	3	6
Foreign currency translation adjustments, net of income tax expense of nil, nil, nil and nil	0	0	0	0
Reclassified to income statement, net of income tax expense of nil, $1, nil and $1	$ 0	$ 1	$ 0	$ 1