Stockholders' Equity (Other Comprehensive Income (Loss), Tax) (Parentheticals) (Details) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Stockholders' Equity Note [Abstract]
Foreign currency translation adjustments arising during period, net of income tax expense (benefit) of nil, ($2) and $2	$ 0	$ (2)	$ 2
Reclassified to income statement, income tax expense of $24, nil and nil	24	0	0
Unrealized losses on cash flow hedges arising during period, tax benefit of nil, nil and nil	0	0	0
Net actuarial gain (loss) arising during period, net of income tax (benefit) of $16, ($22) and ($18)	16	(22)	(18)
Amortization of actuarial loss, prior service cost and transition obligation, net of income tax (benefit) of $12, $12 and ($9)	12	12	9
Foreign currency translation adjustments, net of income tax expense of nil, nil and nil	0	0	0
Reclassified to income statement, income tax expense of $1, nil and nil	$ 1	$ 0	$ 0