Stockholders' Equity Stockholders' Equity (Other Comprehensive Income (Loss), Net of Tax (Phantom)) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013
Equity [Abstract]
Foreign currency translation adjustments arising during period, net of income tax benefit of nil, nil, nil and nil (1)	$ 0	$ 0	$ 0	$ 0
Reclassified to income statement, net of income tax expense of nil, nil, nil and $24(2)	0	0	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
Net actuarial loss and prior service credit arising during period, net of income tax benefit of $6, nil, $6 and nil	6	0	6	0
Amortization of actuarial loss, prior service cost and transition obligation, net of income tax expense of $2, $4, $5 and $10 (3)	2	4	5	10
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, nil, nil and $1	$ 0	$ 0	$ 0	$ 1