Income Taxes (Effective Income Tax Rate) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended	3 Months Ended		6 Months Ended		0 Months Ended	3 Months Ended
	Sep. 30, 2014	Sep. 30, 2014 Successor [Member]	Sep. 30, 2013 Successor [Member]	Sep. 30, 2014 Successor [Member]	Sep. 30, 2013 Successor [Member]	Jul. 10, 2013 Predecessor [Member]	Jul. 10, 2013 Predecessor [Member]
Operating Loss Carryforwards [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate	35.00%
Income tax benefit at the federal statutory rate				$ 240	$ 274		$ (367)
State income taxes, net of federal income tax effect				0	35		(31)
Change in federal and state valuation allowance				(297)	(327)		(1,145)
Other, net				1	(11)		(20)
Income tax benefit (expense)		$ (71)	$ (90)	$ (56)	$ (29)	$ (1,508)	$ (1,563)
Effective income tax rate				8.20%	3.70%		(149.10%)