Income Taxes (Effective Income Tax Rate) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	15 Months Ended	3 Months Ended
	Jun. 30, 2014	Mar. 31, 2014	Jun. 30, 2014 Successor [Member]	Jun. 30, 2013 Successor [Member]	Jun. 30, 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			$ (3)	$ 61	$ 539
State income taxes, net of federal income tax effect			(7)	7	47
Change in valuation allowance			27	0	(621)
Acquisition-related costs	0			(7)	(8)
Other, net			(2)	0	(12)
Income tax benefit (expense)			$ 15	$ 61	$ (55)
Effective income tax rate			187.50%	(35.00%)	3.60%