Income Taxes (Effective Income Tax Rate) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended	0 Months Ended	3 Months Ended	6 Months Ended		9 Months Ended
	Jul. 10, 2013	Sep. 30, 2013	Sep. 30, 2013 Successor [Member]	Sep. 30, 2013 Successor [Member]	Jul. 10, 2013 Predecessor [Member]	Sep. 30, 2012 Predecessor [Member]	Jul. 10, 2013 Predecessor [Member]	Jun. 30, 2012 Predecessor [Member]	Sep. 30, 2012 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				$ 277			$ (155)	$ 1,013
State income taxes, net of federal income tax effect				35			(15)	104
Change in valuation allowance				(327)			(1,410)	(1,210)
Other, net				(15)			(21)	(17)
Income tax expense	$ (1,600)		$ (90)	$ (30)	$ (1,508)	$ (47)	$ (1,601)	$ (110)	$ (110)
Effective income tax rate				(3.80%)			361.40%	(3.80%)