Income Taxes (Schedule of Income Tax (Expense) Benefit) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended	3 Months Ended			12 Months Ended
	Jul. 10, 2013	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2015	Dec. 31, 2013	Dec. 31, 2012
Deferred income tax benefit (expense)
Total income tax benefit (expense)	$ (1,600)
Successor [Member]
Current income tax (expense) benefit
Federal		0	(2)	(3)	5	1
State		(10)	0	0	(39)	(13)
Total current income tax (expense) benefit		(10)	(2)	(3)	(34)	(12)
Deferred income tax benefit (expense)
Federal		(48)	1	(1)	491	(46)
State		2	0	0	118	14
Total deferred income tax benefit (expense)		(46)	1	(1)	609	(32)
Foreign income tax expense		0		0	(1)	(1)
Total income tax benefit (expense)		(56)	(1)	(4)	574	(45)
Predecessor [Member]
Current income tax (expense) benefit
Federal	2		(8)				34
State	(17)		(6)				22
Total current income tax (expense) benefit	(15)		(14)				56
Deferred income tax benefit (expense)
Federal	(1,402)		(19)				(199)
State	(184)		(5)				(10)
Total deferred income tax benefit (expense)	(1,586)		(24)				(209)
Foreign income tax expense	0		0				(1)
Total income tax benefit (expense)	$ (1,601)		$ (38)				$ (154)