Income Taxes (Schedule of Income Tax (Expense) Benefit) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Jul. 10, 2013	Mar. 31, 2016		Mar. 31, 2015	Dec. 31, 2013
Deferred income tax (expense) benefit
Total income tax (expense) benefit			$ (1,600)
Successor [Member]
Current income tax (expense) benefit
Federal	$ 0	$ (2)		$ 13		$ 5	$ 1
State	(10)	0		(30)		(39)	(13)
Total current income tax (expense) benefit	(10)	(2)		(17)	[1]	(34)	(12)
Deferred income tax (expense) benefit
Federal	(48)	1		(206)		491	(46)
State	2	0		83		118	14
Total deferred income tax (expense) benefit	(46)	1		(123)		609	(32)
Foreign income tax expense	0	0		(1)		(1)	(1)
Total income tax (expense) benefit	$ (56)	(1)		$ (141)		$ 574	$ (45)
Predecessor [Member]
Current income tax (expense) benefit
Federal		(8)	2
State		(6)	(17)
Total current income tax (expense) benefit		(14)	(15)
Deferred income tax (expense) benefit
Federal		(19)	(1,402)
State		(5)	(184)
Total deferred income tax (expense) benefit		(24)	(1,586)
Foreign income tax expense		0	0
Total income tax (expense) benefit		$ (38)	$ (1,601)

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