Taxes on Income - Current and Deferred (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2012 Successor	Mar. 25, 2012 Predecessor	Dec. 31, 2011 Predecessor	Dec. 31, 2010 Predecessor
Income Tax Disclosure
Federal	$ (8)	$ 5	$ 24	$ 34
State	(2)	1	(5)	11
Current Income Tax Expense (Benefit)	(10)	6	19	45
Federal	72	17	67	51
State	14	2	9	1
Deferred income taxes	86	19	76	52
Total income tax expense	$ 76	$ 25	$ 95	$ 97
Effective tax rate	46.4396%	38.00%	36.00%	40.00%