Comprehensive Income (Loss) - AOCI Schedule (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012 Successor [Member]	Dec. 31, 2011 Predecessor [Member]
Comprehensive Income Loss [Line Items]
Interest rate hedges, net	$ 0	$ (50)
Commodity hedges, net	(3)	0
Benefit plans:
Net actuarial loss and prior service costs, net - pensions	(11)	(52)
Net actuarial gain and prior service credit, net - OPEB	(11)	(14)
Equity investments, net	0	(3)
Total accumulated other comprehensive income (loss), net of tax	$ (25)	$ (119)