Comprehensive Income (Loss) - Components of AOCI (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012 Successor	Dec. 31, 2011 Predecessor
Comprehensive Income Loss [Line Items]
Other postretirement plan - net actuarial loss and prior service costs, net	$ (9)	$ (13)
Interest rate hedges, net	0	(3)
Total accumulated other comprehensive loss, net of tax	$ (9)	$ (16)