Derivative Instrument and Hedging Activities - Derivative Effects on Income (Details) (USD $) In Millions, unless otherwise specified	0 Months Ended	3 Months Ended
	Mar. 31, 2012 Successor [Member]	Mar. 31, 2013 Successor [Member]	Mar. 25, 2012 Predecessor [Member]
Cash Flow Hedges: Interest rate contracts:
Change in fair value - increase in Accumulated other comprehensive income	$ 0	$ 0	$ 6
Reclassification of unrealized loss from Accumulated other comprehensive income - increase of Interest expense	0	0	8
Cash Flow Hedges: Commodity contracts - Gathering and Processing:
Change in fair value - increase/(decrease) in Accumulated other comprehensive income	2	0	5
Reclassification of unrealized gain from Accumulated other comprehensive income	0	0	2
Economic Hedges: Interest rate contracts: [Abstract]
Change in fair value - increase in interest expense	0	5	0
Economic Hedges: Commodity contracts - Distribution:
Change in fair value - increase/(decrease) in Deferred natural gas purchases	$ 0	$ (13)	$ (2)