SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Summary of Significant Accounting Policies - Inventory (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
System natural gas and operating supplies	$ 203		$ 144
Successor
Natural Gas Volumes	42,843,000		34,891,000
Natural Gas Inventory	184	[1]	124	[1]
Inventory, Raw Materials and Supplies	19		20
Energy Related Inventory	$ 203		$ 144

[1] (1) Natural gas volumes held for operations at December 31, 2013 and 2012 were 42,843,000 MMBtu and 34,891,000 MMBtu, respectively.