FAIR VALUE MEASUREMENTS (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended										12 Months Ended
	Dec. 31, 2012	Dec. 31, 2010	Dec. 31, 2012 Recurring Level 1	Dec. 31, 2011 Recurring Level 1	Dec. 31, 2012 Recurring Level 2	Dec. 31, 2011 Recurring Level 2	Dec. 31, 2012 Recurring Netting and Collateral	Dec. 31, 2011 Recurring Netting and Collateral	Dec. 31, 2012 Recurring Total Fair Value	Dec. 31, 2011 Recurring Total Fair Value	Dec. 31, 2012 Non recurring	Dec. 31, 2010 Non recurring
Assets:
Commodity derivatives			$ 107	$ 310	$ 312	$ 640	$ (301)	$ (758)	$ 118	$ 192
Liabilities:
Commodity derivatives			99	311	398	652	(371)	(782)	126	181
Asset impairments and related items	$ 1,751	$ 275									$ 1,731	$ 275
Percentage of pre-tax impairment charges related to natural gas properties											90.00%
Average period over which natural gas properties were acquired											4 years