SUPPLEMENTARY OIL AND GAS INFORMATION (UNAUDITED) SUPPLEMENTARY OIL AND GAS INFORMATION (UNAUDITED) (Schedule of Changes in the Standardized Measure) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)
Increase (Decrease) in Standardized Measure of Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves [Roll Forward]
Balance at beginning of year	$ 1,392
Sales, net of production expenses	(831)
Net changes in sales and transfer prices, net of production expenses	(341)
Extensions, discoveries and improved recoveries	0
Changes in estimated future development costs, including timing and other	146
Previously estimated development costs incurred during the year	295
Sales of reserves in-place	(1,049)
Revisions of quantity estimates	12
Accretion of discount	139
Net change in income taxes	0
Total changes	(1,629)
Balance at end of year	$ (237)