SUPPLEMENTARY OIL AND GAS INFORMATION (UNAUDITED) SUPPLEMENTARY OIL AND GAS INFORMATION (UNAUDITED) (Schedule of Standardized Measure of Future Net Cash Flows) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves [Line Items]
Future cash inflows	$ 345	$ 10,536	$ 29,504
Future production expense	(175)	(4,768)	(10,991)
Future development costs	(439)	(4,130)	(6,448)
Future income tax expense	0	0	(2,487)
Future net cash flows	(269)	1,638	9,578
Discounted at 10% per year	32	(246)	(3,157)
Standardized Measure	(237)	1,392	6,421	$ 9,417
Asset Retirement Obligation	2,635	2,771	2,744	$ 2,316
United States oil and gas operations
Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves [Line Items]
Asset Retirement Obligation	$ 400	$ 1,900	$ 1,800