FAIR VALUE MEASUREMENT FAIR VALUE MEASUREMENT (Unobservable inputs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	$ 0
Net realized gains (losses)	0
Net unrealized gains (losses) related to assets still held at the end of the year	135
Settlement receipts	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	$ 135	$ 0
Crude Oil Options [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs		316	$ (309)
Net realized gains (losses)		86	(42)
Net unrealized gains (losses) related to assets still held at the end of the year		0	430
Settlement receipts		(402)	237
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs			316
Crude Oil Options [Member] | Sales [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings		87	(41)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net unrealized gains (losses) related to assets still held at the end of the year			432
Crude Oil Options [Member] | Interest Expense [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net realized gains (losses)		(1)	(1)
Net unrealized gains (losses) related to assets still held at the end of the year			(2)
Settlement receipts		$ 4	$ 5