INCOME TAXES (Reserve for Unrecognized tax benefits, interest and penalties) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Decreases:
Amount of unrecognized tax benefit that could impact provision for income taxes	$ 97
Amount of unrecognized tax benefit that could impact provision for income taxes, net of tax benefits	55
Unrecognized Tax Benefits [Member]
Reserve for unrecognized tax benefits, interest and penalties, type [Line Items]
Unrecognized Tax Benefits, Interest and Penalties, Beginning Balance	110	138
Additions:
Prior year tax positions	4	18
Current year tax positions	11	14
Acquisition of PXP		5
Interest and penalties	0	0
Decreases:
Prior year tax positions	(12)	(37)
Current year tax positions	0	0
Settlements with tax authorities	(9)	0
Lapse of statute of limitations	0	(28)
Interest and penalties	0	0
Unrecognized Tax Benefits, Interest and Penalties, Ending Balance	104	110
Interest [Member]
Reserve for unrecognized tax benefits, interest and penalties, type [Line Items]
Unrecognized Tax Benefits, Interest and Penalties, Beginning Balance	21	31
Additions:
Interest and penalties	1	7
Decreases:
Interest and penalties	(7)	(17)
Unrecognized Tax Benefits, Interest and Penalties, Ending Balance	15	21
Penalties [Member]
Reserve for unrecognized tax benefits, interest and penalties, type [Line Items]
Unrecognized Tax Benefits, Interest and Penalties, Beginning Balance	0	0
Additions:
Interest and penalties	0	0
Decreases:
Interest and penalties	0	0
Unrecognized Tax Benefits, Interest and Penalties, Ending Balance	$ 0	$ 0