FAIR VALUE MEASUREMENTS - Schedule of Changes in Level 3 (Details) (Recurring basis, Level 3, USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Recurring basis | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance as of January 1	$ 5	$ 6	$ 57
Purchases	0	0	1
Sales	0	(4)	(45)
Settlements	0	3	23
Other net gains (losses)	0	0	(30)
Balance as of period end	5	5	6
Net unrealized gain (loss) included in net income for the year relating to assets held at December 31	$ 0	$ 0	$ (11)