FAIR VALUE MEASUREMENTS 3 (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	$ 99	$ 61
Realized and unrealized gains (losses)	1	(1)
Allocated transmission instruments	1	0
Settlements	(6)	(2)
Balance at end of period	95	58
Change in unrealized gains (losses) relating to instruments still held at period end	0	0
CRR Auction Rate Per MWh, Minimum	(6)	(11)
CRR Auction Rate Per MWh, Maximum	$ 12	$ 12