PRICE RISK MANAGEMENT ASSETS AND LIABILITIES Derivative Instruments - Income Statement Impact (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Cash Flow Hedging [Member] | Commodity Contract [Member]
Derivative [Line Items]
Change in fair value - decrease in accumulated other comprehensive income	$ 0	$ 0	$ 0	$ (3)
Fair Value Hedging [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Change in fair value - increase (decrease) in interest expense	(13)	1	(6)	(27)
Fair Value Hedging [Member] | Commodity Contract [Member]
Derivative [Line Items]
Change in fair value - increase (decrease) in deferred natural gas purchases	$ 0	$ (4)	$ 0	$ (7)