PRICE RISK MANAGEMENT ASSETS AND LIABILITIES Derivative Instruments - Income Statement Impact (Details) (Fair Value Hedging [Member], Interest Rate Contract [Member], USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Fair Value Hedging [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Change in fair value - increase (decrease) in interest expense	$ 0	$ (3)