PRICE RISK MANAGEMENT ASSETS AND LIABILITIES Derivative Instruments - Income Statement Impact (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Fair Value Hedging [Member] \| Interest Rate Contract [Member]
Derivative [Line Items]
Change in fair value - increase (decrease) in interest expense	$ 0	$ 4	$ 0	$ 7

The net gain (loss) recognized in earnings during the period due to the ineffectiveness on interest rate fair value hedges.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 25

-Section 50

-Paragraph 1

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6886632&loc=d3e76258-113986

Name:	us-gaap_GainLossOnInterestRateFairValueHedgeIneffectiveness
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration