EMPLOYEE BENEFIT PLANS - AMOUNTS RECOGNIZED IN CONSOLIDATED BALANCE SHEETS (DETAILS) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Pension and Other Postretirement Defined Benefit Plans, Liabilities [Abstract]
Accrued benefit liability-long term	$ 246	$ 123
Qualified Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits, Noncurrent	0	60
Pension and Other Postretirement Defined Benefit Plans, Liabilities [Abstract]
Accrued benefit liability-long term	133	0
Total liability recognized	133	0
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax [Abstract]
Prior service cost (credit)	(12)	(14)
Net gain	514	331
Amount recognized in AOCI (pretax)	502	317
Postretirement Medical Benefits [Member]
Pension and Other Postretirement Defined Benefit Plans, Liabilities [Abstract]
Accrued benefit liability-current	4	3
Accrued benefit liability-long term	77	86
Total liability recognized	81	89
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax [Abstract]
Prior service cost (credit)	0	1
Net gain	(32)	(48)
Amount recognized in AOCI (pretax)	$ (32)	$ (47)