EMPLOYEE BENEFIT PLANS - NET PENSION EXPENSE (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Qualified Defined Benefit [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	$ 10	$ 8	$ 20	$ 16
Interest cost	21	20	42	40
Expected return on assets	(30)	(29)	(61)	(58)
Amortization of prior service cost	0	(1)	0	(1)
Recognized actuarial loss (gain)	6	4	13	7
Net pension expense	7	2	14	4
Postretirement Medical Benefits [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	0	0	1	1
Interest cost	1	1	2	2
Expected return on assets	0	0	0	0
Amortization of prior service cost	0	0	0	0
Recognized actuarial loss (gain)	(2)	0	(5)	(1)
Net pension expense	$ (1)	$ 1	$ (2)	$ 2