EMPLOYEE BENEFIT PLANS - NET PENSION EXPENSE (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Qualified Defined Benefit [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	$ 11	$ 8	$ 31	$ 24
Interest cost	21	21	63	61
Expected return on assets	(31)	(30)	(92)	(88)
Amortization of prior service cost	(1)	0	(1)	(1)
Recognized actuarial loss (gain)	7	3	20	10
Net pension expense	7	2	21	6
Postretirement Medical Benefits [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1	1	2	2
Interest cost	0	1	2	3
Expected return on assets	0	0	0	0
Amortization of prior service cost	0	0	0	0
Recognized actuarial loss (gain)	(3)	(1)	(8)	(2)
Net pension expense	$ (2)	$ 1	$ (4)	$ 3