PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS - Estimated Amortization from Cumulative Other Comprehensive Loss in 2015 (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	$ 188
Prior service cost (credit)	(5)
Net effect cost	183
Pension
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	178
Prior service cost (credit)	4
Net effect cost	182
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	10
Prior service cost (credit)	(9)
Net effect cost	$ 1