EMPLOYEE BENEFIT PLANS - PROJECTED AND ACCUMULATED BENEFIT OBLIGATIONS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Benefits
Defined Benefit Pension Plans with Projected Benefit Obligations in Excess of Fair Value of Plan Assets
Projected benefit obligations	$ 941	$ 864	$ 906
Plans with projected benefit obligations	806	758
Excess of fair value of related plan assets	589	570
Accumulated benefit obligation	850	786
Information Relating to Aggregated Defined Benefit Pension Plans with an Accumulated Benefit Obligation in Excess of Plan Assets
Projected benefit obligation	680	642
Accumulated benefit obligation	617	588
Fair value of plan assets	484	474
Postretirement Benefits
Defined Benefit Pension Plans with Projected Benefit Obligations in Excess of Fair Value of Plan Assets
Projected benefit obligations	$ 74	$ 56	$ 69
Information Relating to Aggregated Defined Benefit Pension Plans with an Accumulated Benefit Obligation in Excess of Plan Assets
Annual rate of increase in the per capita cost of covered health care benefits assumed (as a percent)	8.80%	8.10%
Decreased annual rate of increase in the per capita cost of covered healthcare by 2038 and thereafter (as a percent)	8.00%	7.40%
One-Percentage-Point Change in Assumed Health Care Cost Trend Rates
Effect of a One-percentage point increase to total service and interest cost	$ 1
Effect of a One-percentage point increase to postretirement benefit obligation	5
Effect of a One-percentage point decrease to postretirement benefit obligation	$ (5)