RETIREMENT AND POSTRETIREMENT BENEFIT PLANS - Assumptions (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Pension Benefits
Benefit Obligation Assumptions:
Discount rate (as a percent)	3.88%	3.99%
Rate of compensation increase (as a percent)	4.00%	4.00%
Net Periodic Benefit Cost Assumptions:
Discount rate (as a percent)	3.99%	3.82%
Assumed long tem rate of return on assets (as a percent)	6.50%	6.50%
Rate of compensation increase (as a percent)	4.00%	4.00%
Postretirement Benefits
Benefit Obligation Assumptions:
Discount rate (as a percent)	4.58%	4.81%
Net Periodic Benefit Cost Assumptions:
Discount rate (as a percent)	4.81%	4.44%
Assumed health care cost trend rates
Decrease due to changes in mortality assumptions	$ 1
U.S. Consumer Price Index (CPI) increase (as a percent)	1.97%	1.60%
Effect of 1-percent increase or a 1-percent decrease in these assumed health care cost trend rates
Effect of 1-percent increase in assumed health care cost trend rates on postretirement benefit obligation	$ 4
Effect of 1-percent decrease in assumed health care cost trend rates on postretirement benefit obligation	$ 3
Union employees | Postretirement Benefits
Assumed health care cost trend rates
Threshold percentage to decrease projected annual rates	0.25%
Projected healthcare cost rate in 2017 (as a percent)	6.25%
Projected ultimate health care cost trend rates (as a percent)	4.50%
Year the projected health care cost trend rate reaches ultimate trend rate	2024