PENSION AND OTHER POSTRETIREMENT BENEFITS - PLAN ASSETS (Details) - Pension Benefits	12 Months Ended
	Dec. 31, 2016 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Required capitalization for plan asset allocation (less than)	$ 250,000,000.0
Required capitalization for plan asset allocation, small cap (as low as)	$ 50,000,000.0
U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage of assets, equity securities, range minimum	28.00%
Target allocation percentage of assets, equity securities, range maximum	48.00%
International equity securities
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage of assets, equity securities, range minimum	13.00%
Target allocation percentage of assets, equity securities, range maximum	25.00%
Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage of assets, equity securities, range minimum	32.00%
Target allocation percentage of assets, equity securities, range maximum	42.00%
Other investments
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage of assets, equity securities, range minimum	0.00%
Target allocation percentage of assets, equity securities, range maximum	7.00%