PENSION AND POST-RETIREMENT PLANS - ASSET ALLOCATION (Details) - plan	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Employee benefit plans
Number of single-employer defined benefit pension funded plans	2
Pension Benefits
Employee benefit plans
Target allocation (as a percent)	100.00%
Asset allocations (as a percent)	100.00%	100.00%
One year returns (losses) on plan assets (as a percent)	(6.50%)
Three year returns (losses) on plan assets (as a percent)	5.10%
Five year returns (losses) on plan assets (as a percent)	3.80%
Long-term average return on plan assets since inception (as a percent)	7.90%
Pension Benefits | Domestic equity securities
Employee benefit plans
Target allocation (as a percent)	53.00%
Asset allocations (as a percent)	57.00%	59.00%
Pension Benefits | International equity securities
Employee benefit plans
Target allocation (as a percent)	15.00%
Asset allocations (as a percent)	16.00%	17.00%
Pension Benefits | Debt securities
Employee benefit plans
Target allocation (as a percent)	22.00%
Asset allocations (as a percent)	19.00%	17.00%
Pension Benefits | Real estate
Employee benefit plans
Target allocation (as a percent)	5.00%
Asset allocations (as a percent)	7.00%	6.00%
Pension Benefits | Other and cash
Employee benefit plans
Target allocation (as a percent)	5.00%
Asset allocations (as a percent)	1.00%	1.00%