PENSION AND POST-RETIREMENT PLANS - ASSET ALLOCATION (Details) - plan	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
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)	22.50%
Three year returns (losses) on plan assets (as a percent)	9.50%
Five year returns (losses) on plan assets (as a percent)	6.90%
Long-term average return on plan assets since inception (as a percent)	8.40%
Pension Benefits | Domestic equity securities
Employee benefit plans
Target allocation (as a percent)	53.00%
Asset allocations (as a percent)	59.00%	57.00%
Pension Benefits | International equity securities
Employee benefit plans
Target allocation (as a percent)	15.00%
Asset allocations (as a percent)	17.00%	16.00%
Pension Benefits | Debt securities
Employee benefit plans
Target allocation (as a percent)	22.00%
Asset allocations (as a percent)	17.00%	19.00%
Pension Benefits | Real estate
Employee benefit plans
Target allocation (as a percent)	5.00%
Asset allocations (as a percent)	6.00%	7.00%
Pension Benefits | Other and cash
Employee benefit plans
Target allocation (as a percent)	5.00%
Asset allocations (as a percent)	1.00%	1.00%