PENSION AND OTHER POSTRETIREMENT PLANS - Target Allocations for Plan Assets (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Target allocations for Plan assets
Percentage of Plan Assets	100.00%	100.00%
Cash Equivalents
Target allocations for Plan assets
Percentage of Plan Assets	3.00%	8.10%
Weighted-Average Expected Long-term Rate of Return (as a percent)	0.00%
Cash Equivalents | Minimum
Target allocations for Plan assets
Target Allocation 2019 (as a percent)	0.00%
Cash Equivalents | Maximum
Target allocations for Plan assets
Target Allocation 2019 (as a percent)	5.00%
Equity Securities
Target allocations for Plan assets
Percentage of Plan Assets	54.80%	58.70%
Weighted-Average Expected Long-term Rate of Return (as a percent)	9.50%
Equity Securities | Minimum
Target allocations for Plan assets
Target Allocation 2019 (as a percent)	45.00%
Equity Securities | Maximum
Target allocations for Plan assets
Target Allocation 2019 (as a percent)	65.00%
Fixed income securities
Target allocations for Plan assets
Percentage of Plan Assets	42.20%	33.20%
Weighted-Average Expected Long-term Rate of Return (as a percent)	5.00%
Fixed income securities | Minimum
Target allocations for Plan assets
Target Allocation 2019 (as a percent)	35.00%
Fixed income securities | Maximum
Target allocations for Plan assets
Target Allocation 2019 (as a percent)	55.00%