EMPLOYEE BENEFIT PLANS Fair value plan assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure
Total investments	100.00%	100.00%
Defined Benefit Plan, Plan Assets, Amount	$ 86,556	$ 97,182	$ 84,753
Level 1
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Amount	203	3,996
Level 2
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Amount	0	0
Level 3
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Amount	$ 0	$ 0
Fixed Income Investments [Member]
Defined Benefit Plan Disclosure
Total investments	44.70%	41.40%
Defined Benefit Plan, Plan Assets, Amount	$ 38,668	$ 40,193
Fixed Income Investments [Member] \| Level 1
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Amount	0	0
Fixed Income Investments [Member] \| Level 2
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Amount	0	0
Fixed Income Investments [Member] \| Level 3
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Amount	$ 0	$ 0
Other Investments [Member]
Defined Benefit Plan Disclosure
Total investments	15.40%	21.70%
Defined Benefit Plan, Plan Assets, Amount	$ 13,347	$ 21,135
Other Investments [Member] \| Level 1
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Amount	203	3,996
Other Investments [Member] \| Level 2
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Amount	0	0
Other Investments [Member] \| Level 3
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Amount	$ 0	$ 0
Canada \| Equity Securities [Member]
Defined Benefit Plan Disclosure
Total investments	12.40%	11.50%
Defined Benefit Plan, Plan Assets, Amount	$ 10,693	$ 11,211
Canada \| Equity Securities [Member] \| Level 1
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Amount	0	0
Canada \| Equity Securities [Member] \| Level 2
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Amount	0	0
Canada \| Equity Securities [Member] \| Level 3
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Amount	$ 0	$ 0
United States \| Equity Securities [Member]
Defined Benefit Plan Disclosure
Total investments	5.00%	4.60%
Defined Benefit Plan, Plan Assets, Amount	$ 4,356	$ 4,436
United States \| Equity Securities [Member] \| Level 1
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Amount	0	0
United States \| Equity Securities [Member] \| Level 2
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Amount	0	0
United States \| Equity Securities [Member] \| Level 3
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Amount	$ 0	$ 0
Non-US [Member] \| Equity Securities [Member]
Defined Benefit Plan Disclosure
Total investments	22.50%	20.80%
Defined Benefit Plan, Plan Assets, Amount	$ 19,492	$ 20,207
Non-US [Member] \| Equity Securities [Member] \| Level 1
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Amount	0	0
Non-US [Member] \| Equity Securities [Member] \| Level 2
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Amount	0	0
Non-US [Member] \| Equity Securities [Member] \| Level 3
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Amount	0	0
Estimate of Fair Value Measurement [Member]
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Amount	86,353	93,186
Estimate of Fair Value Measurement [Member] \| Fixed Income Investments [Member]
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Amount	38,668	40,193
Estimate of Fair Value Measurement [Member] \| Other Investments [Member]
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Amount	13,144	17,139
Estimate of Fair Value Measurement [Member] \| Canada \| Equity Securities [Member]
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Amount	10,693	11,211
Estimate of Fair Value Measurement [Member] \| United States \| Equity Securities [Member]
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Amount	4,356	4,436
Estimate of Fair Value Measurement [Member] \| Non-US [Member] \| Equity Securities [Member]
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Amount	$ 19,492	$ 20,207