EMPLOYEE BENEFIT PLANS Fair value plan assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure
Total investments	100.00%	100.00%
Defined Benefit Plan, Plan Assets, Amount	$ 103,385	$ 86,556	$ 97,182
Level 1
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Amount	224	203
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	44.80%	44.70%
Defined Benefit Plan, Plan Assets, Amount	$ 46,309	$ 38,668
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	15.20%	15.40%
Defined Benefit Plan, Plan Assets, Amount	$ 15,704	$ 13,347
Other Investments [Member] | Level 1
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Amount	224	203
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	12.50%	12.40%
Defined Benefit Plan, Plan Assets, Amount	$ 12,973	$ 10,693
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%	5.00%
Defined Benefit Plan, Plan Assets, Amount	$ 5,160	$ 4,356
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%	22.50%
Defined Benefit Plan, Plan Assets, Amount	$ 23,239	$ 19,492
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	103,161	86,353
Estimate of Fair Value Measurement [Member] | Fixed Income Investments [Member]
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Amount	46,309	38,668
Estimate of Fair Value Measurement [Member] | Other Investments [Member]
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Amount	15,480	13,144
Estimate of Fair Value Measurement [Member] | Canada | Equity Securities [Member]
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Amount	12,973	10,693
Estimate of Fair Value Measurement [Member] | United States | Equity Securities [Member]
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Amount	5,160	4,356
Estimate of Fair Value Measurement [Member] | Non-US [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Amount	$ 23,239	$ 19,492