EMPLOYEE BENEFITS (Details Textual) - USD ($) $ in Thousands			12 Months Ended
	Apr. 30, 2017	Jan. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Eligible age for health plan coverage			65 years
401k Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service period for employer contribution			1 year
Annual employer contribution per employee percent			4.00%
Employer matching percent of employee percent			25.00%
Employer matching limit			4.00%
Cost recognized			$ 1,800	$ 1,700	$ 2,000
Age at which enhanced contribution commences if age requirement was met on 1/1/2011			50 years
Defined Contribution Plan, Minimum age at 1/1/2011 to qualify for enhanced contribution			40 years
Enhanced Defined Contribution Plan Cost Recognized			$ 1,700	1,600	2,000
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic cost (benefit)			3,007	3,530	2,022
Assets for plan benefits			2,956	2,387
Accumulated benefit obligation			243,500	232,500
Benefit obligation			247,146	235,826	234,350
Settlement loss			118	633	16
Defined Benefit Plan, Benefit Obligation, Special and Contractual Termination Benefits			0	0	(235)
Settlements			921	2,694
Amortization of prior service credit			$ (311)	$ (311)	(318)
Discount rate			3.90%	4.38%
Increase / Decrease in benefit obligation due to change in discount rate			$ 100
Future amortization of gain (loss)			(3,200)
Future amortization of prior service cost (credit)			300
Employer contributions			4,618	$ 4,214
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic cost (benefit)			42	29	35
Assets for plan benefits			0	0
Benefit obligation			1,701	1,729	1,683
Settlement loss			0	0	0
Defined Benefit Plan, Benefit Obligation, Special and Contractual Termination Benefits			0	0	0
Settlements			0	0
Amortization of prior service credit			0	0	0
Future amortization of gain (loss)			40
Employer contributions			$ 98	108
Other Postretirement Benefits Plan [Member] | Kellenberger Stiftung Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Settlement loss	$ 100	$ 600
Defined Benefit Plan, Benefit Obligation, Special and Contractual Termination Benefits					200
Postretirement Health Coverage [Member]
Defined Benefit Plan Disclosure [Line Items]
Eligible service period			10 years
Postretirement Life Insurance [Member]
Defined Benefit Plan Disclosure [Line Items]
Eligible age for electing early retirement			55 years
Eligible service period for employees electing early retirement			15 years
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions in next fiscal year			$ 2,400
Foreign Plan [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Planned asset allocations			38.00%
Foreign Plan [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Planned asset allocations			44.00%
Foreign Plan [Member] | Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Planned asset allocations			18.00%
Foreign Plan [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic cost (benefit)			$ 1,900	2,100	$ 600
Assets for plan benefits			120,500	105,100
Benefit obligation			129,400	120,200
United States
Defined Benefit Plan Disclosure [Line Items]
Employer contributions			2,000	$ 1,600
Employer contributions in next fiscal year			$ 4,000
United States | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Planned asset allocations			55.00%
United States | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Planned asset allocations			36.00%
United States | Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Planned asset allocations			9.00%
United States | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate			3.86%	4.39%
United States | Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate			3.90%	4.38%