ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($)	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Changes in accumulated other comprehensive income (loss) [Abstract]
Net foreign currency translation adjustment	$ (2,209,000)			$ (545,000)			$ (3,513,000)	$ (2,093,000)
Unrealized loss on cash flow hedge	(769,000)			0			(2,475,000)	0
Tax	112,000			0			519,000	0
Net of tax	(657,000)			0			(1,956,000)	0
Net change in postretirement benefit plan (see Note 15 for further information)
Amortization of prior service cost	19,000			17,000			55,000	52,000
Amortization of gain	(12,000)			0			(34,000)	(2,000)
Total before tax	7,000			17,000			21,000	50,000
Tax	(2,000)			(8,000)			(5,000)	(12,000)
Net of tax	5,000			9,000			16,000	38,000
Other comprehensive loss	(2,861,000)	$ (1,508,000)	$ (1,084,000)	(536,000)	$ (2,895,000)	$ 1,376,000	(5,453,000)	(2,055,000)
Gain related to net investment hedge	4,626,000			0			1,715,000	0
Taxes on net investment hedge	$ 456,000			$ 0			$ 456,000	$ 0