INCOME TAXES - Significant Portions of Deferred Tax Assets and Liabilities (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Inventories	$ 1,844,000	$ 1,260,000
Restricted stock and stock options	4,097,000	3,567,000
Lease liabilities	1,456,000	0
Currency and interest rate swap	442,000	0
Other	3,935,000	2,885,000
Total deferred tax assets	11,774,000	7,712,000
Deferred tax liabilities:
Amortization	28,589,000	27,080,000
Depreciation	37,075,000	23,837,000
Prepaid expenses	465,000	0
Right of use assets	1,461,000	0
Other	584,000	1,104,000
Total deferred tax liabilities	68,174,000	52,021,000
Valuation allowance	31,000	0
Net deferred tax liability	$ 56,431,000	$ 44,309,000