INCOME TAXES - Significant Portions of Deferred Tax Assets and Liabilities (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets [Abstract]
Inventories	$ 1,260,000	$ 1,297,000
Restricted stock and stock options	3,567,000	3,248,000
Other	2,885,000	1,764,000
Total deferred tax assets	7,712,000	6,309,000
Deferred tax liabilities [Abstract]
Amortization	27,080,000	31,311,000
Depreciation	23,837,000	22,172,000
Other	1,104,000	1,374,000
Total deferred tax liabilities	52,021,000	54,857,000
Net deferred tax liability	44,309,000	48,548,000
Valuation allowance for deferred tax assets	$ 0	$ 0