ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Leases (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018	Mar. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Package of practical expedients	true
Assets
Other current assets	$ 17,058	$ 14,744	$ 18,731
Total current assets	245,230	321,913	325,900
Property, plant and equipment, net	81,951	81,421	89,489
Other intangible assets, net	16,415	15,258	15,478
Deferred income taxes	69,738	65,065	65,635
Operating lease right-of-use assets	103,676	103,378
Other assets	8,392	8,304	7,766
Total assets	752,034	794,081	703,010
Current liabilities:
Current portion of long-term debt	8,677	7,964	8,583
Accrued expenses and other current liabilities	53,311	50,431	51,783
Current portion of operating lease liabilities	33,675	33,393
Total current liabilities	168,064	202,696	171,274
Long-term debt, less current portion	490,623	489,597	502,090
Operating lease liabilities	83,693	83,662
Other liabilities	40,259	38,489	51,570
Total liabilities	782,639	814,444	724,934
Shareholders' deficit:
Retained Earnings (Accumulated Deficit)	(366,413)	(359,462)	(361,023)
Total shareholders' deficit	(30,605)	(20,363)	(21,924)	$ (53,575)	$ (28,810)	$ (28,051)
Total liabilities and shareholders' deficit	$ 752,034	794,081	$ 703,010
ASU 2016-02 | Restatement Adjustments
Assets
Other current assets		(3,987)
Total current assets		(3,987)
Property, plant and equipment, net		(8,068)
Other intangible assets, net		(220)
Deferred income taxes		(570)
Operating lease right-of-use assets		103,378
Other assets		538
Total assets		91,071
Current liabilities:
Current portion of long-term debt		(619)
Accrued expenses and other current liabilities		(1,352)
Current portion of operating lease liabilities		33,393
Total current liabilities		31,422
Long-term debt, less current portion		(12,493)
Operating lease liabilities		83,662
Other liabilities		(13,081)
Total liabilities		89,510
Shareholders' deficit:
Retained Earnings (Accumulated Deficit)		1,561
Total shareholders' deficit		1,561
Total liabilities and shareholders' deficit		$ 91,071