LONG TERM DEBT AND CREDIT AGREEMENT (Details)												3 Months Ended	12 Months Ended
	May 11, 2020 USD ($)	Jun. 18, 2019 USD ($)	May 13, 2019 USD ($)	May 02, 2019 USD ($)	Apr. 08, 2019 USD ($)	Jan. 22, 2019 USD ($) shares	May 10, 2018 USD ($)	Dec. 15, 2017 USD ($) shares	Feb. 26, 2016 USD ($)	Jun. 15, 2015 USD ($) position trading_day $ / shares shares	Jun. 15, 2015 USD ($) $ / shares shares	Jun. 30, 2017 USD ($)	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jan. 05, 2021 USD ($)	May 09, 2019 shares	Dec. 03, 2018 shares	Feb. 08, 2018 shares	Nov. 09, 2017 USD ($)	Jun. 09, 2015 USD ($)
Line of Credit Facility [Line Items]
Other Long-term Debt, Noncurrent													$ 1,271,000	$ 1,296,000
Term Loan, net													198,629,000	200,105,000
Convertible Notes Payable													0	28,187,000
Short-term Debt, Fair Value													4,941,000	30,554,000
Long-term Debt													202,759,000	199,034,000
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt, Subsequent Adjustments			$ 600,000
Repayments of Debt			72,700,000			$ 3,600,000		$ 1,700,000					$ 14,700,000
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt														(577,000)	$ (74,000)
Gain (Loss) on Extinguishment of Debt			(2,900,000)
ConvertibleDebtRetired | shares						3,900		2,000					16,247				73,986	96,133
ConvertibleDebtIssued | shares						106,753				125,000	125,000								123,000
Extinguishment of Debt, Amount			$ 74,000,000.0			$ 3,900,000		$ 2,000,000.0					$ 16,200,000
Capped Call Transaction Cost Reimbursement														27,000	16,000
Repayments of Lines of Credit													22,000,000	0	0
Debt, Long-term and Short-term, Combined Amount													207,700,000
Payments of Debt Issuance Costs				$ 6,000,000.0	$ 1,600,000
Debt Related Commitment Fees and Debt Issuance Costs					4,400,000
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net													2,579,000
Proceeds From Payroll Protection Program Loan, CARES Act	$ 7,800,000
Repayments of Senior Debt				72,700,000
Cash paid for interest				600,000									17,499,000	12,262,000	14,505,000
Repayments of Long-term Lines of Credit		$ 20,700,000
Proceeds from revolving credit facilities				$ 79,300,000									22,000,000.0	0	$ 0
Cerberus Business Finance LLC [Member]
Line of Credit Facility [Line Items]
Long-term Debt																				$ 115,000,000.0
additional long term debt																				15,000,000.0
Cerberus Business Finance LLC [Member] | Term Loan
Line of Credit Facility [Line Items]
Line Of Credit Facility, Maximum Borrowing Capacity, Increase					$ 100,000,000.0		$ 22,700,000
Cerberus Business Finance LLC [Member] | Revolving Credit Facility
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity							22,500,000
Interest Expense, Long-term Debt													800,000
Line Of Credit Facility, Maximum Borrowing Capacity, Increase							$ 12,500,000
Long-term Debt [Member] | Cerberus Business Finance LLC [Member]
Line of Credit Facility [Line Items]
Unamortized Debt Issuance Expense													0	3,334,000
Interest Expense, Long-term Debt													16,200,000
Convertible Debt [Member]
Line of Credit Facility [Line Items]
Long-term Debt, Gross										$ 125,000,000.0	$ 125,000,000.0
Net Proceeds from Issuance of Convertible Notes Payable										120,300,000	120,300,000
Convertible Debt, Noncurrent										$ 96,700,000	96,700,000
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt, Subsequent Adjustments											$ 28,300,000
Debt Instrument, Interest Rate, Stated Percentage										2.00%	2.00%
Debt Instrument, Interest Rate, Effective Percentage										7.66%	7.66%
Amortization of Debt Discount (Premium)													700,000	3,300,000
Interest Expense, Debt													900,000	4,400,000
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net													$ 0	$ 680,000
Debt Instrument, Convertible, Conversion Ratio										0.0455840
Debt Instrument, Convertible, Conversion Price | $ / shares										$ 21.94	$ 21.94
Debt Instrument, Convertible, Threshold Percentage of Stock Price Trigger										130.00%
Debt Instrument, Convertible, Threshold Trading Days | position										20
Debt Instrument, Convertible, Threshold Consecutive Trading Days | trading_day										30
Debt Instrument, Convertible, Measurement Period Threshold Percentage										98.00%
Debt Instrument, Redemption Price, Percentage										100.00%
Convertible Debt [Member] | Capped call [Member]
Line of Credit Facility [Line Items]
Capped Call Transaction Costs												$ 10,100,000
Derivative, Price Risk Option Strike Price																					21.94
Derivative, Cap Price																					26.00
Long-term Debt [Member] | Cerberus Business Finance LLC [Member]
Line of Credit Facility [Line Items]
Long-term Debt, Gross									$ 100,000,000.0
Debt Instrument, Percent Of Excess Cash Must Use For Debt Repayment									50.00%
Line of Credit [Member] | Cerberus Business Finance LLC [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity									$ 5,000,000.0											$ 10,000,000.0
Convertible Debt [Member]
Line of Credit Facility [Line Items]
Convertible Notes Payable Transaction Costs										$ 4,700,000	$ 4,700,000
Convertible Debt [Member] | Interest Expense [Member]
Line of Credit Facility [Line Items]
Convertible Notes Payable Transaction Costs										3,600,000	3,600,000
Convertible Debt [Member] | Equity [Member]
Line of Credit Facility [Line Items]
Convertible Notes Payable Transaction Costs										$ 1,100,000	$ 1,100,000
Subsequent Event [Member] | JPMorgan Chase [Member] | Term Loan
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity																$ 180,000,000
Subsequent Event [Member] | JPMorgan Chase [Member] | Revolving Credit Facility
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity																$ 70,000,000