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Long-term Debt - Summary of Long-term Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Jan. 30, 2018	Jan. 12, 2018
Debt Instrument [Line Items]
Total debt	$ 264,872	$ 248,169
Less: Current portion	(25,643)	(25,617)
Long-term debt	239,229	222,552
Unamortized debt issuance costs	1,200	1,400
Convertible Debt
Debt Instrument [Line Items]
Total debt	164,370	167,594
Unsecured Debt
Debt Instrument [Line Items]
Total debt	25,000	25,000
Stated interest rate				2.50%
Other debt and finance lease obligations
Debt Instrument [Line Items]
Total debt	5,031	5,041
Revolving Credit Facility
Debt Instrument [Line Items]
Total debt	$ 70,471	50,534
1.5% Convertible Unsecured Senior Notes
Debt Instrument [Line Items]
Stated interest rate	1.50%
1.5% Convertible Unsecured Senior Notes \| Convertible Debt
Debt Instrument [Line Items]
Unamortized debt issuance costs	$ 2,814	3,112
Stated interest rate			1.50%
Long-term debt, gross	$ 186,550	$ 192,250