Financing Arrangements and Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Long-term debt, gross	$ 197,996	$ 179,499
Unamortized discount and debt issuance costs	(16,437)	(17,752)
Long-term debt	181,559	161,747
Long-term debt, current maturities, gross	(1,955)	(2,522)
Unamortized discount and debt issuance costs, current	0	0
Long-term debt, current maturities	(1,955)	(2,522)
Long-term debt, excluding current maturities, gross	196,041	176,977
Unamortized discount and debt issuance costs, noncurrent	(16,437)	(17,752)
Long-term debt, excluding current maturities	179,604	159,225
Other Debt
Debt Instrument [Line Items]
Long-term debt, gross	2,996	3,199
Long-term debt	2,996	3,199
Senior notes | Convertible Notes due 2021
Debt Instrument [Line Items]
Long-term debt, gross	100,000	100,000
Unamortized discount and debt issuance costs	(16,437)	(17,752)
Long-term debt	83,563	82,248
Revolving credit facility | ABL Facility
Debt Instrument [Line Items]
Long-term debt, gross	95,000	76,300
Long-term debt	$ 95,000	$ 76,300