Long-Term Debt (Details) - USD ($)	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2017	Mar. 31, 2016
Debt Instrument [Line Items]
Long-term debt	$ 244,243,000	$ 219,522,000
Long-term Debt and Capital Lease Obligations, Current	(79,217,000)	(58,000)
Long-term debt net of current maturities	165,026,000	219,464,000
Convertible Subordinated Debt | Convertible Senior Notes at 5.00% February 2021 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	61,091,000	61,091,000		$ 150,000,000
Long-term debt	57,573,000	56,628,000
Debt Instrument, Unamortized Discount	(3,092,000)	(3,916,000)
Debt Instrument, Fee Amount	(426,000)	(547,000)
Debt Instrument, Net Carrying Amount	57,573,000	56,628,000
Convertible Subordinated Debt | Convertible Senior Notes at 4.50% February 2022 [Domain]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	120,000,000	120,000,000	$ 120,000,000
Long-term debt	103,499,000	101,815,000
Debt Instrument, Unamortized Discount	(14,566,000)	(16,027,000)
Debt Instrument, Fee Amount	(1,935,000)	(2,158,000)
Debt Instrument, Net Carrying Amount	103,499,000	101,815,000
Convertible Subordinated Debt | Convertible Senior Notes at 5.00% November 2024 [Domain]
Debt Instrument [Line Items]
Long-term debt	61,325,000	60,817,000
Other Notes and Capital Lease Obligations
Debt Instrument [Line Items]
Long-term debt	$ 21,846,000	$ 262,000