Long-Term Debt Components of Convertible Debt (Details) - USD ($)	3 Months Ended				6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2017	Mar. 31, 2016	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Sep. 30, 2017
Debt Instrument [Line Items]
Issuance of warrants				$ 12,376,000
Long-term debt	$ 257,126,000				$ 257,126,000		$ 219,522,000
Convertible Subordinated Debt | Convertible Senior Notes at 5.00% February 2021 [Member]
Debt Instrument [Line Items]
Debt Instrument, Increase, Accrued Interest	631,000	$ 1,875,000			1,376,000	$ 3,750,000
Debt Instrument, Face Amount	$ 25,716,000			$ 150,000,000	$ 25,716,000		61,091,000
Interest rate (as a percent)	5.00%				5.00%
Unamortized discount	$ (944,000)				$ (944,000)		(3,916,000)
Long-term debt	24,644,000				24,644,000		56,628,000
Debt fees	(128,000)				(128,000)		(547,000)
Debt Instrument, Net Carrying Amount	24,644,000				24,644,000		56,628,000
Convertible Subordinated Debt | Convertible Senior Notes at 4.50% February 2022 [Domain]
Debt Instrument [Line Items]
Debt Instrument, Increase, Accrued Interest	1,220,000	$ 1,350,000			2,570,000	$ 2,700,000
Debt Instrument, Face Amount	$ 81,500,000				$ 81,500,000		120,000,000	$ 120,000,000
Issuance of warrants			$ 14,100,000
Interest rate (as a percent)	4.50%				4.50%
Unamortized discount	$ (8,883,000)				$ (8,883,000)		(16,027,000)
Long-term debt	71,454,000				71,454,000		101,815,000
Debt fees	(1,163,000)				(1,163,000)		(2,158,000)
Debt Instrument, Net Carrying Amount	71,454,000				71,454,000		101,815,000
Convertible Subordinated Debt | Convertible Senior Notes at 5.00% November 2024 [Domain]
Debt Instrument [Line Items]
Long-term debt	61,908,000				61,908,000		60,817,000
Convertible Subordinated Debt | Convertible Senior Notes at 5.00% November 2024 [Member]
Debt Instrument [Line Items]
Debt Instrument, Increase, Accrued Interest	912,000				1,823,000
Debt Instrument, Loss on Exchange							5,885,000
Debt Instrument, Face Amount	$ 72,909,000				$ 72,909,000		$ 72,909,000
Interest rate (as a percent)	5.00%				5.00%		5.00%
Unamortized discount	$ (9,831,000)				$ (9,831,000)		$ (10,733,000)
Debt fees	(1,170,000)				(1,170,000)		(1,359,000)
Debt Instrument, Net Carrying Amount	$ 61,908,000				$ 61,908,000		$ 60,817,000