CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interest in Subsidiary	Total
Increase (Decrease) in Stockholders' Equity
Cumulative effect of adopting ASU (Note 1) | Accounting Standards Update 2016-09 and 2016-16		$ 194	$ (497)			$ (303)
Adjusted Beginning balance	$ 15	1,090,555	(604,333)	$ (17,675)	$ 24,822	493,384
Adjusted Beginning balance (in shares)	145,538,063
Beginning balance (in shares) at Dec. 31, 2016	145,538,063
Beginning balance at Dec. 31, 2016	$ 15	1,090,361	(603,836)	(17,675)	24,822	493,687
Increase (Decrease) in Stockholders' Equity
Issuance of common stock, net of offering costs (in shares)	6,112,906
Issuance of common stock, net of offering costs		12,454				12,454
Stock-based compensation		8,423				8,423
Net income (loss)			(79,237)		(2,154)	(81,391)
Other comprehensive income (loss)				16,788		16,788
Ending balance (in shares) at Dec. 31, 2017	151,650,969
Ending balance at Dec. 31, 2017	$ 15	1,111,432	(683,570)	(887)	22,668	449,658
Increase (Decrease) in Stockholders' Equity
Cumulative effect of adopting ASU (Note 1) | ASC 606			(1,293)			(1,293)
Adjusted Beginning balance	$ 15	1,111,432	(684,863)	(887)	22,668	448,365
Adjusted Beginning balance (in shares)	151,650,969
Issuance of common stock, net of offering costs (in shares)	51,948,923
Issuance of common stock, net of offering costs	$ 5	81,766				81,771
Stock-based compensation		5,307				5,307
Net income (loss)			(3,790)		(5,393)	(9,183)
Other comprehensive income (loss)				(1,251)		$ (1,251)
Increase in ownership in subsidiary		264			(264)
Ending balance (in shares) at Dec. 31, 2018	203,599,892					203,599,892
Ending balance at Dec. 31, 2018	$ 20	1,198,769	(688,653)	(2,138)	17,011	$ 525,009
Increase (Decrease) in Stockholders' Equity
Issuance of common stock, net of offering costs (in shares)	1,123,163
Issuance of common stock, net of offering costs		309				309
Stock-based compensation		3,880				3,880
Net income (loss)			20,421		(7,162)	13,259
Other comprehensive income (loss)				572		$ 572
Increase in ownership in subsidiary		228			(228)
Ending balance (in shares) at Dec. 31, 2019	204,723,055					204,723,055
Ending balance at Dec. 31, 2019	$ 20	$ 1,203,186	$ (668,232)	$ (1,566)	$ 9,621	$ 543,029