CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Additional Paid-in Capital	Additional Paid-in Capital Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Accumulated Deficit Cumulative Effect, Period of Adoption, Adjustment
Beginning balance (in shares) at Dec. 31, 2019			104,781,236
Beginning balance at Dec. 31, 2019	$ 507,408		$ 105	$ 520,278		$ (1,618)	$ (11,357)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issuance ESPP Plan (in shares)			34,330
Common stock issuance ESPP Plan	796			796
Issuance of restricted stock, net of forfeitures (in shares)			76,618
Issuance of restricted stock, net of forfeitures	(212)			(212)
Issuance of common stock for stock options (in shares)			503,873
Issuance of common stock for stock options	2,897			2,897
Stock issuance fees and expenses	(15)			(15)
ESPP expense	194			194
Stock-based compensation expense - options and restricted stock	1,991			1,991
Gain (loss) on effective cash flow hedge	(1,038)					(1,038)
Net income (loss)	(6,978)						(6,978)
Ending balance (in shares) at Mar. 31, 2020			105,396,057
Ending balance at Mar. 31, 2020	505,043		$ 105	525,929		(2,656)	(18,335)
Beginning balance (in shares) at Dec. 31, 2019			104,781,236
Beginning balance at Dec. 31, 2019	507,408		$ 105	520,278		(1,618)	(11,357)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net unrealized loss on marketable securities, net of tax	0
Loss on derivative reclassified from AOCI to earnings	2,661
Net income (loss)	(13,802)
Ending balance (in shares) at Jun. 30, 2020			110,396,844
Ending balance at Jun. 30, 2020	654,229		$ 110	679,235		43	(25,159)
Beginning balance (in shares) at Mar. 31, 2020			105,396,057
Beginning balance at Mar. 31, 2020	505,043		$ 105	525,929		(2,656)	(18,335)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issuance ESPP Plan (in shares)			41,058
Common stock issuance ESPP Plan	928			928
Issuance of restricted stock, net of forfeitures (in shares)			24,786
Issuance of restricted stock, net of forfeitures	(824)			(824)
Issuance of common stock for stock options (in shares)			183,443
Issuance of common stock for stock options	2,014			2,014
Issuance of common stock - public offering, net of underwriting discounts (in shares)			4,751,500
Issuance of common stock - public offering, net of underwriting discounts	127,293		$ 5	127,288
Stock issuance fees and expenses	(317)			(317)
ESPP expense	211			211
Stock-based compensation expense - options and restricted stock	2,424			2,424
Equity component of convertible note issuance	30,912			30,912
Tax liability related to convertible note issuance	(9,330)			(9,330)
Net unrealized loss on marketable securities, net of tax	0
Gain (loss) on effective cash flow hedge	38					38
Loss on derivative reclassified from AOCI to earnings	2,661					2,661
Net income (loss)	(6,824)						(6,824)
Ending balance (in shares) at Jun. 30, 2020			110,396,844
Ending balance at Jun. 30, 2020	654,229		$ 110	679,235		43	(25,159)
Beginning balance (in shares) at Dec. 31, 2020			112,075,474
Beginning balance at Dec. 31, 2020	694,294	$ (22,575)	$ 112	701,357	$ (23,271)	10	(7,185)	$ 696
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Premiums paid for capped call confirmations	(29,291)			(29,291)
Common stock issuance ESPP Plan (in shares)			23,917
Common stock issuance ESPP Plan	1,024			1,024
Issuance of restricted stock, net of forfeitures (in shares)			83,220
Issuance of restricted stock, net of forfeitures	(614)			(614)
Issuance of common stock for stock options (in shares)			260,167
Issuance of common stock for stock options	2,239			2,239
Issuance of common stock - public offering, net of underwriting discounts (in shares)			4,693,876
Issuance of common stock - public offering, net of underwriting discounts	218,500		$ 5	218,495
Stock issuance fees and expenses	(242)			(242)
ESPP expense	241			241
Stock-based compensation expense - options and restricted stock	2,412			2,412
Net unrealized loss on marketable securities, net of tax	(160)					(160)
Net income (loss)	(22,114)						(22,114)
Ending balance (in shares) at Mar. 31, 2021			117,136,654
Ending balance at Mar. 31, 2021	843,714		$ 117	872,350		(150)	(28,603)
Beginning balance (in shares) at Dec. 31, 2020			112,075,474
Beginning balance at Dec. 31, 2020	$ 694,294	$ (22,575)	$ 112	701,357	$ (23,271)	10	(7,185)	$ 696
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock for stock options (in shares)	612,307
Net unrealized loss on marketable securities, net of tax	$ (343)
Loss on derivative reclassified from AOCI to earnings	0
Net income (loss)	53,759
Ending balance (in shares) at Jun. 30, 2021			122,711,352
Ending balance at Jun. 30, 2021	1,148,358		$ 123	1,101,298		(333)	47,270
Beginning balance (in shares) at Mar. 31, 2021			117,136,654
Beginning balance at Mar. 31, 2021	843,714		$ 117	872,350		(150)	(28,603)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issuance ESPP Plan (in shares)			31,839
Common stock issuance ESPP Plan	1,245			1,245
Issuance of restricted stock, net of forfeitures (in shares)			146,392
Issuance of restricted stock, net of forfeitures	(163)			(163)
Issuance of common stock for stock options (in shares)			354,310
Issuance of common stock for stock options	4,430		$ 1	4,429
Issuance of common stock - public offering, net of underwriting discounts (in shares)			4,444,445
Issuance of common stock - public offering, net of underwriting discounts	189,863		$ 4	189,859
Issuance of common stock for acquisition (in shares)			597,712
Issuance of common stock for acquisition	29,175		$ 1	29,174
Stock issuance fees and expenses	(102)			(102)
ESPP expense	298			298
Stock-based compensation expense - options and restricted stock	4,208			4,208
Net unrealized loss on marketable securities, net of tax	(183)					(183)
Loss on derivative reclassified from AOCI to earnings	0
Net income (loss)	75,873						75,873
Ending balance (in shares) at Jun. 30, 2021			122,711,352
Ending balance at Jun. 30, 2021	$ 1,148,358		$ 123	$ 1,101,298		$ (333)	$ 47,270