CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Treasury Stock
Beginning balance at Dec. 31, 2019	$ 402,326	$ 157	$ 1,177,984	$ (592,654)	$ (183,161)
Beginning balance (in shares) at Dec. 31, 2019		15,677			2,641
Increase (Decrease) in Stockholders' Equity
Net income (loss) and comprehensive income (loss)	14,401			14,401
Non-cash compensation	11,917		11,917
Issuance of common stock for stock options, restricted stock awards and restricted stock units, net of withholding taxes	(5,087)		(5,087)
Issuance of common stock for stock options, restricted stock awards and restricted stock units, net of withholding taxes (in shares)		27
Other	0		(1)	1
Ending balance at Mar. 31, 2020	423,557	$ 157	1,184,813	(578,252)	$ (183,161)
Ending balance (in shares) at Mar. 31, 2020		15,704			2,641
Beginning balance at Dec. 31, 2019	402,326	$ 157	1,177,984	(592,654)	$ (183,161)
Beginning balance (in shares) at Dec. 31, 2019		15,677			2,641
Increase (Decrease) in Stockholders' Equity
Net income (loss) and comprehensive income (loss)	(15,356)
Ending balance at Jun. 30, 2020	405,977	$ 157	1,196,990	(608,009)	$ (183,161)
Ending balance (in shares) at Jun. 30, 2020		15,731			2,641
Beginning balance at Mar. 31, 2020	423,557	$ 157	1,184,813	(578,252)	$ (183,161)
Beginning balance (in shares) at Mar. 31, 2020		15,704			2,641
Increase (Decrease) in Stockholders' Equity
Net income (loss) and comprehensive income (loss)	(29,757)			(29,757)
Non-cash compensation	13,158		13,158
Issuance of common stock for stock options, restricted stock awards and restricted stock units, net of withholding taxes	(981)		(981)
Issuance of common stock for stock options, restricted stock awards and restricted stock units, net of withholding taxes (in shares)		27
Ending balance at Jun. 30, 2020	405,977	$ 157	1,196,990	(608,009)	$ (183,161)
Ending balance (in shares) at Jun. 30, 2020		15,731			2,641
Beginning balance at Dec. 31, 2020	364,761	$ 158	1,188,673	(640,909)	$ (183,161)
Beginning balance (in shares) at Dec. 31, 2020		15,766			2,641
Increase (Decrease) in Stockholders' Equity
Net income (loss) and comprehensive income (loss)	19,049			19,049
Non-cash compensation	16,436		16,436
Issuance of common stock for stock options, restricted stock awards and restricted stock units, net of withholding taxes	(4,801)		(4,801)
Issuance of common stock for stock options, restricted stock awards and restricted stock units, net of withholding taxes (in shares)		31
Other	(2)		(2)
Ending balance at Mar. 31, 2021	395,443	$ 158	1,200,306	(621,860)	$ (183,161)
Ending balance (in shares) at Mar. 31, 2021		15,797			2,641
Beginning balance at Dec. 31, 2020	364,761	$ 158	1,188,673	(640,909)	$ (183,161)
Beginning balance (in shares) at Dec. 31, 2020		15,766			2,641
Increase (Decrease) in Stockholders' Equity
Net income (loss) and comprehensive income (loss)	25,650
Ending balance at Jun. 30, 2021	420,368	$ 160	1,218,628	(615,259)	$ (183,161)
Ending balance (in shares) at Jun. 30, 2021		15,956			2,641
Beginning balance at Mar. 31, 2021	395,443	$ 158	1,200,306	(621,860)	$ (183,161)
Beginning balance (in shares) at Mar. 31, 2021		15,797			2,641
Increase (Decrease) in Stockholders' Equity
Net income (loss) and comprehensive income (loss)	6,601			6,601
Non-cash compensation	18,294		18,294
Issuance of common stock for stock options, restricted stock awards and restricted stock units, net of withholding taxes	30	$ 2	28
Issuance of common stock for stock options, restricted stock awards and restricted stock units, net of withholding taxes (in shares)		159
Ending balance at Jun. 30, 2021	$ 420,368	$ 160	$ 1,218,628	$ (615,259)	$ (183,161)
Ending balance (in shares) at Jun. 30, 2021		15,956			2,641