CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Comprehensive Income	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Treasury Stock	Noncontrolling Interest
Balance at Dec. 31, 2016	$ 231,435		$ 140	$ 1,018,010	$ (722,630)	$ (64,085)	$ 0
Balance (in shares) at Dec. 31, 2016			13,955,000			2,164,000
Increase (Decrease) in Stockholders' Equity
Net income and comprehensive income	15,578	$ 15,578			15,578
Non-cash compensation	23,361			23,361
Purchase of treasury stock	$ (21,000)					$ (21,000)
Purchase of treasury stock (in shares)	75,393					75,000
Issuance of common stock for stock options, restricted stock awards and restricted stock units, net of withholding taxes	$ 1,601		$ 2	1,599
Issuance of common stock for stock options, restricted stock awards and restricted stock units, net of withholding taxes (in shares)			263,000
Noncontrolling Interest	589			0			589
Cumulative effect adjustment | Accounting Standards Update 2016-09	985			2,287	(1,302)
Issuance of 0.625% Convertible Senior Notes, net	60,415			60,415
Convertible note hedge	(61,500)			(61,500)
Sale of warrants	43,410			43,410
Balance at Dec. 31, 2017	294,874		$ 142	1,087,582	(708,354)	$ (85,085)	589
Balance (in shares) at Dec. 31, 2017			14,218,000			2,239,000
Increase (Decrease) in Stockholders' Equity
Net income and comprehensive income	96,499	96,499			96,499
Non-cash compensation	44,365			44,365
Purchase of treasury stock	$ (92,606)					$ (92,606)
Purchase of treasury stock (in shares)	379,449					379,000
Issuance of common stock for stock options, restricted stock awards and restricted stock units, net of withholding taxes	$ 2,217		$ 12	2,205
Issuance of common stock for stock options, restricted stock awards and restricted stock units, net of withholding taxes (in shares)			1,210,000
Cumulative effect adjustment | Accounting Standards Update 2014-09	1,373			0	1,373
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests	(510)			79			(589)
Stockholders' Equity, Other	(4)			(4)
Balance at Dec. 31, 2018	346,208		$ 154	1,134,227	(610,482)	$ (177,691)	0
Balance (in shares) at Dec. 31, 2018			15,428,000			2,618,000
Increase (Decrease) in Stockholders' Equity
Net income and comprehensive income	17,828	$ 17,828			17,828
Non-cash compensation	52,167			52,167
Purchase of treasury stock	$ (5,470)					$ (5,470)
Purchase of treasury stock (in shares)	22,731					23,000
Issuance of common stock for stock options, restricted stock awards and restricted stock units, net of withholding taxes	$ (8,406)		$ 3	(8,409)
Issuance of common stock for stock options, restricted stock awards and restricted stock units, net of withholding taxes (in shares)			249,000
Stockholders' Equity, Other	(1)			(1)	0
Balance at Dec. 31, 2019	$ 402,326		$ 157	$ 1,177,984	$ (592,654)	$ (183,161)	$ 0
Balance (in shares) at Dec. 31, 2019			15,677,000			2,641,000
Increase (Decrease) in Stockholders' Equity
Interest rate	0.625%