CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Deficit Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Balance at beginning of period (in shares) at Dec. 31, 2018			224,290
Balance at beginning of period at Dec. 31, 2018	$ 1,034,772	$ (700)	$ 2,829	$ 1,062,794	$ 16,860	$ (700)	$ (32,338)	$ (15,373)
Increase (Decrease) in Stockholders' Equity
Net loss	(28,287)				(28,287)
Foreign currency translation adjustments	250						250
Equity-based compensation expense	2,574			2,574
Common shares issued upon vesting of share-based awards (in shares)			720
Common shares issued upon vesting of share-based awards	0		$ 8	(8)
Common shares issued for employee stock purchase plan (in shares)			154
Common shares issued for employee stock purchase plan	692		$ 2	690
Treasury shares withheld (in shares)			(220)
Treasury shares withheld	(1,452)							(1,452)
Balance at end of period (in shares) at Mar. 31, 2019			224,944
Balance at end of period at Mar. 31, 2019	1,007,849		$ 2,839	1,066,050	(12,127)		(32,088)	(16,825)
Balance at beginning of period (in shares) at Dec. 31, 2018			224,290
Balance at beginning of period at Dec. 31, 2018	1,034,772	(700)	$ 2,829	1,062,794	16,860	(700)	(32,338)	(15,373)
Increase (Decrease) in Stockholders' Equity
Net loss	(43,447)
Foreign currency translation adjustments	708
Balance at end of period (in shares) at Jun. 30, 2019			225,115
Balance at end of period at Jun. 30, 2019	996,076		$ 2,841	1,069,065	(28,923)		(29,994)	(16,913)
Balance at beginning of period (in shares) at Mar. 31, 2019			224,944
Balance at beginning of period at Mar. 31, 2019	1,007,849		$ 2,839	1,066,050	(12,127)		(32,088)	(16,825)
Increase (Decrease) in Stockholders' Equity
Net loss	(15,160)				(15,160)
Foreign currency translation adjustments	458						458
Change in marketable securities	0				(1,636)		1,636
Equity-based compensation expense	3,017			3,017
Common shares issued upon vesting of share-based awards (in shares)			186
Common shares issued upon vesting of share-based awards	0		$ 2	(2)
Treasury shares withheld (in shares)			(15)
Treasury shares withheld	(88)							(88)
Balance at end of period (in shares) at Jun. 30, 2019			225,115
Balance at end of period at Jun. 30, 2019	996,076		$ 2,841	1,069,065	(28,923)		(29,994)	(16,913)
Balance at beginning of period (in shares) at Dec. 31, 2019			225,511
Balance at beginning of period at Dec. 31, 2019	810,294	(321)	$ 2,846	1,075,809	(220,805)	(321)	(30,298)	(17,258)
Increase (Decrease) in Stockholders' Equity
Net loss	(85,978)				(85,978)
Foreign currency translation adjustments	424						424
Equity-based compensation expense	2,146			2,146
Common shares issued upon vesting of share-based awards (in shares)			937
Common shares issued upon vesting of share-based awards	0		$ 10	(10)
Common shares issued for employee stock purchase plan (in shares)			126
Common shares issued for employee stock purchase plan	552		$ 1	551
Treasury shares withheld (in shares)			(293)
Treasury shares withheld	(1,056)							(1,056)
Share repurchase program (in shares)			(373)
Share repurchase program	(1,017)							(1,017)
Balance at end of period (in shares) at Mar. 31, 2020			225,908
Balance at end of period at Mar. 31, 2020	725,044		$ 2,857	1,078,496	(307,104)		(29,874)	(19,331)
Balance at beginning of period (in shares) at Dec. 31, 2019			225,511
Balance at beginning of period at Dec. 31, 2019	810,294	$ (321)	$ 2,846	1,075,809	(220,805)	$ (321)	(30,298)	(17,258)
Increase (Decrease) in Stockholders' Equity
Net loss	(120,223)
Foreign currency translation adjustments	285
Balance at end of period (in shares) at Jun. 30, 2020			225,927
Balance at end of period at Jun. 30, 2020	693,664		$ 2,860	1,082,008	(341,349)		(30,013)	(19,842)
Balance at beginning of period (in shares) at Mar. 31, 2020			225,908
Balance at beginning of period at Mar. 31, 2020	725,044		$ 2,857	1,078,496	(307,104)		(29,874)	(19,331)
Increase (Decrease) in Stockholders' Equity
Net loss	(34,245)				(34,245)
Foreign currency translation adjustments	(139)						(139)
Equity-based compensation expense	3,515			3,515
Common shares issued upon vesting of share-based awards (in shares)			229
Common shares issued upon vesting of share-based awards	0		$ 3	(3)
Treasury shares withheld (in shares)			(13)
Treasury shares withheld	(31)							(31)
Share repurchase program (in shares)			(197)
Share repurchase program	(480)							(480)
Balance at end of period (in shares) at Jun. 30, 2020			225,927
Balance at end of period at Jun. 30, 2020	$ 693,664		$ 2,860	$ 1,082,008	$ (341,349)		$ (30,013)	$ (19,842)