Consolidated Statements of Changes in Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Loss, Net [Member]	Accumulated Deficit [Member]	Total
Balances at Dec. 31, 2018	$ 155	$ 2,735,125		$ (73,177)	$ (2,371,364)	$ 290,739
Beginning balance, shares at Dec. 31, 2018	15,488,542
Net loss					(47,705)	(47,705)
Foreign currency translation adjustment				1,073		1,073
Stock-based compensation expense, net of forfeitures		5,625				5,625
Transactions under stock plans, value	$ 1	(1,667)				(1,666)
Transactions under stock plans, shares	107,118
Balances at Mar. 31, 2019	$ 156	2,739,083		(72,104)	(2,419,069)	248,066
Ending balance, shares at Mar. 31, 2019	15,595,660
Balances at Dec. 31, 2018	$ 155	2,735,125		(73,177)	(2,371,364)	290,739
Beginning balance, shares at Dec. 31, 2018	15,488,542
Net loss						(157,196)
Foreign currency translation adjustment						(3,810)
Balances at Sep. 30, 2019	$ 157	2,748,477		(76,987)	(2,528,560)	143,087
Ending balance, shares at Sep. 30, 2019	15,657,357
Balances at Dec. 31, 2018	$ 155	2,735,125		(73,177)	(2,371,364)	290,739
Beginning balance, shares at Dec. 31, 2018	15,488,542
Balances at Dec. 31, 2019	$ 16	2,752,859	$ (4,290)	(71,927)	(2,627,085)	49,573
Ending balance, shares at Dec. 31, 2019	15,689,463
Balances at Mar. 31, 2019	$ 156	2,739,083		(72,104)	(2,419,069)	248,066
Beginning balance, shares at Mar. 31, 2019	15,595,660
Net loss					(71,050)	(71,050)
Foreign currency translation adjustment				(1,916)		(1,916)
Stock-based compensation expense, net of forfeitures		4,650				4,650
Transactions under stock plans, value		(10)				(10)
Transactions under stock plans, shares	11,637
Shares issued under Employee Stock Purchase Plan, value	$ 1	650				651
Shares issued under Employee Stock Purchase Plan	50,019
Balances at Jun. 30, 2019	$ 157	2,744,373		(74,020)	(2,490,119)	180,391
Ending balance, shares at Jun. 30, 2019	15,657,316
Net loss					(38,441)	(38,441)
Foreign currency translation adjustment				(2,967)		(2,967)
Stock-based compensation expense, net of forfeitures		4,104				4,104
Transactions under stock plans, shares	41
Balances at Sep. 30, 2019	$ 157	2,748,477		(76,987)	(2,528,560)	143,087
Ending balance, shares at Sep. 30, 2019	15,657,357
Balances at Dec. 31, 2019	$ 16	2,752,859	(4,290)	(71,927)	(2,627,085)	49,573
Beginning balance, shares at Dec. 31, 2019	15,689,463
Net loss					(79,464)	(79,464)
Foreign currency translation adjustment				(4,538)		(4,538)
Stock-based compensation expense, net of forfeitures		2,527				2,527
Transactions under stock plans, value		(208)				(208)
Transactions under stock plans, shares	108,965
Balances at Mar. 31, 2020	$ 16	2,755,178	(4,290)	(76,465)	(2,706,549)	(32,110)
Ending balance, shares at Mar. 31, 2020	15,798,428
Balances at Dec. 31, 2019	$ 16	2,752,859	(4,290)	(71,927)	(2,627,085)	49,573
Beginning balance, shares at Dec. 31, 2019	15,689,463
Net loss						(301,874)
Foreign currency translation adjustment						(607)
Balances at Sep. 30, 2020	$ 16	2,756,031	(4,290)	(72,534)	(2,928,959)	(249,736)
Ending balance, shares at Sep. 30, 2020	15,799,318
Balances at Mar. 31, 2020	$ 16	2,755,178	(4,290)	(76,465)	(2,706,549)	(32,110)
Beginning balance, shares at Mar. 31, 2020	15,798,428
Net loss					(65,106)	(65,106)
Foreign currency translation adjustment				(285)		(285)
Stock-based compensation expense, net of forfeitures		2,374				2,374
Transactions under stock plans, shares	611
Balances at Jun. 30, 2020	$ 16	2,757,552	(4,290)	(76,750)	(2,771,655)	(95,127)
Ending balance, shares at Jun. 30, 2020	15,799,039
Net loss					(157,304)	(157,304)
Foreign currency translation adjustment				4,216		4,216
Stock-based compensation expense, net of forfeitures		(1,521)				(1,521)
Transactions under stock plans, shares	279
Balances at Sep. 30, 2020	$ 16	$ 2,756,031	$ (4,290)	$ (72,534)	$ (2,928,959)	$ (249,736)
Ending balance, shares at Sep. 30, 2020	15,799,318