CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands		Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]	Difference between Revenue Guidance in Effect before and after Topic 606 [Member]	Difference between Revenue Guidance in Effect before and after Topic 606 [Member] Accumulated Deficit [Member]	[1]
Balance at Dec. 31, 2015		$ 328,168	$ 76	$ 2,236,418	$ (1,903,908)	$ (4,418)
Balance, Shares at Dec. 31, 2015			76,015
Net loss		(72,314)			(72,314)
Other comprehensive loss, net of tax		(2,852)				(2,852)
Issuance of Common Stock under option, stock award and purchase plans		2,800	$ 2	2,798
Issuance of Common Stock under option, stock award and purchase plans, Shares			2,441
Stock-based compensation		13,242		13,242
Issuance of warrant		1,597		1,597
Balance at Dec. 31, 2016		270,641	$ 78	2,254,055	(1,976,222)	(7,270)
Balance, Shares at Dec. 31, 2016			78,456
Cumulative Effect on Retained Earnings, Net of Tax | Accounting Standards Update 2016-09 [Member]				69	(69)
Cumulative Effect on Retained Earnings, Net of Tax | Accounting Standards Update 2016-16 [Member]		1,434			1,434
Balance at Jan. 01, 2017		272,075	$ 78	2,254,124	(1,974,857)	(7,270)
Balance, Shares at Jan. 01, 2017			78,456
Balance at Dec. 31, 2016		270,641	$ 78	2,254,055	(1,976,222)	(7,270)
Balance, Shares at Dec. 31, 2016			78,456
Net loss		(82,955)			(82,955)
Other comprehensive loss, net of tax		10,652				10,652
Issuance of Common Stock under option, stock award and purchase plans		1,959	$ 5	1,954
Issuance of Common Stock under option, stock award and purchase plans, Shares			4,098
Stock-based compensation		16,612		16,612
Balance at Dec. 31, 2017		218,343	$ 83	2,272,690	(2,057,812)	3,382
Balance, Shares at Dec. 31, 2017			82,554
Accumulated deficit		(2,057,812)			(2,057,812)
Cumulative Effect on Retained Earnings, Net of Tax | Accounting Standards Update 2014-09 [Member]	[1]						$ 11,431
Balance at Jan. 01, 2018		229,774	$ 83	2,272,690	(2,046,381)	3,382
Balance, Shares at Jan. 01, 2018			82,554
Balance at Dec. 31, 2017		218,343	$ 83	2,272,690	(2,057,812)	3,382
Balance, Shares at Dec. 31, 2017			82,554
Net loss		(21,035)			(21,035)
Net loss | Accounting Standards Update 2014-09 [Member]							959
Other comprehensive loss, net of tax		(4,598)				(4,598)
Issuance of Common Stock under option, stock award and purchase plans		4,717	$ 4	4,713
Issuance of Common Stock under option, stock award and purchase plans, Shares			4,503
Stock-based compensation		17,097		17,097
Issuance of warrant		2,295		2,295
Balance at Dec. 31, 2018		228,250	$ 87	$ 2,296,795	(2,067,416)	$ (1,216)
Balance, Shares at Dec. 31, 2018			87,057
Accumulated deficit | Accounting Standards Update 2014-09 [Member]					(2,046,381)			$ 11,431
Accumulated deficit		$ (2,067,416)			$ (2,067,416)
Accumulated deficit | Accounting Standards Update 2014-09 [Member]							$ 12,390

[1] See Note 2, “Summary of Significant Accounting Policies-Recently Adopted Accounting Pronouncements,” for more information on the adoption of ASC 606, Revenue from Contracts with Customers (“Topic 606”) issued by the Financial Accounting Standards Board.