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]	Convertible Note due 2020 [Member]	Convertible Note due 2024 [Member]
Balance, Shares at Dec. 31, 2016			78,456
Balance, Shares at Jan. 01, 2017			78,456
Balance at Dec. 31, 2016		$ 270,641	$ 78	$ 2,254,055	$ (1,976,222)	$ (7,270)
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 Dec. 31, 2016			78,456
Balance, Shares at Dec. 31, 2017			82,554
Balance at Dec. 31, 2016		270,641	$ 78	2,254,055	(1,976,222)	(7,270)
Net loss		(82,955)			(82,955)
Other Comprehensive income or 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
Issuance of warrant		0
Balance at Dec. 31, 2017		218,343	$ 83	2,272,690	(2,057,812)	3,382
Balance, Shares at Jan. 01, 2018			82,554
Cumulative Effect on Retained Earnings, Net of Tax | Accounting Standards Update 2014-09 [Member]	[1]						$ 11,431	$ 11,431
Balance at Jan. 01, 2018		229,774	$ 83	2,272,690	(2,046,381)	3,382
Balance, Shares at Dec. 31, 2017			82,554
Balance, Shares at Dec. 31, 2018			87,057
Balance at Dec. 31, 2017		218,343	$ 83	2,272,690	(2,057,812)	3,382
Net loss		(21,035)			(21,035)
Other Comprehensive income or 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 Jan. 01, 2019			87,057
Cumulative Effect on Retained Earnings, Net of Tax | Accounting Standards Update 2016-09 [Member]	[2]	1,400			1,400
Balance at Jan. 01, 2019		229,650	$ 87	2,296,795	(2,066,016)	(1,216)
Balance, Shares at Dec. 31, 2018			87,057
Balance, Shares at Dec. 31, 2019			91,875
Balance at Dec. 31, 2018		228,250	$ 87	2,296,795	(2,067,416)	(1,216)
Net loss		(5,924)			(5,924)
Other Comprehensive income or loss, net of tax		(1,849)
Issuance of Common Stock under option, stock award and purchase plans		6,914	$ 4	6,910
Issuance of Common Stock under option, stock award and purchase plans, Shares			4,014
Stock-based compensation		12,156		12,156
Issuance of warrant		16,142		16,142
Exercise of warrants			804
Exercise of warrant, Amount			$ 1
Adjustments to Additional Paid in Capital - Exercise of Warrants		0		(1)
Reclassification from equity to mezzanine equity for 4.00% Convertible Senior Notes due in 2020		(2,410)		(2,410)
Portion of repurchase price recorded in additional paid-in capital in connection with partial repurchase of 4.00% convertible notes due 2020		(27,111)		(27,111)
Conversion feature of 2.00% convertible notes due 2024		24,878		24,878
Balance at Dec. 31, 2019		252,446	$ 92	2,327,359	(2,071,940)	(3,065)
Debt Instrument, Interest Rate, Stated Percentage										2.00%
Balance, Shares at Dec. 31, 2019			91,875
Net loss		5,570
Balance at Dec. 31, 2019		$ 252,446	$ 92	$ 2,327,359	$ (2,071,940)	$ (3,065)
Debt Instrument, Interest Rate, Stated Percentage									4.00%	2.00%

[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.

[2] See Note 2, “Summary of Significant Accounting Policies-Recently Adopted Accounting Pronouncements,” for more information on the adoption of ASC 718, Compensation-Stock Compensation (“Topic 718”) issued by the Financial Accounting Standards Board.