CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Previously Reported	Revision of Prior Period, Accounting Standards Update, Adjustment	Common Stock [Member]	Common Stock [Member] Previously Reported	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member] Previously Reported	Accumulated Deficit [Member]	Accumulated Deficit [Member] Previously Reported	Accumulated Deficit [Member] Revision of Prior Period, Accounting Standards Update, Adjustment	Accumulated Other Comprehensive Loss [Member]	Accumulated Other Comprehensive Loss [Member] Previously Reported	Convertible Note due 2020 [Member]	Convertible Note due 2020 [Member] Additional Paid-in Capital [Member]	Conversion Note 2022 [Member]	Conversion Note 2022 [Member] Additional Paid-in Capital [Member]	Convertible Note due 2024 [Member]	Convertible Note due 2024 [Member] Additional Paid-in Capital [Member]
Balance, Shares at Dec. 31, 2017				82,554	82,554
Balance, Shares at Dec. 31, 2018				87,057	87,057
Balance at Dec. 31, 2017	$ 229,774	$ 218,343	$ 11,431	$ 83	$ 83	$ 2,272,690	$ 2,272,690	$ (2,046,381)	$ (2,057,812)	$ 11,431	$ 3,382	$ 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	229,650	$ 228,250	$ 1,400	$ 87	$ 87	2,296,795	$ 2,296,795	(2,066,016)	$ (2,067,416)	$ 1,400	(1,216)	$ (1,216)
Balance, Shares at Dec. 31, 2019				91,875
Net loss	(5,924)							(5,924)
Other Comprehensive income or loss, net of tax	(1,849)										(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)
Adjustments to APIC - Reclassification from Equity to Mezzanine equity													$ (2,410)	$ (2,410)
Portion of repurchase price recorded in additional paid-in capital in connection with partial repurchase of 2020 Notes													(27,111)	(27,111)
Conversion feature of 2024 Notes																	$ 24,878	$ 24,878
Balance at Dec. 31, 2019	252,446			$ 92		2,327,359		(2,071,940)			(3,065)
Balance, Shares at Dec. 31, 2020				98,204
Net loss	(29,271)							(29,271)
Other Comprehensive income or loss, net of tax	8,921
Issuance of Common Stock under option, stock award and purchase plans	3,810			$ 3		3,807
Issuance of Common Stock under option, stock award and purchase plans, Shares				3,822
Stock-based compensation	18,034					18,034
Issuance of warrant	0
Exercise of warrants				2,413
Exercise of warrant, Amount				$ 2
Adjustments to Additional Paid in Capital - Exercise of Warrants	0					(2)
Adjustment to APIC - Reclassification from Mezzanine Equity to Equity													$ 2,410	$ 2,410
Portion of repurchase price recorded in additional paid-in capital in connection with partial repurchase of 2020 Notes															$ (6,909)	$ (6,909)
Stock Issued During Period, Value, Conversion of Convertible Securities	607			$ 1		606
Stock Issued During Period, Shares, Conversion of Convertible Securities				94
Conversion feature of 2024 Notes															$ 8,254	$ 8,254
Balance at Dec. 31, 2020	$ 258,302			$ 98		$ 2,353,559		$ (2,101,211)			$ 5,856