CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Income [Member]	Accumulated Deficit [Member]
Balance (in shares) at Dec. 31, 2012		71,030
Beginning Balance at Dec. 31, 2012	$ 277,171	$ 710	$ 759,549	$ 6,302	$ (489,390)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock in connection with employee stock plans and other (in shares)		924
Issuance of common stock in connection with employee stock plans and other	(85)	$ 9	(94)
Employee stock purchase plan (in shares)		351
Employee stock purchase plan	911	$ 4	907
Share-based compensation expense	7,727		7,727
Excess tax benefit for share-based compensation	60		60
Net change in other comprehensive income (loss), net of tax	2,090			2,090
Net income (loss)	(16,327)				(16,327)
Balance (in shares) at Dec. 31, 2013		72,305
Ending Balance at Dec. 31, 2013	271,547	$ 723	768,149	8,392	(505,717)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock in connection with employee stock plans and other (in shares)		1,647
Issuance of common stock in connection with employee stock plans and other	(971)	$ 16	(987)
Employee stock purchase plan (in shares)		335
Employee stock purchase plan	2,178	$ 4	2,174
Share-based compensation expense	12,411		12,411
Net change in other comprehensive income (loss), net of tax	(9,004)			(9,004)
Net income (loss)	(3,834)				(3,834)
Balance (in shares) at Dec. 31, 2014		74,287
Ending Balance at Dec. 31, 2014	272,327	$ 743	781,747	(612)	(509,551)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock in connection with employee stock plans and other (in shares)		2,004
Issuance of common stock in connection with employee stock plans and other	3,088	$ 20	3,068
Employee stock purchase plan (in shares)		355
Employee stock purchase plan	2,568	$ 4	2,564
Share-based compensation expense	14,985		14,985
Excess tax benefit for share-based compensation	167		167
Net change in other comprehensive income (loss), net of tax	(8,768)			(8,768)
Net income (loss)	10,113
Issuance of common stock in connection with at the market offerings (in shares)		3,836
Issuance of common stock in connection with at the market offerings	44,773	$ 38	44,735
Balance (in shares) at Dec. 31, 2015		80,482
Ending Balance at Dec. 31, 2015	$ 339,253	$ 805	$ 847,266	$ (9,380)	$ (499,438)