CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (USD $) In Thousands, except Share data, unless otherwise specified	Total	Series A Nonconvertible Preferred Stock [Member]	Additional Paid-in Capital [Member]	Common Stock [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]
BALANCE at Dec. 31, 2009	$ 59,627				$ (197,109)	$ 25
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Net income (loss)	(19,917)				(19,917)
Other comprehensive income (loss)	(6,063)					(6,063)
Exercise of common stock options and warrants, net of tendered shares (in shares)				1,304,654
Exercise of common stock options, net of tendered shares	17,756		17,743	13
Stock-based employee compensation, net of shares withheld for employee taxes (in shares)				651,384
Stock-based employee compensation, net of shares withheld for employee taxes	3,133		3,126	7	0
Stock-based non-employee compensation (in shares)				491
Stock-based non-employee compensation	47		47	0
Issuance of common stock to Board of Directors and Scientific Advisory Board (in shares)				61,946
Issuance of common stock to Board of Directors and Scientific Advisory Board	1,347		1,346	1
Issuance of common stock in connection with materials and license agreements (in shares)				80,073
Issuance of common stock in connection with materials and license agreements	1,255		1,254	1
Issuance of common stock to employees under an Employee Stock Purchase Plan (ESPP) (in shares)				19,583
Issuance of common stock to employees under an ESPP	245		245	0
BALANCE at Dec. 31, 2010		2	280,102	390
BALANCE (in shares) at Dec. 31, 2010		200,000		38,936,571
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Net income (loss)	3,155				3,155
Other comprehensive income (loss)	181					181
Exercise of common stock options and warrants, net of tendered shares (in shares)				1,266,191
Exercise of common stock options, net of tendered shares	27,755		27,743	12		0
Stock-based employee compensation, net of shares withheld for employee taxes (in shares)				103,112
Stock-based employee compensation, net of shares withheld for employee taxes	2,106		2,105	1		0
Stock-based non-employee compensation (in shares)				174
Stock-based non-employee compensation	7		7	0		0
Issuance of common stock to Board of Directors and Scientific Advisory Board (in shares)				46,536
Issuance of common stock to Board of Directors and Scientific Advisory Board	1,648		1,648	0		0
Issuance of common stock in connection with materials and license agreements (in shares)				181
Issuance of common stock in connection with materials and license agreements	9		9	0
Issuance of common stock to employees under an Employee Stock Purchase Plan (ESPP) (in shares)				10,531
Issuance of common stock to employees under an ESPP	307		307	0
Issuance of common stock through a public offering, net of expenses (in shares)				5,750,000
Issuance of common stock through a public offering, net of expenses of $14,871	249,629		249,571	58
BALANCE at Dec. 31, 2011	342,227	2	561,492	461	(213,871)	(5,857)
BALANCE (in shares) at Dec. 31, 2011		200,000		46,113,296
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Net income (loss)	9,660				9,660
Other comprehensive income (loss)	155				0	155
Exercise of common stock options and warrants, net of tendered shares (in shares)				222,549
Exercise of common stock options, net of tendered shares	855		853	2
Stock-based employee compensation, net of shares withheld for employee taxes (in shares)				170,584
Stock-based employee compensation, net of shares withheld for employee taxes	1,125		1,123	2
Issuance of common stock to Board of Directors and Scientific Advisory Board (in shares)				43,341
Issuance of common stock to Board of Directors and Scientific Advisory Board	1,094		1,094	0
Issuance of common stock to employees under an Employee Stock Purchase Plan (ESPP) (in shares)				11,667
Issuance of common stock to employees under an ESPP	321		321	0
Repurchase of common stock (in shares)							205,902
Repurchase of common stock	(5,202)						(5,202)
BALANCE at Dec. 31, 2012	$ 350,235	$ 2	$ 564,883	$ 465	$ (204,211)	$ (5,702)	$ (5,202)
BALANCE (in shares) at Dec. 31, 2012		200,000		46,561,437			205,902