CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (USD $) In Thousands, except Share data, unless otherwise specified	Total	Series A Nonconvertible Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]
BALANCE at Dec. 31, 2010	$ 57,430	$ 2	$ 390	$ 280,102	$ (217,026)	$ (6,038)	$ 0
BALANCE (in shares) at Dec. 31, 2010		200,000	38,936,571				0
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Net income	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		12	27,743
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		1	2,105
Stock-based non-employee compensation (in shares)			174
Stock-based non-employee compensation	7		0	7
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		0	1,648
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		0	9
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		0	307
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		58	249,571
BALANCE at Dec. 31, 2011	342,227	2	461	561,492	(213,871)	(5,857)	0
BALANCE (in shares) at Dec. 31, 2011		200,000	46,113,296				0
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Net income	9,660				9,660
Other comprehensive income (loss)	155					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		2	853
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		2	1,123
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		0	1,094
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		0	321
Repurchase of common stock (in shares)							205,902
Exercise of common stock options, net of tendered shares	5,202						5,202
BALANCE at Dec. 31, 2012	350,235	2	465	564,883	(204,211)	(5,702)	(5,202)
BALANCE (in shares) at Dec. 31, 2012		200,000	46,561,437				205,902
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Net income	74,052				74,052
Other comprehensive income (loss)	1,334					1,334
Exercise of common stock options and warrants, net of tendered shares (in shares)			223,714
Exercise of common stock options, net of tendered shares	2,558		2	2,556
Stock-based employee compensation, net of shares withheld for employee taxes (in shares)			(13,502)
Stock-based employee compensation, net of shares withheld for employee taxes	3,519		0	3,519
Issuance of common stock to Board of Directors and Scientific Advisory Board (in shares)			39,153
Issuance of common stock to Board of Directors and Scientific Advisory Board	1,101		1	1,100
Issuance of common stock to employees under an Employee Stock Purchase Plan (ESPP) (in shares)			14,366
Issuance of common stock to employees under an ESPP	343		0	343
Repurchase of common stock (in shares)	195,599
Exercise of common stock options, net of tendered shares	5,456
BALANCE at Dec. 31, 2013	$ 427,686	$ 2	$ 468	$ 572,401	$ (130,159)	$ (4,368)	$ (10,658)
BALANCE (in shares) at Dec. 31, 2013		200,000	46,825,168				401,501