CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income Loss [Member]	Treasury Stock [Member]	Series A Nonconvertible Preferred Stock [Member] Preferred Stock [Member]
BALANCE at Dec. 31, 2013	$ 427,686	$ 468	$ 572,401	$ (130,159)	$ (4,368)	$ (10,658)	$ 2
BALANCE (in shares) at Dec. 31, 2013		46,825,168				401,501	200,000
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Net income	24,443			24,443
Other comprehensive income	221				221
Repurchase of common stock, shares						234,800
Repurchase of common stock	(7,000)					(7,000)
Exercise of common stock options, shares		42,597
Exercise of common stock options	664	1	663
Issuance of common stock to employees, shares		82,534
Issuance of common stock to employees	4,272	1	4,271
Shares withheld for employee taxes, shares		(83,385)
Shares withheld for employee taxes	(2,830)	(1)	(2,829)
Issuance of common stock to Board of Directors and Scientific Advisory Board Shares		26,984
Issuance of common stock to Board of Directors and Scientific Advisory Board Value	786	0	786
Issuance of common stock to employees under an Employee Stock Purchase Plan (ESPP) (in shares)		5,951
Issuance of common stock to employees under an ESPP	162	0	162
BALANCE at Jun. 30, 2014	$ 448,404	$ 469	$ 575,454	$ (105,716)	$ (4,147)	$ (17,658)	$ 2
BALANCE (in shares) at Jun. 30, 2014		46,899,849				636,301	200,000