Consolidated Statements of Stockholders' Equity (USD $) In Thousands, unless otherwise specified	Total	Common Stock	Additional Paid - in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Balance at Dec. 31, 2010	$ 245,286	$ 211	$ 614,942	$ (7,028)	$ (362,839)
Balance (in shares) at Dec. 31, 2010		21,137
Increase (Decrease) in Stockholders' Equity
Net shares issued in connection with the exercise of stock options and restricted stock units	121	1	120
Net shares issued in connection with the exercise of stock options and restricted stock units (in shares)		132
Shares issued in connection with employee stock purchase plan	508	1	507
Shares issued in connection with employee stock purchase plan (in shares)		37
Non-cash equity-based compensation	9,564		9,564
Unrealized gains (losses) on securities, net of tax of $0.9 and $1.2 million at December 31, 2012 and 2011, respectively	2,186			2,186
Net loss	(77,069)				(77,069)
Balance at Dec. 31, 2011	180,596	213	625,133	(4,842)	(439,908)
Balance (in shares) at Dec. 31, 2011		21,306
Increase (Decrease) in Stockholders' Equity
Net shares issued in connection with the exercise of stock options and restricted stock units	100	2	98
Net shares issued in connection with the exercise of stock options and restricted stock units (in shares)		178
Shares issued in connection with employee stock purchase plan	270		270
Shares issued in connection with employee stock purchase plan (in shares)		23
Non-cash equity-based compensation	6,986		6,986
Unrealized gains (losses) on securities, net of tax of $0.9 and $1.2 million at December 31, 2012 and 2011, respectively	1,595			1,595
Net loss	(16,750)				(16,750)
Balance at Dec. 31, 2012	172,797	215	632,487	(3,247)	(456,658)
Balance (in shares) at Dec. 31, 2012		21,507
Increase (Decrease) in Stockholders' Equity
Net shares issued in connection with the exercise of stock options and restricted stock units	1,277	3	1,274
Net shares issued in connection with the exercise of stock options and restricted stock units (in shares)		252
Shares issued in connection with employee stock purchase plan	176		176
Shares issued in connection with employee stock purchase plan (in shares)		14
Non-cash equity-based compensation	8,004		8,004
Unrealized gains (losses) on securities, net of tax of $0.9 and $1.2 million at December 31, 2012 and 2011, respectively	(244)			(244)
Net loss	(9,602)				(9,602)
Balance at Dec. 31, 2013	$ 172,408	$ 218	$ 641,941	$ (3,491)	$ (466,260)
Balance (in shares) at Dec. 31, 2013		21,773