Consolidated Statements of Stockholders' Equity (USD $) In Thousands, unless otherwise specified	Total	Common Stock	Additional Paid - in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Balance at Dec. 31, 2009	$ 142,977	$ 174	$ 432,414	$ (281,686)	$ (7,925)
Balance (in shares) at Dec. 31, 2009		17,363
Increase (Decrease) in Stockholders' Equity
Net shares issued in connection with the exercise of stock options and restricted stock units	1,337	1	1,336
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	892		892
Shares issued in connection with employee stock purchase plan (in shares)		42
Non-cash equity-based compensation	14,777		14,777
Unrealized gains on securities, net of tax of $0.9, $1.2 and $0.5 million at December 31, 2012, 2011 and 2010, respectively	897				897
Shares issued in connection with financing, net of financing costs of $8.1 million	165,559	36	165,523
Shares issued in connection with financing, net of financing costs of $8.1 million (in shares)		3,600
Net loss	(81,153)			(81,153)
Balance at Dec. 31, 2010	245,286	211	614,942	(362,839)	(7,028)
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 on securities, net of tax of $0.9, $1.2 and $0.5 million at December 31, 2012, 2011 and 2010, respectively	2,186				2,186
Net loss	(77,069)			(77,069)
Balance at Dec. 31, 2011	180,596	213	625,133	(439,908)	(4,842)
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 on securities, net of tax of $0.9, $1.2 and $0.5 million at December 31, 2012, 2011 and 2010, respectively	1,595				1,595
Net loss	(16,750)			(16,750)
Balance at Dec. 31, 2012	$ 172,797	$ 215	$ 632,487	$ (456,658)	$ (3,247)
Balance (in shares) at Dec. 31, 2012		21,507