Employee Stock Benefit Plans (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended			1 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013 Stock Options [Member]	Feb. 28, 2013 Stock Options [Member] Employees And Consultants [Member]	Feb. 28, 2013 Stock Options [Member] Executive Employees [Member] Executive	Mar. 31, 2013 Non-Employee Director Stock Option Plan [Member]	Mar. 31, 2013 Non-Employee Director Stock Option Plan [Member] Common Stock [Member]	Mar. 31, 2013 Non-Employee Director Stock Option Plan [Member] Stock Options [Member]	Mar. 31, 2013 2005 Equity Plan [Member]	Mar. 31, 2013 2005 Equity Plan [Member] Common Stock [Member]	Mar. 31, 2013 2005 Equity Plan [Member] Stock Options [Member]
Employee Stock Benefit Plan [Abstract]
Common stock authorized in stock option plan (in shares)						120,000			3,000,000
Common stock issued or reserved for issuance (in shares)							7,000	17,285		753,095	1,055,546
Number of Options [Roll Forward]
Outstanding (in shares)			898,541
Granted (in shares)			259,625	177,125	82,500
Exercised (in shares)			(3,333)
Cancelled (in shares)			(9,166)
Outstanding (in shares)			1,145,667
Options exercisable (in shares)			325,042
Weighted Average Exercise Price [Roll Forward]
Outstanding (in dollars per share)			$ 16.65
Granted (in dollars per share)			$ 16.59	$ 15	$ 20
Exercised (in dollars per share)			$ 6.24
Cancelled (in dollars per share)			$ 26.11
Outstanding (in dollars per share)			$ 16.59
Options exercisable (in dollars per share)			$ 17.71
Unrecognized compensation cost related to non-vested option grants and stock awards	$ 12,032
Weighted-average period over which unrecognized compensation is expected to be recognized	3 years 6 months
Weighted average assumptions to estimate fair value of grants of stock options [Abstract]
Risk-free interest rate (in hundredths)			1.26%
Volatility (in hundredths)			85.25%
Expected dividend yield (in hundredths)			0.00%
Expected life			5 years 6 months
Estimated forfeiture rate (in hundredths)			0.00%
Options granted to purchase common stock (in shares)			259,625	177,125	82,500
Strike price of options granted (in dollars per share)			$ 16.59	$ 15	$ 20
Vesting period of options granted				5 years	5 years
Expiration period of options granted				10 years	10 years
Number of executive employees					2
Aggregate fair value of options granted					2,590
Total stock based compensation expense	$ 1,290	$ 1,753