Organization, Description of Business (Details) (USD $)	12 Months Ended				0 Months Ended	1 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Common Stock	Dec. 31, 2011 Common Stock	Jun. 15, 2011 Initial public offering Common Stock	Aug. 31, 2011 Initial public offering Common Stock	Aug. 31, 2011 Initial public offering Common Stock Underwriter option	Apr. 30, 2012 April 2012 public offering Common Stock	Apr. 30, 2012 April 2012 public offering Common Stock Underwriter option
Public Offerings
Reverse stock split					3.522
Issuance of shares, net of issuance costs (in shares)			2,200,000	7,500,000		7,500,000		2,200,000
Price to the public (in dollars per share)						$ 10.00		$ 18.50
Proceeds from initial public offering, net of underwriting discounts and commissions and other offering costs	$ 37,729,000	$ 66,989,000				$ 66,000,000		$ 37,700,000
Offering costs						$ 3,800,000		$ 3,000,000
Stock sold by certain existing stockholders (in shares)						2,585,500	1,315,500	7,000,000	1,200,000