Equity (Details) (USD $)	9 Months Ended		0 Months Ended			9 Months Ended	0 Months Ended			0 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 24, 2013 Common stock purchase agreement	Apr. 16, 2013 Common stock purchase agreement	Jan. 15, 2013 Common stock purchase agreement Aspire Capital	Sep. 30, 2013 Common stock purchase agreement Aspire Capital	Jan. 15, 2013 Maximum Common stock purchase agreement Aspire Capital	Sep. 30, 2013 Series A Junior Participating Preferred Stock	Dec. 31, 2012 Series A Junior Participating Preferred Stock	Jun. 14, 2013 Rights Plan	Jun. 14, 2013 Rights Plan Series A Junior Participating Preferred Stock
Common Stock Purchase Agreement
Number of shares of preferred stock that the holder is entitled against each right											0.001
Par value of preferred stock that the holder of rights is entitled to purchase (in dollars per share)								$ 0.0001	$ 0.0001		$ 0.0001
Purchase price (in dollars per share)											$ 35.00
Authorized shares								30,000	30,000		30,000
Dividend right declared per share of common stock (in shares)											1
Number of common stock for which their voting right is equivalent to voting right of 1/1,000th of a share of Series A Junior Participating Preferred Stock											1
Term of plan										3 years
Minimum percentage of stock that may be required to be acquired by a person or group to cause substantial dilution										15.00%
Value of common stock purchase commitment							$ 25,000,000
Term for purchase of shares by Aspire Capital					2 years
Number of shares of common stock registered on Form S-1 for resale by Aspire					3,000,000
Number of shares of common stock issued to Aspire Capital as commitment fee					80,257
Number of shares authorized for sale and issuance (in shares)							1,856,616
Shares authorized for sale and issuance (as a percent)							19.99%
Common stock sold (in shares)			4,381,500	2,875,000		146,886
Common stock sold including commitment shares (in shares)						227,143
Public Offering
Common stock sold (in shares)			4,381,500	2,875,000		146,886
Common stock offering price (in dollars per share)			$ 10.50	$ 5.25
Shares issued upon exercise of over-allotment options by underwriters			571,500	375,000
Proceeds, net of transaction costs	$ 57,591,000	$ 20,620,000	$ 42,674,000	$ 14,036,000