Fair Value Measurements (Details) (USD $)	Jun. 30, 2013	Mar. 16, 2010 2.45% Convertible Notes	Jun. 30, 2013 Recurring basis Quoted Prices In Active Markets for Identical Assets (Level 1)	Dec. 31, 2012 Recurring basis Quoted Prices In Active Markets for Identical Assets (Level 1)	Dec. 31, 2012 Recurring basis Significant Unobservable Inputs (Level 3)	Jun. 30, 2013 Recurring basis Balance	Dec. 31, 2012 Recurring basis Balance
Fair Value Measurements
Interest rate (as a percent)		2.45%
Assets:
Cash and cash equivalents			$ 92,685,912	$ 2,025,338		$ 92,685,912	$ 2,025,338
Total assets at fair value			92,685,912	2,025,338		92,685,912	2,025,338
Liabilities:
Put Option					(30,415)		(30,415)
Total liabilities at fair value					(30,415)		(30,415)
Transfers of assets between Level 1 to Level 2	0
Transfers of assets between Level 2 to Level 1	$ 0