Cash, Cash Equivalents, and Investments (Details) (USD $)	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011	Dec. 31, 2010
Summary of cash, cash equivalents and held-to-maturity investments by type
Cost	$ 25,965,711	$ 21,300,733	$ 24,574,858	$ 42,684,241
Gross Unrealized Losses	(3,263)	(3,307)
Gross Unrealized Gains
Fair Value	29,140,498	26,405,615
Cash and money market funds [Member]
Summary of cash, cash equivalents and held-to-maturity investments by type
Cost	25,965,711	21,300,733
Gross Unrealized Losses
Gross Unrealized Gains
Fair Value	25,965,711	21,300,733
Commercial Paper [Member]
Summary of cash, cash equivalents and held-to-maturity investments by type
Cost	1,498,050	5,008,189
Gross Unrealized Losses	(1,775)	(3,238)
Gross Unrealized Gains
Fair Value	1,496,275	5,004,951
Certificates of Deposit [Member]
Summary of cash, cash equivalents and held-to-maturity investments by type
Cost	1,680,000	100,000
Gross Unrealized Losses	(1,488)	(69)
Gross Unrealized Gains
Fair Value	$ 1,678,512	$ 99,931