2012, 2011 and 2010 Quarterly Results of Operations (Unaudited) (Details) (USD $)	3 Months Ended																								12 Months Ended
	Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Dec. 31, 2010		Sep. 30, 2010		Jun. 30, 2010		Mar. 31, 2010		Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Revenues, net of commissions	$ 42,802,955		$ 46,854,671		$ 48,537,233		$ 52,616,400		$ 70,010,899		$ 80,323,369		$ 76,405,388		$ 86,692,775		$ 72,353,918		$ 72,825,583		$ 65,612,840		$ 54,243,725		$ 190,811,259		$ 313,432,431		$ 265,036,066
Total Operating Expenses	53,587,700		54,718,097		59,605,359		60,118,356		60,857,843		72,507,439		66,123,996		82,274,862		57,502,627		51,248,337		42,069,392		38,556,526		228,029,512		281,764,140		189,376,882
Operating Income (Loss)	(10,784,745)		(7,863,426)		(11,068,126)		(7,501,956)		9,153,056		7,815,930		10,281,392		4,417,913		14,851,291		21,577,246		23,543,448		15,687,199		(37,218,253)		31,668,291		75,659,184
Net Income (loss)	$ (32,423,775)		$ (29,837,360)		$ (23,106,239)		$ (17,433,529)		$ (1,698,979)		$ (5,872,211)		$ (1,438,278)		$ (5,810,281)		$ 3,032,942		$ 8,226,153		$ 11,011,921		$ 4,573,634		$ (102,800,903)		$ (14,819,749)		$ 26,844,650
Basic Net Loss Per Share (in dollars per share) [1]	$ (1.92)	[1]	$ (1.77)	[1]	$ (1.46)	[1]	$ (1.11)	[1]	$ (0.11)	[1]	$ (0.37)	[1]	$ (0.09)	[1]	$ (0.37)	[1]	$ 0.19	[1]	$ 0.53	[1]	$ 0.71	[1]	$ 0.29	[1]	$ (6.30)	[1]	$ (0.95)	[1]	$ 1.73	[1]
Diluted Net Loss Per Share (in dollars per share) [1]	$ (1.92)	[1]	$ (1.77)	[1]	$ (1.46)	[1]	$ (1.11)	[1]	$ (0.11)	[1]	$ (0.37)	[1]	$ (0.09)	[1]	$ (0.37)	[1]	$ 0.19	[1]	$ 0.53	[1]	$ 0.71	[1]	$ 0.29	[1]	$ (6.30)	[1]	$ (0.95)	[1]	$ 1.72	[1]

[1] Adjusted to give effect to the 1 for 4 reverse stock split that became effective on May 22, 2012, see Note 11.