Consolidated Statements of Comprehensive (Loss) Income (Parenthetical) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Statement Of Income And Comprehensive Income [Abstract]
Income tax on unrealized holding during the period	$ (11,419,131)	$ 2,198,375	$ (13,144,225)	$ 2,401,239
Income tax on reclassification adjustment for gains	$ 426,354	$ 519,633	$ 882,146	$ 1,305,026