Condensed Statements of Cash Flows (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Net cash used in operating activities	$ 61,046,939	$ 48,729,569	$ 33,377,997
Net cash provided by (used in) investing activities	(7,796,777)	(9,365,100)	(20,309,900)
Net cash (used in) provided by financing activities	590,441	(992,846)	(2,550,960)
CASH AND CASH EQUIVALENTS, at the beginning of the year	144,300,290	105,637,627	90,609,340
CASH AND CASH EQUIVALENTS, at the end of the year	203,406,220	144,300,290	105,637,627
Parent
Net cash used in operating activities	(2,818,130)	(3,333,914)	(2,267,880)
Net cash provided by (used in) investing activities	2,206,684	4,390,775	2,496,427
Net cash (used in) provided by financing activities	590,461	(992,846)	(228,547)
CASH AND CASH EQUIVALENTS, at the beginning of the year	64,015	0	0
CASH AND CASH EQUIVALENTS, at the end of the year	$ 43,010	$ 64,015	$ 0