Condensed Consolidated Statements of Cash Flows (Unaudited) (Parenthetical) - USD ($)	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Statement Of Cash Flows [Abstract]
Cash and cash equivalents	$ 53,959,775	$ 69,597,699	$ 22,778,461
Restricted cash	1,115,880	1,985,630	5,911,527
Total cash, cash equivalents and restricted cash	$ 55,075,655	$ 71,583,329	$ 28,689,988	$ 27,506,220