Summary of Significant Accounting Policies - Schedule of Restricted Cash (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounting Policies [Abstract]
Cash and cash equivalents	$ 142,078,166	$ 171,228,485	$ 66,224,027
Restricted cash	12,114,277	33,867,523	27,553,851
Total cash, cash equivalents and restricted cash	$ 154,192,443	$ 205,096,008	$ 93,777,878	$ 59,777,393