Income tax provision (benefit) (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Current:
Federal	$ 21,058,703	$ 19,219,251
State	9,646,172	5,336,885
Current Income Tax Expense (Benefit)	30,704,875	24,556,136
Deferred:
Federal	(5,954,666)	(18,718,113)
State	(2,390,569)	(1,951,238)
Deferred Income Tax Expense (Benefit)	(8,345,235)	(20,675,807)
Total provision for income taxes	$ 22,359,640	$ 3,886,785