Employee Benefits and Retirement Plans - Amounts Recognized in Comprehensive Income (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Retirement Benefits [Abstract]
Net loss (gain)	$ (503,167)	$ 110,306	$ 1,032,035
Prior service costs	0	0	0
Total recognized in other comprehensive income (loss)	(503,167)	110,306	1,032,035
Net periodic pension cost	583,427	646,160	235,151
Partial recognition of loss due to settlement	0	426,599	0
Total recognized in net periodic pension cost and other comprehensive income	$ (80,260)	$ 1,183,065	$ 1,267,186