Retirement Agreements and Other Postretirement Benefit Plan Development of the Accumulated Postretirement Benefit Obligation (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Accrued postretirement benefit obligation at beginning of year	$ (928,492)	$ (882,623)
Service cost – benefits earned during the year	0	(10,180)	$ (16,748)
Interest cost on projected benefit obligation	(36,869)	(35,123)	(30,772)
Actuarial gain (loss)	69,634	(566)
Accrued postretirement benefit obligation at end of year	$ (895,727)	$ (928,492)	$ (882,623)