Accumulated Other Comprehensive Income Reclassification Out Of Accumulated Other Comprehensive Income (Details) - USD ($)		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net realized gain (loss) on investment		$ 1,040,901	$ 768,436	$ (116,163)
Prior year service cost		0	0	(4,390)
Unrecognized loss		(8,612)	(8,941)	(3,514)
Income before Income Taxes		30,270,570	28,131,452	17,777,053
Tax		(4,570,000)	(8,616,000)	(5,228,000)
Net income		25,700,570	19,515,452	12,549,053
Reclassification Out Of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net income		785,375	479,215	(23,776)
Reclassification Out Of Accumulated Other Comprehensive Income | Unrealized Gains And Losses On Available-For-Sale Securities
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net realized gain (loss) on investment		1,227,265	972,672	718,837
Other-than-temporary impairments		(25,411)	(233,941)	(751,059)
Income before Income Taxes		1,201,854	738,731	(32,222)
Tax		(410,793)	(253,616)	13,662
Net income		791,061	485,115	(18,560)
Reclassification Out Of Accumulated Other Comprehensive Income | Postretirement Benefits Plans
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Prior year service cost		0	0	(4,390)
Unrecognized loss		(8,612)	(8,941)	(3,514)
Income before Income Taxes	[1]	(8,612)	(8,941)	(7,904)
Tax		2,926	3,041	2,688
Net income		$ (5,686)	$ (5,900)	$ (5,216)

[1] These accumulated other comprehensive income components are not reclassified to net income in their entirety in the same reporting period. The amounts are presented within salaries, employee benefits and payroll taxes on the Consolidated Statements of Income as amortized. Amortization related to postretirement benefit plans is included in the computation of net periodic pension costs, as discussed in Note 10.