Accumulated Other Comprehensive Income Balances Of Each Component Of Accumulated Other Comprehensive Income, Net Of Tax (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 11,483,015	$ 12,856,509	$ 11,347,404
Other comprehensive income (loss) before reclassifications	757,647	(1,397,270)	1,843,011
Amounts reclassified from accumulated other comprehensive income	(479,215)	23,776	(333,906)
Other comprehensive income (loss)	278,432	(1,373,494)	1,509,105
Ending balance	11,761,447	11,483,015	12,856,509
Unrealized Gains And Losses On Available-For-Sale Securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	11,597,741	12,934,497	11,395,757
Other comprehensive income (loss) before reclassifications	758,021	(1,355,316)	1,874,111
Amounts reclassified from accumulated other comprehensive income	(485,115)	18,560	(335,371)
Other comprehensive income (loss)	272,906	(1,336,756)	1,538,740
Ending balance	11,870,647	11,597,741	12,934,497
Postretirement Benefits Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(114,726)	(77,988)	(48,353)
Other comprehensive income (loss) before reclassifications	(374)	(41,954)	(31,100)
Amounts reclassified from accumulated other comprehensive income	5,900	5,216	1,465
Other comprehensive income (loss)	5,526	(36,738)	(29,635)
Ending balance	$ (109,200)	$ (114,726)	$ (77,988)