Consolidated Statements Of Comprehensive Income - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 25,700,570	$ 19,515,452	$ 12,549,053
Other comprehensive income (loss), before tax:
Amortization related to prior year service cost	0	0	4,390
Amortization of unrecognized loss	8,612	8,941	3,514
Accumulated postretirement expense (benefit) obligation adjustment	69,634	(566)	(63,566)
Unrealized gains (losses) on investments arising during the period	7,478,490	1,145,529	(2,077,542)
Reclassification adjustment for sale of securities included in net income	(1,227,265)	(972,672)	(718,837)
Reclassification adjustment for write-down of securities included in net income	25,411	233,941	751,059
Other comprehensive income (loss), before tax	6,354,882	415,173	(2,100,982)
Income tax expense (benefit) related to postretirement health benefits	26,602	2,849	(18,924)
Income tax expense (benefit) related to unrealized gains (losses) on investments arising during the year	2,555,694	387,508	(722,226)
Income tax benefit related to reclassification adjustment for sale of securities included in net income	(419,462)	(333,426)	(245,200)
Income tax expense related to reclassification adjustment for write-down of securities included in net income	8,669	79,810	258,862
Net income tax expense (benefit) on other comprehensive income (loss)	2,171,503	136,741	(727,488)
Other comprehensive income (loss)	4,183,379	278,432	(1,373,494)
Comprehensive Income	29,883,949	19,793,884	11,175,559
Less: Comprehensive loss (income) attributable to noncontrolling interests	5,932	7,666	(15,148)
Comprehensive Income Attributable to the Company	$ 29,889,881	$ 19,801,550	$ 11,160,411