Schedule II [Disclosure] - Condensed Statement of Cash Flows (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Activities
Net income	$ 25,700,570	$ 19,515,452	$ 12,549,053
Depreciation	1,434,771	1,306,643	1,105,839
Amortization of investments, net	788,390	772,100	728,510
Net loss on disposals of property	(22,499)	(12,439)	(24,867)
Net realized (gain) loss on securities	(1,201,854)	(738,731)	32,222
Net loss (earnings) from other investments	(21,714)	(29,705)	(149,128)
(Benefit) provision for deferred income taxes	(4,664,000)	2,790,000	1,015,000
Decrease (increase) in receivables	(1,505,358)	(261,464)	217,594
(Increase) decrease in income taxes recoverable	(385,109)	0	0
(Increase) decrease in other assets	388,113	2,631,205	(4,879,418)
(Decrease) increase in accounts payable and accrued liabilities	1,463,814	(581,518)	6,689,204
Net cash (used in) provided by operating activities	19,893,180	22,567,262	16,916,506
Investing Activities
Purchases of available-for-sale securities	(23,066,396)	(19,424,849)	(20,164,353)
Purchases of short-term securities	(26,413,954)	(1,775,239)	(4,593,240)
Purchases of and net earnings from other investments	(1,873,398)	(2,743,413)	(3,717,978)
Proceeds from sales and maturities of available-for-sale securities	22,126,726	20,258,089	22,151,408
Proceeds from sales and maturities of short-term securities	9,227,942	2,081,805	304,827
Proceeds from sales and distributions of other investments	2,695,670	3,437,999	3,911,286
Proceeds from sales of other assets	21,714	17,601	149,128
Purchases of property	(2,882,732)	(2,456,951)	(2,742,619)
Proceeds from disposals of property	51,022	91,656	75,060
Net cash used in investing activities	(20,288,406)	(8,838,598)	(4,699,081)
Financing Activities
Repurchases of common stock	(244,831)	(6,219,670)	(5,483,953)
Exercise of stock appreciation rights and options	(737)	(200)	54,988
Proceeds from note payable	0	6,000,000	0
Payments on note payable	0	(6,000,000)	0
Cash Dividends Paid per Common Share	(7,073,210)	(1,370,390)	(789,907)
Net cash used in financing activities	(7,318,778)	(7,590,260)	(6,253,872)
Net (Decrease) Increase in Cash and Cash Equivalents	(7,714,004)	6,138,404	5,963,553
Cash and Cash Equivalents, Beginning of Period	27,928,472	21,790,068	15,826,515
Cash and Cash Equivalents, End of Period	20,214,468	27,928,472	21,790,068
Parent Company
Operating Activities
Net income	25,700,570	19,515,452	12,549,053
Equity in net earnings of subsidiaries	(25,633,964)	(19,665,205)	(12,640,260)
Depreciation	97,407	93,086	112,690
Amortization of investments, net	157,674	163,989	192,654
Share-based compensation expense related to stock appreciation rights and options	219,315	132,098	137,759
Net loss on disposals of property	2,955	0	1,683
Net realized (gain) loss on securities	(35,834)	(77,895)	152,026
Net loss (earnings) from other investments	4,994	(13,135)	(237,686)
(Benefit) provision for deferred income taxes	(211,000)	(18,000)	13,000
Decrease (increase) in receivables	362,233	1,037,423	(847,177)
(Increase) decrease in income taxes recoverable	(1,316,235)	(796,982)	169,803
(Increase) decrease in other assets	(111,816)	33,888	7,852
(Decrease) increase in accounts payable and accrued liabilities	(454,710)	(896,311)	1,192,927
Net cash (used in) provided by operating activities	(1,218,411)	(491,592)	804,324
Investing Activities
Purchase of subsidiary	0	(10,918,003)	0
Dividends received from subsidiaries	14,816,379	17,330,948	7,630,835
Purchases of available-for-sale securities	(13,178,177)	(1,783,223)	(260,044)
Purchases of short-term securities	(5,835,325)	(3,162,283)	(2,721,578)
Purchases of and net earnings from other investments	(1,049,680)	(1,552,769)	(2,007,798)
Proceeds from sales and maturities of available-for-sale securities	6,616,875	6,815,907	2,475,557
Proceeds from sales and maturities of short-term securities	3,188,641	3,005,647	0
Proceeds from sales and distributions of other investments	195,881	321,758	734,170
Purchases of property	(13,623)	(144,915)	(32,071)
Net cash used in investing activities	4,740,971	9,913,067	5,819,071
Financing Activities
Repurchases of common stock	(244,831)	(6,219,670)	(5,483,953)
Exercise of stock appreciation rights and options	(737)	(200)	54,988
Proceeds from note payable	0	6,000,000	0
Payments on note payable	0	(6,000,000)	0
Capital Contribution to Subsidiary	(510,000)	0	0
Cash Dividends Paid per Common Share	(7,073,210)	(1,370,390)	(789,907)
Net cash used in financing activities	(7,828,778)	(7,590,260)	(6,218,872)
Net (Decrease) Increase in Cash and Cash Equivalents	(4,306,218)	1,831,215	404,523
Cash and Cash Equivalents, Beginning of Period	10,178,219	8,347,004	7,942,481
Cash and Cash Equivalents, End of Period	5,872,001	10,178,219	8,347,004
Supplemental Disclosures:
Income tax payments, net	$ 11,447,000	$ 4,964,000	$ 4,598,000