Shareholders Equity - USD ($) $ in Thousands	Common Stock	Capital in Excess of Par Value	Retained Earnings	Accumulated Other Comprehensive Income, net of tax	Total Shareholders' Equity	Noncontrolling Interest	Total
Beginning balance, shares at Dec. 31, 2018	9,969,174
Beginning balance, amount at Dec. 31, 2018	$ 997	$ 58,004	$ 306,307	$ (701)	$ 364,607	$ 18,648	$ 383,255
Exercise of stock options, shares	11,304
Exercise of stock options, amount	$ 1	346			347		347
Stock option compensation		86			86		86
Restricted stock compensation							0
Shares granted to employee, shares	1,012
Shares granted to employee, amount		50			50		50
Shares granted to Directors, shares	1,460
Shares granted to Directors, amount		70			70		70
Shares purchased and canceled, shares	(159,282)
Shares purchased and canceled, amount	$ (16)	(929)	(6,769)		(7,714)		(7,714)
Net income			13,724		13,724		13,724
Income (loss) attributable to noncontrolling interest						(380)	(380)
Distributions to partners						(1,086)	(1,086)
Minimum pension liability, net							0
Unrealized gain (loss) on investments, net				1,862	1,862		1,862
Ending balance, shares at Sep. 30, 2019	9,823,668
Ending balance, amount at Sep. 30, 2019	$ 982	57,627	313,262	1,161	373,032	17,182	390,214
Beginning balance, shares at Jun. 30, 2019	9,863,451
Beginning balance, amount at Jun. 30, 2019	$ 986	57,562	313,373	1,210	373,131	17,870	391,001
Exercise of stock options, shares	6,500
Exercise of stock options, amount	$ 1	201			202		202
Stock option compensation		29			29		29
Restricted stock compensation							0
Shares granted to employee, shares	1,012
Shares granted to employee, amount		50			50		50
Shares granted to Directors, shares	1,460
Shares granted to Directors, amount		70			70		70
Shares purchased and canceled, shares	(48,755)
Shares purchased and canceled, amount	$ (5)	(285)	(2,112)		(2,402)		(2,402)
Net income			2,001		2,001		2,001
Income (loss) attributable to noncontrolling interest						(112)	(112)
Distributions to partners						(576)	(576)
Minimum pension liability, net							0
Unrealized gain (loss) on investments, net				(49)	(49)		(49)
Ending balance, shares at Sep. 30, 2019	9,823,668
Ending balance, amount at Sep. 30, 2019	$ 982	57,627	313,262	1,161	373,032	17,182	390,214
Beginning balance, shares at Dec. 31, 2019	9,817,429
Beginning balance, amount at Dec. 31, 2019	$ 982	57,705	315,278	923	374,888	16,757	$ 391,645
Exercise of stock options, shares							0
Stock option compensation		71			71		$ 71
Restricted stock compensation		140			140		140
Shares granted to employee, shares	11,448
Shares granted to employee, amount	$ 1	529			530		530
Shares granted to Directors, shares	12,050
Shares granted to Directors, amount	$ 1	499			500		500
Restricted stock award, shares	20,520
Restricted stock award, amount	$ 2	(2)			0		0
Shares purchased and canceled, shares	(379,809)
Shares purchased and canceled, amount	$ (38)	(2,252)	(13,397)		(15,687)		(15,687)
Net income			11,222		11,222		11,222
Income (loss) attributable to noncontrolling interest						(475)	(475)
Distributions to partners						(713)	(713)
Minimum pension liability, net				143	143		143
Unrealized gain (loss) on investments, net				(70)	(70)		(70)
Ending balance, shares at Sep. 30, 2020	9,481,638
Ending balance, amount at Sep. 30, 2020	$ 948	56,690	313,103	996	371,737	15,569	387,306
Beginning balance, shares at Jun. 30, 2020	9,563,144
Beginning balance, amount at Jun. 30, 2020	$ 956	57,107	310,486	1,194	369,743	16,058	385,801
Stock option compensation		24			24		24
Restricted stock compensation		46			46		46
Shares purchased and canceled, shares	(81,506)
Shares purchased and canceled, amount	$ (8)	(487)	(2,838)		(3,333)		(3,333)
Net income			5,455		5,455		5,455
Income (loss) attributable to noncontrolling interest						(184)	(184)
Distributions to partners						(305)	(305)
Minimum pension liability, net				143	143		143
Unrealized gain (loss) on investments, net				(341)	(341)		(341)
Ending balance, shares at Sep. 30, 2020	9,481,638
Ending balance, amount at Sep. 30, 2020	$ 948	$ 56,690	$ 313,103	$ 996	$ 371,737	$ 15,569	$ 387,306