Unaudited Condensed Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]	Total	Class A [Member] Common Stock [Member]	Class B [Member] Common Stock [Member]	Class B [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Additional Paid-in Capital [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Accumulated Other Comprehensive Income (Loss) [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Retained Earnings [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Class A [Member] Common Stock [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Class B [Member] Common Stock [Member]
Beginning balance at Dec. 31, 2018	$ 54,720	$ (7,347)	$ 308,075	$ 356,082	$ 112	$ 522
Beginning balance (in shares) at Dec. 31, 2018					2,615,000	12,254,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss (income)	0	0	3,576	3,576	$ 0	$ 0
Foreign currency translation adjustment, net of tax	0	402	0	402	0	0
Change in unrealized gain (loss) on investments, net of tax	0	16,539	0	16,539	0	0
Common stock dividends	0	0	(4,429)	(4,429)	0	0
Repurchase of common shares	(2,590)	0	(7,669)	(10,283)	$ 0	$ (24)
Repurchase of common shares (in shares)					(6,000)	(595,000)
Restricted stock grants	1,540	0	0	1,543	$ 0	$ 3
Restricted stock grants (in shares)					0	80,000
Ending balance at Sep. 30, 2019	53,670	9,594	299,553	363,430	$ 112	$ 501
Ending balance (in shares) at Sep. 30, 2019					2,609,000	11,739,000
Beginning balance at Jun. 30, 2019	54,065	8,217	304,513	367,416	$ 112	$ 509
Beginning balance (in shares) at Jun. 30, 2019					2,612,000	11,932,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss (income)	0	0	(707)	(707)	$ 0	$ 0
Foreign currency translation adjustment, net of tax	0	(189)	0	(189)	0	0
Change in unrealized gain (loss) on investments, net of tax	0	1,566	0	1,566	0	0
Common stock dividends	0	0	(1,442)	(1,442)	0	0
Repurchase of common shares	(976)	0	(2,811)	(3,796)	$ 0	$ (9)
Repurchase of common shares (in shares)					(3,000)	(224,000)
Restricted stock grants	581	0	0	582	$ 0	$ 1
Restricted stock grants (in shares)					0	31,000
Ending balance at Sep. 30, 2019	53,670	9,594	299,553	363,430	$ 112	$ 501
Ending balance (in shares) at Sep. 30, 2019					2,609,000	11,739,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of the adoption of updated accounting guidance for credit losses, net of tax | ASU 2016-13 [Member]								$ 0	$ 0	$ (12,281)	$ (12,281)	$ 0	$ 0
Beginning balance at Dec. 31, 2019	53,349	9,369	300,988	364,316	$ 111	$ 499
Beginning balance (ASU 2016-13 [Member]) at Dec. 31, 2019										$ (12,281)
Beginning balance (in shares) at Dec. 31, 2019					2,603,000	11,676,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss (income)	0	0	(7,508)	(7,508)	$ 0	$ 0
Foreign currency translation adjustment, net of tax	0	(307)	0	(307)	0	0
Change in unrealized gain (loss) on investments, net of tax	0	5,123	0	5,123	0	0
Common stock dividends	0	0	(4,275)	(4,275)	0	0
Repurchase of common shares	(563)	0	(1,214)	(1,782)	$ 0	$ (5)
Repurchase of common shares (in shares)					0	(127,000)	(126,764)
Restricted stock grants	1,374	0	0	1,378	$ 0	$ 4
Restricted stock grants (in shares)					0	101,000
Ending balance at Sep. 30, 2020	54,160	14,185	275,710	344,664	$ 111	$ 498
Ending balance (in shares) at Sep. 30, 2020					2,603,000	11,650,000
Beginning balance at Jun. 30, 2020	53,692	7,893	273,846	336,038	$ 111	$ 496
Beginning balance (in shares) at Jun. 30, 2020					2,603,000	11,610,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss (income)	0	0	3,281	3,281	$ 0	$ 0
Foreign currency translation adjustment, net of tax	0	159	0	159	0	0
Change in unrealized gain (loss) on investments, net of tax	0	6,133	0	6,133	0	0
Common stock dividends	0	0	(1,417)	(1,417)	0	0
Repurchase of common shares	0	0	0	0	$ 0	$ 0
Repurchase of common shares (in shares)					0	0
Restricted stock grants	468	0	0	470	$ 0	$ 2
Restricted stock grants (in shares)					0	40,000
Ending balance at Sep. 30, 2020	$ 54,160	$ 14,185	$ 275,710	$ 344,664	$ 111	$ 498
Ending balance (in shares) at Sep. 30, 2020					2,603,000	11,650,000