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]
Balance at January 1, 2018 at Dec. 31, 2017	$ 55,078	$ 46,391	$ 316,700	$ 418,811	$ 112	$ 530
Balance at January 1, 2018 (ASU 2016-01 [Member]) at Dec. 31, 2017								$ 0	$ (46,157)	$ 46,157	$ 0	$ 0	$ 0
Balance at January 1, 2018 (ASU 2018-02 [Member]) at Dec. 31, 2017								0	117	(117)	0	$ 0	$ 0
Beginning balance (in shares) at Dec. 31, 2017					2,623,000	12,424,000
Beginning balance (in shares) (ASU 2016-01 [Member]) at Dec. 31, 2017												0	0
Beginning balance (in shares) (ASU 2018-02 [Member]) at Dec. 31, 2017												0	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	0	0	(34,075)	(34,075)	$ 0	$ 0
Foreign currency translation adjustment, net of tax	0	(830)	0	(830)	0	0
Change in unrealized gain (loss) on investments, net of tax	0	(6,868)	0	(6,868)	0	0
Common stock dividends	0	0	(16,835)	(16,835)	0	0
Repurchase of common stock	(832)	0	(3,755)	(4,596)	$ 0	$ (9)
Repurchase of common stock (in shares)					(8,000)	(192,000)
Restricted stock grants	474	0	0	475	$ 0	$ 1
Restricted stock grants (in shares)					0	22,000
Balance at December 31, 2019 at Dec. 31, 2018	54,720	(7,347)	308,075	356,082	$ 112	$ 522
Ending balance (in shares) at Dec. 31, 2018					2,615,000	12,254,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	0	0	7,347	7,347	$ 0	$ 0
Foreign currency translation adjustment, net of tax	0	645	0	645	0	0
Change in unrealized gain (loss) on investments, net of tax	0	16,071	0	16,071	0	0
Common stock dividends	0	0	(5,857)	(5,857)	0	0
Repurchase of common stock	(2,896)	0	(8,577)	(11,501)	$ (1)	$ (27)
Repurchase of common stock (in shares)					(12,000)	(665,000)
Restricted stock grants	1,525	0	0	1,529	$ 0	$ 4
Restricted stock grants (in shares)					0	87,000
Balance at December 31, 2019 at Dec. 31, 2019	53,349	9,369	300,988	364,316	$ 111	$ 499
Balance at December 31, 2019 (ASU 2016-13 [Member]) at Dec. 31, 2019								$ 0	$ 0	$ (12,281)	$ (12,281)	$ 0	$ 0
Ending balance (in shares) at Dec. 31, 2019					2,603,000	11,676,000
Ending balance (in shares) (ASU 2016-13 [Member]) at Dec. 31, 2019												0	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	0	0	4,463	4,463	$ 0	$ 0
Foreign currency translation adjustment, net of tax	0	249	0	249	0	0
Change in unrealized gain (loss) on investments, net of tax	0	12,141	0	12,141	0	0
Common stock dividends	0	0	(5,813)	(5,813)	0	0
Repurchase of common stock	(563)	0	(1,214)	(1,782)	$ 0	$ (5)
Repurchase of common stock (in shares)					0	(127,000)	(126,764)
Restricted stock grants	1,785	0	0	1,789	$ 0	$ 4
Restricted stock grants (in shares)					0	126,000
Balance at December 31, 2019 at Dec. 31, 2020	$ 54,571	$ 21,759	$ 286,143	$ 363,082	$ 111	$ 498
Ending balance (in shares) at Dec. 31, 2020					2,603,000	11,675,000