CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Common Stock Class A Common Stock	Common Stock Class B Common Stock	Common Stock	Additional Paid In Capital	Retained Earnings Class A Common Stock	Retained Earnings Class B Common Stock	Retained Earnings	Accumulated Other Comprehensive Income	Class A Common Stock	Class B Common Stock	Total
Balance at beginning of period at Dec. 31, 2020			$ 4,899	$ 143,637			$ 666,278	$ 8,509			$ 823,323
Balance (in shares) at Dec. 31, 2020	18,697	2,199
Increase (Decrease) in Stockholders' Equity
Net income							49,975				49,975
Net change in accumulated other comprehensive income (loss)								(1,946)			(1,946)
Dividends declared on Common Stock:
Dividends declared on Common Stock					$ (11,423)	$ (1,224)			$ (11,423)	$ (1,224)
Stock options exercised, net of shares withheld			13	(155)							(142)
Stock options exercised, net of shares withheld (in shares)	28
Conversion of Class B Common Stock to Class A Common Stock (in shares)	33	(33)
Repurchase of Class A Common Stock			(75)	(2,350)			(12,804)				(15,229)
Repurchase of Class A Common Stock (in shares)	(362)
Net change in notes receivable on Class A Common Stock				50							50
Deferred director compensation expense - Class A Common Stock				209							209
Deferred director compensation expense - Class A Common Stock (in shares)	4
Deferred designed key employee compensation expense - Class A Common Stock				303							303
Employee stock purchase plan - Class A Common Stock			2	316							318
Employee stock purchase plan - Class A Common Stock (in shares)	7
Stock-based awards, Performance stock units				65							65
Stock-based awards, Restricted stock			2	519							521
Stock-based awards, Restricted stock (in shares)	14
Stock options				290							290
Balance at end of period at Jun. 30, 2021			4,841	142,884			690,802	6,563			845,090
Balance (in shares) at Jun. 30, 2021	18,421	2,166
Balance at beginning of period at Mar. 31, 2021	$ 18,628	$ 2,198	4,884	143,563			682,264	6,998			837,709
Increase (Decrease) in Stockholders' Equity
Net income							23,922				23,922
Net change in accumulated other comprehensive income (loss)								(435)			(435)
Dividends declared on Common Stock:
Dividends declared on Common Stock					(5,680)	(608)			(5,680)	(608)
Stock options exercised, net of shares withheld			5	(54)							(49)
Stock options exercised, net of shares withheld (in shares)	12
Conversion of Class B Common Stock to Class A Common Stock			(51)	(1,614)			(9,096)				(10,761)
Conversion of Class B Common Stock to Class A Common Stock (in shares)	(255)
Repurchase of Class A Common Stock (in shares)	32	(32)
Net change in notes receivable on Class A Common Stock				(44)							(44)
Deferred director compensation expense - Class A Common Stock				95							95
Deferred designed key employee compensation expense - Class A Common Stock				167							167
Employee stock purchase plan - Class A Common Stock			1	162							163
Employee stock purchase plan - Class A Common Stock (in shares)	4
Stock-based awards, Performance stock units				33							33
Stock-based awards, Restricted stock			2	409							411
Stock options				167							167
Balance at end of period at Jun. 30, 2021			4,841	142,884			690,802	6,563			845,090
Balance (in shares) at Jun. 30, 2021	18,421	2,166
Balance at beginning of period at Dec. 31, 2021			4,702	139,956			687,700	1,874			834,232
Balance (in shares) at Dec. 31, 2021	17,816	2,165
Increase (Decrease) in Stockholders' Equity
Net income							51,827				51,827
Net change in accumulated other comprehensive income (loss)								(23,528)			(23,528)
Dividends declared on Common Stock:
Dividends declared on Common Stock					(12,128)	(1,341)			(12,128)	(1,341)
Stock options exercised, net of shares withheld			2	40							42
Stock options exercised, net of shares withheld (in shares)	3
Conversion of Class B Common Stock to Class A Common Stock (in shares)	4	(4)
Repurchase of Class A Common Stock			(43)	(1,384)			(7,409)				(8,836)
Repurchase of Class A Common Stock (in shares)	(215)
Net change in notes receivable on Class A Common Stock				18							18
Deferred director compensation expense - Class A Common Stock				211							211
Deferred director compensation expense - Class A Common Stock (in shares)	6
Deferred designed key employee compensation expense - Class A Common Stock				357							357
Employee stock purchase plan - Class A Common Stock			2	325							327
Employee stock purchase plan - Class A Common Stock (in shares)	7
Stock-based awards, Performance stock units				76							76
Stock-based awards, Restricted stock				610							610
Stock-based awards, Restricted stock (in shares)	8
Stock options				307							307
Balance at end of period at Jun. 30, 2022			4,663	140,516			718,649	(21,654)			842,174
Balance (in shares) at Jun. 30, 2022	17,629	2,161
Balance at beginning of period at Mar. 31, 2022			4,703	140,795			708,874	(14,043)			840,329
Balance (in shares) at Mar. 31, 2022	17,834	2,165
Increase (Decrease) in Stockholders' Equity
Net income							23,901				23,901
Net change in accumulated other comprehensive income (loss)								(7,611)			(7,611)
Dividends declared on Common Stock:
Dividends declared on Common Stock					$ (6,047)	$ (670)			$ (6,047)	$ (670)
Stock options exercised, net of shares withheld			2	88							90
Stock options exercised, net of shares withheld (in shares)	3
Conversion of Class B Common Stock to Class A Common Stock (in shares)	4	(4)
Repurchase of Class A Common Stock			(43)	(1,384)			(7,409)				(8,836)
Repurchase of Class A Common Stock (in shares)	(215)
Net change in notes receivable on Class A Common Stock				(42)							(42)
Deferred director compensation expense - Class A Common Stock				82							82
Deferred designed key employee compensation expense - Class A Common Stock				178							178
Employee stock purchase plan - Class A Common Stock			1	163							164
Employee stock purchase plan - Class A Common Stock (in shares)	3
Stock-based awards, Performance stock units				38							38
Stock-based awards, Restricted stock				447							447
Stock options				151							151
Balance at end of period at Jun. 30, 2022			$ 4,663	$ 140,516			$ 718,649	$ (21,654)			$ 842,174
Balance (in shares) at Jun. 30, 2022	17,629	2,161