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							69,984				69,984
Net change in AOCI								(3,361)			(3,361)
Dividends declared on Common Stock:
Dividends declared on Common Stock					$ (16,980)	$ (1,830)			$ (16,980)	$ (1,830)
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)	34	(34)
Repurchase of Class A Common Stock			(165)	(5,205)			(29,537)				(34,907)
Repurchase of Class A Common Stock (in shares)	(749)
Net change in notes receivable on Class A Common Stock				150							150
Deferred director compensation expense - Class A Common Stock				330							330
Deferred director compensation expense - Class A Common Stock (in shares)	4
Deferred designed key employee compensation expense - Class A Common Stock				478							478
Employee stock purchase plan - Class A Common Stock			3	507							510
Employee stock purchase plan - Class A Common Stock (in shares)	11
Stock-based awards, Performance stock units				97							97
Stock-based awards, Restricted stock			2	583							585
Stock-based awards, Restricted stock (in shares)	15
Stock options				420							420
Balance at end of period at Sep. 30, 2021			4,752	140,842			687,915	5,148			838,657
Balance (in shares) at Sep. 30, 2021	18,040	2,165
Balance at beginning 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
Increase (Decrease) in Stockholders' Equity
Net income							20,009				20,009
Net change in AOCI								(1,415)			(1,415)
Dividends declared on Common Stock:
Dividends declared on Common Stock					(5,557)	(606)			(5,557)	(606)
Conversion of Class B Common Stock to Class A Common Stock		$ (1)
Conversion of Class B Common Stock to Class A Common Stock (in shares)	1
Repurchase of Class A Common Stock			(90)	(2,855)			(16,733)				(19,678)
Repurchase of Class A Common Stock (in shares)	(387)
Net change in notes receivable on Class A Common Stock				100							100
Deferred director compensation expense - Class A Common Stock				121							121
Deferred designed key employee compensation expense - Class A Common Stock				175							175
Employee stock purchase plan - Class A Common Stock			1	191							192
Employee stock purchase plan - Class A Common Stock (in shares)	4
Stock-based awards, Performance stock units				32							32
Stock-based awards, Restricted stock	$ 1			64							64
Stock options				130							130
Balance at end of period at Sep. 30, 2021			4,752	140,842			687,915	5,148			838,657
Balance (in shares) at Sep. 30, 2021	18,040	2,165
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							71,310				71,310
Net change in AOCI								(35,162)			(35,162)
Dividends declared on Common Stock:
Dividends declared on Common Stock					(18,123)	(2,010)			(18,123)	(2,010)
Stock options exercised, net of shares withheld			2	38							40
Stock options exercised, net of shares withheld (in shares)	3
Conversion of Class B Common Stock to Class A Common Stock (in shares)	5	(5)
Repurchase of Class A Common Stock			(58)	(1,868)			(10,238)				(12,164)
Repurchase of Class A Common Stock (in shares)	(263)
Net change in notes receivable on Class A Common Stock				61							61
Deferred director compensation expense - Class A Common Stock				403							403
Deferred director compensation expense - Class A Common Stock (in shares)	6
Deferred designed key employee compensation expense - Class A Common Stock				541							541
Employee stock purchase plan - Class A Common Stock			3	506							509
Employee stock purchase plan - Class A Common Stock (in shares)	12
Stock-based awards, Performance stock units				114							114
Stock-based awards, Restricted stock				771							771
Stock-based awards, Restricted stock (in shares)	8
Stock options				436							436
Balance at end of period at Sep. 30, 2022			4,649	140,958			728,639	(33,288)			840,958
Balance (in shares) at Sep. 30, 2022	17,587	2,160
Balance at beginning 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
Increase (Decrease) in Stockholders' Equity
Net income							19,483				19,483
Net change in AOCI								(11,634)			(11,634)
Dividends declared on Common Stock:
Dividends declared on Common Stock					$ (5,995)	$ (669)			$ (5,995)	$ (669)
Stock options exercised, net of shares withheld				(2)							(2)
Conversion of Class B Common Stock to Class A Common Stock (in shares)	1	(1)
Repurchase of Class A Common Stock			(15)	(484)			(2,829)				(3,328)
Repurchase of Class A Common Stock (in shares)	(48)
Net change in notes receivable on Class A Common Stock				43							43
Deferred director compensation expense - Class A Common Stock				192							192
Deferred designed key employee compensation expense - Class A Common Stock				184							184
Employee stock purchase plan - Class A Common Stock			1	181							182
Employee stock purchase plan - Class A Common Stock (in shares)	5
Stock-based awards, Performance stock units				38							38
Stock-based awards, Restricted stock				161							161
Stock options				129							129
Balance at end of period at Sep. 30, 2022			$ 4,649	$ 140,958			$ 728,639	$ (33,288)			$ 840,958
Balance (in shares) at Sep. 30, 2022	17,587	2,160