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 Cumulative Effect, Period of Adoption, Adjustment	Retained Earnings	Accumulated Other Comprehensive Income	Class A Common Stock	Class B Common Stock	Cumulative Effect, Period of Adoption, Adjustment	Total
Increase (Decrease) in Stockholders' Equity
Adjustment for adoption							$ 126					$ 126
Balance at beginning of period at Dec. 31, 2018			$ 4,900	$ 141,018				$ 545,013	$ (997)				$ 689,934
Balance (in shares) at Dec. 31, 2018	18,675	2,213
Increase (Decrease) in Stockholders' Equity
Net income								91,699					91,699
Net change in accumulated other comprehensive income (loss)									4,095				4,095
Dividends declared on Common Stock:
Dividends declared on Common Stock					$ (19,771)	$ (2,121)				$ (19,771)	$ (2,121)
Stock options exercised, net of shares withheld			11	(202)									(191)
Stock options exercised, net of shares withheld (in shares)	44
Conversion of Class B Common Stock to Class A Common Stock (in shares)	7	(7)
Repurchase of Class A Common Stock			(6)	(637)				(775)					(1,418)
Repurchase of Class A Common Stock (in shares)	(32)
Net change in notes receivable on Class A Common Stock				(222)									(222)
Deferred director compensation expense - Class A Common Stock				213									213
Deferred director compensation expense - Class A Common Stock (in shares)	6
Deferred designed key employee compensation expense - Class A Common Stock				371									371
Employee stock purchase plan - Class A Common Stock			2	492									494
Employee stock purchase plan - Class A Common Stock (in shares)	11
Stock-based awards, Performance stock units				(57)									(57)
Stock-based awards, Performance stock units (in shares)	23
Stock-based awards, Restricted stock				728									728
Stock-based awards, Restricted stock (in shares)	3
Stock options				364									364
Balance at end of period at Dec. 31, 2019			4,907	142,068				614,171	3,098				764,244
Balance (in shares) at Dec. 31, 2019	18,737	2,206
Increase (Decrease) in Stockholders' Equity
Adjustment for adoption							$ (4,291)					$ (4,291)
Net income								83,246					83,246
Net change in accumulated other comprehensive income (loss)									5,411				5,411
Dividends declared on Common Stock:
Dividends declared on Common Stock					(21,433)	(2,288)				(21,433)	(2,288)
Stock options exercised, net of shares withheld			13	197									210
Stock options exercised, net of shares withheld (in shares)	25
Conversion of Class B Common Stock to Class A Common Stock (in shares)	7	(7)
Repurchase of Class A Common Stock			(26)	(782)				(3,127)					(3,935)
Repurchase of Class A Common Stock (in shares)	(115)
Net change in notes receivable on Class A Common Stock				(35)									(35)
Deferred director compensation expense - Class A Common Stock				352									352
Deferred director compensation expense - Class A Common Stock (in shares)	4
Deferred designed key employee compensation expense - Class A Common Stock				566									566
Employee stock purchase plan - Class A Common Stock			4	623									627
Employee stock purchase plan - Class A Common Stock (in shares)	20
Stock-based awards, Performance stock units				(200)									(200)
Stock-based awards, Performance stock units (in shares)	18
Stock-based awards, Restricted stock			1	385									386
Stock-based awards, Restricted stock (in shares)	1
Stock options				463									463
Balance at end 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								86,789					86,789
Net change in accumulated other comprehensive income (loss)									(6,635)				(6,635)
Dividends declared on Common Stock:
Dividends declared on Common Stock					$ (22,451)	$ (2,435)				$ (22,451)	$ (2,435)
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			(216)	(6,831)				(40,481)					(47,528)
Repurchase of Class A Common Stock (in shares)	(980)
Net change in notes receivable on Class A Common Stock				151									151
Deferred director compensation expense - Class A Common Stock				417									417
Deferred director compensation expense - Class A Common Stock (in shares)	4
Deferred designed key employee compensation expense - Class A Common Stock				607									607
Employee stock purchase plan - Class A Common Stock			4	691									695
Employee stock purchase plan - Class A Common Stock (in shares)	15
Stock-based awards, Performance stock units				129									129
Stock-based awards, Restricted stock			2	736									738
Stock-based awards, Restricted stock (in shares)	18
Stock options				574									574
Balance at end 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