Consolidated Statements Of Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Treasury Stock [Member]	Total
Balance (in shares) at Dec. 31, 2018	6,981
Balance at Dec. 31, 2018	$ 7,441	$ 10,360	$ 362,709	$ 21	$ (14,408)	$ 366,123
Net earnings			14,107			14,107
Unrealized gain on available-for-sale securities, net of tax				158		158
Other (in shares)	16
Other		554	1		342	898
Dividends paid			(42,087)			(42,087)
Balance (in shares) at Jun. 30, 2019	6,997
Balance at Jun. 30, 2019	$ 7,441	10,914	334,730	180	(14,066)	339,199
Balance (in shares) at Mar. 31, 2019	6,995
Balance at Mar. 31, 2019	$ 7,441	10,692	326,574	90	(14,128)	330,669
Net earnings			8,156			8,156
Unrealized gain on available-for-sale securities, net of tax				89		89
Other (in shares)	2
Other		222			62	285
Balance (in shares) at Jun. 30, 2019	6,997
Balance at Jun. 30, 2019	$ 7,441	10,914	334,730	180	(14,066)	339,199
Balance (in shares) at Dec. 31, 2019	7,006
Balance at Dec. 31, 2019	$ 7,441	11,447	362,842	136	(13,909)	367,957
Net earnings			20,879			20,879
Unrealized gain on available-for-sale securities, net of tax				158		158
Other (in shares)	13
Other				397	476	873
Dividends paid			(42,172)			(42,172)
Balance (in shares) at Jun. 28, 2020	7,019
Balance at Jun. 28, 2020	$ 7,441	11,923	341,549	294	(13,512)	347,695
Balance (in shares) at Mar. 29, 2020	7,016
Balance at Mar. 29, 2020	$ 7,441	11,728	328,892	229	(13,600)	334,690
Net earnings			12,657			12,657
Unrealized gain on available-for-sale securities, net of tax				65		65
Other (in shares)	3
Other		195			88	283
Balance (in shares) at Jun. 28, 2020	7,019
Balance at Jun. 28, 2020	$ 7,441	$ 11,923	$ 341,549	$ 294	$ (13,512)	$ 347,695