CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $) In Thousands, unless otherwise specified	Total	Class A [Member]	Class B [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Common Stock [Member] Class A [Member]	Common Stock [Member] Class B [Member]	Additional Paid-in Capital (APIC) [Member]
Balance at Dec. 31, 2009	$ 208,932			$ 185,014	$ 1,092	$ 217	$ 946	$ 21,663
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends declared on Class A common stock	(522)			(522)
Cash dividends declared on Class B common stock	(2,664)			(2,664)
Issuance of restricted common stock	0						7	(7)
Foreign currency translation adjustment	(907)				(907)
Unrealized holding gains on marketable securities arising during the year	457				457
Reclassification adjustment for unrealized holding gains included in net earnings, net of taxes	0
Reclassification adjustment for unrealized holding losses included in net earnings, net of taxes	0
Reduction in APIC pool associated with tax deficiencies related to restricted stock awards	(131)							(131)
Stock-based compensation expense	2,200							2,200
Change in unfunded SERP liability, net of taxes	(681)				(681)
Net earnings	13,649	2,394	11,255	13,649
Balance at Dec. 31, 2010	220,333			195,477	(39)	217	953	23,725
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends declared on Class A common stock	(522)			(522)
Cash dividends declared on Class B common stock	(2,690)			(2,690)
Issuance of restricted common stock	0						13	(13)
Forfeiture of restricted common stock	0						(2)	2
Foreign currency translation adjustment	(236)				(236)
Unrealized holding gains on marketable securities arising during the year	(507)				(507)
Reclassification adjustment for unrealized holding gains included in net earnings, net of taxes	(74)				(74)
Reclassification adjustment for unrealized holding losses included in net earnings, net of taxes	0
Reduction in APIC pool associated with tax deficiencies related to restricted stock awards	(3)							(3)
Stock-based compensation expense	1,709							1,709
Change in unfunded SERP liability, net of taxes	(694)				(694)
Net earnings	3,764	620	3,144	3,764
Balance at Dec. 31, 2011	221,080			196,029	(1,550)	217	964	25,420
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends declared on Class A common stock	(522)			(522)
Cash dividends declared on Class B common stock	(2,697)			(2,697)
Issuance of restricted common stock	0						13	(13)
Forfeiture of restricted common stock	0						(3)	3
Repurchase/retirement of Class B common stock	(6,644)		(6,600)				(37)	(6,607)
Foreign currency translation adjustment	281				281
Unrealized holding gains on marketable securities arising during the year	(251)				(251)
Reclassification adjustment for unrealized holding gains included in net earnings, net of taxes	0
Reclassification adjustment for unrealized holding losses included in net earnings, net of taxes	569				569
Reduction in APIC pool associated with tax deficiencies related to restricted stock awards	(118)							(118)
Stock-based compensation expense	1,767							1,767
Change in unfunded SERP liability, net of taxes	(476)				(476)
Net earnings	2,402	377	2,025	2,402
Balance at Dec. 31, 2012	$ 215,391			$ 195,212	$ (1,427)	$ 217	$ 937	$ 20,452