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 Dec. 31, 2012			$ 4,932	$ 132,686			$ 393,472	$ 5,612			$ 536,702
Balance (in shares) at Dec. 31, 2012	18,694	2,271
Increase (Decrease) in Stockholders' Equity
Net income							25,423				25,423
Net change in accumulated other comprehensive income								(2,491)			(2,491)
Dividend declared Common Stock:
Dividend declared Common Stock					$ (12,735)	$ (1,424)			$ (12,735)	$ (1,424)
Stock options exercised, net of shares redeemed			5	610			(148)				467
Stock options exercised, net of shares redeemed (in shares)	24
Repurchase of Class A Common Stock			(43)	(1,230)			(2,822)				(4,095)
Repurchase of Class A Common Stock (in shares)	(193)
Conversion of Class B Common Stock to Class A Common Stock (in shares)	11	(11)
Net change in notes receivable on Class A Common Stock				250							250
Deferred director compensation expense - Class A Common Stock				193							193
Deferred director compensation expense - Class A Common Stock (in shares)	5
Stock based compensation - restricted stock				298							298
Stock based compensation expense - stock options				205							205
Balance at Dec. 31, 2013			4,894	133,012			401,766	3,121			542,793
Balance (in shares) at Dec. 31, 2013	18,541	2,260
Increase (Decrease) in Stockholders' Equity
Net income							28,787				28,787
Net change in accumulated other comprehensive income								1,194			1,194
Dividend declared Common Stock:
Dividend declared Common Stock					(13,680)	(1,508)			(13,680)	(1,508)
Stock options exercised, net of shares redeemed			13	1,586			(496)				1,103
Stock options exercised, net of shares redeemed (in shares)	62
Repurchase of Class A Common Stock			(3)	(95)			(249)				(347)
Repurchase of Class A Common Stock (in shares)	(15)
Conversion of Class B Common Stock to Class A Common Stock (in shares)	15	(15)
Net change in notes receivable on Class A Common Stock				(256)							(256)
Deferred director compensation expense - Class A Common Stock				187							187
Deferred director compensation expense - Class A Common Stock (in shares)	2
Stock based compensation - restricted stock				402			3				405
Stock based compensation - restricted stock (in shares)	(2)
Stock based compensation expense - stock options				53							53
Balance at Dec. 31, 2014			4,904	134,889			414,623	4,315			558,731
Balance (in shares) at Dec. 31, 2014	18,603	2,245
Increase (Decrease) in Stockholders' Equity
Net income							35,166				35,166
Net change in accumulated other comprehensive income								(2,266)			(2,266)
Dividend declared Common Stock:
Dividend declared Common Stock					$ (14,531)	$ (1,594)			$ (14,531)	$ (1,594)
Stock options exercised, net of shares redeemed			16	1,708			(588)				1,136
Stock options exercised, net of shares redeemed (in shares)	67
Repurchase of Class A Common Stock			(5)	(143)			(403)				(551)
Repurchase of Class A Common Stock (in shares)	(22)
Net change in notes receivable on Class A Common Stock				(189)							(189)
Deferred director compensation expense - Class A Common Stock				223							223
Deferred director compensation expense - Class A Common Stock (in shares)	5
Stock based compensation - restricted stock				253							253
Stock based compensation - restricted stock (in shares)	(1)
Stock based compensation expense - stock options				169							169
Balance at Dec. 31, 2015			$ 4,915	$ 136,910			$ 432,673	$ 2,049			$ 576,547
Balance (in shares) at Dec. 31, 2015	18,652	2,245