Consolidated Statements of Stockholders' Equity (USD $) In Thousands, except Share data	Total	Common Class A [Member]	Common Class B [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]
Balance at Dec. 31, 2011	$ 92,975	$ 64	$ 8	$ 50,662	$ 70,831	$ (28,590)
Balance, shares at Dec. 31, 2011		6,359,000	797,000
Net income	17,925				17,925
Net proceeds from exercised options	267			267
Net proceeds from exercised options (in shares)		10,000
Dividends declared per common share	(7,010)				(7,010)
Compensation expense related to restricted stock awards	110			110
Share-based compensation cost	22			22
Purchase of shares held in treasury	(80)					(80)
Balance at Dec. 31, 2012	104,209	64	8	51,061	81,746	(28,670)
Balance, shares at Dec. 31, 2012		6,369,000	797,000
Net income	15,273				15,273
Conversion of shares from Class B to Class A	0
Conversion of shares from Class B to Class A (in shares)		1,000	(1,000)
Issuance of restricted stock	0
Issuance of restricted stock (in shares)		30,000	20,000
Net proceeds from exercised options	275			275
Net proceeds from exercised options (in shares)		9,000
Dividends declared per common share	(10,326)				(10,326)
Compensation expense related to restricted stock awards	135			135
Purchase of shares held in treasury	(95)					(95)
401(k) plan contribution	230			(15)		245
Balance at Dec. 31, 2013	109,701	64	8	51,456	86,693	(28,520)
Balance, shares at Dec. 31, 2013		6,409,000	816,000
Net income	14,904				14,904
Conversion of shares from Class B to Class A (in shares)		3,000	(3,000)
Issuance of restricted stock (in shares)		27,000	30,000
Net proceeds from exercised options	244			244
Net proceeds from exercised options (in shares)		7,000
Dividends declared per common share	(10,419)				(10,419)
Compensation expense related to restricted stock awards	826			826
Purchase of shares held in treasury	(254)					(254)
401(k) plan contribution	243			(30)		273
Balance at Dec. 31, 2014	$ 115,245	$ 64	$ 8	$ 52,496	$ 91,178	$ (28,501)
Balance, shares at Dec. 31, 2014		6,446,000	843,000