Consolidated Statements of Changes in Stockholders' Equity (unaudited) - USD ($) $ in Thousands	Total	Class A Common Stock [Member]	Class B Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Retained Earnings [Member] Class A Common Stock [Member]	Retained Earnings [Member] Class B Common Stock [Member]	Accumulated Other Comprehensive Loss [Member]
Beginning balance at Dec. 31, 2014	$ 192,500	$ 3,601	$ 1,967	$ 12,292	$ 200,411			$ (25,771)
Net income	10,884	8,549	2,335		10,884
Other comprehensive income, net of tax:
Unrealized holding (losses) gains arising during period, net of taxes	(100)							(100)
Accretion of unrealized losses on securities transferred to held-to-maturity net of taxes	1,762							1,762
Pension liability adjustment, net of taxes	426							426
Cash dividends	(865)					$ (865)	$ (234)
Ending balance at Jun. 30, 2015	204,373	3,601	1,967	12,292	210,196			(23,683)
Beginning balance at Dec. 31, 2015	214,544	3,601	1,967	12,292	221,232			(24,548)
Net income	11,549	9,071	2,478		11,549
Other comprehensive income, net of tax:
Unrealized holding (losses) gains arising during period, net of taxes	(38)							(38)
Accretion of unrealized losses on securities transferred to held-to-maturity net of taxes	1,747							1,747
Pension liability adjustment, net of taxes	485							485
Cash dividends	(866)					$ (866)	$ (235)
Ending balance at Jun. 30, 2016	$ 227,186	$ 3,601	$ 1,967	$ 12,292	$ 231,680			$ (22,354)