Consolidated Statements of Changes in Stockholders' Equity - 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, 2013	$ 176,472	$ 3,580	$ 1,976	$ 11,932	$ 180,747			$ (21,763)
Net income	21,860	17,157	4,703		21,860
Other comprehensive income, net of tax:
Unrealized holding gains arising during period, net of taxes	1,122							1,122
Accretion of net unrealized losses transferred during the period, net of taxes	3,188							3,188
Pension liability adjustment, net of taxes	(8,318)							(8,318)
Conversion of Class B Common Stock to Class A Common Stock		9
Conversion of Class B Common Stock to Class A Common Stock			(9)
Stock options exercised	361	12		349
Cashless stock options exercised	11			11
Cash dividends						$ (1,723)	$ (473)
Ending balance at Dec. 31, 2014	192,500	3,601	1,967	12,292	200,411			(25,771)
Net income	23,021	18,081	4,940		23,021
Other comprehensive income, net of tax:
Unrealized holding gains arising during period, net of taxes	(323)							(323)
Accretion of net unrealized losses transferred during the period, net of taxes	3,583							3,583
Pension liability adjustment, net of taxes	(2,037)							(2,037)
Cash dividends						(1,728)	(472)
Ending balance at Dec. 31, 2015	214,544	3,601	1,967	12,292	221,232			(24,548)
Net income	24,534	19,270	5,264		24,534
Other comprehensive income, net of tax:
Unrealized holding gains arising during period, net of taxes	(321)							(321)
Accretion of net unrealized losses transferred during the period, net of taxes	2,812							2,812
Pension liability adjustment, net of taxes	673							673
Cash dividends						$ (1,729)	$ (472)
Ending balance at Dec. 31, 2016	$ 240,041	$ 3,601	$ 1,967	$ 12,292	$ 243,565			$ (21,384)