Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock Voting and Nonvoting Common Stock	Accumulated Other Comprehensive Loss	Retained Earnings
Balance at Dec. 31, 2013	$ 90,908	$ 71,378	$ (2,372)	$ 21,902
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	4,324
Other comprehensive income (loss)	2,237		2,237
Cash dividends declared	(1,080)			(1,080)
Recognition of the fair value of share-based compensation	507	507
Common stock redeemed for the net settlement of share-based awards	(71)	(71)
Other	(40)	(40)
Balance at Dec. 31, 2014	96,785	71,774	(135)	25,146
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	8,929
Other comprehensive income (loss)	(1,074)		(1,074)
Cash dividends declared	(1,095)			(1,095)
Recognition of the fair value of share-based compensation	762	762
Deferred stock rights and restricted stock units issued in lieu of cash dividends payable on outstanding deferred stock rights and restricted stock units	25	25
Excess tax benefit on share-based compensation	36	36
Common stock redeemed for the net settlement of share-based awards	(38)	(38)
Balance at Dec. 31, 2015	104,330	72,559	(1,209)	32,980
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	12,074
Other comprehensive income (loss)	(8,059)		(8,059)
Cash dividends declared	(1,350)			(1,350)
Net cash proceeds from common stock issuance	46,223	46,223
Recognition of the fair value of share-based compensation	736	736
Deferred stock rights and restricted stock units issued in lieu of cash dividends payable on outstanding deferred stock rights and restricted stock units	30	30
Excess tax benefit on share-based compensation	49	49
Common stock redeemed for the net settlement of share-based awards	(91)	(91)
Balance at Dec. 31, 2016	$ 153,942	$ 119,506	$ (9,268)	$ 43,704