Condensed Consolidated Statements of Changes in Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock Voting and Nonvoting Common Stock	Retained Earnings	Accumulated Other Comprehensive Loss
Balance, beginning of period at Dec. 31, 2018	$ 288,735	$ 227,587	$ 77,689	$ (16,541)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	5,696		5,696
Other comprehensive income (loss)	2,373			2,373
Dividends declared	(618)		(618)
Recognition of the fair value of share-based compensation	478	478
Repurchase of common stock	(1,746)	(1,746)
Deferred stock rights and restricted stock units issued in lieu of cash dividends payable on outstanding deferred stock rights and restricted stock units	10	10
Common stock redeemed for the net settlement of share-based awards	(94)	(94)
Balance, end of period at Mar. 31, 2019	294,013	226,235	81,946	(14,168)
Balance, beginning of period at Dec. 31, 2019	304,913	219,423	99,681	(14,191)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	6,019		6,019
Other comprehensive income (loss)	(5,675)			(5,675)
Dividends declared	(600)		(600)
Recognition of the fair value of share-based compensation	555	555
Deferred stock rights and restricted stock units issued in lieu of cash dividends payable on outstanding deferred stock rights and restricted stock units	8	8
Common stock redeemed for the net settlement of share-based awards	(93)	(93)
Balance, end of period at Mar. 31, 2020	$ 305,127	$ 219,893	$ 105,100	$ (19,866)