Consolidated Statement of Shareholders' Equity - 6 months ended Jun. 30, 2016 - USD ($) $ in Thousands	Total	Common Shares	Retained Earnings	Accumulated Other Comprehensive (Loss) Income	Treasury Stock	Restricted Shares	Restricted Shares Common Shares	Restricted Shares Treasury Stock
Balance, December 31, 2015 at Dec. 31, 2015	$ 419,789	$ 343,948	$ 90,790	$ (359)	$ (14,590)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	15,957		15,957
Other comprehensive income, net of tax	11,493			11,493
Cash dividends declared	(5,652)		(5,652)
Reissuance of treasury stock for deferred compensation plan for Boards of Directors	201				201	$ 0	$ (1,245)	$ 1,245
Adjustments to Additional Paid in Capital, Income Tax Deficiency from Share-based Compensation	(3)	(3)
Repurchase of common shares in connection with employee incentive and director compensation plans	316				(316)
Common shares repurchased under share repurchase program	(4,965)				4,965
Common shares issued under dividend reinvestment plan	219	219
Common shares issued under compensation plan for Boards of Directors	178	24			202
Common shares issued under employee stock purchase plan	(189)	(18)			(207)
Stock-based compensation expense	663	663
Balance, June 30, 2016 at Jun. 30, 2016	$ 437,753	$ 343,540	$ 101,095	$ 11,134	$ (18,016)