Shareholders' Equity and Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Jan. 23, 2017
Earnings Per Share Reconciliation [Abstract]
Net income		$ 6,859	$ 6,373	$ 18,764	$ 16,911
Weighted average shares outstanding (in shares)	[1]	21,334	21,232	21,325	21,421
Effect of stock options (in shares)		138	149	144	150
Stock units for deferred compensation plan for non-employee directors (in shares)		121	116	120	115
Performance share units (in shares)		59	52	57	42
Restricted stock units (in shares)		0	0	0	46
Weighted average shares outstanding for calculation of diluted earnings per share (in shares)		21,652	21,549	21,646	21,774
Net income per common share [Abstract]
Basic (in dollars per share)	[1]	$ 0.32	$ 0.30	$ 0.88	$ 0.79
Diluted (in dollars per share)		$ 0.32	$ 0.30	$ 0.87	$ 0.78
Common Stock [Member]
Class of Stock [Line Items]
Stock repurchase program percentage of shares authorized to be repurchased						5.00%
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of diluted loss per share (in shares)		0	30	0	30

[1] Basic net income per common share includes weighted average common shares outstanding during the period and participating share awards.