Shareholders' Equity and Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	3 Months Ended		9 Months Ended
		May 31, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Jun. 30, 2019	Dec. 18, 2018
Share Repurchase Plan [Abstract]
Share repurchase plan percentage of shares authorized to be repurchased								5.00%
Stock repurchased (in shares)			25,000		1,204,688
Stock repurchased			$ 502		$ 26,284
Earnings Per Share Reconciliation [Abstract]
Net Income			$ 12,445	$ 11,925	$ 32,556	$ 29,903
Weighted average shares outstanding (in shares)	[1]		22,486,000	24,149,000	23,033,000	23,218,000
Stock units for deferred compensation plan for non-employee directors (in shares)			132,000	129,000	131,000	126,000
Effect of stock options (in shares)			110,000	182,000	116,000	180,000
Performance share units (in shares)			42,000	55,000	39,000	52,000
Weighted average shares outstanding for calculation of diluted earnings per share (in shares)			22,770,000	24,515,000	23,319,000	23,576,000
Net income per common share [Abstract]
Basic (in dollars per share)	[1]		$ 0.55	$ 0.49	$ 1.41	$ 1.29
Diluted (in dollars per share)			$ 0.55	$ 0.49	$ 1.40	$ 1.27
Common Stock [Member]
Share Repurchase Plan [Abstract]
Share repurchase plan percentage of shares repurchased		5.00%
Number of shares authorized for repurchase (in shares)							300,000
Stock repurchased (in shares)					1,204,688	0
Stock repurchased			$ 502		$ 26,284	$ 0
Stock Options [Member]
Antidilutive Securities [Abstract]
Antidilutive shares excluded from computation of diluted loss per share (in shares)			0	0	0	0

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