Shareholders' Equity and Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 18, 2018
Share Repurchase Plan [Abstract]
Share repurchase plan percentage of shares authorized to be repurchased						5.00%
Stock repurchased (in shares)		1,063,901		1,179,688
Stock repurchased		$ 23,252		$ 25,782
Earnings Per Share Reconciliation [Abstract]
Net Income		$ 10,730	$ 8,817	$ 20,111	$ 17,978
Weighted average shares outstanding (in shares)	[1]	23,036,000	24,109,000	23,310,000	22,745,000
Stock units for deferred compensation plan for non-employee directors (in shares)		128,000	126,000	130,000	125,000
Effect of stock options (in shares)		112,000	224,000	119,000	179,000
Performance share units (in shares)		37,000	51,000	39,000	50,000
Weighted average shares outstanding for calculation of diluted earnings per share (in shares)		23,313,000	24,510,000	23,598,000	23,099,000
Net income per common share [Abstract]
Basic (in dollars per share)	[1]	$ 0.47	$ 0.37	$ 0.86	$ 0.79
Diluted (in dollars per share)		$ 0.46	$ 0.36	$ 0.85	$ 0.78
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		300,000
Stock repurchased (in shares)				1,179,688	0
Stock repurchased		$ 23,252		$ 25,782	$ 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.