EPS (Computation of Basic and Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share [Abstract]
Net income		$ 16,775	$ 14,488	$ 41,208	$ 41,965
Dividends and undistributed earnings allocated to participating securities	[1]	(47)	(33)	(101)	(86)
Net income available to common shareholders		$ 16,728	$ 14,455	$ 41,107	$ 41,879
Weighted-average common shares outstanding for basic EPS		14,961,465	15,339,093	15,008,004	15,482,765
Dilutive effect of stock-based awards (shares)	[2]	39,582	42,835	36,423	39,736
Weighted-average common and potential common shares for diluted EPS (shares)		15,001,047	15,381,928	15,044,427	15,522,501
Basic EPS (in dollars per share)		$ 1.12	$ 0.94	$ 2.74	$ 2.70
Diluted EPS (in dollars per share)		$ 1.11	$ 0.94	$ 2.73	$ 2.70
Antidilutive Stock options (shares)	[3]	8,206	0	3,206	0

[1] (1)    Represents dividends paid and undistributed earnings allocated to nonvested stock-based awards that contain non-forfeitable rights to dividends.

[2] (2)    Represents the assumed dilutive effect of unexercised and/or unvested stock options, restricted shares, restricted share units and contingently issuable performance-based awards utilizing the treasury stock method.

[3] (3)    Represents stock-based awards not included in the computation of potential common shares for purposes of calculating diluted EPS as the exercise prices were greater than the average market price of the Company's common stock, and, therefore, are considered anti-dilutive.