Earnings Per Common Share (Calculations of Basic and Diluted Earnings per Common Share) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Distributed earnings allocated to common shareholders									$ 26,503	$ 21,334	$ 15,159
Undistributed earnings allocated to common shareholders									26,796	24,660	23,115
Net earnings allocated to common shareholders									$ 53,299	$ 45,994	$ 38,274
Weighted-average number of common shares outstanding – basic	20,407,505	20,415,245	20,277,028	19,366,008	19,337,403	19,325,457	19,160,728	18,126,089	20,120,119	18,991,768	18,050,189
Effect of potentially dilutive common shares									153,606	130,492	158,495
Total weighted-average diluted common shares outstanding	20,599,127	20,595,769	20,442,366	19,508,868	19,483,452	19,466,865	19,293,381	18,256,035	20,273,725	19,122,260	18,208,684
Earnings per common share – basic	$ 0.72	$ 0.72	$ 0.47	$ 0.74	$ 0.71	$ 0.65	$ 0.41	$ 0.64	$ 2.65	$ 2.42	$ 2.12
Earnings per common share – diluted	$ 0.72	$ 0.72	$ 0.46	$ 0.73	$ 0.71	$ 0.65	$ 0.41	$ 0.64	$ 2.63	$ 2.41	$ 2.10
Antidilutive Securities Excluded from Computation of Earnings Per Share
Restricted shares, stock options and stock appreciation rights									0	1,748	453