Summary Of Significant Accounting Policies (Calculation Of Earnings Per 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
Summary Of Significant Accounting Policies [Abstract]
Net income		$ 9,187	$ 10,783	$ 10,744	$ 10,841	$ 10,090	$ 10,057	$ 10,315	$ 11,111	$ 41,555	$ 41,573	$ 35,122
Income allocated to participating securities	[1]										115	128
Income allocated to common stockholders										$ 41,555	$ 41,458	$ 34,994
Common shares										24,663,726	25,293,698	24,219,813
Dilutive stock options and restricted stock units	[1]									184,800	164,301	255,333
Total										24,848,526	25,457,999	24,475,146
Earnings per share:
Basic		$ 0.38	$ 0.44	$ 0.43	$ 0.43	$ 0.40	$ 0.39	$ 0.41	$ 0.44	$ 1.68	$ 1.64	$ 1.44
Diluted		$ 0.38	$ 0.44	$ 0.43	$ 0.43	$ 0.39	$ 0.39	$ 0.40	$ 0.44	$ 1.67	$ 1.63	$ 1.43

[1] RSUs awarded in 2016 accrued dividends at the same rate as the dividends declared by the Board of Directors on the Corporation’s common stock. For purposes of computing EPS, these RSUs were considered to participate with common stock in the earnings of the Corporation and, therefore, during 2018 and 2017, the Corporation calculated basic and diluted EPS using the two-class method. Substantially all of the RSUs awarded in 2016 vested on December 31, 2018. As a result, beginning in 2019, the Corporation calculates basic and dilutive EPS using the treasury stock method.