Earnings Per Share (Calculation Of Earnings Per Share) (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended						9 Months Ended
		Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share [Abstract]
Net income		$ 10,783	$ 10,744	$ 10,841	$ 10,057	$ 10,315	$ 11,111	$ 32,368	$ 31,483
Income allocated to participating securities	[1]				26				86
Income allocated to common stockholders		$ 10,783			$ 10,031			$ 32,368	$ 31,397
Common shares		24,470,249			25,409,087			24,855,562	25,236,889
Dilutive stock options and restricted stock units	[1]	192,860			144,933			177,072	174,095
Total		24,663,109			25,554,020			25,032,634	25,410,984
Basic		$ 0.44			$ 0.39			$ 1.30	$ 1.24
Diluted		$ 0.44			$ 0.39			$ 1.29	$ 1.24

[1] Restricted stock units (“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, 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.