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, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Summary Of Significant Accounting Policies [Abstract]
Net income		$ 10,090	$ 10,057	$ 10,315	$ 11,111	$ 7,566	$ 9,342	$ 9,133	$ 9,081	$ 41,573	$ 35,122	$ 30,880
Income allocated to participating securities	[1]									115	128	127
Income allocated to common stockholders										$ 41,458	$ 34,994	$ 30,753
Common shares										25,293,698	24,219,813	22,745,967
Dilutive stock options and restricted stock units	[1]									164,301	255,333	271,929
Total										25,457,999	24,475,146	23,017,896
Earnings per share:
Basic		$ 0.40	$ 0.39	$ 0.41	$ 0.44	$ 0.31	$ 0.38	$ 0.38	$ 0.38	$ 1.64	$ 1.44	$ 1.35
Diluted		$ 0.39	$ 0.39	$ 0.40	$ 0.44	$ 0.30	$ 0.38	$ 0.37	$ 0.38	$ 1.63	$ 1.43	$ 1.34

[1] RSUs awarded in 2016 accrue 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 are considered to participate with common stock in the earnings of the Corporation and, therefore, the Corporation calculates basic and diluted EPS using the two-class method. Under the two-class method, net income for the period is allocated between common stockholders and participating securities according to dividends declared and participation rights in undistributed earnings. Substantially all of the RSUs awarded in 2016 vested on December 31, 2018.