Short-Term Borrowings (Schedule Of Short-Term Debt) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Short-term Debt [Line Items]
Maximum outstanding at any month end	$ 36,627	$ 47,920	$ 36,666
Average outstanding	13,044	15,091	13,977
Overnight Borrowings [Member]
Short-term Debt [Line Items]
Maximum outstanding at any month end	17,862	27,236	13,694
Average outstanding	$ 2,805	$ 4,823	$ 2,628
Weighted-average rate during the year	0.65%	0.39%	0.31%
Rate at year-end		0.48%
Repurchase Agreements [Member]
Short-term Debt [Line Items]
Maximum outstanding at any month end	$ 18,765	$ 20,684	$ 22,972
Average outstanding	$ 10,239	$ 10,268	$ 11,349
Weighted-average rate during the year	0.19%	0.17%	0.18%
Rate at year-end	0.13%	0.15%	0.15%