Short-term Borrowings And Long-Term Debt (Summary Of Aggregate Short-term Borrowings) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Short-term Debt [Line Items]
Short-term borrowings, Amount outstanding at end of year	$ 7,925	$ 7,022
Repurchase Agreements [Member]
Short-term Debt [Line Items]
Short-term borrowings, Amount outstanding at end of year	$ 7,925	$ 7,022	$ 10,295
Short-term borrowings, Weighted average interest rate at end of year	0.53%	0.52%	0.56%
Short-term borrowings, Maximum amount outstanding at any month-end	$ 9,986	$ 12,964	$ 28,596
Short-term borrowings, Daily average amount outstanding	$ 7,891	$ 9,911	$ 22,078
Short-term borrowings, Approximate weighted average interest rate for the year	0.54%	0.56%	0.56%
Other Short Term Borrowings [Member]
Short-term Debt [Line Items]
Short-term borrowings, Amount outstanding at end of year	$ 0	$ 0	$ 10,200
Short-term borrowings, Weighted average interest rate at end of year	0.00%	0.00%	1.55%
Short-term borrowings, Maximum amount outstanding at any month-end	$ 0	$ 15,000	$ 30,000
Short-term borrowings, Daily average amount outstanding	$ 1	$ 193	$ 16,910
Short-term borrowings, Approximate weighted average interest rate for the year	1.97%	1.86%	1.14%