Short-Term Borrowings (Short Term Borrowing) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Short-term Borrowings
Short-term borrowings	$ (316,977)	$ (356,198)
Interest on short-term borrowings	4,712	5,238	$ 1,534
Retail Repurchase Agreements
Short-term Borrowings
Short-term borrowings	(42,968)	(51,202)	(76,899)
Average balance	46,686	64,519	75,344
Highest month-end balance	49,081	72,822	80,649
Interest on short-term borrowings	$ 266	$ 194	$ 128
Weighted Average Interest Rate, End of Year	0.37%	0.48%	0.17%
Short-term Debt, Weighted Average Interest Rate, over Time	0.57%	0.30%	0.17%
FHLB Advances
Short-term Borrowings
Short-term borrowings	$ (274,009)	$ (305,000)	$ (92,592)
Average balance	197,987	219,897	100,205
Highest month-end balance	274,009	307,561	208,000
Interest on short-term borrowings	$ 4,455	$ 4,494	$ 1,160
Weighted Average Interest Rate, End of Year	1.74%	2.32%	1.91%
Short-term Debt, Weighted Average Interest Rate, over Time	2.25%	2.04%	1.16%
National Market Repurchase Agreements
Short-term Borrowings
Short-term borrowings	$ 0	$ 0	$ (40,000)
Average balance	0	14,329	6,685
Highest month-end balance	0	30,000	40,000
Interest on short-term borrowings	$ 0	$ 527	$ 246
Weighted Average Interest Rate, End of Year	0.00%	0.00%	3.68%
Short-term Debt, Weighted Average Interest Rate, over Time	0.00%	3.68%	3.68%
Other
Short-term Borrowings
Short-term borrowings	$ 0	$ (4)	$ 0
Average balance	126	301	13
Highest month-end balance	2,200	1,553	0
Interest on short-term borrowings	$ 0	$ 23	$ 0
Weighted Average Interest Rate, End of Year	0.00%	0.00%	0.00%
Short-term Debt, Weighted Average Interest Rate, over Time			1.30%