Short-Term Borrowings (Short Term Borrowing) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Short-term Borrowings
Short-term borrowings	$ (73,261)	$ (316,977)
Interest on short-term borrowings	2,571	4,712	$ 5,238
Retail Repurchase Agreements
Short-term Borrowings
Short-term borrowings	(53,261)	(42,968)	(51,202)
Average balance	44,902	46,686	64,519
Highest month-end balance	53,261	49,081	72,822
Interest on short-term borrowings	$ 77	$ 266	$ 194
Weighted Average Interest Rate, End of Year	0.06%	0.37%	0.48%
Short-term Debt, Weighted Average Interest Rate, over Time	0.17%	0.57%	0.30%
FHLB Advances
Short-term Borrowings
Short-term borrowings	$ (20,000)	$ (274,009)	$ (305,000)
Average balance	129,928	197,987	219,897
Highest month-end balance	235,989	274,009	307,561
Interest on short-term borrowings	$ 2,489	$ 4,455	$ 4,494
Weighted Average Interest Rate, End of Year	1.78%	1.74%	2.32%
Short-term Debt, Weighted Average Interest Rate, over Time	1.92%	2.25%	2.04%
National Market Repurchase Agreements
Short-term Borrowings
Short-term borrowings	$ 0	$ 0	$ 0
Average balance	0	0	14,329
Highest month-end balance	0	0	30,000
Interest on short-term borrowings	$ 0	$ 0	$ 527
Weighted Average Interest Rate, End of Year	0.00%	0.00%	0.00%
Short-term Debt, Weighted Average Interest Rate, over Time	0.00%	0.00%	3.68%
Other
Short-term Borrowings
Short-term borrowings	$ 0	$ 0	$ (4)
Average balance	1,803	126	301
Highest month-end balance	64,000	2,200	1,553
Interest on short-term borrowings	$ 5	$ 0	$ 23
Weighted Average Interest Rate, End of Year	0.00%	0.00%	0.00%
Short-term Debt, Weighted Average Interest Rate, over Time	0.25%

The aggregate interest expense incurred on short-term borrowings including commercial paper and Federal funds purchased and securities sold under agreements to repurchase.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.7)
-URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(19)(a))
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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