Allowance for Loan Losses, Allowance for Losses on Lending-Related Commitments and Impaired Loans (Summary of Impaired Loans, Including Restructured Loans) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Receivables [Abstract]
Impaired loans with an allowance for loan loss required	$ 62,886	$ 60,219
Impaired loans with no allowance for loan loss required	57,159	67,050
Impaired loans-collateral based	120,045	127,269
Allowance for loan losses related to impaired loans	12,336	11,437
TDRs	63,836	66,102
Reduction of interest income from non-accrual loans	5,202	3,422
Interest income recognized on impaired loans	$ 9,383	$ 7,347	$ 6,300

Amount of financing receivable modified as troubled debt restructuring.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953676-111524

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-Section 50
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-URI http://asc.fasb.org/extlink&oid=118939409&loc=d3e18845-111554

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- Definition

Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
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Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

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-Publisher FASB
-Name Accounting Standards Codification
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Amount of allowance for credit losses related to recorded investment.

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Amount of investment in impaired financing receivables for which there is no related allowance for credit losses.

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Amount of investment in impaired financing receivables for which there is a related allowance for credit losses.

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Reflects the amount of additional interest income that would have been recorded if impaired or nonperforming loans were instead current, in compliance with their original terms, and outstanding throughout the reporting period or since origination (if held for part of the period).

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