Loans, Allowance for Credit Losses, and Asset Quality Information (Summary of Nonperforming Assets) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Loans and Leases Receivable Disclosure [Line Items]
Nonaccrual loans	$ 39,566	$ 35,076
Loans	4,624,054	4,731,315	$ 4,552,708
Foreclosed properties	1,811	2,424
Nonperforming assets
Loans and Leases Receivable Disclosure [Line Items]
Nonaccrual loans	39,566	35,076
TDRs - accruing	8,601	9,497
Accruing loans > 90 days past due	0	0
Loans	48,167	44,573
Foreclosed properties	1,811	2,424
Total nonperforming assets	$ 49,978	$ 46,997

Financing Receivable, Including Foreclosed Real Estate

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Amount of financing receivable modified as troubled debt restructuring.

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Amount of financing receivable 90 days or more past due and still accruing.

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Amount of financing receivable on nonaccrual status.

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Amount, before allowance for credit loss, of financing receivable.

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Carrying amount as of the balance sheet date of other real estate and foreclosed assets. Other real estate may include real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations may also be included in real estate owned. Foreclosed assets include all assets obtained in full or partial satisfaction of a debt arrangement through foreclosure proceedings.

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