Mergers and acquisitions - Atlantic Capital Bank Narrative (Details) $ in Thousands	Apr. 05, 2019 USD ($) branch
Business Acquisition [Line Items]
Percentage of loans outstanding	99.32%
Atlantic Capital Bank
Business Acquisition [Line Items]
Total purchase price	$ 36,790
Customer deposits	$ 588,877
Deposit premium percentage	6.25%
Loans, net of fair value adjustments	$ 374,966
TENNESSEE \| Atlantic Capital Bank
Business Acquisition [Line Items]
Number of branches acquired \| branch	11
GEORGIA \| Atlantic Capital Bank
Business Acquisition [Line Items]
Number of branches acquired \| branch	3

Business Acquisition, Transaction Value

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Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Customer Deposits

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Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Percentage of Loans Outstanding

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Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deposit Premium, Percentage

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Number Of Branches Acquired

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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The amount of financial assets (as defined) recognized as of the acquisition date.

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