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Loans and Allowance for Credit Losses - Concentrations of Credit Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans, at amortized cost	$ 2,088,556	$ 1,843,286
Commercial real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Percentage of loans by class to all loans	61.00%	68.00%
Commercial real estate | California
Financing Receivable, Allowance for Credit Loss [Line Items]
Percentage of loans by class and geographic location	85.00%	84.00%
Loans secured by real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Percentage of loans by class to all loans	77.00%	88.00%
Commercial and industrial | Commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans, at amortized cost	$ 498,408	$ 246,687
Commercial and industrial | Commercial | Small Business Administration Paycheck Protection Program
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans, at amortized cost	$ 291,600

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

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