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Allowance for Credit Losses - Collateral Dependent Loans by Class of Loan (Details) - USD ($) $ in Thousands | Jun. 30, 2021 | Dec. 31, 2020
--- | --- | ---
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | $ 7,007,351 | $ 7,225,860
Real Estate |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 81,767 | 108,525
Business Assets |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 15,602 | 16,699
Investment/Cash |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 0 | 0
Other |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 0 | 689
Commercial |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 5,499,044 | 5,673,707
Commercial | Commercial real estate |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 2,740,296 | 2,791,947
Commercial | Commercial real estate | Real Estate |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 76,437 | 100,450
Commercial | Commercial real estate | Business Assets |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 0 | 0
Commercial | Commercial real estate | Investment/Cash |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 0 | 0
Commercial | Commercial real estate | Other |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 0 | 0
Commercial | Commercial and industrial |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 1,546,247 | 1,559,552
Commercial | Commercial and industrial | Real Estate |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 302 | 1,040
Commercial | Commercial and industrial | Business Assets |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 14,461 | 15,080
Commercial | Commercial and industrial | Investment/Cash |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 0 | 0
Commercial | Commercial and industrial | Other |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 0 | 0
Commercial | Commercial construction |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 467,871 | 466,077
Commercial | Commercial construction | Real Estate |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 3,222 | 3,552
Commercial | Commercial construction | Business Assets |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 0 | 0
Commercial | Commercial construction | Investment/Cash |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 0 | 0
Commercial | Commercial construction | Other |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 0 | 0
Commercial | Business banking |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 1,070,875 | 1,160,067
Commercial | Business banking | Real Estate |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 1,806 | 3,085
Commercial | Business banking | Business Assets |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 1,141 | 1,619
Commercial | Business banking | Investment/Cash |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 0 | 0
Commercial | Business banking | Other |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 0 | 689
Consumer |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 1,508,307 | 1,552,153
Consumer | Business banking |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance |  | 303,900
Consumer | Consumer real estate |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 1,093,878 | 1,167,332
Consumer | Consumer real estate | Real Estate |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 0 | 398
Consumer | Consumer real estate | Business Assets |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 0 | 0
Consumer | Consumer real estate | Investment/Cash |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 0 | 0
Consumer | Consumer real estate | Other |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | $ 0 | $ 0

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