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Allowance for Credit Losses - Recorded Investment in Consumer Loan Classes by Performing and Nonperforming Status (Details) - USD ($) $ in Thousands | Sep. 30, 2020 | Dec. 31, 2019
--- | --- | ---
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | $ 7,394,868 | $ 7,137,152
Consumer |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 1,584,834 | $ 1,624,356
Percentage of Total |  | 100.00%
Consumer | Performing |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance |  | $ 1,614,158
Percentage of Total |  | 99.40%
Consumer | Nonperforming |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance |  | $ 10,198
Percentage of Total |  | 0.60%
Consumer | Residential Mortgage |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 950,887 | $ 998,585
Percentage of Total |  | 100.00%
Consumer | Residential Mortgage | Performing |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance |  | $ 991,066
Percentage of Total |  | 99.20%
Consumer | Residential Mortgage | Nonperforming |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance |  | $ 7,519
Percentage of Total |  | 0.80%
Consumer | Home equity |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 537,869 | $ 538,348
Percentage of Total |  | 100.00%
Consumer | Home equity | Performing |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance |  | $ 535,709
Percentage of Total |  | 99.50%
Consumer | Home equity | Nonperforming |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance |  | $ 2,639
Percentage of Total |  | 0.50%
Consumer | Installment and other consumer |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | 80,735 | $ 79,033
Percentage of Total |  | 100.00%
Consumer | Installment and other consumer | Performing |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance |  | $ 78,993
Percentage of Total |  | 99.90%
Consumer | Installment and other consumer | Nonperforming |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance |  | $ 40
Percentage of Total |  | 0.10%
Consumer | Consumer construction |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance | $ 15,343 | $ 8,390
Percentage of Total |  | 100.00%
Consumer | Consumer construction | Performing |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance |  | $ 8,390
Percentage of Total |  | 100.00%
Consumer | Consumer construction | Nonperforming |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Loans held for investment, outstanding balance |  | $ 0
Percentage of Total |  | 0.00%

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