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Fair Values of Assets and Liabilities - Schedule of Valuation Techniques and Significant Unobservable Inputs Used to Measure Both Recurring and Non Recurring (Details) | Sep. 30, 2023 USD ($) $ / shares year | Jun. 30, 2023 USD ($) | Dec. 31, 2022 USD ($) | Sep. 30, 2022 USD ($) | Jun. 30, 2022 USD ($) | Dec. 31, 2021 USD ($)
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Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
Available-for-sale securities | $ 3,611,835,000 |  | $ 3,243,017,000 | $ 2,923,653,000 |  |
Loans held-for-investment | 171,178,000 |  |  | 156,893,000 |  |
MSRs | 210,524,000 | $ 200,692,000 | 230,225,000 | 229,671,000 | $ 212,664,000 | $ 147,571,000
Individually assessed loans - foreclosure probable and collateral-dependent | 77,937,000 |  |  | 105,365,000 |  |
Municipal securities |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
Available-for-sale securities | 168,523,000 |  | 168,655,000 | 174,001,000 |  |
U.S. government agencies |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
Available-for-sale securities | 72,430,000 |  | 74,222,000 | 44,013,000 |  |
Level 3 |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
Individually assessed loans - foreclosure probable and collateral-dependent | 77,900,000 |  |  |  |  |
Measured at fair value on a recurring basis: |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
Mortgage loans held-for-sale | 304,808,000 |  | 299,935,000 | 376,160,000 |  |
Loans held-for-investment | 171,178,000 |  | 179,932,000 | 156,893,000 |  |
MSRs | 210,524,000 |  | 230,225,000 | 229,671,000 |  |
Derivative assets | 323,705,000 |  | 296,848,000 | 313,480,000 |  |
Measured at fair value on a recurring basis: | Municipal securities |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
Available-for-sale securities | 168,523,000 |  | 168,655,000 | 174,001,000 |  |
Measured at fair value on a recurring basis: | U.S. government agencies |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
Available-for-sale securities | 72,430,000 |  | 74,222,000 | 44,013,000 |  |
Measured at fair value on a recurring basis: | Level 3 |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
Mortgage loans held-for-sale | 25,187,000 |  | 48,655,000 | 48,420,000 |  |
Loans held-for-investment | 57,961,000 |  | 84,165,000 | 98,567,000 |  |
MSRs | 210,524,000 |  | 230,225,000 | 229,671,000 |  |
Derivative assets | 2,516,000 |  | 1,711,000 | 141,000 |  |
Measured at fair value on a recurring basis: | Level 3 | Municipal securities |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
Available-for-sale securities | 113,219,000 |  | 117,537,000 | 122,432,000 |  |
Measured at fair value on a recurring basis: | Level 3 | U.S. government agencies |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
Available-for-sale securities | 0 |  | $ 0 | $ 0 |  |
Mortgage loans held-for-sale | $ 25,187,000 |  |  |  |  |
Measured at fair value on a recurring basis: | Discount rate | Level 3 | Discounted cash flows |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
Mortgage loans held-for-sale, measurement input | 0.0698 |  |  |  |  |
Measured at fair value on a recurring basis: | Discount rate | Level 3 | Discounted cash flows | Minimum |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
Loans held-for-investment, measurement input | 0.0698 |  |  |  |  |
MSRs, measurement input | 0.04 |  |  |  |  |
Measured at fair value on a recurring basis: | Discount rate | Level 3 | Discounted cash flows | Maximum |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
Loans held-for-investment, measurement input | 0.0750 |  |  |  |  |
MSRs, measurement input | 0.21 |  |  |  |  |
Measured at fair value on a recurring basis: | Discount rate | Level 3 | Discounted cash flows | Weighted Average |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
Mortgage loans held-for-sale, measurement input | 0.0698 |  |  |  |  |
Loans held-for-investment, measurement input | 0.0704 |  |  |  |  |
MSRs, measurement input | 0.1051 |  |  |  |  |
Measured at fair value on a recurring basis: | Credit discount | Level 3 | Discounted cash flows | Minimum |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
Mortgage loans held-for-sale, measurement input | 0 |  |  |  |  |
Loans held-for-investment, measurement input | 0 |  |  |  |  |
Measured at fair value on a recurring basis: | Credit discount | Level 3 | Discounted cash flows | Maximum |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
Mortgage loans held-for-sale, measurement input | 0.10 |  |  |  |  |
Loans held-for-investment, measurement input | 0.29 |  |  |  |  |
Measured at fair value on a recurring basis: | Credit discount | Level 3 | Discounted cash flows | Weighted Average |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
Mortgage loans held-for-sale, measurement input | 0.0022 |  |  |  |  |
Loans held-for-investment, measurement input | 0.0098 |  |  |  |  |
Measured at fair value on a recurring basis: | Constant prepayment rate (CPR) - current loans | Level 3 | Discounted cash flows |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
Loans held-for-investment, measurement input | 0.0694 |  |  |  |  |
Measured at fair value on a recurring basis: | Constant prepayment rate (CPR) - current loans | Level 3 | Discounted cash flows | Minimum |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
MSRs, measurement input | 0 |  |  |  |  |
Measured at fair value on a recurring basis: | Constant prepayment rate (CPR) - current loans | Level 3 | Discounted cash flows | Maximum |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
MSRs, measurement input | 0.90 |  |  |  |  |
Measured at fair value on a recurring basis: | Constant prepayment rate (CPR) - current loans | Level 3 | Discounted cash flows | Weighted Average |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
Loans held-for-investment, measurement input | 0.0694 |  |  |  |  |
MSRs, measurement input | 0.0694 |  |  |  |  |
Measured at fair value on a recurring basis: | Average life - delinquent loans (in years) | Level 3 | Discounted cash flows | Minimum |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
Loans held-for-investment, measurement input | year | 1.3 |  |  |  |  |
Measured at fair value on a recurring basis: | Average life - delinquent loans (in years) | Level 3 | Discounted cash flows | Maximum |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
Loans held-for-investment, measurement input | year | 10.1 |  |  |  |  |
Measured at fair value on a recurring basis: | Average life - delinquent loans (in years) | Level 3 | Discounted cash flows | Weighted Average |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
Loans held-for-investment, measurement input | year | 5.9 |  |  |  |  |
Measured at fair value on a recurring basis: | Cost of servicing | Level 3 | Discounted cash flows | Minimum |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
MSRs, measurement input | $ / shares | 70 |  |  |  |  |
Measured at fair value on a recurring basis: | Cost of servicing | Level 3 | Discounted cash flows | Maximum |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
MSRs, measurement input | $ / shares | 200 |  |  |  |  |
Measured at fair value on a recurring basis: | Cost of servicing | Level 3 | Discounted cash flows | Weighted Average |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
MSRs, measurement input | 77 |  |  |  |  |
Measured at fair value on a recurring basis: | Cost of servicing - delinquent | Level 3 | Discounted cash flows | Minimum |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
MSRs, measurement input | $ / shares | 200 |  |  |  |  |
Measured at fair value on a recurring basis: | Cost of servicing - delinquent | Level 3 | Discounted cash flows | Maximum |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
MSRs, measurement input | $ / shares | 1,000 |  |  |  |  |
Measured at fair value on a recurring basis: | Cost of servicing - delinquent | Level 3 | Discounted cash flows | Weighted Average |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
MSRs, measurement input | 407 |  |  |  |  |
Measured at fair value on a recurring basis: | Pull-through rate | Level 3 | Discounted cash flows | Minimum |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
Derivatives, measurement input | 0.13 |  |  |  |  |
Measured at fair value on a recurring basis: | Pull-through rate | Level 3 | Discounted cash flows | Maximum |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
Derivatives, measurement input | 1 |  |  |  |  |
Measured at fair value on a recurring basis: | Pull-through rate | Level 3 | Discounted cash flows | Weighted Average |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
Derivatives, measurement input | 0.8302 |  |  |  |  |
Measured at fair value on a non-recurring basis: |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
Individually assessed loans - foreclosure probable and collateral-dependent | $ 77,937,000 |  |  |  |  |
Other real estate owned | 14,060,000 |  |  |  |  |
Measured at fair value on a non-recurring basis: | Level 3 |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
Individually assessed loans - foreclosure probable and collateral-dependent | 77,937,000 |  |  |  |  |
Other real estate owned | $ 14,060,000 |  |  |  |  |
Measured at fair value on a non-recurring basis: | Appraisal adjustment - cost of sale | Level 3 | Appraisal value |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
Impaired loans - collateral based, measurement input | 0.10 |  |  |  |  |
Other real estate owned, measurement input | 0.10 |  |  |  |  |
Measured at fair value on a non-recurring basis: | Appraisal adjustment - cost of sale | Level 3 | Appraisal value | Weighted Average |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |
Impaired loans - collateral based, measurement input | 0.1000 |  |  |  |  |
Other real estate owned, measurement input | 0.1000 |  |  |  |  |

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- Definition Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479130/326-30-45-1 + Details
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- Definition Fair value, after offset of derivative liability, of financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, before offset against an obligation to return collateral under a master netting arrangement. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 55 -Paragraph 9 -SubTopic 20 -Topic 210 -Publisher FASB -URI https://asc.fasb.org//1943274/2147483444/210-20-55-9 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (c) -SubTopic 20 -Topic 210 -Publisher FASB -URI https://asc.fasb.org//1943274/2147483466/210-20-50-3 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 55 -Paragraph 10 -SubTopic 20 -Topic 210 -Publisher FASB -URI https://asc.fasb.org//1943274/2147483444/210-20-55-10 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 8 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480434/815-10-50-8 + Details
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- Definition The balance of financing receivables that were individually evaluated for impairment. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 11C -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481962/310-10-50-11C Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 4 -Subparagraph (SAB Topic 6.L(5)(a)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480418/310-10-S99-4 + Details
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- Definition Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 860 -SubTopic 50 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (a)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481229/860-50-50-3 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 860 -SubTopic 50 -Name Accounting Standards Codification -Section 45 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481260/860-50-45-2 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 860 -SubTopic 50 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481260/860-50-45-1 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 860 -SubTopic 50 -Name Accounting Standards Codification -Section 45 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481260/860-50-45-2 + Details
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