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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) (Detail) | Mar. 31, 2022 USD ($) $ / shares | Dec. 31, 2021 USD ($) | Mar. 31, 2021 USD ($) | Dec. 31, 2020 USD ($)
--- | --- | --- | --- | ---
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Available-for-sale securities, at fair value | $ 2,998,898,000 | $ 2,327,793,000 | $ 2,430,749,000 |
Loans held-for-investment | 57,984,000 |  | 51,916,000 |
MSRs | 199,146,000 | 147,571,000 | 124,316,000 | $ 92,081,000
Individually assessed loans - foreclosure probable and collateral-dependent | 72,846,000 |  | 124,404,000 |
Level 3 |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Individually assessed loans - foreclosure probable and collateral-dependent | 72,800,000 |  |  |
Measured at fair value on a recurring basis: |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Loans held-for-investment | 57,984,000 | 38,598,000 | 51,916,000 |
MSRs | 199,146,000 | 147,571,000 | 124,316,000 |
Derivative assets | 153,534,000 | 165,008,000 | 253,509,000 |
Measured at fair value on a recurring basis: | Level 3 |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Loans held-for-investment | 44,464,000 | 15,891,000 | 6,408,000 |
MSRs | 199,146,000 | 147,571,000 | 124,316,000 |
Derivative assets | 3,447,000 | 10,560,000 | 25,634,000 |
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 | 44,844,000 |  |  |
Other real estate owned | 6,203,000 |  |  |
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 | 44,844,000 |  |  |
Other real estate owned | 6,203,000 |  |  |
Municipal Securities |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Available-for-sale securities, at fair value | 155,489,000 | 165,594,000 | 148,300,000 |
Municipal Securities | Measured at fair value on a recurring basis: |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Available-for-sale securities, at fair value | 155,489,000 | 165,594,000 | 148,300,000 |
Municipal Securities | Measured at fair value on a recurring basis: | Level 3 |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Available-for-sale securities, at fair value | $ 100,401,000 | $ 105,687,000 | $ 101,748,000 |
Discount rate | Discounted cash flows | Minimum | Measured at fair value on a recurring basis: | Level 3 |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Loans held-for-investment, measurement input | 0.0400 |  |  |
MSRs, measurement input | 0.06 |  |  |
Discount rate | Discounted cash flows | Maximum | Measured at fair value on a recurring basis: | Level 3 |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Loans held-for-investment, measurement input | 0.0425 |  |  |
MSRs, measurement input | 0.19 |  |  |
Discount rate | Discounted cash flows | Weighted Average | Measured at fair value on a recurring basis: | Level 3 |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Loans held-for-investment, measurement input | 0.0425 |  |  |
MSRs, measurement input | 0.0979 |  |  |
Credit discount | Discounted cash flows | Minimum | Measured at fair value on a recurring basis: | Level 3 |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Loans held-for-investment, measurement input | 0 |  |  |
Credit discount | Discounted cash flows | Maximum | Measured at fair value on a recurring basis: | Level 3 |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Loans held-for-investment, measurement input | 0.03 |  |  |
Credit discount | Discounted cash flows | Weighted Average | Measured at fair value on a recurring basis: | Level 3 |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Loans held-for-investment, measurement input | 0.0036 |  |  |
Constant prepayment rate (CPR) | Discounted cash flows | Measured at fair value on a recurring basis: | Level 3 |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Loans held-for-investment, measurement input | 0.0711 |  |  |
Constant prepayment rate (CPR) | Discounted cash flows | Minimum | Measured at fair value on a recurring basis: | Level 3 |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
MSRs, measurement input | 0 |  |  |
Constant prepayment rate (CPR) | Discounted cash flows | Maximum | Measured at fair value on a recurring basis: | Level 3 |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
MSRs, measurement input | 1 |  |  |
Constant prepayment rate (CPR) | Discounted cash flows | Weighted Average | Measured at fair value on a recurring basis: | Level 3 |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Loans held-for-investment, measurement input | 0.0711 |  |  |
MSRs, measurement input | 0.0711 |  |  |
Cost of servicing | Discounted cash flows | Minimum | Measured at fair value on a recurring basis: | Level 3 |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
MSRs, measurement input | $ / shares | 70 |  |  |
Cost of servicing | Discounted cash flows | Maximum | Measured at fair value on a recurring basis: | Level 3 |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
MSRs, measurement input | $ / shares | 200 |  |  |
Cost of servicing | Discounted cash flows | Weighted Average | Measured at fair value on a recurring basis: | Level 3 |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
MSRs, measurement input | 75 |  |  |
Cost of servicing - delinquent | Discounted cash flows | Minimum | Measured at fair value on a recurring basis: | Level 3 |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
MSRs, measurement input | $ / shares | 200 |  |  |
Cost of servicing - delinquent | Discounted cash flows | Maximum | Measured at fair value on a recurring basis: | Level 3 |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
MSRs, measurement input | $ / shares | 1,000 |  |  |
Cost of servicing - delinquent | Discounted cash flows | Weighted Average | Measured at fair value on a recurring basis: | Level 3 |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
MSRs, measurement input | 305 |  |  |
Pull-through rate | Discounted cash flows | Minimum | Measured at fair value on a recurring basis: | Level 3 |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Derivatives, measurement input | 0 |  |  |
Pull-through rate | Discounted cash flows | Maximum | Measured at fair value on a recurring basis: | Level 3 |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Derivatives, measurement input | 1 |  |  |
Pull-through rate | Discounted cash flows | Weighted Average | Measured at fair value on a recurring basis: | Level 3 |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Derivatives, measurement input | 0.871 |  |  |
Appraisal adjustment - cost of sale | Appraisal value | 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, measurement input | 0.10 |  |  |
Other real estate owned, measurement input | 0.10 |  |  |
Appraisal adjustment - cost of sale | Appraisal value | Weighted Average | 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, 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 -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454 + Details
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- Definition Fair value, after the effects of master netting arrangements, of a 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. Includes assets not subject to a master netting arrangement and not elected to be offset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226008-175313 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 22 -URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226052-175313 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=123594938&loc=d3e13433-108611 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 + Details
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