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Fair Values of Assets and Liabilities (Narrative) (Detail) | Mar. 31, 2022 USD ($) $ / shares | Dec. 31, 2021 USD ($) | Mar. 31, 2021 USD ($) | Dec. 31, 2020 USD ($)
--- | --- | --- | --- | ---
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [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 |
Estimate of Fair Value Measurement |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Available-for-sale securities, at fair value | 2,998,898,000 | 2,327,793,000 | 2,430,749,000 |
Remaining contractual principal balance outstanding, mortgage loans held-for-sale | 606,700,000 | 801,600,000 | 1,200,000,000 |
Non-performing |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Mortgage loans held-for-sale | $ 113,000,000 | 125,500,000 | 115,200,000 |
Appraisal adjustment - cost of sale | Other real estate owned |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Other real estate owned, measurement input | 0.10 |  |  |
Measured at fair value on a recurring basis: |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [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 |
Mortgage loans held-for-sale | 606,545,000 | 817,912,000 | 1,260,193,000 |
Measured at fair value on a non-recurring basis: |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Individually assessed loans - foreclosure probable and collateral-dependent | 44,844,000 |  |  |
Other real estate owned | 6,203,000 |  |  |
Level 3 |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Individually assessed loans - foreclosure probable and collateral-dependent | 72,800,000 |  |  |
Level 3 | Portion at Other than Fair Value Measurement |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Individually assessed loans - foreclosure probable and collateral-dependent | 28,000,000 |  |  |
Level 3 | Measured at fair value on a recurring basis: |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [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 | 3,400,000 |  |  |
Mortgage loans held-for-sale | $ 0 | 0 | 0 |
Level 3 | Measured at fair value on a recurring basis: | Discount rate | Weighted Average | Discounted cash flows |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
MSRs, measurement input | 0.0979 |  |  |
Level 3 | Measured at fair value on a recurring basis: | Discount rate | Weighted Average | Loans held-for-investment |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Discount rate | 0.0425 |  |  |
Level 3 | Measured at fair value on a recurring basis: | Discount rate | Weighted Average | Mortgage servicing rights |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Discount rate | 0.0979 |  |  |
Level 3 | Measured at fair value on a recurring basis: | Discount rate | Minimum | Discounted cash flows |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
MSRs, measurement input | 0.06 |  |  |
Level 3 | Measured at fair value on a recurring basis: | Discount rate | Minimum | Mortgage servicing rights |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Discount rate | 0.06 |  |  |
Level 3 | Measured at fair value on a recurring basis: | Discount rate | Maximum | Discounted cash flows |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
MSRs, measurement input | 0.19 |  |  |
Level 3 | Measured at fair value on a recurring basis: | Discount rate | Maximum | Mortgage servicing rights |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Discount rate | 0.19 |  |  |
Level 3 | Measured at fair value on a recurring basis: | Constant prepayment rate (CPR) | Loans held-for-investment |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Discount rate | 0.0711 |  |  |
Level 3 | Measured at fair value on a recurring basis: | Constant prepayment rate (CPR) | Weighted Average | Discounted cash flows |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
MSRs, measurement input | 0.0711 |  |  |
Level 3 | Measured at fair value on a recurring basis: | Constant prepayment rate (CPR) | Weighted Average | Mortgage servicing rights |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Discount rate | 0.0711 |  |  |
Level 3 | Measured at fair value on a recurring basis: | Constant prepayment rate (CPR) | Minimum | Discounted cash flows |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
MSRs, measurement input | 0 |  |  |
Level 3 | Measured at fair value on a recurring basis: | Constant prepayment rate (CPR) | Minimum | Mortgage servicing rights |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Discount rate | 0 |  |  |
Level 3 | Measured at fair value on a recurring basis: | Constant prepayment rate (CPR) | Maximum | Discounted cash flows |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
MSRs, measurement input | 1 |  |  |
Level 3 | Measured at fair value on a recurring basis: | Constant prepayment rate (CPR) | Maximum | Mortgage servicing rights |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Discount rate | 1 |  |  |
Level 3 | Measured at fair value on a recurring basis: | Credit discount | Weighted Average | Loans held-for-investment |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Discount rate | 0.0036 |  |  |
Level 3 | Measured at fair value on a recurring basis: | Credit discount | Minimum | Loans held-for-investment |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Discount rate | 0 |  |  |
Level 3 | Measured at fair value on a recurring basis: | Credit discount | Maximum | Loans held-for-investment |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Discount rate | 0.03 |  |  |
Level 3 | Measured at fair value on a recurring basis: | Cost of servicing | Weighted Average | Discounted cash flows |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
MSRs, measurement input | 75 |  |  |
Level 3 | Measured at fair value on a recurring basis: | Cost of servicing | Minimum | Discounted cash flows |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
MSRs, measurement input | $ / shares | 70 |  |  |
Level 3 | Measured at fair value on a recurring basis: | Cost of servicing | Maximum | Discounted cash flows |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
MSRs, measurement input | $ / shares | 200 |  |  |
Level 3 | Measured at fair value on a recurring basis: | Cost of servicing - delinquent | Weighted Average | Discounted cash flows |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
MSRs, measurement input | 305 |  |  |
Level 3 | Measured at fair value on a recurring basis: | Cost of servicing - delinquent | Minimum | Discounted cash flows |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
MSRs, measurement input | $ / shares | 200 |  |  |
Level 3 | Measured at fair value on a recurring basis: | Cost of servicing - delinquent | Maximum | Discounted cash flows |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
MSRs, measurement input | $ / shares | 1,000 |  |  |
Level 3 | Measured at fair value on a recurring basis: | Pull-through rate | Weighted Average | Discounted cash flows |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Derivatives, measurement input | 0.871 |  |  |
Level 3 | Measured at fair value on a recurring basis: | Pull-through rate | Minimum | Discounted cash flows |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Derivatives, measurement input | 0 |  |  |
Level 3 | Measured at fair value on a recurring basis: | Pull-through rate | Maximum | Discounted cash flows |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Derivatives, measurement input | 1 |  |  |
Level 3 | Measured at fair value on a non-recurring basis: |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Individually assessed loans - foreclosure probable and collateral-dependent | $ 44,844,000 |  |  |
Other real estate owned | 6,203,000 |  |  |
Municipal Securities |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [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, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Available-for-sale securities, at fair value | 155,489,000 | 165,594,000 | 148,300,000 |
Municipal Securities | Level 3 | Measured at fair value on a recurring basis: |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Available-for-sale securities, at fair value | $ 100,401,000 | $ 105,687,000 | $ 101,748,000 |

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