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Investment Securities - Summary of Debt Securities Held-to-Maturity (Detail) - USD ($) $ in Thousands | Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
--- | --- | --- | --- | ---
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Amortized Cost | $ 8,444,362 | $ 7,074,797 |  |
Unrealized Gains | 1,502 | 22,167 |  |
Unrealized Losses | (992,741) | (832,341) |  |
Fair Value | 7,453,123 | 6,264,623 |  |
Allowance for Credit Losses | 171 | 209 | $ 182 | $ 214
Net Carrying Value | 8,444,191 | 7,074,588 |  |
Held-to-maturity Securities |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Interest receivable | 30,500 | 24,900 |  |
Agency CMO |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Amortized Cost | 19,847 | 23,470 |  |
Unrealized Gains | 0 | 0 |  |
Unrealized Losses | (1,671) | (1,728) |  |
Fair Value | 18,176 | 21,742 |  |
Allowance for Credit Losses | 0 | 0 |  |
Net Carrying Value | 19,847 | 23,470 |  |
Agency MBS |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Amortized Cost | 3,109,411 | 2,409,521 |  |
Unrealized Gains | 771 | 1,141 |  |
Unrealized Losses | (333,039) | (284,776) |  |
Fair Value | 2,777,143 | 2,125,886 |  |
Allowance for Credit Losses | 0 | 0 |  |
Net Carrying Value | 3,109,411 | 2,409,521 |  |
Agency CMBS |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Amortized Cost | 4,357,505 | 3,625,627 |  |
Unrealized Gains | 414 | 18,586 |  |
Unrealized Losses | (613,914) | (514,534) |  |
Fair Value | 3,744,005 | 3,129,679 |  |
Allowance for Credit Losses | 0 | 0 |  |
Net Carrying Value | 4,357,505 | 3,625,627 |  |
Municipal bonds and notes |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Amortized Cost | 891,909 | 916,104 |  |
Unrealized Gains | 317 | 2,440 |  |
Unrealized Losses | (40,266) | (24,877) |  |
Fair Value | 851,960 | 893,667 |  |
Allowance for Credit Losses | 171 | 209 |  |
Net Carrying Value | 891,738 | 915,895 |  |
CMBS |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Amortized Cost | 65,690 | 100,075 |  |
Unrealized Gains | 0 | 0 |  |
Unrealized Losses | (3,851) | (6,426) |  |
Fair Value | 61,839 | 93,649 |  |
Allowance for Credit Losses | 0 | 0 |  |
Net Carrying Value | $ 65,690 | $ 100,075 |  |

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