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Fair Value Measurements - Narrative (Detail) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Jun. 30, 2024 | Mar. 31, 2024 | Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |  |  |
Net unrealized gain for alternative investments |  |  | $ 3,500 |  |
Broker dealer deposit program fair value |  |  | 2,500,000 |  |
Total credit-related financial instruments with off-balance sheet risk |  |  | 12,237,964 | $ 12,563,441 |
Total write-ups |  |  | 2,800 |  |
Total write-downs due to impairment |  |  | 1,300 |  |
Proceeds from sales of alternative investments |  |  | 19,588 | 0 | $ 0
Gains on sale |  |  | 14,763 | 0 | $ 0
Loans transferred to held-for-sale |  |  | 27,300 | 3,900 |
Amortized cost of consumer loans |  |  | 12,000 |  |
Fair Value, Nonrecurring |  |  |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |  |  |
Investments held in Rabbi Trust |  |  | 400 | 9,100 |
Carrying amount of alternative investments |  |  | 3,500 |  |
Proceeds from sales of alternative investments |  |  | 18,400 |  |
Gains on sale |  |  | 14,900 |  |
Rabbi Trust |  |  |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |  |  |
Investments held in Rabbi Trust |  |  | 9,200 | 9,200 |
Alternative investments |  |  |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |  |  |
Investments held in Rabbi Trust |  |  | 30,100 | 29,800 |
Equity investment, carrying amount |  |  |  | 900 |
Additional funds committed to borrowers in TDR status |  |  |  | 0 |
Readily determinable fair value proceeds | $ 1,200 |  |  |  |
Write-down of TDR's |  | $ 300 |  |  |
Alternative investments, carrying amount |  |  | 43,400 | 35,900 |
Alternative investments | Fair Value, Nonrecurring |  |  |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |  |  |
Total credit-related financial instruments with off-balance sheet risk |  |  | 61,500 | 53,100 |
Alternative investments measured at fair value |  |  | $ 8,300 | $ 7,900 |

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- Definition Amount of loss from downward price adjustment on investment in equity security without readily determinable fair value. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 321 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479536/321-10-50-3 + Details
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- Definition The difference between the carrying value and the sale price of an investment. A gain would be recognized when the sale price of the investment is greater than the carrying value of the investment. This element refers to the Gain included in earnings and not to the cash proceeds of the sale. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(9)(a)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(7)(c)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 230 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 28 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482740/230-10-45-28 Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 942 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(13)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478524/942-220-S99-1 + Details
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- Definition Amount of realized gain (loss) on investment. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(3)(a)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147477250/944-220-S99-1 + Details
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