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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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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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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.

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Amount of cash inflow from the sale of investments classified as other.

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