Fair Value Measurements - Assets and Liabilities Measured at Estimated Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available For Sale Securities Debt Securities	$ 8,704,955	$ 3,955,804
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Trading account	133,855	49,545
Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Trading account		200
U.S. Treasury and Federal Agencies [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available For Sale Securities Debt Securities	5,182,571	678,690
Commercial [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available For Sale Securities Debt Securities	614,784
Residential [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available For Sale Securities Debt Securities	2,726,769	3,155,312
Other Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available For Sale Securities Debt Securities	180,831	121,802
Fair Value Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Trading account	133,855	49,745
Available For Sale Securities Debt Securities	8,704,955	3,955,804
Equity Securities Fv Ni	101,872	77,640
Real estate loans held for sale	319,421	899,282
Other assets	243,764	442,453
Total assets	9,503,867	5,424,924
Other liabilities	808,439	93,843
Total liabilities	808,439	93,843
Fair Value Measurements, Recurring [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Trading account	133,855	49,545
Equity Securities Fv Ni	91,820	68,850
Total assets	225,675	118,395
Fair Value Measurements, Recurring [Member] \| Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Trading account		200
Available For Sale Securities Debt Securities	8,704,955	3,955,804
Equity Securities Fv Ni	10,052	8,790
Real estate loans held for sale	319,421	899,282
Other assets	237,240	430,725
Total assets	9,271,668	5,294,801
Other liabilities	777,734	88,555
Total liabilities	777,734	88,555
Fair Value Measurements, Recurring [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Other assets	6,524	11,728
Total assets	6,524	11,728
Other liabilities	30,705	5,288
Total liabilities	30,705	5,288
Fair Value Measurements, Recurring [Member] \| U.S. Treasury and Federal Agencies [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available For Sale Securities Debt Securities	5,182,571	678,690
Fair Value Measurements, Recurring [Member] \| U.S. Treasury and Federal Agencies [Member] \| Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available For Sale Securities Debt Securities	5,182,571	678,690
Fair Value Measurements, Recurring [Member] \| Commercial [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available For Sale Securities Debt Securities	614,784
Fair Value Measurements, Recurring [Member] \| Commercial [Member] \| Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available For Sale Securities Debt Securities	614,784
Fair Value Measurements, Recurring [Member] \| Residential [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available For Sale Securities Debt Securities	2,726,769	3,155,312
Fair Value Measurements, Recurring [Member] \| Residential [Member] \| Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available For Sale Securities Debt Securities	2,726,769	3,155,312
Fair Value Measurements, Recurring [Member] \| Other Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available For Sale Securities Debt Securities	180,831	121,802
Fair Value Measurements, Recurring [Member] \| Other Debt Securities [Member] \| Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available For Sale Securities Debt Securities	$ 180,831	$ 121,802

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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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), classified as current.

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Fair value of financial and nonfinancial obligations.

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Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

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Fair value portion of other assets.

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Fair value portion of other liabilities.

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

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