Commitments and Contingencies (Detail)	12 Months Ended
Dec. 31, 2020 USD ($) shares	Jan. 01, 2020 USD ($)	Dec. 31, 2019 USD ($)
Loss Contingencies [Line Items]
Loan commitments	$ 3,720,000,000		$ 2,779,000,000
Standby letters of credit	86,900,000		87,800,000
Fixed rate loan commitment	3,463,000,000
Floating rate loan commitment	$ 257,800,000
Loan commitments floating rate, minimum	0.00%
Loan commitments floating rate, maximum	14.00%
Allowance for unfunded loan commitments	$ 11,700,000		2,700,000
Extended credit	7,900,000		8,700,000
Credit extensions with collateral	$ 7,500,000		$ 7,700,000
Class B Restricted Shares \| Visa
Loss Contingencies [Line Items]
Restricted stock conversion ratio	1.6228
Investment owned, balance (in shares) \| shares	65,466
Investment owned, at cost	$ 0
Adjustment
Loss Contingencies [Line Items]
Increase in allowance for credit losses on unfunded loan		$ 4,549,000

Amount of valuation allowance recorded for unfunded commitments to extend credit.

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Amount of credit extended with unaffiliated banks related to letter of credit commitments issued on behalf of our clients.

+ References

No definition available.

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Amount of collateral provided to secure credit extended with unaffiliated banks related to letter of credit commitments issued on behalf of our clients.

+ References

No definition available.

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Amount of agreement to extend credit in the form of a loan.

+ References

No definition available.

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Maximum floating rate percentage charged on loan commitments.

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Minimum floating rate percentage charged on loan commitments.

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No definition available.

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- Definition

Amount of agreement to extend credit in the form of a standby letter of credit.

+ References

No definition available.

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Restricted stock conversion ratio.

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No definition available.

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Cost of the investment.

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Balance held at close of period in number of shares.

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Reflects the amount of cash required to fully fund agreements to provide advances to borrowers and lessees at stated interest rates.

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- Definition

Reflects the amount of cash required to fully fund agreements to provide advances to borrowers and lessees at interest rates that increase or decrease depending on certain facts or circumstances.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of expected credit loss for credit exposure on off-balance-sheet commitment, including but not limited to, loan commitment, standby letter of credit, financial guarantee not accounted for as insurance. Excludes off-balance sheet credit exposure accounted for as insurance and instrument accounted for under derivatives and hedging.

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