Commitments and Contingencies - Additional Information (Detail)	12 Months Ended
Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($)
Loss Contingencies [Line Items]
Loan commitments	$ 2,779,000,000	$ 3,566,000,000
Fixed rate loan commitment	2,545,000,000
Floating rate loan commitment	234,500,000
Standby letters of credit	$ 87,800,000	319,000,000.0
Loan commitments floating rate, minimum	1.00%
Loan commitments floating rate, maximum	15.00%
Allowance for unfunded loan commitments	$ 2,700,000	2,500,000
Extended credit	8,700,000	15,500,000
Credit extensions with collateral	$ 7,700,000	$ 7,800,000
Class B Restricted Shares [Member] \| Visa [Member]
Loss Contingencies [Line Items]
Restricted stock conversion ratio	1.6228
Investment owned, balance, shares \| shares	65,466
Investment owned, at cost	$ 0

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

No definition available.

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- Definition

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

+ References

No definition available.

+ Details

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- Definition

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.

+ Details

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- Definition

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

+ References

No definition available.

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- Definition

Maximum floating rate percentage charged on loan commitments.

+ References

No definition available.

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- Definition

Minimum floating rate percentage charged on loan commitments.

+ References

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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- Definition

Restricted stock conversion ratio.

+ References

No definition available.

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- Definition

Cost of the investment.

+ References

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- Definition

Balance held at close of period in number of shares.

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- Definition

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

+ References

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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.

+ References

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- Definition

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.

+ References

No definition available.

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