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Loans and Allowance for Credit Losses - Additional Information (Details)	6 Months Ended
	Jun. 30, 2023 USD ($) segment portfolio	Dec. 31, 2022 USD ($)
Financing Receivable, Allowance for Credit Losses [Line Items]
Number of loan portfolios | portfolio	4
Number of loan segments | segment	7
Accrued interest receivable on loans	$ 149,900,000	$ 137,700,000
Loan placed on nonaccrual when past due, number of days	90 days
Loan participations	$ 2,600,000,000
Loan participations sold	1,200,000,000
Loan participations retained	1,400,000,000
Unfunded commitments on TDRs	$ 0
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Percentage of risk-based capital (in percent)	240.00%
Regulatory guideline limit (in percent)	300.00%

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- Definition

Commercial real estate loans as a percentage of risk-based capital.

+ References

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- Definition

The regulatory guideline limit for commercial real estate loans as a percentage of risk-based capital.

+ References

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- Definition

Maximum number of days past due before loan is placed on nonaccrual status.

+ References

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- Definition

Financing Receivable, Number Of Loan Portfolios

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- Definition

Financing Receivable, Number Of Loan Segments

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- Definition

Amount of loan participations with other financial institutions.

+ References

No definition available.

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- Definition

Amount of loan participations retained.

+ References

No definition available.

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- Definition

Amount of loan participations sold to other financial institutions.

+ References

No definition available.

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- Definition

Amount, before allowance for credit loss, of accrued interest on financing receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3B
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-3B

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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

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-K (SK)
-Number 229
-Section 1405
-Paragraph c
-Publisher SEC

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- Definition

Amount of commitment to lend additional funds to debtor experiencing financial difficulty for which creditor has modified terms of financing receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 36
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481962/310-10-50-36

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-SubTopic 40
-Topic 310
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481746/310-40-50-1

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