Loans and Allowance for Credit Losses, Loans by Portfolio Type (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Loan receivables disclosure [Abstract]
Loans, fixed rate of interest	$ 6,927,954	$ 8,078,873
Loans, variable rate of interest	13,278,035	14,693,954
Loans, non-accrual	141,947	234,693
Total	20,347,936	23,007,520
Credit Commitments [Abstract]
Outstanding commitments to extend credit	12,000,000
Outstanding standby letters of credit	638,000
Commercial [Member]
Loan receivables disclosure [Abstract]
Loans, fixed rate of interest	3,337,034	3,174,203
Loans, variable rate of interest	8,757,432	9,736,173
Loans, non-accrual	80,674	167,159
Total	12,175,140	13,077,535
Commercial real estate [Member]
Loan receivables disclosure [Abstract]
Loans, fixed rate of interest	968,223	1,047,486
Loans, variable rate of interest	3,127,446	3,623,806
Loans, non-accrual	21,223	27,246
Total	4,116,892	4,698,538
Paycheck Protection Program [Member]
Loan receivables disclosure [Abstract]
Loans, fixed rate of interest	536,052	1,682,310
Loans, variable rate of interest	0	0
Loans, non-accrual	0	0
Total	536,052	1,682,310
Loans to individuals [Member]
Loan receivables disclosure [Abstract]
Loans, fixed rate of interest	2,086,645	2,174,874
Loans, variable rate of interest	1,393,157	1,333,975
Loans, non-accrual	40,050	40,288
Total	$ 3,519,852	$ 3,549,137

-- None. No documentation exists for this element. --

No definition available.

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- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

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- References

No definition available.

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- Definition

Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=124259787&loc=d3e4428-111522

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- Definition

Reflects the carrying amount of loans deemed to be questionable as to collection on which no interest is continuing to be recognized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5111-111524

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- Definition

Amount of loan with fixed rate of interest.

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- Definition

Amount of loan with variable or adjustable rate of interest.

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- Definition

Unused amount of commitments to extend credit to customers.

+ References

No definition available.

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