Mortgage Banking Activities, Mortgage Servicing Rights (Details)	3 Months Ended	9 Months Ended	12 Months Ended
Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Dec. 31, 2024 USD ($)
Summary of Mortgage Servicing Rights [Abstract]
Number of residential mortgage loans serviced for others	124,909		124,909		125,728
Outstanding principal balance of residential mortgage loans serviced for others	$ 22,145,687,000		$ 22,145,687,000		$ 22,269,513,000
Weighted average interest rate	3.82%		3.82%		3.73%
Remaining term (in months)			272 months		276 months
Servicing Asset at Fair Value, Amount [Roll Forward]
Beginning balance	$ 334,644,000	$ 333,246,000	$ 338,145,000	$ 293,884,000	$ 293,884,000
Additions	3,403,000	3,842,000	8,975,000	10,812,000
Acquisitions	0	3,334,000	14,615,000	34,755,000
Changes due to principal payments	(9,273,000)	(8,049,000)	(20,702,000)	(21,508,000)
Change in fair value due to market assumption changes	(2,375,000)	(16,453,000)	(14,634,000)	(2,023,000)
Ending balance	$ 326,399,000	$ 315,920,000	$ 326,399,000	$ 315,920,000	$ 338,145,000
Servicing Assets at Fair Value, Assumptions Used to Estimate Fair Value [Abstract]
Discount rate - risk-free rate plus a market premium (in hundredths)			9.21%		9.60%
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Prepayment Speed			7.10%		7.09%
Loan servicing costs - annually per loan based upon loan type, performing, minimum (in dollars per loan)			$ 73		$ 73
Loan servicing costs - annually per loan based upon loan type, performing, maximum (in dollars per loan)			94		94
Loan servicing costs - annually per loan based upon loan type, delinquent, minimum (in dollars per loan)			150		150
Loan servicing costs - annually per loan based upon loan type, delinquent, maximum (in dollars per loan)			500		500
Loan servicing costs - annually per loan based upon loan type, foreclosure, minimum (in dollars per loan)			875		875
Loan servicing costs - annually per loan based upon loan type, foreclosure, maximum (in dollars per loan)			$ 6,000		$ 6,000
Escrow earnings rate - indexed to rates paid on deposit accounts with comparable average life (in hundredths)			3.58%		4.44%
Primary secondary mortgage rate spread	128		128		115
Delinquency rate			2.24%		2.19%

The decrease in fair value as a result of loan runoff.

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- Definition

Mortgage rate spread between the primary and secondary market.

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No definition available.

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Indicates the number of mortgage loans being serviced.

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No definition available.

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Dollar amount of principal outstanding on mortgage loans being serviced.

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Represents the weighted average remaining term of mortgage loans being serviced fro others.

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No definition available.

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The value of new servicing assets, subsequently measured at fair value, acquired during the current period through purchases of financial assets.

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No definition available.

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- Definition

Servicing Assets at Fair Value Assumptions Used to Estimate Fair Value Delinquent Loan Service Cost Minimum

+ References

No definition available.

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Servicing Assets At Fair Value Assumptions Used to Estimate Fair Value Delinquent

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No definition available.

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- Definition

The escrow earning rate used to estimate the fair value of servicing assets, based on rates paid on deposit accounts.

+ References

No definition available.

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- Definition

Servicing Assets At Fair Value Assumptions Used to Estimate Fair Value Foreclosure Loan Service Cost Maximum

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No definition available.

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Servicing Assets at Fair Value Assumptions Used to Estimate Fair Value Foreclosure Loan Service Cost Minimum

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No definition available.

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- Definition

The maximum cost to service a performing loan for the period used as a variable in estimating fair value.

+ References

No definition available.

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- Definition

The minimum cost to service a performing loan for the period used as a variable in estimating fair value.

+ References

No definition available.

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Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Delinquency Rate

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No definition available.

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- Definition

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

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- Definition

Represents the weighted average interest rate of loans servicedf for others as of the balance sheet date.

+ References

No definition available.

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- Definition

Amount of increase (decrease) in fair value from changes in the assumptions or model used to calculate the fair value of a contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

+ References

No definition available.

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- Definition

The value of new servicing assets, subsequently measured at fair value, acquired or created during the current period through purchases or from transfers of financial assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition

Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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- Definition

Discount rate used to estimate the fair value of servicing assets and servicing liabilities.

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- Definition

Estimated rate of prepayments of principal on servicing assets and servicing liabilities.

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