Fair Value Accounting - Schedule of Assets and Liabilities Measured at Estimated Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Assets
Investment securities available for sale	$ 7,575,468	$ 7,551,018
Mortgage loans held for sale	41,083	33,448
Derivatives Not Designated as Hedging Instruments
Liabilities
Estimated fair value of derivative liabilities	120,958	201,917
Visa derivative \| Derivatives Not Designated as Hedging Instruments
Liabilities
Estimated fair value of derivative liabilities	2,964	64
U.S. Treasury securities
Assets
Investment securities available for sale	1,221,154	1,212,742
Mortgage-backed securities issued by U.S. Government agencies
Assets
Investment securities available for sale	1,429,706	1,462,790
Mortgage-backed securities issued by U.S. Government sponsored enterprises
Assets
Investment securities available for sale	2,006,151	2,034,035
Collateralized mortgage obligations issued by U.S. Government sponsored enterprises
Assets
Investment securities available for sale	519,199	550,201
Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises
Assets
Investment securities available for sale	2,360,210	2,253,116
Corporate debt securities and other debt securities
Assets
Investment securities available for sale	9,191	8,971
Level 1
Assets
Total trading securities	2,004	0
Investment securities available for sale	1,221,154	1,212,742
Other investments	0	0
Mutual funds and mutual funds held in rabbi trusts	72,883	63,371
Derivative assets	0	0
Liabilities
Mutual funds held in rabbi trusts	57,339	48,351
Derivative liabilities	0	0
Level 2
Assets
Total trading securities	19,185	9,713
Investment securities available for sale	6,354,314	6,338,276
Other investments	0	0
Mutual funds and mutual funds held in rabbi trusts	0	0
Derivative assets	85,822	83,895
Liabilities
Mutual funds held in rabbi trusts	0	0
Derivative liabilities	117,994	216,325
Level 3
Assets
Total trading securities	0	0
Investment securities available for sale	0	0
Other investments	18,012	14,831
Mutual funds and mutual funds held in rabbi trusts	0	0
Derivative assets	0	0
Liabilities
Mutual funds held in rabbi trusts	0	0
Derivative liabilities	0	0
Fair Value, Measurements, Recurring Basis
Assets
Total trading securities	21,189	9,713
Investment securities available for sale	7,575,468	7,551,018
Mortgage loans held for sale	41,083	33,448
Other investments	18,012	14,831
Mutual funds and mutual funds held in rabbi trusts	72,883	63,371
Derivative assets	85,822	83,895
Liabilities
Mutual funds held in rabbi trusts	57,339	48,351
Derivative liabilities	117,994	216,325
Fair Value, Measurements, Recurring Basis \| U.S. Treasury securities
Assets
Total trading securities	2,004	0
Investment securities available for sale	1,221,154	1,212,742
Fair Value, Measurements, Recurring Basis \| State and municipal securities
Assets
Total trading securities	658	473
Fair Value, Measurements, Recurring Basis \| Asset-backed securities
Assets
Total trading securities	18,524	9,240
Fair Value, Measurements, Recurring Basis \| Other Investments
Assets
Total trading securities	3	0
Fair Value, Measurements, Recurring Basis \| U.S. Government agency securities
Assets
Investment securities available for sale	29,857	29,163
Fair Value, Measurements, Recurring Basis \| Mortgage-backed securities issued by U.S. Government agencies
Assets
Investment securities available for sale	1,429,706	1,462,790
Fair Value, Measurements, Recurring Basis \| Mortgage-backed securities issued by U.S. Government sponsored enterprises
Assets
Investment securities available for sale	2,006,151	2,034,035
Fair Value, Measurements, Recurring Basis \| Collateralized mortgage obligations issued by U.S. Government sponsored enterprises
Assets
Investment securities available for sale	519,199	550,201
Fair Value, Measurements, Recurring Basis \| Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises
Assets
Investment securities available for sale	2,360,210	2,253,116
Fair Value, Measurements, Recurring Basis \| Corporate debt securities and other debt securities
Assets
Investment securities available for sale	9,191	8,971
Fair Value, Measurements, Recurring Basis \| Level 1
Assets
Total trading securities	2,004	0
Investment securities available for sale	1,221,154	1,212,742
Mortgage loans held for sale	0	0
Other investments	0	0
Mutual funds and mutual funds held in rabbi trusts	72,883	63,371
Derivative assets	0	0
Liabilities
Mutual funds held in rabbi trusts	57,339	48,351
Derivative liabilities	0	0
Fair Value, Measurements, Recurring Basis \| Level 1 \| U.S. Treasury securities
Assets
Total trading securities	2,004	0
Investment securities available for sale	1,221,154	1,212,742
Fair Value, Measurements, Recurring Basis \| Level 1 \| State and municipal securities
Assets
Total trading securities	0	0
Fair Value, Measurements, Recurring Basis \| Level 1 \| Asset-backed securities
Assets
Total trading securities	0	0
Fair Value, Measurements, Recurring Basis \| Level 1 \| Other Investments
Assets
Total trading securities	0	0
Fair Value, Measurements, Recurring Basis \| Level 1 \| U.S. Government agency securities
Assets
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring Basis \| Level 1 \| Mortgage-backed securities issued by U.S. Government agencies
Assets
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring Basis \| Level 1 \| Mortgage-backed securities issued by U.S. Government sponsored enterprises
Assets
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring Basis \| Level 1 \| Collateralized mortgage obligations issued by U.S. Government sponsored enterprises
Assets
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring Basis \| Level 1 \| Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises
Assets
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring Basis \| Level 1 \| Corporate debt securities and other debt securities
Assets
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring Basis \| Level 2
Assets
Total trading securities	19,185	9,713
Investment securities available for sale	6,354,314	6,338,276
Mortgage loans held for sale	41,083	33,448
Other investments	0	0
Mutual funds and mutual funds held in rabbi trusts	0	0
Derivative assets	85,822	83,895
Liabilities
Mutual funds held in rabbi trusts	0	0
Derivative liabilities	117,994	216,325
Fair Value, Measurements, Recurring Basis \| Level 2 \| U.S. Treasury securities
Assets
Total trading securities	0	0
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring Basis \| Level 2 \| State and municipal securities
Assets
Total trading securities	658	473
Fair Value, Measurements, Recurring Basis \| Level 2 \| Asset-backed securities
Assets
Total trading securities	18,524	9,240
Fair Value, Measurements, Recurring Basis \| Level 2 \| Other Investments
Assets
Total trading securities	3	0
Fair Value, Measurements, Recurring Basis \| Level 2 \| U.S. Government agency securities
Assets
Investment securities available for sale	29,857	29,163
Fair Value, Measurements, Recurring Basis \| Level 2 \| Mortgage-backed securities issued by U.S. Government agencies
Assets
Investment securities available for sale	1,429,706	1,462,790
Fair Value, Measurements, Recurring Basis \| Level 2 \| Mortgage-backed securities issued by U.S. Government sponsored enterprises
Assets
Investment securities available for sale	2,006,151	2,034,035
Fair Value, Measurements, Recurring Basis \| Level 2 \| Collateralized mortgage obligations issued by U.S. Government sponsored enterprises
Assets
Investment securities available for sale	519,199	550,201
Fair Value, Measurements, Recurring Basis \| Level 2 \| Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises
Assets
Investment securities available for sale	2,360,210	2,253,116
Fair Value, Measurements, Recurring Basis \| Level 2 \| Corporate debt securities and other debt securities
Assets
Investment securities available for sale	9,191	8,971
Fair Value, Measurements, Recurring Basis \| Level 3
Assets
Total trading securities	0	0
Investment securities available for sale	0	0
Mortgage loans held for sale	0	0
Other investments	18,012	14,831
Mutual funds and mutual funds held in rabbi trusts	0	0
Derivative assets	0	0
Liabilities
Mutual funds held in rabbi trusts	0	0
Derivative liabilities	0	0
Fair Value, Measurements, Recurring Basis \| Level 3 \| U.S. Treasury securities
Assets
Total trading securities	0	0
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring Basis \| Level 3 \| State and municipal securities
Assets
Total trading securities	0	0
Fair Value, Measurements, Recurring Basis \| Level 3 \| Asset-backed securities
Assets
Total trading securities	0	0
Fair Value, Measurements, Recurring Basis \| Level 3 \| Other Investments
Assets
Total trading securities	0	0
Fair Value, Measurements, Recurring Basis \| Level 3 \| U.S. Government agency securities
Assets
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring Basis \| Level 3 \| Mortgage-backed securities issued by U.S. Government agencies
Assets
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring Basis \| Level 3 \| Mortgage-backed securities issued by U.S. Government sponsored enterprises
Assets
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring Basis \| Level 3 \| Collateralized mortgage obligations issued by U.S. Government sponsored enterprises
Assets
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring Basis \| Level 3 \| Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises
Assets
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring Basis \| Level 3 \| Corporate debt securities and other debt securities
Assets
Investment securities available for sale	$ 0	$ 0

Mutual Funds And Mutual Funds Held In Rabbi Trusts In Assets

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- Definition

Mutual Funds And Mutual Funds Held In Rabbi Trusts In Liability

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- Definition

Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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