Fair Value Accounting - Schedule of Assets and Liabilities Measured at Estimated Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Assets
Investment securities available for sale	$ 7,840,385	$ 7,551,018
Mortgage loans held for sale	34,859	33,448
Derivatives Not Designated as Hedging Instruments
Liabilities
Estimated fair value of derivative liabilities	161,854	201,917
Visa derivative \| Derivatives Not Designated as Hedging Instruments
Liabilities
Estimated fair value of derivative liabilities	2,228	64
U.S. Treasury securities
Assets
Investment securities available for sale	1,231,557	1,212,742
Mortgage-backed securities issued by U.S. Government agencies
Assets
Investment securities available for sale	1,495,803	1,462,790
Mortgage-backed securities issued by U.S. Government sponsored enterprises
Assets
Investment securities available for sale	2,085,468	2,034,035
Collateralized mortgage obligations issued by U.S. Government sponsored enterprises
Assets
Investment securities available for sale	547,370	550,201
Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises
Assets
Investment securities available for sale	2,441,698	2,253,116
Corporate debt securities and other debt securities
Assets
Investment securities available for sale	9,013	8,971
Level 1
Assets
Trading securities	6,991	0
Investment securities available for sale	1,231,557	1,212,742
Other investments	0	0
Mutual funds and mutual funds held in rabbi trusts	65,467	63,371
Derivative assets	0	0
Liabilities
Mutual funds held in rabbi trusts	50,188	48,351
Derivative liabilities	0	0
Level 2
Assets
Trading securities	20,011	9,713
Investment securities available for sale	6,608,828	6,338,276
Other investments	0	0
Mutual funds and mutual funds held in rabbi trusts	0	0
Derivative assets	78,379	83,895
Liabilities
Mutual funds held in rabbi trusts	0	0
Derivative liabilities	167,547	216,325
Level 3
Assets
Trading securities	0	0
Investment securities available for sale	0	0
Other investments	15,350	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
Trading securities	27,002	9,713
Investment securities available for sale	7,840,385	7,551,018
Mortgage loans held for sale	34,859	33,448
Other investments	15,350	14,831
Mutual funds and mutual funds held in rabbi trusts	65,467	63,371
Derivative assets	78,379	83,895
Liabilities
Mutual funds held in rabbi trusts	50,188	48,351
Derivative liabilities	167,547	216,325
Fair Value, Measurements, Recurring Basis \| U.S. Treasury securities
Assets
Trading securities	6,991	0
Investment securities available for sale	1,231,557	1,212,742
Fair Value, Measurements, Recurring Basis \| State and municipal securities
Assets
Trading securities	0	473
Fair Value, Measurements, Recurring Basis \| Asset-backed securities
Assets
Trading securities	19,556	9,240
Fair Value, Measurements, Recurring Basis \| Other Investments
Assets
Trading securities	455	0
Fair Value, Measurements, Recurring Basis \| U.S. Government agency securities
Assets
Investment securities available for sale	29,476	29,163
Fair Value, Measurements, Recurring Basis \| Mortgage-backed securities issued by U.S. Government agencies
Assets
Investment securities available for sale	1,495,803	1,462,790
Fair Value, Measurements, Recurring Basis \| Mortgage-backed securities issued by U.S. Government sponsored enterprises
Assets
Investment securities available for sale	2,085,468	2,034,035
Fair Value, Measurements, Recurring Basis \| Collateralized mortgage obligations issued by U.S. Government sponsored enterprises
Assets
Investment securities available for sale	547,370	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	2,441,698	2,253,116
Fair Value, Measurements, Recurring Basis \| Corporate debt securities and other debt securities
Assets
Investment securities available for sale	9,013	8,971
Fair Value, Measurements, Recurring Basis \| Level 1
Assets
Trading securities	6,991	0
Investment securities available for sale	1,231,557	1,212,742
Mortgage loans held for sale	0	0
Other investments	0	0
Mutual funds and mutual funds held in rabbi trusts	65,467	63,371
Derivative assets	0	0
Liabilities
Mutual funds held in rabbi trusts	50,188	48,351
Derivative liabilities	0	0
Fair Value, Measurements, Recurring Basis \| Level 1 \| U.S. Treasury securities
Assets
Trading securities	6,991	0
Investment securities available for sale	1,231,557	1,212,742
Fair Value, Measurements, Recurring Basis \| Level 1 \| State and municipal securities
Assets
Trading securities	0	0
Fair Value, Measurements, Recurring Basis \| Level 1 \| Asset-backed securities
Assets
Trading securities	0	0
Fair Value, Measurements, Recurring Basis \| Level 1 \| Other Investments
Assets
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
Trading securities	20,011	9,713
Investment securities available for sale	6,608,828	6,338,276
Mortgage loans held for sale	34,859	33,448
Other investments	0	0
Mutual funds and mutual funds held in rabbi trusts	0	0
Derivative assets	78,379	83,895
Liabilities
Mutual funds held in rabbi trusts	0	0
Derivative liabilities	167,547	216,325
Fair Value, Measurements, Recurring Basis \| Level 2 \| U.S. Treasury securities
Assets
Trading securities	0	0
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring Basis \| Level 2 \| State and municipal securities
Assets
Trading securities	0	473
Fair Value, Measurements, Recurring Basis \| Level 2 \| Asset-backed securities
Assets
Trading securities	19,556	9,240
Fair Value, Measurements, Recurring Basis \| Level 2 \| Other Investments
Assets
Trading securities	455	0
Fair Value, Measurements, Recurring Basis \| Level 2 \| U.S. Government agency securities
Assets
Investment securities available for sale	29,476	29,163
Fair Value, Measurements, Recurring Basis \| Level 2 \| Mortgage-backed securities issued by U.S. Government agencies
Assets
Investment securities available for sale	1,495,803	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	2,085,468	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	547,370	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	2,441,698	2,253,116
Fair Value, Measurements, Recurring Basis \| Level 2 \| Corporate debt securities and other debt securities
Assets
Investment securities available for sale	9,013	8,971
Fair Value, Measurements, Recurring Basis \| Level 3
Assets
Trading securities	0	0
Investment securities available for sale	0	0
Mortgage loans held for sale	0	0
Other investments	15,350	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
Trading securities	0	0
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring Basis \| Level 3 \| State and municipal securities
Assets
Trading securities	0	0
Fair Value, Measurements, Recurring Basis \| Level 3 \| Asset-backed securities
Assets
Trading securities	0	0
Fair Value, Measurements, Recurring Basis \| Level 3 \| Other Investments
Assets
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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Mutual Funds And Mutual Funds Held In Rabbi Trusts In Liability

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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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- Definition

Fair value portion of mortgage loans held-for-sale.

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

Amount of investments classified as other.

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Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading) and investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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