Fair Value Accounting (Financial Instruments Measured at Fair Value on Recurring Basis) (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Assets
Investment securities available for sale	$ 9,732,618	$ 9,678,103
Mortgage loans held for sale	44,400	51,136
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises
Assets
Investment securities available for sale	648,559	655,127
U.S. Treasury securities
Assets
Investment securities available for sale	480,280	471,813
Mortgage-backed securities issued by U.S. Government agencies
Assets
Investment securities available for sale	708,545	792,749
Mortgage-backed securities issued by U.S. Government sponsored enterprises
Assets
Investment securities available for sale	7,025,500	6,895,070
Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises
Assets
Investment securities available for sale	812,023	805,945
Corporate debt securities and other debt securities
Assets
Investment securities available for sale	8,766	8,601
Level 1
Assets
Trading securities	0	0
Investment securities available for sale	480,280	471,813
Other investments	0	0
Mutual funds and mutual funds held in rabbi trusts	48,428	42,659
SBA loans servicing asset	0	0
Derivative assets	0	0
Liabilities
Securities sold short	3,152	3,370
Mutual funds held in rabbi trusts	33,470	27,944
Derivative liabilities	0	0
Level 2
Assets
Trading securities	25,915	8,295
Investment securities available for sale	9,252,338	9,206,290
Other investments	0	0
Mutual funds and mutual funds held in rabbi trusts	0	0
SBA loans servicing asset	0	0
Derivative assets	88,257	89,815
Liabilities
Securities sold short	0	0
Mutual funds held in rabbi trusts	0	0
Derivative liabilities	318,999	339,227
Level 3
Assets
Trading securities	0	0
Investment securities available for sale	0	0
Other investments	11,655	11,172
Mutual funds and mutual funds held in rabbi trusts	0	0
SBA loans servicing asset	2,412	2,354
Derivative assets	0	0
Liabilities
Securities sold short	0	0
Mutual funds held in rabbi trusts	0	0
Derivative liabilities	1,111	3,453
Fair Value, Measurements, Recurring Basis
Assets
Trading securities	25,915	8,295
Investment securities available for sale	9,732,618	9,678,103
Mortgage loans held for sale	44,400	51,136
Other investments	11,655	11,172
Mutual funds and mutual funds held in rabbi trusts	48,428	42,659
SBA loans servicing asset	2,412	2,354
Derivative assets	88,257	89,815
Liabilities
Securities sold short	3,152	3,370
Mutual funds held in rabbi trusts	33,470	27,944
Derivative liabilities	320,110	342,680
Fair Value, Measurements, Recurring Basis \| Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises
Assets
Trading securities	2,954	2,991
Investment securities available for sale	648,559	655,127
Fair Value, Measurements, Recurring Basis \| Other mortgage-backed securities
Assets
Trading securities	2,909	3,185
Fair Value, Measurements, Recurring Basis \| State and municipal securities
Assets
Trading securities	69	48
Fair Value, Measurements, Recurring Basis \| Asset-backed securities
Assets
Trading securities	19,185	2,071
Fair Value, Measurements, Recurring Basis \| Other Investments
Assets
Trading securities	798	0
Fair Value, Measurements, Recurring Basis \| U.S. Treasury securities
Assets
Investment securities available for sale	480,280	471,813
Fair Value, Measurements, Recurring Basis \| U.S. Government agency securities
Assets
Investment securities available for sale	48,945	48,798
Fair Value, Measurements, Recurring Basis \| Mortgage-backed securities issued by U.S. Government agencies
Assets
Investment securities available for sale	708,545	792,749
Fair Value, Measurements, Recurring Basis \| Mortgage-backed securities issued by U.S. Government sponsored enterprises
Assets
Investment securities available for sale	7,025,500	6,895,070
Fair Value, Measurements, Recurring Basis \| Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises
Assets
Investment securities available for sale	812,023	805,945
Fair Value, Measurements, Recurring Basis \| Corporate debt securities and other debt securities
Assets
Investment securities available for sale	8,766	8,601
Fair Value, Measurements, Recurring Basis \| Level 1
Assets
Trading securities	0	0
Investment securities available for sale	480,280	471,813
Mortgage loans held for sale	0	0
Other investments	0	0
Mutual funds and mutual funds held in rabbi trusts	48,428	42,659
SBA loans servicing asset	0	0
Derivative assets	0	0
Liabilities
Securities sold short	3,152	3,370
Mutual funds held in rabbi trusts	33,470	27,944
Derivative liabilities	0	0
Fair Value, Measurements, Recurring Basis \| Level 1 \| Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises
Assets
Trading securities	0	0
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring Basis \| Level 1 \| Other mortgage-backed securities
Assets
Trading securities	0	0
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. Treasury securities
Assets
Investment securities available for sale	480,280	471,813
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 \| 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	25,915	8,295
Investment securities available for sale	9,252,338	9,206,290
Mortgage loans held for sale	44,400	51,136
Other investments	0	0
Mutual funds and mutual funds held in rabbi trusts	0	0
SBA loans servicing asset	0	0
Derivative assets	88,257	89,815
Liabilities
Securities sold short	0	0
Mutual funds held in rabbi trusts	0	0
Derivative liabilities	318,999	339,227
Fair Value, Measurements, Recurring Basis \| Level 2 \| Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises
Assets
Trading securities	2,954	2,991
Investment securities available for sale	648,559	655,127
Fair Value, Measurements, Recurring Basis \| Level 2 \| Other mortgage-backed securities
Assets
Trading securities	2,909	3,185
Fair Value, Measurements, Recurring Basis \| Level 2 \| State and municipal securities
Assets
Trading securities	69	48
Fair Value, Measurements, Recurring Basis \| Level 2 \| Asset-backed securities
Assets
Trading securities	19,185	2,071
Fair Value, Measurements, Recurring Basis \| Level 2 \| Other Investments
Assets
Trading securities	798	0
Fair Value, Measurements, Recurring Basis \| Level 2 \| U.S. Treasury securities
Assets
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring Basis \| Level 2 \| U.S. Government agency securities
Assets
Investment securities available for sale	48,945	48,798
Fair Value, Measurements, Recurring Basis \| Level 2 \| Mortgage-backed securities issued by U.S. Government agencies
Assets
Investment securities available for sale	708,545	792,749
Fair Value, Measurements, Recurring Basis \| Level 2 \| Mortgage-backed securities issued by U.S. Government sponsored enterprises
Assets
Investment securities available for sale	7,025,500	6,895,070
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	812,023	805,945
Fair Value, Measurements, Recurring Basis \| Level 2 \| Corporate debt securities and other debt securities
Assets
Investment securities available for sale	8,766	8,601
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	11,655	11,172
Mutual funds and mutual funds held in rabbi trusts	0	0
SBA loans servicing asset	2,412	2,354
Derivative assets	0	0
Liabilities
Securities sold short	0	0
Mutual funds held in rabbi trusts	0	0
Derivative liabilities	1,111	3,453
Fair Value, Measurements, Recurring Basis \| Level 3 \| Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises
Assets
Trading securities	0	0
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring Basis \| Level 3 \| Other mortgage-backed securities
Assets
Trading securities	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. Treasury securities
Assets
Investment securities available for sale	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 \| 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 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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Fair value, before effects of master netting arrangements, of a financial liability or 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 liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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- Definition

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

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Amount of investments classified as other.

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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.

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Fair value portion of liabilities pertaining to principal and customer trading transactions, or which may be incurred with the objective of generating a profit from short-term fluctuations in price as part of an entity's market-making, hedging and proprietary trading. Examples include, but are not limited to, short positions in securities, derivatives and commodities.

+ References

No definition available.

+ Details

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- Definition

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+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483467/210-10-45-1

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.4)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479853/942-210-S99-1

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