Fair Value - Assets and liabilities measured at fair value on a recurring basis (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2023	Dec. 31, 2022
Fair Value
Percentage of loans individually evaluated based on fair value of collateral	66.67%
Assets
Trading securities	$ 16,039	$ 31,263
Securities available for sale	5,159,999	5,326,822
SBA servicing asset	6,500	6,100
U.S. Treasuries
Assets
Securities available for sale	268,096	265,638
U.S. Government agencies
Assets
Trading securities	3,925	11,190
Securities available for sale	220,259	219,088
Residential mortgage-backed securities issued by U.S. government agencies or sponsored enterprises
Assets
Trading securities	3,439
Securities available for sale	1,673,162	1,698,353
Commercial mortgage-backed securities issued by U.S. government agencies or sponsored enterprises
Assets
Trading securities	1,304	4,589
Securities available for sale	987,437	1,000,398
State and municipal obligations
Assets
Trading securities	7,122	13,993
Securities available for sale	966,957	1,064,852
Corporate securities.
Assets
Securities available for sale	27,184	32,638
Significant Other Observable Inputs (Level 2)
Assets
Loans held for sale	27,289	28,968
Trading securities	16,039	31,263
Significant Unobservable Inputs (Level 3)
Assets
Mortgage servicing rights	85,406	86,610
SBA servicing asset	6,521	6,068
Changes in fair value of assets
Changes in hierarchy classifications of Level 3 assets	0
Changes in hierarchy classifications of Level 3 liabilities	0
Recurring basis
Assets
Derivative financial instruments	159,287	211,016
Loans held for sale	27,289	28,968
Trading securities	16,039	31,263
Securities available for sale	5,159,999	5,326,822
Mortgage servicing rights	85,406	86,610
SBA servicing asset	6,521	6,068
Fair value of Assets, Total	5,454,541	5,690,747
Liabilities
Derivative financial instruments	806,584	1,034,143
Recurring basis \| U.S. Treasuries
Assets
Securities available for sale	268,096	265,638
Recurring basis \| U.S. Government agencies
Assets
Securities available for sale	220,259	219,088
Recurring basis \| Residential mortgage-backed securities issued by U.S. government agencies or sponsored enterprises
Assets
Securities available for sale	1,673,162	1,698,353
Recurring basis \| Residential Collateralized Mortgage-Obligations Issued By U.S. Government Agencies Or Sponsored Enterprises [Member]
Assets
Securities available for sale	591,412	601,045
Recurring basis \| Commercial mortgage-backed securities issued by U.S. government agencies or sponsored enterprises
Assets
Securities available for sale	987,437	1,000,398
Recurring basis \| State and municipal obligations
Assets
Securities available for sale	966,957	1,064,852
Recurring basis \| Mortgage-backed securities
Assets
Securities available for sale	425,492	444,810
Recurring basis \| Corporate securities.
Assets
Securities available for sale	27,184	32,638
Recurring basis \| Significant Other Observable Inputs (Level 2)
Assets
Derivative financial instruments	159,287	211,016
Loans held for sale	27,289	28,968
Trading securities	16,039	31,263
Securities available for sale	5,159,999	5,326,822
Fair value of Assets, Total	5,362,614	5,598,069
Liabilities
Derivative financial instruments	806,584	1,034,143
Recurring basis \| Significant Other Observable Inputs (Level 2) \| U.S. Treasuries
Assets
Securities available for sale	268,096	265,638
Recurring basis \| Significant Other Observable Inputs (Level 2) \| U.S. Government agencies
Assets
Securities available for sale	220,259	219,088
Recurring basis \| Significant Other Observable Inputs (Level 2) \| Residential mortgage-backed securities issued by U.S. government agencies or sponsored enterprises
Assets
Securities available for sale	1,673,162	1,698,353
Recurring basis \| Significant Other Observable Inputs (Level 2) \| Residential Collateralized Mortgage-Obligations Issued By U.S. Government Agencies Or Sponsored Enterprises [Member]
Assets
Securities available for sale	591,412	601,045
Recurring basis \| Significant Other Observable Inputs (Level 2) \| Commercial mortgage-backed securities issued by U.S. government agencies or sponsored enterprises
Assets
Securities available for sale	987,437	1,000,398
Recurring basis \| Significant Other Observable Inputs (Level 2) \| State and municipal obligations
Assets
Securities available for sale	966,957	1,064,852
Recurring basis \| Significant Other Observable Inputs (Level 2) \| Mortgage-backed securities
Assets
Securities available for sale	425,492	444,810
Recurring basis \| Significant Other Observable Inputs (Level 2) \| Corporate securities.
Assets
Securities available for sale	27,184	32,638
Recurring basis \| Significant Unobservable Inputs (Level 3)
Assets
Mortgage servicing rights	85,406	86,610
SBA servicing asset	6,521	6,068
Fair value of Assets, Total	$ 91,927	$ 92,678
Changes in fair value of assets
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Revenue from Contract with Customer, Excluding Assessed Tax
Unrealized losses included in accumulated other comprehensive (loss) income related to Level 3 financial assets and liabilities	$ 0
Recurring basis \| Significant Unobservable Inputs (Level 3) \| Mortgage Servicing Rights
Changes in fair value of assets
Fair value of assets at the beginning of the period	86,610
Servicing assets that resulted from transfers of financial assets	1,494
Changes in fair value assets due to valuation inputs or assumptions	(1,289)
Changes in fair value due to decay	(1,409)
Fair value of assets at the end of the period	85,406
Recurring basis \| Significant Unobservable Inputs (Level 3) \| SBA servicing asset
Changes in fair value of assets
Fair value of assets at the beginning of the period	6,068
Servicing assets that resulted from transfers of financial assets	334
Changes in fair value assets due to valuation inputs or assumptions	$ 355
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Revenue from Contract with Customer, Excluding Assessed Tax
Changes in fair value due to decay	$ (236)
Fair value of assets at the end of the period	$ 6,521

Represents the amount of servicing assets that resulted from transfers of financial assets.

No definition available.

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- Definition

The percentage of loans individually evaluated based on fair value of collateral.

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- Definition

The element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, the element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. The item represents residential mortgage servicing rights as presented on the statement of financial position which are due to the entity as of the balance sheet date.

+ References

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- Definition

Fair value portion of Small Business administration servicing assets.

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- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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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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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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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

Amount of gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3).

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Amount of gain (loss) recognized in other comprehensive income (OCI) from asset measured at fair value on recurring basis using unobservable input (level 3).

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- Definition

Amount of settlement of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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- Definition

Amount of transfer of financial instrument classified as an asset into (out of) level 3 of the fair value hierarchy.

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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of transfers of financial instrument classified as a liability into (out of) level 3 of the fair value hierarchy.

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Indicates line item in statement in which net income is reported that includes gain (loss) from asset measured at fair value using unobservable input (level 3).

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- Definition

Fair value as of the balance sheet date of interest rate derivative assets, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as assets.

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Fair value as of the balance sheet date of interest rate derivative liabilities, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as liabilities.

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- Definition

Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

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Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading).

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