Fair Value - Assets and liabilities measured at fair value on a recurring basis (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Dec. 31, 2024
Assets
Derivative financial instruments	$ 175,100	$ 160,300
Trading securities	107,401	102,932
Securities available for sale	5,853,369	4,320,593
Liabilities
Derivative financial instruments	698,400,000	878,000,000
U.S. Treasuries
Assets
Securities available for sale	18,293	10,656
U.S. Government agencies
Assets
Trading securities	5,573	15,002
Securities available for sale		150,418
Residential mortgage-backed securities issued by U.S. government agencies or sponsored enterprises
Assets
Trading securities	26,500	14,803
Securities available for sale	1,447,116	1,377,525
Commercial mortgage-backed securities issued by U.S. government agencies or sponsored enterprises
Assets
Trading securities	19,345	14,419
Securities available for sale	560,634	1,040,555
State and municipal obligations
Assets
Trading securities	37,516	35,896
Securities available for sale	910,649	945,723
Small Business Administration loan-backed securities
Assets
Trading securities	14,577	22,571
Securities available for sale	542,553	310,112
Corporate securities
Assets
Securities available for sale	26,990	26,509
Significant Other Observable Inputs (Level 2)
Assets
Mortgage loans held for sale	357,918	281,662
Trading securities	107,401	102,932
Significant Unobservable Inputs (Level 3)
Assets
Mortgage servicing rights	87,742	89,795
SBA servicing asset	6,209	6,028
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	177,262	161,490
Mortgage loans held for sale	86,772	98,115
Trading securities	107,401	102,932
Securities available for sale	5,853,369	4,320,593
Mortgage servicing rights	87,742	89,795
SBA servicing asset	6,209	6,028
Fair value of Assets, Total	6,318,755	4,778,953
Liabilities
Derivative financial instruments	698,933	879,855
Recurring basis | U.S. Treasuries
Assets
Securities available for sale	18,293	10,656
Recurring basis | U.S. Government agencies
Assets
Securities available for sale		150,418
Recurring basis | Residential mortgage-backed securities issued by U.S. government agencies or sponsored enterprises
Assets
Securities available for sale	1,447,116	1,377,525
Recurring basis | Residential Collateralized Mortgage-Obligations Issued By U.S. Government Agencies Or Sponsored Enterprises
Assets
Securities available for sale	2,347,134	459,095
Recurring basis | Commercial mortgage-backed securities issued by U.S. government agencies or sponsored enterprises
Assets
Securities available for sale	560,634	1,040,555
Recurring basis | State and municipal obligations
Assets
Securities available for sale	910,649	945,723
Recurring basis | Small Business Administration loan-backed securities
Assets
Securities available for sale	542,553	310,112
Recurring basis | Corporate securities
Assets
Securities available for sale	26,990	26,509
Recurring basis | Significant Other Observable Inputs (Level 2)
Assets
Derivative financial instruments	177,262	161,490
Mortgage loans held for sale	86,772	98,115
Trading securities	107,401	102,932
Securities available for sale	5,853,369	4,320,593
Fair value of Assets, Total	6,224,804	4,683,130
Liabilities
Derivative financial instruments	698,933	879,855
Recurring basis | Significant Other Observable Inputs (Level 2) | U.S. Treasuries
Assets
Securities available for sale	18,293	10,656
Recurring basis | Significant Other Observable Inputs (Level 2) | U.S. Government agencies
Assets
Securities available for sale		150,418
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	1,447,116	1,377,525
Recurring basis | Significant Other Observable Inputs (Level 2) | Residential Collateralized Mortgage-Obligations Issued By U.S. Government Agencies Or Sponsored Enterprises
Assets
Securities available for sale	2,347,134	459,095
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	560,634	1,040,555
Recurring basis | Significant Other Observable Inputs (Level 2) | State and municipal obligations
Assets
Securities available for sale	910,649	945,723
Recurring basis | Significant Other Observable Inputs (Level 2) | Small Business Administration loan-backed securities
Assets
Securities available for sale	542,553	310,112
Recurring basis | Significant Other Observable Inputs (Level 2) | Corporate securities
Assets
Securities available for sale	26,990	26,509
Recurring basis | Significant Unobservable Inputs (Level 3)
Assets
Mortgage servicing rights	87,742	89,795
SBA servicing asset	6,209	6,028
Fair value of Assets, Total	$ 93,951	$ 95,823
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	89,795
Servicing assets that resulted from transfers of financial assets	2,056
Changes in fair value due to valuation inputs or assumptions	(3,081)
Changes in fair value due to decay	(1,028)
Fair value of assets at the end of the period	87,742
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	6,028
Servicing assets that resulted from transfers of financial assets	420
Changes in fair value due to valuation inputs or assumptions	$ 62
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	$ (301)
Fair value of assets at the end of the period	$ 6,209