Fair Value - Estimated fair value and related carrying amount, of the Company's financial instruments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Financial assets:
Trading securities	$ 107,401		$ 102,932
Financial liabilities:
Other derivative financial instruments (mortgage banking related)	(188,610)	$ 150,302
Carrying Amount
Financial assets:
Cash and cash equivalents	3,299,690		1,392,067
Trading securities	107,401		102,932
Investment securities	8,395,044		6,798,876
Mortgage loans held for sale	357,918		279,426
Loans, net of allowance for credit losses	46,143,042		33,437,647
Accrued interest receivable	227,921		163,402
Mortgage servicing rights	87,742		89,795
SBA servicing asset	6,209		6,028
Interest rate swap - non-designated hedge	175,155		160,407
Other derivative financial instruments (mortgage banking related)	$ 2,107		$ 1,083
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Derivative Asset, Noncurrent		Derivative Asset, Noncurrent
Financial liabilities:
Noninterest-bearing	$ 13,757,255		$ 10,192,117
Interest-bearing other than time deposits	32,422,118		23,703,027
Time deposits	7,158,242		4,165,722
Federal funds purchased and securities sold under agreements to repurchase	679,337		514,912
Corporate and subordinated debentures	752,798		391,534
Accrued interest payable	39,694		40,739
Interest rate swap - non-designated hedge	698,392		878,046
Other derivative financial instruments (mortgage banking related)			1,809
Other derivative financial instruments (mortgage banking related)	541
Fair Value
Financial assets:
Cash and cash equivalents	3,299,690		1,392,067
Trading securities	107,401		102,932
Investment securities	8,019,537		6,378,734
Mortgage loans held for sale	357,918		281,662
Loans, net of allowance for credit losses	45,562,297		32,448,618
Accrued interest receivable	227,921		163,402
Mortgage servicing rights	87,742		89,795
SBA servicing asset	6,209		6,028
Interest rate swap - non-designated hedge	175,155		160,407
Other derivative financial instruments (mortgage banking related)	$ 2,107		$ 1,083
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Derivative Asset, Noncurrent		Derivative Asset, Noncurrent
Financial liabilities:
Noninterest-bearing	$ 13,757,255		$ 10,192,117
Interest-bearing other than time deposits	32,422,118		23,703,027
Time deposits	7,133,462		4,145,687
Federal funds purchased and securities sold under agreements to repurchase	679,337		514,912
Corporate and subordinated debentures	756,080		377,616
Accrued interest payable	39,694		40,739
Interest rate swap - non-designated hedge	698,392		878,046
Other derivative financial instruments (mortgage banking related)			1,809
Other derivative financial instruments (mortgage banking related)	541
Quoted Prices In Active Markets for Identical Assets (Level 1)
Financial assets:
Cash and cash equivalents	3,299,690		1,392,067
Investment securities	280,119		187,266
Significant Other Observable Inputs (Level 2)
Financial assets:
Trading securities	107,401		102,932
Investment securities	7,673,842		6,155,120
Mortgage loans held for sale	357,918		281,662
Accrued interest receivable	33,900		25,035
Interest rate swap - non-designated hedge	175,155		160,407
Other derivative financial instruments (mortgage banking related)	$ 2,107		$ 1,083
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Derivative Asset, Noncurrent		Derivative Asset, Noncurrent
Financial liabilities:
Noninterest-bearing	$ 13,757,255		$ 10,192,117
Interest-bearing other than time deposits	32,422,118		23,703,027
Time deposits	7,133,462		4,145,687
Federal funds purchased and securities sold under agreements to repurchase	679,337		514,912
Corporate and subordinated debentures	756,080		377,616
Accrued interest payable	39,694		40,739
Interest rate swap - non-designated hedge	698,392		878,046
Other derivative financial instruments (mortgage banking related)			1,809
Other derivative financial instruments (mortgage banking related)	541
Significant Unobservable Inputs (Level 3)
Financial assets:
Investment securities	65,576		36,348
Loans, net of allowance for credit losses	45,562,297		32,448,618
Accrued interest receivable	194,021		138,367
Mortgage servicing rights	87,742		89,795
SBA servicing asset	$ 6,209		$ 6,028