Loans - Allowance for Credit Losses by Portfolio Segment (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance			$ 69,903
Ending balance	$ 70,475		70,475
Non-PCI Loans and Leases
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	70,468	$ 70,597	69,903	$ 70,147
Charge-offs	(1,893)	(12,377)	(5,064)	(15,567)
Recoveries	629	1,013	1,202	2,256
Credit loss expense (recovery)	1,271	7,523	4,434	9,920
Ending balance	70,475	66,756	70,475	66,756
Real Estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance			51,670
Ending balance	49,126		49,126
Real Estate \| Non-PCI Loans and Leases
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	50,108	51,302	51,670	45,099
Charge-offs	(28)	(8,615)	(160)	(8,785)
Recoveries	39	194	84	618
Credit loss expense (recovery)	(992)	5,140	(2,467)	11,089
Ending balance	49,127	48,021	49,127	48,021
Commercial and Industrial
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance			7,792
Ending balance	8,681		8,681
Commercial and Industrial \| Non-PCI Loans and Leases
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	8,811	6,242	7,792	10,006
Charge-offs	(275)	(811)	(402)	(1,033)
Recoveries	37	198	76	234
Credit loss expense (recovery)	107	1,306	1,214	(2,272)
Ending balance	8,680	6,935	8,680	6,935
Equipment Financing Agreements
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance			10,441
Ending balance	12,668		12,668
Equipment Financing Agreements \| Non-PCI Loans and Leases
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	11,549	13,053	10,441	15,042
Charge-offs	(1,590)	(2,951)	(4,502)	(5,749)
Recoveries	553	621	1,042	1,404
Credit loss expense (recovery)	2,156	1,077	5,687	1,103
Ending balance	$ 12,668	$ 11,800	$ 12,668	$ 11,800