Loans and Allowance for Credit Losses - Summary of Loan Classes and Aging of Past Due Loans (Detail) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	$ 37,706,507	$ 25,642,301
Nonaccrual Loans	131,965	19,282
30-89 Days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	84,446	11,503
Greater than 90 days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	6,131	7,602
Total Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	222,542	38,387
Current [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	37,483,965	25,603,914
Commercial and Industrial Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	15,198,082	10,993,771
Nonaccrual Loans	33,610	4,423
Commercial and Industrial Portfolio [Member] \| 30-89 Days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	32,711	446
Commercial and Industrial Portfolio [Member] \| Greater than 90 days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	110	1
Commercial and Industrial Portfolio [Member] \| Total Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	66,431	4,870
Commercial and Industrial Portfolio [Member] \| Current [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	15,131,651	10,988,901
Specialty Lending Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	561,394	469,194
Specialty Lending Portfolio [Member] \| Current [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	561,394	469,194
Commercial Real Estate Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	16,583,095	10,131,285
Nonaccrual Loans	69,859	805
Commercial Real Estate Portfolio [Member] \| 30-89 Days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	27,634	1,013
Commercial Real Estate Portfolio [Member] \| Total Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	97,493	1,818
Commercial Real Estate Portfolio [Member] \| Current [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	16,485,602	10,129,467
Consumer Real Estate Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	4,342,559	3,187,130
Nonaccrual Loans	24,633	13,614
Consumer Real Estate Portfolio [Member] \| 30-89 Days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	5,826	553
Consumer Real Estate Portfolio [Member] \| Total Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	30,459	14,167
Consumer Real Estate Portfolio [Member] \| Current [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	4,312,100	3,172,963
Consumer Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	223,453	193,860
Nonaccrual Loans	828	40
Consumer Portfolio [Member] \| 30-89 Days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	5,518	175
Consumer Portfolio [Member] \| Greater than 90 days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans		12
Consumer Portfolio [Member] \| Total Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	6,346	227
Consumer Portfolio [Member] \| Current [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	217,107	193,633
Credit Cards Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	689,807	578,766
Nonaccrual Loans	3,035	400
Credit Cards Portfolio [Member] \| 30-89 Days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	12,757	9,316
Credit Cards Portfolio [Member] \| Greater than 90 days Past Due and Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	6,021	7,589
Credit Cards Portfolio [Member] \| Total Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	21,813	17,305
Credit Cards Portfolio [Member] \| Current [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	667,994	561,461
Leases and Other Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	108,117	88,295
Nonaccrual Loans	0	0
Leases and Other Portfolio [Member] \| Total Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans		0
Leases and Other Portfolio [Member] \| Current [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	$ 108,117	$ 88,295