Loans and the Allowance for Credit Losses - Allowance for Credit Losses and Recorded Investments in Loans (Detail) - USD ($) $ in Thousands	Jun. 30, 2025	Dec. 31, 2024	Jun. 30, 2024	Dec. 31, 2023
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loans individually evaluated for impairment	$ 23,059	$ 17,814
Allowance for loans collectively evaluated for impairment	200,807	120,952
Allowance for loan commitments	6,168	6,120	$ 9,194	$ 8,604
Total allowance for credit losses - loans and commitments	230,034	144,886	145,703	139,279
Individually evaluated for credit loss	43,784	52,340
Collectively-evaluated for credit losses	18,784,842	12,604,089
Total loans	18,828,626	12,656,429
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loans individually evaluated for impairment	6,054	5,353
Allowance for loans collectively evaluated for impairment	57,883	37,045
Allowance for loan commitments				429
Total allowance for credit losses - loans and commitments	63,937	42,398	41,405	37,073
Individually evaluated for credit loss	6,965	7,116
Collectively-evaluated for credit losses	2,812,131	1,780,161
Total loans	2,819,096	1,787,277
Deposit Overdraft [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loans collectively evaluated for impairment	2,321	1,713
Total allowance for credit losses - loans and commitments	2,321	1,713	1,551	1,366
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	10,600,210	7,326,681
Commercial Real Estate [Member] | Commercial Real Estate - Land and Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loans collectively evaluated for impairment	10,916	8,411
Allowance for loan commitments	5,359	5,105	7,940	6,894
Total allowance for credit losses - loans and commitments	16,275	13,516	15,766	14,017
Collectively-evaluated for credit losses	1,732,088	1,352,083
Total loans	1,732,088	1,352,083
Commercial Real Estate [Member] | Commercial Real Estate - Improved Property [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loans individually evaluated for impairment	17,005	12,461
Allowance for loans collectively evaluated for impairment	82,239	47,367
Total allowance for credit losses - loans and commitments	99,244	59,828	58,577	59,351
Individually evaluated for credit loss	36,819	45,224
Collectively-evaluated for credit losses	8,831,303	5,929,374
Total loans	8,868,122	5,974,598
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loans collectively evaluated for impairment	34,514	21,790
Allowance for loan commitments	809	1,015	1,254	1,276
Total allowance for credit losses - loans and commitments	35,323	22,805	23,657	22,494
Collectively-evaluated for credit losses	3,939,796	2,520,086
Total loans	3,939,796	2,520,086
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loans collectively evaluated for impairment	10,717	3,391
Total allowance for credit losses - loans and commitments	10,717	3,391	3,643	3,956
Collectively-evaluated for credit losses	417,190	201,275
Total loans	417,190	201,275
Home Equity [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loans collectively evaluated for impairment	2,217	1,235
Allowance for loan commitments				5
Total allowance for credit losses - loans and commitments	2,217	1,235	$ 1,104	$ 1,022
Collectively-evaluated for credit losses	1,052,334	821,110
Total loans	$ 1,052,334	$ 821,110