Loans and the Allowance for Credit Losses - Allowance for Credit Losses and Recorded Investments in Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loans individually evaluated for impairment	$ 5,745	$ 3,118
Allowance for loans collectively evaluated for impairment	124,930	114,672
Allowance for loan commitments	8,604	8,368	$ 7,775	$ 9,514
Total allowance for credit losses - loans and commitments	139,279	126,158	129,397	195,341
Individually evaluated for credit loss	37,045	50,399
Collectively-evaluated for credit losses	11,601,416	10,652,329
Total loans	11,638,461	10,702,728
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loans individually evaluated for impairment	0	130
Allowance for loans collectively evaluated for impairment	36,644	31,410
Allowance for loan commitments	429	0	1,497	1,275
Total allowance for credit losses - loans and commitments	37,073	31,540	28,372	39,125
Individually evaluated for credit loss	116	401
Collectively-evaluated for credit losses	1,670,543	1,578,994
Total loans	1,670,659	1,579,395
Deposit Overdraft [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loans collectively evaluated for impairment	1,366	1,285
Total allowance for credit losses - loans and commitments	1,366	1,285	2,220	639
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	6,565,448	6,061,344
Commercial Real Estate [Member] | Commercial Real Estate - Land and Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loans individually evaluated for impairment	0
Allowance for loans collectively evaluated for impairment	7,123	6,737
Allowance for loan commitments	6,894	6,025	4,180	6,508
Total allowance for credit losses - loans and commitments	14,017	12,762	11,490	17,349
Individually evaluated for credit loss		24,629
Collectively-evaluated for credit losses	1,055,865	919,258
Total loans	1,055,865	943,887
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	5,745	2,988
Allowance for loans collectively evaluated for impairment	53,606	49,671
Allowance for loan commitments	0	0	201	712
Total allowance for credit losses - loans and commitments	59,351	52,659	65,556	111,364
Individually evaluated for credit loss	36,929	25,369
Collectively-evaluated for credit losses	5,472,654	5,092,088
Total loans	5,509,583	5,117,457
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loans collectively evaluated for impairment	21,218	18,208
Allowance for loan commitments	1,276	2,215	1,576	955
Total allowance for credit losses - loans and commitments	22,494	20,423	16,977	18,806
Collectively-evaluated for credit losses	2,438,574	2,140,584
Total loans	2,438,574	2,140,584
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loans collectively evaluated for impairment	3,956	3,127
Allowance for loan commitments	0	0	272	19
Total allowance for credit losses - loans and commitments	3,956	3,127	4,009	6,526
Collectively-evaluated for credit losses	229,561	226,340
Total loans	229,561	226,340
Home Equity [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loans collectively evaluated for impairment	1,017	4,234
Allowance for loan commitments	5	128	49	45
Total allowance for credit losses - loans and commitments	1,022	4,362	$ 773	$ 1,532
Collectively-evaluated for credit losses	734,219	695,065
Total loans	$ 734,219	$ 695,065