Loans and the Allowance for Credit Losses - Summary of Age Analysis of Loan Categories (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	$ 11,315,873	$ 10,702,728
90 Days or More Past Due and Accruing	8,606	5,443
Loans held for sale	17,677	8,249
Total loans, current	11,289,294	10,662,148
Total loans	11,333,550	10,710,977
Total Non-performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income		41,415
Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	715,186	695,065
90 Days or More Past Due and Accruing	1,475	1,063
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	6,387,183	6,061,344
90 Days or More Past Due and Accruing	4,131	713
Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	2,392,531	2,140,584
90 Days or More Past Due and Accruing	1,991	1,551
Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	233,362	226,340
90 Days or More Past Due and Accruing	717	530
Commercial Real Estate - Land and Construction [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	870,066	943,887
90 Days or More Past Due and Accruing		629
Commercial Real Estate - Improved Property [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	5,517,117	5,117,457
90 Days or More Past Due and Accruing	4,131	84
Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	1,587,611	1,579,395
90 Days or More Past Due and Accruing	292	1,586
Non-Accrual Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	29,878	38,185
TDRs Accruing Interest [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income		3,230
Current [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	11,271,617	10,653,899
Loans held for sale, current	17,677	8,249
Current [Member] | Total Non-performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income		13,468
Current [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	705,435	686,762
Current [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	6,369,135	6,041,578
Current [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	2,383,834	2,129,095
Current [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	228,391	222,153
Current [Member] | Commercial Real Estate - Land and Construction [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	870,066	942,236
Current [Member] | Commercial Real Estate - Improved Property [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	5,499,069	5,099,342
Current [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	1,584,822	1,574,311
Current [Member] | Non-Accrual Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	10,258	10,337
Current [Member] | TDRs Accruing Interest [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income		3,131
30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	10,612	11,222
30-59 Days Past Due [Member] | Total Non-performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income		1,502
30-59 Days Past Due [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	3,599	3,885
30-59 Days Past Due [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	2,161	2,147
30-59 Days Past Due [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	1,134	853
30-59 Days Past Due [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	3,152	2,910
30-59 Days Past Due [Member] | Commercial Real Estate - Improved Property [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	2,161	2,147
30-59 Days Past Due [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	566	1,427
30-59 Days Past Due [Member] | Non-Accrual Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	626	1,495
30-59 Days Past Due [Member] | TDRs Accruing Interest [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income		7
60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	6,916	6,621
60-89 Days Past Due [Member] | Total Non-performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income		902
60-89 Days Past Due [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	1,209	621
60-89 Days Past Due [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	1,279	1,241
60-89 Days Past Due [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	2,955	3,536
60-89 Days Past Due [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	1,035	704
60-89 Days Past Due [Member] | Commercial Real Estate - Land and Construction [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income		910
60-89 Days Past Due [Member] | Commercial Real Estate - Improved Property [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	1,279	331
60-89 Days Past Due [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	438	519
60-89 Days Past Due [Member] | Non-Accrual Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	872	870
60-89 Days Past Due [Member] | TDRs Accruing Interest [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income		32
90 Days or More Past Due [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	26,728	30,986
90 Days or More Past Due [Member] | Total Non-performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income		25,543
90 Days or More Past Due [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	4,943	3,797
90 Days or More Past Due [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	14,608	16,378
90 Days or More Past Due [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	4,608	7,100
90 Days or More Past Due [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	784	573
90 Days or More Past Due [Member] | Commercial Real Estate - Land and Construction [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income		741
90 Days or More Past Due [Member] | Commercial Real Estate - Improved Property [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	14,608	15,637
90 Days or More Past Due [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	1,785	3,138
90 Days or More Past Due [Member] | Non-Accrual Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	18,122	25,483
90 Days or More Past Due [Member] | TDRs Accruing Interest [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income		60
Total Past Due [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	44,256	48,829
Total Past Due [Member] | Total Non-performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income		27,947
Total Past Due [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	9,751	8,303
Total Past Due [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	18,048	19,766
Total Past Due [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	8,697	11,489
Total Past Due [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	4,971	4,187
Total Past Due [Member] | Commercial Real Estate - Land and Construction [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income		1,651
Total Past Due [Member] | Commercial Real Estate - Improved Property [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	18,048	18,115
Total Past Due [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	2,789	5,084
Total Past Due [Member] | Non-Accrual Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income	$ 19,620	27,848
Total Past Due [Member] | TDRs Accruing Interest [Member]
Financing Receivable, Recorded Investment [Line Items]
Portfolio loans, net of unearned income		$ 99