Revenue Recognition - Summary of Disaggregation of Revenue According to Revenue Stream and Business Segment (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Disaggregation Of Revenue [Line Items]
Revenue (Expense) out of Scope of ASC 606	$ 3,550	$ 10,627	$ 27,635	$ 13,926
Noninterest income	144,919	138,082	304,163	268,282
Trust and Securities Processing [Member]
Disaggregation Of Revenue [Line Items]
Noninterest income	70,010	61,589	139,488	123,948
Trading and Investment Banking [Member]
Disaggregation Of Revenue [Line Items]
Revenue (Expense) out of Scope of ASC 606	4,960	4,645	10,377	9,795
Noninterest income	5,461	4,800	10,923	10,108
Service Charges On Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue (Expense) out of Scope of ASC 606	28	24	55	42
Noninterest income	22,261	21,381	43,018	42,540
Insurance Fees and Commissions [Member]
Disaggregation Of Revenue [Line Items]
Noninterest income	267	225	550	499
Brokerage Fees [Member]
Disaggregation Of Revenue [Line Items]
Noninterest income	14,020	13,604	27,180	27,280
Bankcard Fees [Member]
Disaggregation Of Revenue [Line Items]
Revenue (Expense) out of Scope of ASC 606	(10,383)	(10,649)	(18,266)	(20,381)
Noninterest income	22,346	18,579	44,314	36,751
Investment Securities Gains (Losses), Net [Member]
Disaggregation Of Revenue [Line Items]
Revenue (Expense) out of Scope of ASC 606	(1,867)	900	7,504	(4,424)
Noninterest income	(1,867)	900	7,504	(4,424)
Other [Member]
Disaggregation Of Revenue [Line Items]
Revenue (Expense) out of Scope of ASC 606	10,812	15,707	27,965	28,894
Noninterest income	12,421	17,004	31,186	31,580
Commercial Banking [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	29,494	26,876	56,599	51,323
Noninterest income	27,720	25,666	70,686	48,568
Commercial Banking [Member] | Service Charges On Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	10,492	9,778	20,843	18,305
Commercial Banking [Member] | Brokerage Fees [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	65	65	133	128
Commercial Banking [Member] | Bankcard Fees [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	18,775	16,868	35,323	32,500
Commercial Banking [Member] | Other [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	162	165	300	390
Institutional Banking [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	87,601	77,596	172,261	156,603
Noninterest income	95,092	86,813	187,808	171,051
Institutional Banking [Member] | Trust and Securities Processing [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	55,310	48,413	110,551	97,592
Institutional Banking [Member] | Trading and Investment Banking [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	501	(155)	546	313
Institutional Banking [Member] | Service Charges On Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	10,424	10,159	19,519	20,898
Institutional Banking [Member] | Brokerage Fees [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	12,079	11,687	23,402	23,482
Institutional Banking [Member] | Bankcard Fees [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	8,499	6,662	16,656	13,340
Institutional Banking [Member] | Other [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	788	520	1,587	978
Personal Banking [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	24,274	22,983	47,668	46,430
Noninterest income	22,107	25,603	45,669	48,663
Personal Banking [Member] | Trust and Securities Processing [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	14,700	13,176	28,937	26,356
Personal Banking [Member] | Service Charges On Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	1,317	1,420	2,601	3,295
Personal Banking [Member] | Insurance Fees and Commissions [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	267	225	550	499
Personal Banking [Member] | Brokerage Fees [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	1,876	1,852	3,645	3,670
Personal Banking [Member] | Bankcard Fees [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	5,455	5,698	10,601	11,292
Personal Banking [Member] | Other [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	$ 659	$ 612	$ 1,334	$ 1,318