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, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Disaggregation Of Revenue [Line Items]
Revenue (Expense) out of Scope of ASC 606	$ 43,449	$ 42,694	$ 58,872	$ 42,252
Noninterest income	245,505	222,185	450,298	388,383
Trust and Securities Processing [Member]
Disaggregation Of Revenue [Line Items]
Noninterest income	98,295	83,263	192,962	163,044
Trading and Investment Banking [Member]
Disaggregation Of Revenue [Line Items]
Revenue (Expense) out of Scope of ASC 606	5,170	6,085	12,788	11,667
Noninterest income	5,314	6,170	13,054	12,081
Service Charges On Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue (Expense) out of Scope of ASC 606	29	38	61	77
Noninterest income	29,588	28,865	59,062	56,322
Insurance Fees and Commissions [Member]
Disaggregation Of Revenue [Line Items]
Noninterest income	207	189	462	367
Brokerage Fees [Member]
Disaggregation Of Revenue [Line Items]
Noninterest income	25,400	20,525	46,489	38,627
Bankcard Fees [Member]
Disaggregation Of Revenue [Line Items]
Revenue (Expense) out of Scope of ASC 606	(13,517)	(13,706)	(25,690)	(25,502)
Noninterest income	29,954	29,018	58,832	55,311
Investment Securities Gains, Net [Member]
Disaggregation Of Revenue [Line Items]
Revenue (Expense) out of Scope of ASC 606	27,087	37,685	30,133	32,903
Noninterest income	27,087	37,685	30,133	32,903
Other [Member]
Disaggregation Of Revenue [Line Items]
Revenue (Expense) out of Scope of ASC 606	24,680	12,592	41,580	23,107
Noninterest income	29,660	16,470	49,304	29,728
Commercial Banking [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	48,318	46,560	92,560	87,130
Commercial Banking [Member] \| Trust and Securities Processing [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	858	752	1,619	1,231
Commercial Banking [Member] \| Service Charges On Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	16,579	16,199	32,723	30,780
Commercial Banking [Member] \| Brokerage Fees [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	97	62	184	129
Commercial Banking [Member] \| Bankcard Fees [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	27,779	27,285	53,865	51,449
Commercial Banking [Member] \| Other [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	3,005	2,262	4,169	3,541
Institutional Banking [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	119,321	99,396	230,622	195,128
Institutional Banking [Member] \| Trust and Securities Processing [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	76,843	63,577	150,168	124,825
Institutional Banking [Member] \| Trading and Investment Banking [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	144	85	266	414
Institutional Banking [Member] \| Service Charges On Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	10,583	10,162	21,440	21,021
Institutional Banking [Member] \| Brokerage Fees [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	22,802	17,573	41,167	32,945
Institutional Banking [Member] \| Bankcard Fees [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	7,981	7,304	15,875	14,546
Institutional Banking [Member] \| Other [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	968	695	1,706	1,377
Personal Banking [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	34,417	33,535	68,244	63,873
Personal Banking [Member] \| Trust and Securities Processing [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	20,594	18,934	41,175	36,988
Personal Banking [Member] \| Service Charges On Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	2,397	2,466	4,838	4,444
Personal Banking [Member] \| Insurance Fees and Commissions [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	207	189	462	367
Personal Banking [Member] \| Brokerage Fees [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	2,501	2,890	5,138	5,553
Personal Banking [Member] \| Bankcard Fees [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	7,711	8,135	14,782	14,818
Personal Banking [Member] \| Other [Member]
Disaggregation Of Revenue [Line Items]
Revenue Scope of ASC 606	$ 1,007	$ 921	$ 1,849	$ 1,703

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The total amount of noninterest income which may be derived from: (1) fees and commissions; (2) premiums earned; (3) insurance policy charges; (4) the sale or disposal of assets; and (5) other sources not otherwise specified.

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