Revenue from Contracts with Customers - Summary of Sources of Noninterest Income that are Subject to Noted Accounting Guidance (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation Of Revenue [Line Items]
Brokerage services income	$ 20,490	$ 11,602	$ 43,868	$ 35,194
Other revenues from operations:
Total other income	569,126	520,561	1,588,357	1,537,194
Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	105,426	91,355	296,721	274,971
Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	156,876	149,937	475,889	450,570
ASU 2014-09 [Member]
Disaggregation Of Revenue [Line Items]
Brokerage services income	20,490	11,602	43,868	35,194
Other revenues from operations:
Merchant discount and credit card fees	36,274	25,654	94,739	73,876
Other	19,828	21,407	62,749	60,477
Total other income	338,894	299,955	973,966	895,088
ASU 2014-09 [Member] | Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	105,426	91,355	296,721	274,971
ASU 2014-09 [Member] | Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	156,876	149,937	475,889	450,570
ASU 2014-09 [Member] | Business Banking [Member]
Other revenues from operations:
Merchant discount and credit card fees	14,376	10,533	37,570	29,023
Total other income	28,581	22,060	77,214	67,089
ASU 2014-09 [Member] | Business Banking [Member] | Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	14,205	11,527	39,644	38,048
ASU 2014-09 [Member] | Business Banking [Member] | Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer				18
ASU 2014-09 [Member] | Commercial Banking [Member]
Other revenues from operations:
Merchant discount and credit card fees	14,970	10,785	39,812	32,992
Other	1,879	2,940	3,890	5,913
Total other income	41,903	36,542	118,006	108,834
ASU 2014-09 [Member] | Commercial Banking [Member] | Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	25,054	22,816	74,304	69,487
ASU 2014-09 [Member] | Commercial Banking [Member] | Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer		1		442
ASU 2014-09 [Member] | Commercial Real Estate [Member]
Other revenues from operations:
Merchant discount and credit card fees	878	492	1,823	1,720
Other	2,180	929	5,197	2,960
Total other income	6,035	3,768	15,788	12,404
ASU 2014-09 [Member] | Commercial Real Estate [Member] | Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	2,977	2,347	8,768	7,724
ASU 2014-09 [Member] | Discretionary Portfolio [Member]
Other revenues from operations:
Other	283	205	1,043	1,212
Total other income	283	205	1,043	1,212
ASU 2014-09 [Member] | Residential Mortgage Banking [Member]
Other revenues from operations:
Other	1,501	1,127	4,670	3,101
Total other income	1,501	1,127	4,670	3,101
ASU 2014-09 [Member] | Retail Banking [Member]
Disaggregation Of Revenue [Line Items]
Brokerage services income	(20)
Other revenues from operations:
Merchant discount and credit card fees	5,912	4,159	15,741	9,880
Other	5,674	5,994	17,493	15,142
Total other income	73,262	63,532	202,968	180,095
ASU 2014-09 [Member] | Retail Banking [Member] | Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	61,696	53,379	169,734	155,073
ASU 2014-09 [Member] | All Other [Member]
Disaggregation Of Revenue [Line Items]
Brokerage services income	20,510	11,602	43,868	35,194
Other revenues from operations:
Merchant discount and credit card fees	138	(315)	(207)	261
Other	8,311	10,212	30,456	32,149
Total other income	187,329	172,721	554,277	522,353
ASU 2014-09 [Member] | All Other [Member] | Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	1,494	1,286	4,271	4,639
ASU 2014-09 [Member] | All Other [Member] | Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	$ 156,876	$ 149,936	$ 475,889	$ 450,110