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		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Disaggregation Of Revenue [Line Items]
Brokerage services income	$ 10,265	$ 10,463	$ 23,378	$ 23,592
Other revenues from operations:
Total other income	513,633	487,273	1,019,231	1,016,633
Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	98,518	77,455	191,295	183,616
Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	162,991	151,882	319,013	300,633
ASU 2014-09 [Member]
Disaggregation Of Revenue [Line Items]
Brokerage services income	10,265	10,463	23,378	23,592
Other revenues from operations:
Merchant discount and credit card fees	34,102	21,055	58,465	48,222
Other	20,011	15,764	42,921	39,070
Total other income	325,887	276,619	635,072	595,133
ASU 2014-09 [Member] | Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	98,518	77,455	191,295	183,616
ASU 2014-09 [Member] | Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	162,991	151,882	319,013	300,633
ASU 2014-09 [Member] | Business Banking [Member]
Other revenues from operations:
Merchant discount and credit card fees	13,713	8,159	23,194	18,490
Total other income	26,655	19,436	48,633	45,029
ASU 2014-09 [Member] | Business Banking [Member] | Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	12,942	11,271	25,439	26,521
ASU 2014-09 [Member] | Business Banking [Member] | Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer		6		18
ASU 2014-09 [Member] | Commercial Banking [Member]
Other revenues from operations:
Merchant discount and credit card fees	14,435	8,891	24,842	22,207
Other	1,053	787	2,011	2,973
Total other income	40,443	32,329	76,103	72,292
ASU 2014-09 [Member] | Commercial Banking [Member] | Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	24,955	22,514	49,250	46,671
ASU 2014-09 [Member] | Commercial Banking [Member] | Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer		137		441
ASU 2014-09 [Member] | Commercial Real Estate [Member]
Other revenues from operations:
Merchant discount and credit card fees	500	379	945	1,228
Other	1,926	1,188	3,017	2,031
Total other income	5,324	4,132	9,753	8,636
ASU 2014-09 [Member] | Commercial Real Estate [Member] | Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	2,898	2,565	5,791	5,377
ASU 2014-09 [Member] | Discretionary Portfolio [Member]
Other revenues from operations:
Other	376	150	760	1,007
Total other income	376	150	760	1,007
ASU 2014-09 [Member] | Residential Mortgage Banking [Member]
Other revenues from operations:
Other	1,447	1,052	3,169	1,974
Total other income	1,447	1,052	3,169	1,974
ASU 2014-09 [Member] | Retail Banking [Member]
Disaggregation Of Revenue [Line Items]
Brokerage services income	20		20
Other revenues from operations:
Merchant discount and credit card fees	5,908	3,450	9,829	5,721
Other	6,012	3,166	11,819	9,148
Total other income	68,526	46,640	129,706	116,563
ASU 2014-09 [Member] | Retail Banking [Member] | Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	56,586	40,024	108,038	101,694
ASU 2014-09 [Member] | All Other [Member]
Disaggregation Of Revenue [Line Items]
Brokerage services income	10,245	10,463	23,358	23,592
Other revenues from operations:
Merchant discount and credit card fees	(454)	176	(345)	576
Other	9,197	9,421	22,145	21,937
Total other income	183,116	172,880	366,948	349,632
ASU 2014-09 [Member] | All Other [Member] | Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	1,137	1,081	2,777	3,353
ASU 2014-09 [Member] | All Other [Member] | Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	$ 162,991	$ 151,739	$ 319,013	$ 300,174