Loans and Leases and the Allowance for Credit Losses - Changes in Allowance for Credit Losses (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	$ 1,998,366	$ 1,823,790	$ 1,925,331	$ 1,469,226
Allowance on acquired PCD loans				99,000
Provision for credit losses	150,000	115,000	420,000	427,000
Net charge-offs
Charge-offs	(122,128)	(101,267)	(379,291)	(227,919)
Recoveries	25,889	38,068	86,087	108,284
Net (charge-offs) recoveries	(96,239)	(63,199)	(293,204)	(119,635)
Ending balance	2,052,127	1,875,591	2,052,127	1,875,591
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	511,929	414,473	502,153	283,899
Allowance on acquired PCD loans				41,003
Provision for credit losses	45,637	43,343	69,801	167,985
Net charge-offs
Charge-offs	(26,844)	(37,396)	(67,104)	(94,555)
Recoveries	6,976	22,022	32,848	44,110
Net (charge-offs) recoveries	(19,868)	(15,374)	(34,256)	(50,445)
Ending balance	537,698	442,442	537,698	442,442
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	765,676	708,393	676,684	557,239
Allowance on acquired PCD loans				55,812
Provision for credit losses	73,588	26,949	290,672	116,288
Net charge-offs
Charge-offs	(51,574)	(35,213)	(183,548)	(45,809)
Recoveries	4,290	401	8,172	17,000
Net (charge-offs) recoveries	(47,284)	(34,812)	(175,376)	(28,809)
Ending balance	791,980	700,530	791,980	700,530
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	118,392	124,326	115,092	71,726
Allowance on acquired PCD loans				1,833
Provision for credit losses	(3,390)	(11,169)	(955)	40,719
Net charge-offs
Charge-offs	(1,332)	(2,572)	(4,105)	(9,407)
Recoveries	824	2,234	4,462	7,948
Net (charge-offs) recoveries	(508)	(338)	(357)	(1,459)
Ending balance	114,494	112,819	114,494	112,819
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	602,369	576,598	631,402	556,362
Allowance on acquired PCD loans				352
Provision for credit losses	34,165	55,877	60,482	102,008
Net charge-offs
Charge-offs	(42,378)	(26,086)	(124,534)	(78,148)
Recoveries	13,799	13,411	40,605	39,226
Net (charge-offs) recoveries	(28,579)	(12,675)	(83,929)	(38,922)
Ending balance	$ 607,955	$ 619,800	$ 607,955	$ 619,800