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, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning balance	$ 1,823,790	$ 1,575,128	$ 1,469,226	$ 1,736,387
Allowance on acquired PCD loans			99,000
Provision for credit losses	115,000	(20,000)	427,000	(60,000)
Net charge-offs
Charge-offs	(101,267)	(64,273)	(227,919)	(267,567)
Recoveries	38,068	24,169	108,284	106,204
Net charge-offs	(63,199)	(40,104)	(119,635)	(161,363)
Ending balance	1,875,591	1,515,024	1,875,591	1,515,024
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning balance	414,473	314,852	283,899	405,846
Allowance on acquired PCD loans			41,003
Provision for credit losses	43,343	(292)	167,985	(57,610)
Net charge-offs
Charge-offs	(37,396)	(26,598)	(94,555)	(93,638)
Recoveries	22,022	3,785	44,110	37,149
Net charge-offs	(15,374)	(22,813)	(50,445)	(56,489)
Ending balance	442,442	291,747	442,442	291,747
Commercial Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning balance	708,393	679,963	557,239	670,719
Allowance on acquired PCD loans			55,812
Provision for credit losses	26,949	(42,016)	116,288	32,650
Net charge-offs
Charge-offs	(35,213)	(14,242)	(45,809)	(87,417)
Recoveries	401	2,362	17,000	10,115
Net charge-offs	(34,812)	(11,880)	(28,809)	(77,302)
Ending balance	700,530	626,067	700,530	626,067
Residential Portfolio Segment [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning balance	124,326	77,869	71,726	103,590
Allowance on acquired PCD loans			1,833
Provision for credit losses	(11,169)	(3,522)	40,719	(29,026)
Net charge-offs
Charge-offs	(2,572)	(1,925)	(9,407)	(6,586)
Recoveries	2,234	1,903	7,948	6,347
Net charge-offs	(338)	(22)	(1,459)	(239)
Ending balance	112,819	74,325	112,819	74,325
Consumer [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning balance	576,598	502,444	556,362	556,232
Allowance on acquired PCD loans			352
Provision for credit losses	55,877	25,830	102,008	(6,014)
Net charge-offs
Charge-offs	(26,086)	(21,508)	(78,148)	(79,926)
Recoveries	13,411	16,119	39,226	52,593
Net charge-offs	(12,675)	(5,389)	(38,922)	(27,333)
Ending balance	$ 619,800	$ 522,885	$ 619,800	$ 522,885