Loans and Leases and the Allowance for Credit Losses - Summary of Current, Past Due and Nonaccrual Loans (Detail) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	$ 124,377,234	$ 89,043,040
30-89 Days Past Due	952,219	845,930
Accruing Loans Past Due 90 Days or More	523,662	963,399
Nonaccrual	2,633,005	2,060,083
Loans and leases, net of unearned discount	128,486,120	92,912,452
Commercial, Financial, Leasing, etc. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	38,521,001	23,101,810
30-89 Days Past Due	133,014	142,208
Accruing Loans Past Due 90 Days or More	12,165	8,284
Nonaccrual	442,496	221,022
Loans and leases, net of unearned discount	39,108,676	23,473,324
Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	35,601,423	24,712,643
30-89 Days Past Due	243,578	319,099
Accruing Loans Past Due 90 Days or More	34,815	31,733
Nonaccrual	1,476,658	1,069,280
Loans and leases, net of unearned discount	37,356,474	26,132,755
Residential Builder and Developer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	1,368,677	1,400,437
30-89 Days Past Due	1,219	2,904
Nonaccrual	518	3,005
Loans and leases, net of unearned discount	1,370,414	1,406,346
Other Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	7,877,882	7,722,049
30-89 Days Past Due	117,323	17,175
Nonaccrual	73,046	111,405
Loans and leases, net of unearned discount	8,068,251	7,850,629
Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	20,476,197	13,294,872
30-89 Days Past Due	345,622	239,561
Accruing Loans Past Due 90 Days or More	473,541	920,080
Nonaccrual	331,376	355,858
Loans and leases, net of unearned discount	21,626,736	14,810,371
Residential Limited Documentation [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	1,014,151	1,124,520
30-89 Days Past Due	13,612	16,666
Nonaccrual	112,608	122,888
Loans and leases, net of unearned discount	1,140,371	1,264,074
Home Equity Lines and Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	4,959,003	3,476,617
30-89 Days Past Due	21,243	15,486
Nonaccrual	79,445	70,488
Loans and leases, net of unearned discount	5,059,691	3,562,591
Recreational Finance [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	8,403,078	7,985,173
30-89 Days Past Due	32,654	40,544
Nonaccrual	33,414	27,811
Loans and leases, net of unearned discount	8,469,146	8,053,528
Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	4,369,475	4,604,772
30-89 Days Past Due	32,220	40,064
Nonaccrual	36,266	34,037
Loans and leases, net of unearned discount	4,437,961	4,678,873
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	1,786,347	1,620,147
30-89 Days Past Due	11,734	12,223
Accruing Loans Past Due 90 Days or More	3,141	3,302
Nonaccrual	47,178	44,289
Loans and leases, net of unearned discount	$ 1,848,400	$ 1,679,961