Loans and Leases - Summary of Current, Past Due and Nonaccrual Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	$ 87,968,321	$ 84,400,551
30-89 Days Past Due	1,025,245	1,135,296
Accruing Loans Past Due 90 Days or More	300,659	317,441
Purchased Impaired	578,032	768,329
Nonaccrual	920,015	799,409
Loans and leases, net of unearned discount	90,853,416	87,489,499
Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More	61,144	68,473
Commercial, Financial, Leasing, etc. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	22,287,857	20,122,648
30-89 Days Past Due	53,503	52,868
Accruing Loans Past Due 90 Days or More	6,195	2,310
Purchased Impaired	641	1,902
Nonaccrual	261,434	241,917
Loans and leases, net of unearned discount	22,610,047	20,422,338
Commercial, Financial, Leasing, etc. [Member] | Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More	417	693
Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	25,076,684	23,111,673
30-89 Days Past Due	183,531	172,439
Accruing Loans Past Due 90 Days or More	7,054	12,963
Purchased Impaired	31,404	46,790
Nonaccrual	176,201	179,606
Loans and leases, net of unearned discount	25,487,744	23,532,261
Commercial [Member] | Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More	12,870	8,790
Residential Builder and Developer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	1,884,989	1,507,856
30-89 Days Past Due	4,667	7,969
Accruing Loans Past Due 90 Days or More	5	5,760
Purchased Impaired	14,006	28,734
Nonaccrual	16,707	28,429
Loans and leases, net of unearned discount	1,922,326	1,585,673
Residential Builder and Developer [Member] | Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More	1,952	6,925
Other Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	5,985,118	3,962,620
30-89 Days Past Due	77,701	65,932
Accruing Loans Past Due 90 Days or More	922	7,936
Purchased Impaired	14,274	24,525
Nonaccrual	18,111	16,363
Loans and leases, net of unearned discount	6,096,324	4,079,377
Other Commercial Construction [Member] | Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More	198	2,001
Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	17,631,377	20,507,551
30-89 Days Past Due	485,468	560,312
Accruing Loans Past Due 90 Days or More	281,298	284,451
Purchased Impaired	378,549	488,599
Nonaccrual	229,242	153,281
Loans and leases, net of unearned discount	19,017,471	22,010,273
Residential [Member] | Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More	11,537	16,079
Residential Limited Documentation [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	3,239,344	3,885,073
30-89 Days Past Due	88,366	137,289
Purchased Impaired	139,158	175,518
Nonaccrual	106,573	61,950
Loans and leases, net of unearned discount	3,573,441	4,259,830
Home Equity Lines and Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	5,502,091	5,805,222
30-89 Days Past Due	44,565	45,604
Purchased Impaired		2,261
Nonaccrual	81,815	84,467
Loans and leases, net of unearned discount	5,641,149	5,952,776
Home Equity Lines and Loans [Member] | Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More	12,678	15,222
Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	2,869,232	2,446,473
30-89 Days Past Due	56,158	56,181
Nonaccrual	18,674	16,597
Loans and leases, net of unearned discount	2,944,065	2,519,257
Automobile [Member] | Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More	1	6
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	3,491,629	3,051,435
30-89 Days Past Due	31,286	36,702
Accruing Loans Past Due 90 Days or More	5,185	4,021
Nonaccrual	11,258	16,799
Loans and leases, net of unearned discount	3,560,849	3,127,714
Other [Member] | Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More	$ 21,491	$ 18,757