Loans and Leases and the Allowance for Credit Losses - Summary of Current, Past Due and Nonaccrual Loans (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	$ 61,901,851	$ 61,664,881
30-89 Days Past Due	610,933	704,658
Purchased Impaired	303,388	330,792
Nonaccrual	890,893	874,156
Total	64,135,078	64,073,159
Commercial, Financial, Leasing, etc. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	18,686,680	18,489,474
30-89 Days Past Due	43,019	77,538
Purchased Impaired	15,560	15,706
Nonaccrual	138,271	110,739
Total	18,896,070	18,705,216
Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	21,309,518	21,236,071
30-89 Days Past Due	158,281	145,749
Purchased Impaired	91,312	88,034
Nonaccrual	175,984	173,048
Total	21,776,525	21,741,858
Residential Builder and Developer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	1,073,532	1,025,984
30-89 Days Past Due	3,613	8,486
Purchased Impaired	122,757	137,544
Nonaccrual	89,563	96,427
Total	1,298,277	1,276,512
Other commercial construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	2,915,804	2,986,598
30-89 Days Past Due	41,861	42,234
Purchased Impaired	44,175	57,707
Nonaccrual	25,063	35,268
Total	3,029,284	3,129,838
Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	7,530,046	7,630,368
30-89 Days Past Due	254,376	295,131
Purchased Impaired	26,986	29,184
Nonaccrual	259,678	252,805
Total	8,402,297	8,545,837
Residential Alt-A [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	272,463	283,253
30-89 Days Past Due	20,815	18,009
Purchased Impaired
Nonaccrual	78,520	81,122
Total	371,798	382,384
Home equity lines and loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	5,914,788	5,972,365
30-89 Days Past Due	36,440	40,537
Purchased Impaired	2,598	2,617
Nonaccrual	82,555	78,516
Total	6,062,420	6,121,789
Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	1,454,199	1,314,246
30-89 Days Past Due	20,441	29,144
Purchased Impaired
Nonaccrual	16,351	21,144
Total	1,491,167	1,364,900
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	2,744,821	2,726,522
30-89 Days Past Due	32,087	47,830
Purchased Impaired
Nonaccrual	24,908	25,087
Total	2,807,240	2,804,825
Non-Acquired [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
90 Days Or More Past Due And Accruing - Non-Acquired	307,017	368,510
Non-Acquired [Member] | Commercial, Financial, Leasing, etc. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
90 Days Or More Past Due And Accruing - Non-Acquired	8,245	4,981
Non-Acquired [Member] | Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
90 Days Or More Past Due And Accruing - Non-Acquired	7,870	63,353
Non-Acquired [Member] | Residential Builder and Developer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
90 Days Or More Past Due And Accruing - Non-Acquired		141
Non-Acquired [Member] | Other commercial construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
90 Days Or More Past Due And Accruing - Non-Acquired
Non-Acquired [Member] | Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
90 Days Or More Past Due And Accruing - Non-Acquired	285,478	294,649
Non-Acquired [Member] | Residential Alt-A [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
90 Days Or More Past Due And Accruing - Non-Acquired
Non-Acquired [Member] | Home equity lines and loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
90 Days Or More Past Due And Accruing - Non-Acquired
Non-Acquired [Member] | Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
90 Days Or More Past Due And Accruing - Non-Acquired
Non-Acquired [Member] | Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
90 Days Or More Past Due And Accruing - Non-Acquired	5,424	5,386
Acquired [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
90 Days Or More Past Due And Accruing - Non-Acquired	120,996	130,162
Acquired [Member] | Commercial, Financial, Leasing, etc. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
90 Days Or More Past Due And Accruing - Non-Acquired	4,295	6,778
Acquired [Member] | Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
90 Days Or More Past Due And Accruing - Non-Acquired	33,560	35,603
Acquired [Member] | Residential Builder and Developer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
90 Days Or More Past Due And Accruing - Non-Acquired	8,812	7,930
Acquired [Member] | Other commercial construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
90 Days Or More Past Due And Accruing - Non-Acquired	2,381	8,031
Acquired [Member] | Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
90 Days Or More Past Due And Accruing - Non-Acquired	45,733	43,700
Acquired [Member] | Residential Alt-A [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
90 Days Or More Past Due And Accruing - Non-Acquired
Acquired [Member] | Home equity lines and loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
90 Days Or More Past Due And Accruing - Non-Acquired	26,039	27,754
Acquired [Member] | Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
90 Days Or More Past Due And Accruing - Non-Acquired	176	366
Acquired [Member] | Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
90 Days Or More Past Due And Accruing - Non-Acquired