Loans and Leases and the Allowance for Credit Losses - Changes in Allowance for Credit Losses (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	$ 917,666	$ 927,065	$ 916,676	$ 925,860
Provision for credit losses	29,000	48,000	91,000	143,000
Allowance related to loans securitized and sold		(11,000)		(11,000)
Net charge-offs
Charge-offs	(43,092)	(64,194)	(132,369)	(189,768)
Recoveries	15,059	16,499	43,326	48,278
Net charge-offs	(28,033)	(47,695)	(89,043)	(141,490)
Ending balance	918,633	916,370	918,633	916,370
Net charge-offs	(28,033)	(47,695)	(89,043)	(141,490)
Ending balance	918,633	916,370	918,633	916,370
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	292,251	268,867	273,383	246,759
Provision for credit losses	2,373	20,209	40,527	93,736
Allowance related to loans securitized and sold
Net charge-offs
Charge-offs	(15,921)	(30,931)	(44,872)	(86,787)
Recoveries	7,849	5,150	17,514	9,587
Net charge-offs	(8,072)	(25,781)	(27,358)	(77,200)
Ending balance	286,552	263,295	286,552	263,295
Net charge-offs	(8,072)	(25,781)	(27,358)	(77,200)
Ending balance	286,552	263,295	286,552	263,295
Real Estate Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	311,254	324,264	324,978	337,101
Provision for credit losses	8,046	12,139	(4,067)	914
Allowance related to loans securitized and sold
Net charge-offs
Charge-offs	(1,666)	(7,701)	(7,966)	(21,493)
Recoveries	1,267	4,751	5,956	16,931
Net charge-offs	(399)	(2,950)	(2,010)	(4,562)
Ending balance	318,901	333,453	318,901	333,453
Net charge-offs	(399)	(2,950)	(2,010)	(4,562)
Ending balance	318,901	333,453	318,901	333,453
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	72,404	85,311	78,656	88,807
Provision for credit losses	(3,187)	315	(916)	3,913
Allowance related to loans securitized and sold
Net charge-offs
Charge-offs	(4,193)	(5,320)	(17,124)	(18,583)
Recoveries	2,498	2,399	6,906	8,568
Net charge-offs	(1,695)	(2,921)	(10,218)	(10,015)
Ending balance	67,522	82,705	67,522	82,705
Net charge-offs	(1,695)	(2,921)	(10,218)	(10,015)
Ending balance	67,522	82,705	67,522	82,705
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	165,871	174,291	164,644	179,418
Provision for credit losses	21,815	14,935	54,632	43,478
Allowance related to loans securitized and sold		(11,000)		(11,000)
Net charge-offs
Charge-offs	(21,312)	(20,242)	(62,407)	(62,905)
Recoveries	3,445	4,199	12,950	13,192
Net charge-offs	(17,867)	(16,043)	(49,457)	(49,713)
Ending balance	169,819	162,183	169,819	162,183
Net charge-offs	(17,867)	(16,043)	(49,457)	(49,713)
Ending balance	169,819	162,183	169,819	162,183
Unallocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	75,886	74,332	75,015	73,775
Provision for credit losses	(47)	402	824	959
Allowance related to loans securitized and sold
Net charge-offs
Charge-offs
Recoveries
Net charge-offs
Ending balance	75,839	74,734	75,839	74,734
Net charge-offs
Ending balance	$ 75,839	$ 74,734	$ 75,839	$ 74,734