Carrying Amounts and Estimated Fair Values for Certain Financial Instruments (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2010
Financial assets:
Cash and due from banks	$ 3,178	[1]	$ 2,441	[1]	$ 2,663	$ 2,159
Held-to-maturity securities	208	[2]	284	[2]
Other short-term investments	5,116		2,421
Loans held for sale	944	[3]	2,939	[3]
Portfolio loans and leases, net	87,032		83,928
Other securities, fair value	18,597	[4]	15,207	[4]
Held-to-maturity securities, fair value	208		284
Loans held for sale	890		2,856
Financial liabilities:
Deposits	99,275		89,517
Federal funds purchased	284		901
Other short-term borrowings	1,380		6,280
Long-term debt	9,633	[1]	7,085	[1]
Carrying (Reported) Amount, Fair Value Disclosure
Financial assets:
Cash and due from banks	3,178		2,441
Other securities	751		844
Held-to-maturity securities	208		284
Other short-term investments	5,116		2,421
Loans held for sale	54		83
Portfolio loans and leases, net	86,940	[5]	83,852	[6]
Unallocated Allowance for Loan and Lease Losses	(110)		(111)
Financial liabilities:
Deposits	99,275		89,517
Federal funds purchased	284		901
Other short-term borrowings	1,380		6,280
Long-term debt	9,633		7,085
Carrying (Reported) Amount, Fair Value Disclosure | Commercial And Industrial Loans [Member]
Financial assets:
Portfolio loans and leases, net	38,549		35,236
Carrying (Reported) Amount, Fair Value Disclosure | Commercial Mortgage Loans [Member]
Financial assets:
Portfolio loans and leases, net	7,854		8,770
Carrying (Reported) Amount, Fair Value Disclosure | Commercial Construction
Financial assets:
Portfolio loans and leases, net	1,013		665
Carrying (Reported) Amount, Fair Value Disclosure | Commercial Leases [Member]
Financial assets:
Portfolio loans and leases, net	3,572		3,481
Carrying (Reported) Amount, Fair Value Disclosure | Residential Mortgage [Member]
Financial assets:
Portfolio loans and leases, net	12,399	[5]	11,712	[6]
Carrying (Reported) Amount, Fair Value Disclosure | Home Equity
Financial assets:
Portfolio loans and leases, net	9,152		9,875
Carrying (Reported) Amount, Fair Value Disclosure | Automobile Loan
Financial assets:
Portfolio loans and leases, net	11,961		11,944
Carrying (Reported) Amount, Fair Value Disclosure | Credit Card Loan [Member]
Financial assets:
Portfolio loans and leases, net	2,202		2,010
Carrying (Reported) Amount, Fair Value Disclosure | Other Consumer Loans And Leases [Member]
Financial assets:
Portfolio loans and leases, net	348		270
Portion at Fair Value, Fair Value Disclosure
Financial assets:
Cash and due from banks, fair value	3,178		2,441
Other securities, fair value	751		844
Held-to-maturity securities, fair value	208		284
Other Short Term Investments Fair Value Disclosure	5,116		2,421
Loans held for sale	54		83
Portfolio loans and leases at fair value	86,562	[5]	84,164	[6]
Financial liabilities:
Deposits, fair value	99,288		85,592
Federal funds purchased, fair value	284		901
Other short-term borrowings, fair value	1,380		6,280
Long term debt, fair value	10,222		7,809
Portion at Fair Value, Fair Value Disclosure | Commercial And Industrial Loans [Member]
Financial assets:
Portfolio loans and leases at fair value	39,804		36,496
Portion at Fair Value, Fair Value Disclosure | Commercial Mortgage Loans [Member]
Financial assets:
Portfolio loans and leases at fair value	7,430		8,020
Portion at Fair Value, Fair Value Disclosure | Commercial Construction
Financial assets:
Portfolio loans and leases at fair value	856		505
Portion at Fair Value, Fair Value Disclosure | Commercial Leases [Member]
Financial assets:
Portfolio loans and leases at fair value	3,261		3,310
Portion at Fair Value, Fair Value Disclosure | Residential Mortgage [Member]
Financial assets:
Portfolio loans and leases at fair value	11,541	[5]	11,532	[6]
Portion at Fair Value, Fair Value Disclosure | Home Equity
Financial assets:
Portfolio loans and leases at fair value	9,181		9,798
Portion at Fair Value, Fair Value Disclosure | Automobile Loan
Financial assets:
Portfolio loans and leases at fair value	11,748		12,076
Portion at Fair Value, Fair Value Disclosure | Credit Card Loan [Member]
Financial assets:
Portfolio loans and leases at fair value	2,380		2,139
Portion at Fair Value, Fair Value Disclosure | Other Consumer Loans And Leases [Member]
Financial assets:
Portfolio loans and leases at fair value	361		288
Portion at Fair Value, Fair Value Disclosure | Fair Value, Inputs, Level 1
Financial assets:
Cash and due from banks, fair value	3,178		2,441
Other Short Term Investments Fair Value Disclosure	5,116		2,421
Financial liabilities:
Federal funds purchased, fair value	284		901
Long term debt, fair value	9,645		6,925
Portion at Fair Value, Fair Value Disclosure | Fair Value, Inputs, Level 2
Financial assets:
Other securities, fair value	751		844
Financial liabilities:
Deposits, fair value	99,288		85,592
Other short-term borrowings, fair value	1,380		6,280
Long term debt, fair value	577		884
Portion at Fair Value, Fair Value Disclosure | Fair Value, Inputs, Level 3
Financial assets:
Held-to-maturity securities, fair value	208		284
Loans held for sale	54		83
Portfolio loans and leases at fair value	86,562	[5]	84,164	[6]
Portion at Fair Value, Fair Value Disclosure | Fair Value, Inputs, Level 3 | Commercial And Industrial Loans [Member]
Financial assets:
Portfolio loans and leases at fair value	39,804		36,496
Portion at Fair Value, Fair Value Disclosure | Fair Value, Inputs, Level 3 | Commercial Mortgage Loans [Member]
Financial assets:
Portfolio loans and leases at fair value	7,430		8,020
Portion at Fair Value, Fair Value Disclosure | Fair Value, Inputs, Level 3 | Commercial Construction
Financial assets:
Portfolio loans and leases at fair value	856		505
Portion at Fair Value, Fair Value Disclosure | Fair Value, Inputs, Level 3 | Commercial Leases [Member]
Financial assets:
Portfolio loans and leases at fair value	3,261		3,310
Portion at Fair Value, Fair Value Disclosure | Fair Value, Inputs, Level 3 | Residential Mortgage [Member]
Financial assets:
Portfolio loans and leases at fair value	11,541	[5]	11,532	[6]
Portion at Fair Value, Fair Value Disclosure | Fair Value, Inputs, Level 3 | Home Equity
Financial assets:
Portfolio loans and leases at fair value	9,181		9,798
Portion at Fair Value, Fair Value Disclosure | Fair Value, Inputs, Level 3 | Automobile Loan
Financial assets:
Portfolio loans and leases at fair value	11,748		12,076
Portion at Fair Value, Fair Value Disclosure | Fair Value, Inputs, Level 3 | Credit Card Loan [Member]
Financial assets:
Portfolio loans and leases at fair value	2,380		2,139
Portion at Fair Value, Fair Value Disclosure | Fair Value, Inputs, Level 3 | Other Consumer Loans And Leases [Member]
Financial assets:
Portfolio loans and leases at fair value	$ 361		$ 288

[1] At December 31, 2013 and 2012, includes $49 and $0 of cash and due from banks, $48 and $50 of commercial mortgage loans, $ 1,010 and $0 of automobile loans, $(15) and $(5) of ALLL, $13 and $3 of other assets, $1 and $0 of other liabilities, $ 1,048 and $0 of long-term debt from consolidated VIEs that are included in their respective captions. See Note 10.

[2] Fair value of $208 and $284 at December 31, 2013 and 2012, respectively.

[3] Includes $890 and $2,856 of residential mortgage loans held for sale measured at fair value at December 31, 2013, and 2012, respectively.

[4] Amortized cost of $18,409 and $ 14,571 at December 31, 2013 and 2012, respectively.

[5] Excludes $92 of residential mortgage loans measured at fair value on a recurring basis.

[6] Excludes $76 of residential mortgage loans measured at fair value on a recurring basis.