Carrying Amounts and Estimated Fair Values for Certain Financial Instruments (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014		Dec. 31, 2013		Jun. 30, 2013	Dec. 31, 2012
Financial assets:
Cash and due from banks	$ 3,312	[1]	$ 3,178	[1]	$ 2,390	$ 2,441
Held-to-maturity securities, amortized cost	194	[2]	208	[2]
Other short-term investments	2,386		5,116
Loans held for sale	682	[3]	944	[3]
Portfolio loans and leases, net	89,026		87,032
Other securities, fair value	22,814	[4]	18,597	[4]
Held-to-maturity securities, fair value	194		208
Loans held for sale	598		890
Financial liabilities:
Deposits	95,952		99,275
Federal funds purchased	153		284
Other short-term borrowings	3,146		1,380
Long-term debt	13,961	[1]	9,633	[1]
Carrying (Reported) Amount, Fair Value Disclosure
Financial assets:
Cash and due from banks	3,312		3,178
Held-to-maturity securities, amortized cost	194		208
Other short-term investments	2,386		5,116
Unallocated Allowance For Loan And Lease Losses	(102)		(110)
Portfolio loans and leases at fair value	88,927		86,940
Financial liabilities:
Deposits	95,952		99,275
Federal funds purchased	153		284
Other short-term borrowings	3,146		1,380
Long-term debt	13,961		9,633
Carrying (Reported) Amount, Fair Value Disclosure | Non Fair Value Option Held For Sale Loans [Member]
Financial assets:
Loans held for sale	84		54
Carrying (Reported) Amount, Fair Value Disclosure | FHLB and FRB restricted stock holdings
Financial assets:
Other securities	599		751
Carrying (Reported) Amount, Fair Value Disclosure | Commercial And Industrial Loans [Member]
Financial assets:
Portfolio loans and leases, net	40,578		38,549
Carrying (Reported) Amount, Fair Value Disclosure | Commercial Mortgage Loans [Member]
Financial assets:
Portfolio loans and leases, net	7,629		7,854
Carrying (Reported) Amount, Fair Value Disclosure | Commercial Construction
Financial assets:
Portfolio loans and leases, net	1,406		1,013
Carrying (Reported) Amount, Fair Value Disclosure | Commercial Leases [Member]
Financial assets:
Portfolio loans and leases, net	3,521		3,572
Carrying (Reported) Amount, Fair Value Disclosure | Residential Mortgage
Financial assets:
Portfolio loans and leases, net	12,379		12,399
Carrying (Reported) Amount, Fair Value Disclosure | Home Equity
Financial assets:
Portfolio loans and leases, net	8,960		9,152
Carrying (Reported) Amount, Fair Value Disclosure | Automobile Loan
Financial assets:
Portfolio loans and leases, net	12,023		11,961
Carrying (Reported) Amount, Fair Value Disclosure | Credit Card Loan [Member]
Financial assets:
Portfolio loans and leases, net	2,177		2,202
Carrying (Reported) Amount, Fair Value Disclosure | Other Consumer Loans And Leases [Member]
Financial assets:
Portfolio loans and leases, net	356		348
Portion at Fair Value, Fair Value Disclosure
Financial assets:
Cash and due from banks, fair value	3,312		3,178
Held-to-maturity securities, fair value	194		208
Other short term investments, fair value	2,386		5,116
Portfolio loans and leases at fair value	88,853		86,562
Financial liabilities:
Deposits, fair value	95,972		99,288
Federal funds purchased, fair value	153		284
Other short-term borrowings, fair value	3,146		1,380
Long term debt, fair value	14,696		10,222
Portion at Fair Value, Fair Value Disclosure | Non Fair Value Option Held For Sale Loans [Member]
Financial assets:
Loans held for sale	84		54
Portion at Fair Value, Fair Value Disclosure | FHLB and FRB restricted stock holdings
Financial assets:
Other securities, fair value	599		751
Portion at Fair Value, Fair Value Disclosure | Commercial And Industrial Loans [Member]
Financial assets:
Portfolio loans and leases at fair value	41,505		39,804
Portion at Fair Value, Fair Value Disclosure | Commercial Mortgage Loans [Member]
Financial assets:
Portfolio loans and leases at fair value	7,266		7,430
Portion at Fair Value, Fair Value Disclosure | Commercial Construction
Financial assets:
Portfolio loans and leases at fair value	1,190		856
Portion at Fair Value, Fair Value Disclosure | Commercial Leases [Member]
Financial assets:
Portfolio loans and leases at fair value	3,262		3,261
Portion at Fair Value, Fair Value Disclosure | Residential Mortgage
Financial assets:
Portfolio loans and leases at fair value	12,001		11,541
Portion at Fair Value, Fair Value Disclosure | Home Equity
Financial assets:
Portfolio loans and leases at fair value	9,053		9,181
Portion at Fair Value, Fair Value Disclosure | Automobile Loan
Financial assets:
Portfolio loans and leases at fair value	11,779		11,748
Portion at Fair Value, Fair Value Disclosure | Credit Card Loan [Member]
Financial assets:
Portfolio loans and leases at fair value	2,431		2,380
Portion at Fair Value, Fair Value Disclosure | Other Consumer Loans And Leases [Member]
Financial assets:
Portfolio loans and leases at fair value	366		361
Portion at Fair Value, Fair Value Disclosure | Fair Value, Inputs, Level 1
Financial assets:
Cash and due from banks, fair value	3,312		3,178
Other short term investments, fair value	2,386		5,116
Financial liabilities:
Federal funds purchased, fair value	153		284
Long term debt, fair value	14,077		9,645
Portion at Fair Value, Fair Value Disclosure | Fair Value, Inputs, Level 2
Financial liabilities:
Deposits, fair value	95,972		99,288
Other short-term borrowings, fair value	3,146		1,380
Long term debt, fair value	619		577
Portion at Fair Value, Fair Value Disclosure | Fair Value, Inputs, Level 2 | FHLB and FRB restricted stock holdings
Financial assets:
Other securities, fair value	599		751
Portion at Fair Value, Fair Value Disclosure | Fair Value, Inputs, Level 3
Financial assets:
Held-to-maturity securities, fair value	194		208
Portfolio loans and leases at fair value	88,853		86,562
Portion at Fair Value, Fair Value Disclosure | Fair Value, Inputs, Level 3 | Non Fair Value Option Held For Sale Loans [Member]
Financial assets:
Loans held for sale	84		54
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	41,505		39,804
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	7,266		7,430
Portion at Fair Value, Fair Value Disclosure | Fair Value, Inputs, Level 3 | Commercial Construction
Financial assets:
Portfolio loans and leases at fair value	1,190		856
Portion at Fair Value, Fair Value Disclosure | Fair Value, Inputs, Level 3 | Commercial Leases [Member]
Financial assets:
Portfolio loans and leases at fair value	3,262		3,261
Portion at Fair Value, Fair Value Disclosure | Fair Value, Inputs, Level 3 | Residential Mortgage
Financial assets:
Portfolio loans and leases at fair value	12,001		11,541
Portion at Fair Value, Fair Value Disclosure | Fair Value, Inputs, Level 3 | Home Equity
Financial assets:
Portfolio loans and leases at fair value	9,053		9,181
Portion at Fair Value, Fair Value Disclosure | Fair Value, Inputs, Level 3 | Automobile Loan
Financial assets:
Portfolio loans and leases at fair value	11,779		11,748
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	2,431		2,380
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	$ 366		$ 361

[1] Includes $158 and $49 of cash and due from banks, $48 and $48 of commercial mortgage loans, $3,200 and $1,010 of automobile loans, $(20) and $(15) of ALLL, $32 and $13 of other assets, $6 and $1 of other liabilities, and $3,333 and $1,048 of long-term debt from consolidated VIEs that are included in their respective captions above at June 30, 2014 and December 31, 2013, respectively. See Note 9.

[2] Fair value of $194 and $208 at June 30, 2014 and December 31, 2013, respectively.

[3] Includes $598 and $890 of residential mortgage loans held for sale measured at fair value at June 30, 2014 and December 31, 2013, respectively.

[4] Amortized cost of $22,184 and $18,409 at June 30, 2014 and December 31, 2013, respectively.