Carrying Amounts and Estimated Fair Values for Certain Financial Instruments (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009	Dec. 31, 2008
Financial assets:
Cash and due from banks	$ 2,663	[1]	$ 2,159	[1]	$ 2,318	$ 2,739
Held-to-maturity securities	322		353
Other short-term investments	1,781		1,515
Loans held for sale	2,751		1,892
Portfolio loans and leases:
Commercial and industrial loans	30,783		27,191
Commercial mortgage loans	10,138	[1]	10,845	[1]
Commercial construction loans	1,020		2,048
Commercial leases	3,531		3,378
Residential mortgage loans	10,672	[2]	8,956	[2]
Home equity	10,719	[1]	11,513	[1]
Automobile loans	11,827	[1]	10,983	[1]
Credit card	1,978		1,896
Other consumer loans and leases	350		681
Financial liabilities:
Federal funds purchased	346		279
Carrying (Reported) Amount, Fair Value Disclosure
Financial assets:
Cash and due from banks	2,663		2,159
Other securities	842		868
Held-to-maturity securities	322		353
Other short-term investments	1,781		1,515
Loans held for sale	203		324
Portfolio loans and leases:
Commercial and industrial loans	29,854		26,068
Commercial mortgage loans	9,697		10,248
Commercial construction loans	943		1,890
Commercial leases	3,451		3,267
Residential mortgage loans	10,380	[3]	8,600	[4]
Home equity	10,524		11,248
Automobile loans	11,784		10,910
Credit card	1,872		1,738
Other consumer loans and leases	329		622
Unallocated allowance for loan and lease losses	(136)		(150)
Total portfolio loans and leases, net	78,698	[3]	74,441	[4]
Financial liabilities:
Deposits	85,710		81,648
Federal funds purchased	346		279
Other short-term borrowings	3,239		1,574
Long-term debt	9,682		9,558
Portion at Fair Value, Fair Value Disclosure
Financial assets:
Cash and due from banks	2,663		2,159
Other securities	842		868
Held-to-maturity securities	322		353
Other short-term investments	1,781		1,515
Loans held for sale	203		324
Portfolio loans and leases:
Commercial and industrial loans	30,300		27,322
Commercial mortgage loans	8,870		9,513
Commercial construction loans	791		1,471
Commercial leases	3,237		2,934
Residential mortgage loans	9,978	[3]	7,577	[4]
Home equity	9,737		9,366
Automobile loans	11,747		10,975
Credit card	1,958		1,786
Other consumer loans and leases	346		682
Total portfolio loans and leases, net	76,964	[3]	71,626	[4]
Financial liabilities:
Deposits	85,599		81,860
Federal funds purchased	346		279
Other short-term borrowings	3,239		1,574
Long-term debt	$ 10,197		$ 9,921

[1] At December 31, 2011 and 2010, includes $30 and $52 of cash, $7 of other short-term investments, $50 and $29 of commercial mortgage loans, $223 and $241 of home equity loans, $259 and $648 of automobile loans, ($10) and ($14) of ALLL, $4 and $7 of other assets, $4 and $12 of other liabilities, $191 and $692 of long-term debt from consolidated VIEs that are included in their respective captions. See Note 11.

[2] Includes $65 and $46 of residential mortgage loans measured at fair value at December 31, 2011 and 2010, respectively.

[3] Excludes $65 of residential mortgage loans measured at fair value on a recurring basis.

[4] Excludes $46 of residential mortgage loans measured at fair value on a recurring basis.