Carrying Amounts and Estimated Fair Values for Certain Financial Instruments (Detail) (USD $) In Millions	Sep. 30, 2011		Dec. 31, 2010		Sep. 30, 2010		Dec. 31, 2009
Financial assets:
Cash and due from banks	$ 2,348	[1]	$ 2,159	[1]	$ 2,215	[1]	$ 2,318
Held-to-maturity securities	337		353		354
Other short-term investments	2,028	[1]	1,515	[1]	3,271	[1]
Loans held for sale	1,593		1,892		1,879
Portfolio loans and leases:
Commercial and industrial loans	29,258		27,191		26,302
Commercial mortgage loans	10,330	[1]	10,845	[1]	10,985	[1]
Commercial construction loans	1,213		2,048		2,349
Commercial leases	3,368		3,378		3,304
Residential mortgage loans	10,249	[2]	8,956	[2]	7,975	[2]
Home equity	10,920	[1]	11,513	[1]	11,774	[1]
Automobile loans	11,593	[1]	10,983	[1]	10,738	[1]
Credit card	1,878		1,896		1,832
Other consumer loans and leases	407		681		750
Unallocated allowance for loan and lease losses	0
Financial liabilities:
Federal funds purchased	427		279		368
Carrying (Reported) Amount, Fair Value Disclosure
Financial assets:
Cash and due from banks			2,159		2,215
Other securities	842		868		894
Held-to-maturity securities			353		354
Other short-term investments			1,515		3,271
Loans held for sale	247		324		854
Portfolio loans and leases:
Commercial and industrial loans	28,245		26,068		25,080
Commercial mortgage loans	9,857		10,248		10,328
Commercial construction loans	1,134		1,890		2,131
Commercial leases	3,284		3,267		3,198
Residential mortgage loans	9,954		8,600		7,637
Home equity	10,711		11,248		11,513
Automobile loans	11,536		10,910		10,654
Credit card	1,759		1,738		1,664
Other consumer loans and leases	384		622		729
Unallocated allowance for loan and lease losses	149		150		161
Total portfolio loans and leases, net	76,715		74,441		72,773
Financial liabilities:
Deposits			81,648		81,362
Federal funds purchased			279		368
Other short-term borrowings			1,574		1,775
Long-term debt			9,921		10,953
Portion at Fair Value, Fair Value Disclosure
Financial assets:
Cash and due from banks			2,159		2,215
Other securities	842		868		894
Held-to-maturity securities			353		354
Other short-term investments			1,515		3,271
Loans held for sale	247		324		854
Portfolio loans and leases:
Commercial and industrial loans	29,538		27,322		26,481
Commercial mortgage loans	9,167		9,513		9,745
Commercial construction loans	889		1,471		1,742
Commercial leases	3,131		2,934		2,957
Residential mortgage loans	9,516	[3]	7,577	[4]	7,009
Home equity	9,765		9,366		9,450
Automobile loans	11,575		10,975		10,919
Credit card	1,831		1,786		1,721
Other consumer loans and leases	430		682		750
Unallocated allowance for loan and lease losses			0
Total portfolio loans and leases, net	75,842	[3]	71,626	[4]	70,774
Financial liabilities:
Deposits	82,196		81,860		81,648
Federal funds purchased					368
Other short-term borrowings					1,775
Long-term debt	$ 10,199				$ 11,374

[1] Includes $35, $52, and $56 of cash, $7, $7 and $7 of other short-term investments, $29, $29 and $29 of commercial mortgage loans, $228, $241 and $248 of home equity loans, $334, $648 and $771 of automobile loans, ($10), ($14) and ($15) of ALLL, $3, $7 and $7 of other assets, $5, $12 and $17 of other liabilities and $270, $692 and $834 of long-term debt from consolidated VIEs that are included in their respective captions above at September 30, 2011, December 31, 2010 and September 30, 2010, respectively. See Note 9.

[2] Includes $62, $46 and $42 of residential mortgage loans measured at fair value at September 30, 2011, December 31, 2010 and September 30, 2010, respectively.

[3] Excludes $62 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.