Summary of Average Impaired Loans and Leases and Interest Income by Class (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Average Recorded Investment	$ 2,968	$ 3,200	$ 2,900
Interest Income Recognized	83	74	54
Commercial Portfolio Segment | Commercial And Industrial Loans [Member]
Average Recorded Investment	532
Interest Income Recognized	5
Commercial Portfolio Segment | Commercial Mortgage Loans Owner Occupied [Member]
Average Recorded Investment	117
Interest Income Recognized	2
Commercial Portfolio Segment | Commercial Mortgage Loans Non Owner Occupied [Member]
Average Recorded Investment	288
Interest Income Recognized	5
Commercial Portfolio Segment | Commercial Construction
Average Recorded Investment	198
Interest Income Recognized	3
Commercial Portfolio Segment | Commercial Leases [Member]
Average Recorded Investment	16
Residential Mortgage Loans
Average Recorded Investment	1,217
Interest Income Recognized	41
Consumer Portfolio Segment | Home Equity
Average Recorded Investment	444
Interest Income Recognized	23
Consumer Portfolio Segment | Automobile Loan
Average Recorded Investment	41
Interest Income Recognized	1
Consumer Portfolio Segment | Credit Card
Average Recorded Investment	94
Interest Income Recognized	3
Consumer Portfolio Segment | Consumer Other Financing Receivable
Average Recorded Investment	$ 21