Summary of Subsequent Defaults (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Financing Receivable, Modifications [Line Items]
Number of contracts	2,346	[1]	2,225	[1]	2,316	[1]
Recorded Investment in Loans Modified in a TDR During the Period	$ 87	[1]	$ 85	[1]	$ 86	[1]
Commercial Portfolio Segment | Commercial and Industrial Loans
Financing Receivable, Modifications [Line Items]
Number of contracts	11	[1]	6	[1]	2	[1]
Recorded Investment in Loans Modified in a TDR During the Period	36	[1]	11	[1]	3	[1]
Commercial Portfolio Segment | Commercial Mortgage Loans Owner Occupied [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	3	[1]	7	[1]	3	[1]
Recorded Investment in Loans Modified in a TDR During the Period	4	[1]	1	[1]	2	[1]
Commercial Portfolio Segment | Commercial Mortgage Loans Non Owner Occupied [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	2	[1]			2	[1]
Recorded Investment in Loans Modified in a TDR During the Period	1	[1]			1	[1]
Commercial Portfolio Segment | Commercial Construction
Financing Receivable, Modifications [Line Items]
Number of contracts					2	[1]
Recorded Investment in Loans Modified in a TDR During the Period					3	[1]
Residential Mortgage Loans
Financing Receivable, Modifications [Line Items]
Number of contracts	235	[1]	375	[1]	332	[1]
Recorded Investment in Loans Modified in a TDR During the Period	32	[1]	58	[1]	57	[1]
Consumer Portfolio Segment | Home Equity
Financing Receivable, Modifications [Line Items]
Number of contracts	30	[1]	65	[1]	101	[1]
Recorded Investment in Loans Modified in a TDR During the Period	2	[1]	4	[1]	7	[1]
Consumer Portfolio Segment | Automobile Loans
Financing Receivable, Modifications [Line Items]
Number of contracts	6	[1]	4	[1]	42	[1]
Consumer Portfolio Segment | Credit Card
Financing Receivable, Modifications [Line Items]
Number of contracts	2,059	[1]	1,768	[1]	1,832	[1]
Recorded Investment in Loans Modified in a TDR During the Period	$ 12	[1]	$ 11	[1]	$ 13	[1]

[1] Excludes all loans and leases held for sale and loans acquired with deteriorated credit quality.