Summary of Subsequent Defaults (Detail) (Quarter to date, USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Financing Receivable, Modifications [Line Items]
Number of contracts	637	[1]	568	[1]
Recorded Investment in Loans Modified in a TDR During the Period	$ 8	[1]	$ 26	[1]
Residential Mortgage Loans
Financing Receivable, Modifications [Line Items]
Number of contracts	40	[1]	41	[1]
Recorded Investment in Loans Modified in a TDR During the Period	5	[1]	6	[1]
Commercial Portfolio Segment | Commercial and Industrial Loans
Financing Receivable, Modifications [Line Items]
Number of contracts			6	[1]
Recorded Investment in Loans Modified in a TDR During the Period			14	[1]
Commercial Portfolio Segment | Commercial Mortgage Loans, Owner-occupied
Financing Receivable, Modifications [Line Items]
Number of contracts			2	[1]
Recorded Investment in Loans Modified in a TDR During the Period			3	[1]
Consumer Portfolio Segment | Home Equity
Financing Receivable, Modifications [Line Items]
Number of contracts	5	[1]	10	[1]
Consumer Portfolio Segment | Automobile Loans
Financing Receivable, Modifications [Line Items]
Number of contracts	4	[1]	2	[1]
Consumer Portfolio Segment | Credit Card
Financing Receivable, Modifications [Line Items]
Number of contracts	588	[1]	507	[1]
Recorded Investment in Loans Modified in a TDR During the Period	$ 3	[1]	$ 3	[1]

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