Summary of Loans Modified in a TDR (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 number		Dec. 31, 2011 number
Financing Receivable, Modifications [Line Items]
Number of Loans Modified in a TDR During the Period	16,064	[1],[2]	16,912	[1],[2]
Recorded Investment in Loans Modified in a TDR During the Period	$ 793	[2]	$ 810	[2]
Increase (Decrease) to ALLL Upon Modification	24	[2]	9	[2]
Charge-offs Recognized Upon Modification	11	[2]	9	[2]
Commercial Portfolio Segment | CommercialAndIndustrialLoansMember [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans Modified in a TDR During the Period	108	[1],[2]	52	[1],[2]
Recorded Investment in Loans Modified in a TDR During the Period	84	[2]	83	[2]
Increase (Decrease) to ALLL Upon Modification	(7)	[2]	(4)	[2]
Charge-offs Recognized Upon Modification	9	[2]	3	[2]
Commercial Portfolio Segment | Commercial Mortgage Loans Owner Occupied [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans Modified in a TDR During the Period	67	[1],[2]	32	[1],[2]
Recorded Investment in Loans Modified in a TDR During the Period	53	[2]	55	[2]
Increase (Decrease) to ALLL Upon Modification	(8)	[2]	(6)	[2]
Charge-offs Recognized Upon Modification	2	[2]	2	[2]
Commercial Portfolio Segment | Commercial Mortgage Loans Non Owner Occupied [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans Modified in a TDR During the Period	67	[1],[2]	39	[1],[2]
Recorded Investment in Loans Modified in a TDR During the Period	91	[2]	90	[2]
Increase (Decrease) to ALLL Upon Modification	(7)	[2]	(21)	[2]
Charge-offs Recognized Upon Modification			3	[2]
Commercial Portfolio Segment | Commercial Construction
Financing Receivable, Modifications [Line Items]
Number of Loans Modified in a TDR During the Period	17	[1],[2]	26	[1],[2]
Recorded Investment in Loans Modified in a TDR During the Period	38	[2]	59	[2]
Increase (Decrease) to ALLL Upon Modification	(4)	[2]	(9)	[2]
Charge-offs Recognized Upon Modification			1	[2]
Commercial Portfolio Segment | Commercial Leases [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans Modified in a TDR During the Period	8	[1],[2]	2	[1],[2]
Recorded Investment in Loans Modified in a TDR During the Period	7	[2]
Increase (Decrease) to ALLL Upon Modification	1	[2]
Residential Mortgage Loans
Financing Receivable, Modifications [Line Items]
Number of Loans Modified in a TDR During the Period	1,758	[1],[2]	1,728	[1],[2]
Recorded Investment in Loans Modified in a TDR During the Period	340	[2]	338	[2]
Increase (Decrease) to ALLL Upon Modification	35	[2]	34	[2]
Consumer Portfolio Segment | Home Equity
Financing Receivable, Modifications [Line Items]
Number of Loans Modified in a TDR During the Period	1,343	[1],[2]	1,317	[1],[2]
Recorded Investment in Loans Modified in a TDR During the Period	82	[2]	80	[2]
Increase (Decrease) to ALLL Upon Modification	1	[2]	1	[2]
Consumer Portfolio Segment | Automobile Loans
Financing Receivable, Modifications [Line Items]
Number of Loans Modified in a TDR During the Period	1,289	[1],[2]	1,482	[1],[2]
Recorded Investment in Loans Modified in a TDR During the Period	23	[2]	26	[2]
Increase (Decrease) to ALLL Upon Modification	2	[2]	3	[2]
Consumer Portfolio Segment | Credit Card
Financing Receivable, Modifications [Line Items]
Number of Loans Modified in a TDR During the Period	11,407	[1],[2]	12,234	[1],[2]
Recorded Investment in Loans Modified in a TDR During the Period	75	[2]	79	[2]
Increase (Decrease) to ALLL Upon Modification	$ 11	[2]	$ 11	[2]

[1] Represents number of loans post-modification.

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