Summary of Loans Modified in a TDR (Detail) $ in Millions		3 Months Ended				6 Months Ended
		Jun. 30, 2015 USD ($)		Jun. 30, 2014 USD ($)	[7]	Jun. 30, 2015 USD ($)		Jun. 30, 2014 USD ($)
Financing Receivable, Modifications [Line Items]
Number of Loans Modified in a TDR During the Period						7,676	[1],[2]	4,698	[3],[4]
Recorded Investment in Loans Modified in a TDR During the Period						$ 232	[1]	$ 292	[4]
Increase (Decrease) to ALLL Upon Modification						8	[1]	$ 9	[4]
Charge-offs Recognized Upon Modification	[1]					$ 6
Quarterly
Financing Receivable, Modifications [Line Items]
Number of Loans Modified in a TDR During the Period		3,468	[5],[6]	2,241	[8]
Recorded Investment in Loans Modified in a TDR During the Period		$ 136	[5]	$ 195
Increase (Decrease) to ALLL Upon Modification		11	[5]	$ 10
Charge-offs Recognized Upon Modification	[5]	$ 3
Commercial Portfolio Segment | Commercial and Industrial Loans
Financing Receivable, Modifications [Line Items]
Number of Loans Modified in a TDR During the Period						48	[1],[2]	66	[3],[4]
Recorded Investment in Loans Modified in a TDR During the Period						$ 88	[1]	$ 119	[4]
Increase (Decrease) to ALLL Upon Modification	[4]							$ 2
Charge-offs Recognized Upon Modification	[1]					$ 3
Commercial Portfolio Segment | Commercial and Industrial Loans | Quarterly
Financing Receivable, Modifications [Line Items]
Number of Loans Modified in a TDR During the Period		27	[5],[6]	44	[8]
Recorded Investment in Loans Modified in a TDR During the Period		$ 70	[5]	$ 100
Increase (Decrease) to ALLL Upon Modification		$ 7	[5]	$ 6
Commercial Portfolio Segment | Commercial Mortgage Loans, Owner-occupied
Financing Receivable, Modifications [Line Items]
Number of Loans Modified in a TDR During the Period						13	[1],[2]	20	[3],[4]
Recorded Investment in Loans Modified in a TDR During the Period						$ 15	[1]	$ 51	[4]
Increase (Decrease) to ALLL Upon Modification						$ (2)	[1]	$ (1)	[4]
Commercial Portfolio Segment | Commercial Mortgage Loans, Owner-occupied | Quarterly
Financing Receivable, Modifications [Line Items]
Number of Loans Modified in a TDR During the Period		6	[5],[6]	4	[8]
Recorded Investment in Loans Modified in a TDR During the Period		$ 7	[5]	$ 39
Increase (Decrease) to ALLL Upon Modification	[5]	$ (1)
Commercial Portfolio Segment | Commercial Mortgage Loans, Nonowner-Occupied
Financing Receivable, Modifications [Line Items]
Number of Loans Modified in a TDR During the Period						11	[1],[2]	11	[3],[4]
Recorded Investment in Loans Modified in a TDR During the Period						$ 7	[1]	$ 7	[4]
Increase (Decrease) to ALLL Upon Modification	[4]							$ (1)
Commercial Portfolio Segment | Commercial Mortgage Loans, Nonowner-Occupied | Quarterly
Financing Receivable, Modifications [Line Items]
Number of Loans Modified in a TDR During the Period		5	[5],[6]	4	[8]
Recorded Investment in Loans Modified in a TDR During the Period		$ 4	[5]	$ 1
Residential Mortgage Loans
Financing Receivable, Modifications [Line Items]
Number of Loans Modified in a TDR During the Period						554	[1],[2]	572	[3],[4]
Recorded Investment in Loans Modified in a TDR During the Period						$ 77	[1]	$ 84	[4]
Increase (Decrease) to ALLL Upon Modification						$ 4	[1]	$ 5	[4]
Residential Mortgage Loans | Quarterly
Financing Receivable, Modifications [Line Items]
Number of Loans Modified in a TDR During the Period		254	[5],[6]	262	[8]
Recorded Investment in Loans Modified in a TDR During the Period		$ 35	[5]	$ 39
Increase (Decrease) to ALLL Upon Modification		$ 3	[5]	$ 2
Consumer Portfolio Segment | Home Equity
Financing Receivable, Modifications [Line Items]
Number of Loans Modified in a TDR During the Period						143	[1],[2]	106	[3],[4]
Recorded Investment in Loans Modified in a TDR During the Period						$ 7	[1]	$ 4	[4]
Increase (Decrease) to ALLL Upon Modification	[1]					$ (1)
Consumer Portfolio Segment | Home Equity | Quarterly
Financing Receivable, Modifications [Line Items]
Number of Loans Modified in a TDR During the Period		67	[5],[6]	71	[8]
Recorded Investment in Loans Modified in a TDR During the Period		$ 3	[5]	$ 3
Increase (Decrease) to ALLL Upon Modification	[5]	$ (1)
Consumer Portfolio Segment | Automobile Loans
Financing Receivable, Modifications [Line Items]
Number of Loans Modified in a TDR During the Period						259	[1],[2]	259	[3],[4]
Recorded Investment in Loans Modified in a TDR During the Period						$ 4	[1]	$ 4	[4]
Consumer Portfolio Segment | Automobile Loans | Quarterly
Financing Receivable, Modifications [Line Items]
Number of Loans Modified in a TDR During the Period		128	[5],[6]	143	[8]
Recorded Investment in Loans Modified in a TDR During the Period		$ 2	[5]	$ 2
Consumer Portfolio Segment | Credit Card
Financing Receivable, Modifications [Line Items]
Number of Loans Modified in a TDR During the Period						6,648	[1],[2]	3,664	[3],[4]
Recorded Investment in Loans Modified in a TDR During the Period						$ 34	[1]	$ 23	[4]
Increase (Decrease) to ALLL Upon Modification						7	[1]	$ 4	[4]
Charge-offs Recognized Upon Modification	[1]					$ 3
Consumer Portfolio Segment | Credit Card | Quarterly
Financing Receivable, Modifications [Line Items]
Number of Loans Modified in a TDR During the Period		2,981	[5],[6]	1,713	[8]
Recorded Investment in Loans Modified in a TDR During the Period		$ 15	[5]	$ 11
Increase (Decrease) to ALLL Upon Modification		3	[5]	$ 2
Charge-offs Recognized Upon Modification	[5]	$ 3

[1] Excludes all loans and leases held for sale and loans acquired with deteriorated credit quality which were accounted for within a pool.

[2] Represents number of loans post-modification.

[3] Excludes all loans and leases held for sale and loans acquired with deteriorated credit quality which were accounted for within a pool.

[4] Excludes all loans and leases held for sale and loans acquired with deteriorated credit quality which were accounted for within a pool.

[5] Excludes all loans and leases held for sale and loans acquired with deteriorated credit quality which were accounted for within a pool.

[6] Represents number of loans post-modification.

[7] Excludes all loans and leases held for sale and loans acquired with deteriorated credit quality which were accounted for within a pool.

[8] Represents number of loans post-modification.