Loans And The Allowance For Credit Losses (Loans By Class Modified In TDR) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2012	Jun. 30, 2012
Financing Receivable, Modifications [Line Items]
Number of Obligors	1,305	2,734
Recorded Investment	$ 718	$ 1,574
Increase in Allowance at Modification	17	34
Commercial And Industrial [Member]
Financing Receivable, Modifications [Line Items]
Number of Obligors	160	359
Recorded Investment	185	336
Increase in Allowance at Modification	1	2
Commercial Real Estate Mortgage - Owner Occupied [Member]
Financing Receivable, Modifications [Line Items]
Number of Obligors	91	236
Recorded Investment	94	210
Increase in Allowance at Modification	1	2
Commercial Real Estate Construction - Owner Occupied [Member]
Financing Receivable, Modifications [Line Items]
Number of Obligors	1	7
Recorded Investment	2	6
Total Commercial [Member]
Financing Receivable, Modifications [Line Items]
Number of Obligors	252	602
Recorded Investment	281	552
Increase in Allowance at Modification	2	4
Commercial Investor Real Estate Mortgage [Member]
Financing Receivable, Modifications [Line Items]
Number of Obligors	160	347
Recorded Investment	287	737
Increase in Allowance at Modification	2	6
Commercial Investor Real Estate Construction [Member]
Financing Receivable, Modifications [Line Items]
Number of Obligors	59	129
Recorded Investment	34	76
Increase in Allowance at Modification		1
Total Investor Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Obligors	219	476
Recorded Investment	321	813
Increase in Allowance at Modification	2	7
Residential First Mortgage [Member]
Financing Receivable, Modifications [Line Items]
Number of Obligors	416	768
Recorded Investment	92	159
Increase in Allowance at Modification	12	20
Home Equity [Member]
Financing Receivable, Modifications [Line Items]
Number of Obligors	277	586
Recorded Investment	21	44
Increase in Allowance at Modification	1	3
Indirect And Other Consumer [Member]
Financing Receivable, Modifications [Line Items]
Number of Obligors	141	302
Recorded Investment	3	6
Total Consumer [Member]
Financing Receivable, Modifications [Line Items]
Number of Obligors	834	1,656
Recorded Investment	116	209
Increase in Allowance at Modification	$ 13	$ 23

Loans And The Allowance For Credit Losses (Loans By Class Modified In TDR) (Detail) (USD $)
In Millions, unless otherwise specified

3 Months Ended

6 Months Ended

Jun. 30, 2012

Financing Receivable, Modifications [Line Items]

Number of Obligors

1,305

2,734

Recorded Investment

$ 718

$ 1,574

Increase in Allowance at Modification