LHFI Considered Impaired (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2012		Sep. 30, 2012		Dec. 31, 2011
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Interest Income, Cash Basis Method	$ 6		$ 15		$ 25
Unpaid Principal Balance	3,526		3,526		4,150
Amortized Cost	3,094	[1]	3,094	[1]	3,592	[2]
Related Allowance	344		344		448
Average Amortized Cost	3,167		3,214		3,751
Interest Income Recognized	33	[3]	99	[3]	132	[4]
Impaired Financing Receivables With No Related Allowance [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	208		208		196
Amortized Cost	149	[1]	149	[1]	163	[2]
Related Allowance	0		0		0
Average Amortized Cost	213		240		212
Interest Income Recognized	2	[3]	5	[3]	5	[4]
Impaired Financing Receivables With No Related Allowance [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	102		102		93
Amortized Cost	66	[1]	66	[1]	73	[2]
Related Allowance	0		0		0
Average Amortized Cost	97		107		109
Interest Income Recognized	0	[3]	1	[3]	3	[4]
Impaired Financing Receivables With No Related Allowance [Member] | Commercial Portfolio Segment [Member] | Commercial Real Estate
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	47		47		58
Amortized Cost	28	[1]	28	[1]	50	[2]
Related Allowance	0		0		0
Average Amortized Cost	52		62		56
Interest Income Recognized	2	[3]	3	[3]	1	[4]
Impaired Financing Receivables With No Related Allowance [Member] | Commercial Portfolio Segment [Member] | Commercial Construction [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	59		59		45
Amortized Cost	55	[1]	55	[1]	40	[2]
Related Allowance	0		0		0
Average Amortized Cost	64		71		47
Interest Income Recognized	0	[3]	1	[3]	1	[4]
Impaired Financing Receivables with Related Allowance [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	80		80		319
Amortized Cost	69	[1]	69	[1]	249	[2]
Related Allowance	8		8		34
Average Amortized Cost	71		70		292
Interest Income Recognized	0	[3]	1	[3]	5	[4]
Impaired Financing Receivables with Related Allowance [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	46		46		76
Amortized Cost	44	[1]	44	[1]	67	[2]
Related Allowance	6		6		9
Average Amortized Cost	44		42		68
Interest Income Recognized	0	[3]	1	[3]	1	[4]
Impaired Financing Receivables with Related Allowance [Member] | Commercial Portfolio Segment [Member] | Commercial Real Estate
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	26		26		111
Amortized Cost	19	[1]	19	[1]	82	[2]
Related Allowance	0		0		15
Average Amortized Cost	21		22		103
Interest Income Recognized	0	[3]	0	[3]	2	[4]
Impaired Financing Receivables with Related Allowance [Member] | Commercial Portfolio Segment [Member] | Commercial Construction [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	8		8		132
Amortized Cost	6	[1]	6	[1]	100	[2]
Related Allowance	2		2		10
Average Amortized Cost	6		6		121
Interest Income Recognized	0	[3]	0	[3]	2	[4]
Impaired Financing Receivables with Related Allowance [Member] | Residential Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	3,172		3,172		3,596
Amortized Cost	2,810	[1]	2,810	[1]	3,141	[2]
Related Allowance	328		328		405
Average Amortized Cost	2,816		2,834		3,208
Interest Income Recognized	30	[3]	90	[3]	119	[4]
Impaired Financing Receivables with Related Allowance [Member] | Residential Portfolio Segment [Member] | Residential Nonguaranteed [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	2,326		2,326		2,797
Amortized Cost	2,050	[1]	2,050	[1]	2,405	[2]
Related Allowance	215		215		293
Average Amortized Cost	2,053		2,059		2,451
Interest Income Recognized	20	[3]	62	[3]	88	[4]
Impaired Financing Receivables with Related Allowance [Member] | Residential Portfolio Segment [Member] | Home Equity
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	574		574		553
Amortized Cost	534	[1]	534	[1]	515	[2]
Related Allowance	88		88		86
Average Amortized Cost	536		541		528
Interest Income Recognized	7	[3]	20	[3]	23	[4]
Impaired Financing Receivables with Related Allowance [Member] | Residential Portfolio Segment [Member] | Residential Construction
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	272		272		246
Amortized Cost	226	[1]	226	[1]	221	[2]
Related Allowance	25		25		26
Average Amortized Cost	227		234		229
Interest Income Recognized	3	[3]	8	[3]	8	[4]
Impaired Financing Receivables with Related Allowance [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	66		66		39
Amortized Cost	66	[1]	66	[1]	39	[2]
Related Allowance	8		8		9
Average Amortized Cost	67		70		39
Interest Income Recognized	1	[3]	3	[3]	3	[4]
Impaired Financing Receivables with Related Allowance [Member] | Consumer Portfolio Segment [Member] | Consumer Other Direct
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	13		13		12
Amortized Cost	13	[1]	13	[1]	12	[2]
Related Allowance	1		1		1
Average Amortized Cost	13		13		13
Interest Income Recognized	0	[3]	0	[3]	1	[4]
Impaired Financing Receivables with Related Allowance [Member] | Consumer Portfolio Segment [Member] | Consumer Indirect
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	30		30
Amortized Cost	30	[1]	30	[1]
Related Allowance	1		1
Average Amortized Cost	31		32
Interest Income Recognized	1	[3]	2	[3]
Impaired Financing Receivables with Related Allowance [Member] | Consumer Portfolio Segment [Member] | Consumer Credit Card
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	23		23		27
Amortized Cost	23	[1]	23	[1]	27	[2]
Related Allowance	6		6		8
Average Amortized Cost	23		25		26
Interest Income Recognized	$ 0	[3]	$ 1	[3]	$ 2	[4]

[1] Amortized cost reflects charge-offs that have been recognized plus other amounts that have been applied to reduce the net book balance.

[2] Amortized cost reflects charge-offs that have been recognized plus other amounts that have been applied to reduce net book balance.

[3] Of the interest income recognized for the three and nine months ended September 30, 2012, cash basis interest income was $6 million and $15 million, respectively. As of December 31, 2011 Year Ended December 31, 2011(Dollars in millions)UnpaidPrincipalBalance Amortized Cost1 RelatedAllowance AverageAmortized Cost InterestIncomeRecognized2Impaired loans with no related allowance recorded: Commercial loans: Commercial & industrial$93 $73 $— $109 $3Commercial real estate58 50 — 56 1Commercial construction45 40 — 47 1Total commercial loans196 163 — 212 5Impaired loans with an allowance recorded: Commercial loans: Commercial & industrial76 67 9 68 1Commercial real estate111 82 15 103 2Commercial construction132 100 10 121 2Total commercial loans319 249 34 292 5Residential loans: Residential mortgages - nonguaranteed2,797 2,405 293 2,451 88Home equity products553 515 86 528 23Residential construction246 221 26 229 8Total residential loans3,596 3,141 405 3,208 119Consumer loans: Other direct12 12 1 13 1Credit cards27 27 8 26 2Total consumer loans39 39 9 39 3Total impaired loans$4,150 $3,592 $448 $3,751 $132

[4] Of the interest income recognized for the year ended December 31, 2011, cash basis interest income was $25 million.