Business Segments - Summary on Reconciliation of Results Under Ifrs to Us Gaap (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012		Dec. 31, 2012
Operating Statistics [Line Items]
US GAAP Based, Net interest income	$ 492	[1]	$ 510	[1]	$ 1,515	[1]	$ 1,632	[1]
US GAAP Based, Other operating income	432		407		1,590		1,670
US GAAP Based, Total operating income	924		917		3,105		3,302
US GAAP Based, Loan impairment charges	54	[2]	84	[2]	142	[2]	173	[2]
US GAAP Based, Operating income, net	870		833		2,963		3,129
US GAAP Based, Operating expenses	855	[3]	1,627	[3]	2,432	[3]	4,067	[3]
Income (loss) from continuing operations before income tax expense	15		(794)		531		(938)
Total assets	187,375	[4]	198,583		187,375	[4]	198,583		191,446	[4]
US GAAP Based, Total loans, net	67,115		60,815		67,115		60,815		62,611
US GAAP Based, Goodwill	2,228		2,228		2,228		2,228		2,228
US GAAP Based, Total deposits	112,921		121,335		112,921		121,335		117,671
Adjustments Or Reconciling Items [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	(2)	[1]	(3)	[1]	(9)	[1]	(10)	[1]
IFRS Based, Other operating income	2		3		9		10
IFRS Based, Total operating income	0		0		0		0
IFRS Loan Impairment charges	0	[2]	0	[2]	0	[2]	0	[2]
IFRS Based, Operating income, net	0		0		0		0
IFRS Based Operating expenses	0	[3]	0	[3]	0	[3]	0	[3]
IFRS Based, Profit before income tax expense	0		0		0		0
IFRS Based, Total assets			0				0
IFRS Based, Total loans, net	0		0		0		0
IFRS Based, Goodwill	0		0		0		0
IFRS Based, Total deposits	0		0		0		0
IFRS Based, Assets	0				0
Aggregate [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	502	[1]	539	[1]	1,558	[1]	1,690	[1]
IFRS Based, Other operating income	438		390		1,546		1,569
IFRS Based, Total operating income	940		929		3,104		3,259
IFRS Loan Impairment charges	70	[2]	86	[2]	148	[2]	166	[2]
IFRS Based, Operating income, net	870		843		2,956		3,093
IFRS Based Operating expenses	839	[3]	1,672	[3]	2,456	[3]	4,047	[3]
IFRS Based, Profit before income tax expense	31		(829)		500		(954)
IFRS Based, Total assets			272,108				272,108
IFRS Based, Total loans, net	65,242		73,249		65,242		73,249
IFRS Based, Goodwill	1,744		1,744		1,744		1,744
IFRS Based, Total deposits	110,912		114,494		110,912		114,494
IFRS Based, Assets	240,842				240,842
IFRS Adjustments [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	(17)	[1],[5]	(22)	[1],[5]	(55)	[1],[5]	(73)	[1],[5]
IFRS Based, Other operating income	(1)	[5]	5	[5]	53	[5]	41	[5]
IFRS Based, Total operating income	(18)	[5]	(17)	[5]	(2)	[5]	(32)	[5]
IFRS Loan Impairment charges	(11)	[2],[5]	(4)	[2],[5]	(15)	[2],[5]	0	[2],[5]
IFRS Based, Operating income, net	(7)	[5]	(13)	[5]	13	[5]	(32)	[5]
IFRS Based Operating expenses	9	[3],[5]	(48)	[3],[5]	(18)	[3],[5]	(48)	[3],[5]
IFRS Based, Profit before income tax expense	(16)	[5]	35	[5]	31	[5]	16	[5]
IFRS Based, Total assets			(73,460)	[5]			(73,460)	[5]
IFRS Based, Total loans, net	1,794	[5]	(1,124)	[5]	1,794	[5]	(1,124)	[5]
IFRS Based, Goodwill	484	[5]	484	[5]	484	[5]	484	[5]
IFRS Based, Total deposits	(4,491)	[5]	(5,897)	[5]	(4,491)	[5]	(5,897)	[5]
IFRS Based, Assets	(53,563)	[5]			(53,563)	[5]
IFRS Reclassifications [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	7	[1],[6]	(7)	[1],[6]	12	[1],[6]	15	[1],[6]
IFRS Based, Other operating income	(5)	[6]	12	[6]	(9)	[6]	60	[6]
IFRS Based, Total operating income	2	[6]	5	[6]	3	[6]	75	[6]
IFRS Loan Impairment charges	(5)	[2],[6]	2	[2],[6]	9	[2],[6]	7	[2],[6]
IFRS Based, Operating income, net	7	[6]	3	[6]	(6)	[6]	68	[6]
IFRS Based Operating expenses	7	[3],[6]	3	[3],[6]	(6)	[3],[6]	68	[3],[6]
IFRS Based, Profit before income tax expense	0	[6]	0	[6]	0	[6]	0	[6]
IFRS Based, Total assets			(65)	[6]			(65)	[6]
IFRS Based, Total loans, net	79	[6]	(11,310)	[6]	79	[6]	(11,310)	[6]
IFRS Based, Goodwill	0	[6]	0	[6]	0	[6]	0	[6]
IFRS Based, Total deposits	6,500	[6]	12,738	[6]	6,500	[6]	12,738	[6]
IFRS Based, Assets	96	[6]			96	[6]
RBWM [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	205	[1]	209	[1]	626	[1]	653	[1]
IFRS Based, Other operating income	81		138		270		497
IFRS Based, Total operating income	286		347		896		1,150
IFRS Loan Impairment charges	44	[2]	72	[2]	97	[2]	174	[2]
IFRS Based, Operating income, net	242		275		799		976
IFRS Based Operating expenses	301	[3]	368	[3]	892	[3]	1,010	[3]
IFRS Based, Profit before income tax expense	(59)		(93)		(93)		(34)
IFRS Based, Total assets			23,726				23,726
IFRS Based, Total loans, net	16,221		16,334		16,221		16,334
IFRS Based, Goodwill	581		581		581		581
IFRS Based, Total deposits	30,594		35,494		30,594		35,494
IFRS Based, Assets	19,297				19,297
CMB [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	181	[1]	172	[1]	523	[1]	502	[1]
IFRS Based, Other operating income	77		136		219		471
IFRS Based, Total operating income	258		308		742		973
IFRS Loan Impairment charges	26	[2]	6	[2]	41	[2]	(3)	[2]
IFRS Based, Operating income, net	232		302		701		976
IFRS Based Operating expenses	169	[3]	154	[3]	502	[3]	487	[3]
IFRS Based, Profit before income tax expense	63		148		199		489
IFRS Based, Total assets			24,012				24,012
IFRS Based, Total loans, net	21,414		19,066		21,414		19,066
IFRS Based, Goodwill	358		358		358		358
IFRS Based, Total deposits	21,614		22,012		21,614		22,012
IFRS Based, Assets	22,571				22,571
GBM [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	78	[1]	129	[1]	312	[1]	439	[1]
IFRS Based, Other operating income	296		251		973		742
IFRS Based, Total operating income	374		380		1,285		1,181
IFRS Loan Impairment charges	(3)	[2]	6	[2]	6	[2]	(2)	[2]
IFRS Based, Operating income, net	377		374		1,279		1,183
IFRS Based Operating expenses	255	[3]	249	[3]	735	[3]	744	[3]
IFRS Based, Profit before income tax expense	122		125		544		439
IFRS Based, Total assets			217,185				217,185
IFRS Based, Total loans, net	21,738		32,559		21,738		32,559
IFRS Based, Goodwill	480		480		480		480
IFRS Based, Total deposits	46,829		44,669		46,829		44,669
IFRS Based, Assets	190,174				190,174
PB [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	46	[1]	45	[1]	140	[1]	137	[1]
IFRS Based, Other operating income	27		26		85		83
IFRS Based, Total operating income	73		71		225		220
IFRS Loan Impairment charges	3	[2]	2	[2]	4	[2]	(3)	[2]
IFRS Based, Operating income, net	70		69		221		223
IFRS Based Operating expenses	62	[3]	57	[3]	189	[3]	178	[3]
IFRS Based, Profit before income tax expense	8		12		32		45
IFRS Based, Total assets			7,093				7,093
IFRS Based, Total loans, net	5,869		5,290		5,869		5,290
IFRS Based, Goodwill	325		325		325		325
IFRS Based, Total deposits	11,875		12,319		11,875		12,319
IFRS Based, Assets	7,996				7,996
Other [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	(6)	[1]	(13)	[1]	(34)	[1]	(31)	[1]
IFRS Based, Other operating income	(45)		(164)		(10)		(234)
IFRS Based, Total operating income	(51)		(177)		(44)		(265)
IFRS Loan Impairment charges	0	[2]	0	[2]	0	[2]	0	[2]
IFRS Based, Operating income, net	(51)		(177)		(44)		(265)
IFRS Based Operating expenses	52	[3]	844	[3]	138	[3]	1,628	[3]
IFRS Based, Profit before income tax expense	(103)		(1,021)		(182)		(1,893)
IFRS Based, Total assets			92				92
IFRS Based, Total loans, net	0		0		0		0
IFRS Based, Goodwill	0		0		0		0
IFRS Based, Total deposits	0		0		0		0
IFRS Based, Assets	$ 804				$ 804

[1] Net interest income of each segment represents the difference between actual interest earned on assets and interest paid on liabilities of the segment adjusted for a funding charge or credit. Segments are charged a cost to fund assets (e.g. customer loans) and receive a funding credit for funds provided (e.g. customer deposits) based on equivalent market rates. The objective of these charges/credits is to transfer interest rate risk from the segments to one centralized unit in Treasury and more appropriately reflect the profitability of segments.

[2] The provision assigned to the segments is based on the segments’ net charge offs and the change in allowance for credit losses.

[3] Expenses for the segments include fully apportioned corporate overhead expenses.

[4] The following table summarizes assets and liabilities related to our consolidated variable interest entities (“VIEs”) as of September 30, 2013 and December 31, 2012 which are consolidated on our balance sheet. Assets and liabilities exclude intercompany balances that eliminate in consolidation. September 30, December 31, 2013 2012 (in millions)Assets Interest bearing deposits with banks$5 $—Securities held-to-maturity208 —Other assets479 533Total assets$692 $533Liabilities Long-term debt92 92Interest, taxes and other liabilities99 152Total liabilities$191 $244

[5] Represents adjustments associated with differences between IFRSs and U.S. GAAP bases of accounting.

[6] Represents differences in financial statement presentation between IFRSs and U.S. GAAP.