Business Segments - Summary on Reconciliation of Results Under Ifrs to Us Gaap (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012		Dec. 31, 2012
Operating Statistics [Line Items]
US GAAP Based, Net interest income	$ 518	[1]	$ 535	[1]	$ 1,023	[1]	$ 1,122	[1]
US GAAP Based, Other operating income	566		879		1,158		1,263
US GAAP Based, Total operating income	1,084		1,414		2,181		2,385
US GAAP Based, Loan impairment charges	67	[2]	89	[2]	88	[2]	89	[2]
US GAAP Based, Operating income, net	1,017		1,325		2,093		2,296
US GAAP Based, Operating expenses	788	[3]	1,567	[3]	1,577	[3]	2,440	[3]
Income (loss) from continuing operations before income tax expense	229		(242)		516		(144)
Total assets	192,386	[4]	200,427		192,386	[4]	200,427		196,567	[4]
US GAAP Based, Total loans, net	66,100		55,445		66,100		55,445		62,611
US GAAP Based, Goodwill	2,228		2,228		2,228		2,228		2,228
US GAAP Based, Total deposits	111,735		123,227		111,735		123,227		117,671
RBWM [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	206	[1]	197	[1]	421	[1]	444	[1]
IFRS Based, Other operating income	82		262		189		359
IFRS Based, Total operating income	288		459		610		803
IFRS Loan Impairment charges	21	[2]	61	[2]	53	[2]	102	[2]
IFRS Based,operating income, net	267		398		557		701
IFRS Based Operating expenses	300	[3]	321	[3]	591	[3]	642	[3]
IFRS Based, Profit before income tax expense	(33)		77		(34)		59
IFRS Based, Total assets	19,563		25,654		19,563		25,654
IFRS Based, Total loans, net	16,508		16,312		16,508		16,312
IFRS Based, Goodwill	581		581		581		581
IFRS Based, Total deposits	31,855		36,770		31,855		36,770
CMB [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	172	[1]	160	[1]	342	[1]	330	[1]
IFRS Based, Other operating income	77		267		142		335
IFRS Based, Total operating income	249		427		484		665
IFRS Loan Impairment charges	1	[2]	8	[2]	15	[2]	(9)	[2]
IFRS Based,operating income, net	248		419		469		674
IFRS Based Operating expenses	171	[3]	168	[3]	333	[3]	332	[3]
IFRS Based, Profit before income tax expense	77		251		136		342
IFRS Based, Total assets	20,799		22,691		20,799		22,691
IFRS Based, Total loans, net	19,693		18,080		19,693		18,080
IFRS Based, Goodwill	358		358		358		358
IFRS Based, Total deposits	21,382		21,125		21,382		21,125
GBM [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	125	[1]	167	[1]	234	[1]	310	[1]
IFRS Based, Other operating income	295		165		677		491
IFRS Based, Total operating income	420		332		911		801
IFRS Loan Impairment charges	6	[2]	23	[2]	9	[2]	(8)	[2]
IFRS Based,operating income, net	414		309		902		809
IFRS Based Operating expenses	250	[3]	236	[3]	480	[3]	495	[3]
IFRS Based, Profit before income tax expense	164		73		422		314
IFRS Based, Total assets	200,591		219,724		200,591		219,724
IFRS Based, Total loans, net	21,374		33,386		21,374		33,386
IFRS Based, Goodwill	480		480		480		480
IFRS Based, Total deposits	47,969		42,071		47,969		42,071
PB [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	49	[1]	47	[1]	94	[1]	92	[1]
IFRS Based, Other operating income	30		28		58		57
IFRS Based, Total operating income	79		75		152		149
IFRS Loan Impairment charges	0	[2]	(3)	[2]	1	[2]	(5)	[2]
IFRS Based,operating income, net	79		78		151		154
IFRS Based Operating expenses	67	[3]	63	[3]	127	[3]	121	[3]
IFRS Based, Profit before income tax expense	12		15		24		33
IFRS Based, Total assets	7,499		6,860		7,499		6,860
IFRS Based, Total loans, net	5,874		5,081		5,874		5,081
IFRS Based, Goodwill	325		325		325		325
IFRS Based, Total deposits	12,152		12,727		12,152		12,727
Other [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	(14)	[1]	(7)	[1]	(28)	[1]	(18)	[1]
IFRS Based, Other operating income	60		165		35		(70)
IFRS Based, Total operating income	46		158		7		(88)
IFRS Loan Impairment charges	0	[2]	0	[2]	0	[2]	0	[2]
IFRS Based,operating income, net	46		158		7		(88)
IFRS Based Operating expenses	44	[3]	745	[3]	86	[3]	785	[3]
IFRS Based, Profit before income tax expense	2		(587)		(79)		(873)
IFRS Based, Total assets	1,088		622		1,088		622
IFRS Based, Total loans, net	0		0		0		0
IFRS Based, Goodwill	0		0		0		0
IFRS Based, Total deposits	0		0		0		0
Adjustments Or Reconciling Items [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	(3)	[1]	(1)	[1]	(7)	[1]	(7)	[1]
IFRS Based, Other operating income	3		1		7		7
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		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
Aggregate [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	535	[1]	563	[1]	1,056	[1]	1,151	[1]
IFRS Based, Other operating income	547		888		1,108		1,179
IFRS Based, Total operating income	1,082		1,451		2,164		2,330
IFRS Loan Impairment charges	28	[2]	89	[2]	78	[2]	80	[2]
IFRS Based,operating income, net	1,054		1,362		2,086		2,250
IFRS Based Operating expenses	832	[3]	1,533	[3]	1,617	[3]	2,375	[3]
IFRS Based, Profit before income tax expense	222		(171)		469		(125)
IFRS Based, Total assets	249,540		275,551		249,540		275,551
IFRS Based, Total loans, net	63,449		72,859		63,449		72,859
IFRS Based, Goodwill	1,744		1,744		1,744		1,744
IFRS Based, Total deposits	113,358		112,693		113,358		112,693
IFRS Adjustments [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	(21)	[1],[5]	(36)	[1],[5]	(38)	[1],[5]	(51)	[1],[5]
IFRS Based, Other operating income	20	[5]	(32)	[5]	54	[5]	36	[5]
IFRS Based, Total operating income	(1)	[5]	(68)	[5]	16	[5]	(15)	[5]
IFRS Loan Impairment charges	19	[2],[5]	7	[2],[5]	(4)	[2],[5]	4	[2],[5]
IFRS Based,operating income, net	(20)	[5]	(75)	[5]	20	[5]	(19)	[5]
IFRS Based Operating expenses	(27)	[3],[5]	(4)	[3],[5]	(27)	[3],[5]	0	[3],[5]
IFRS Based, Profit before income tax expense	7	[5]	(71)	[5]	47	[5]	(19)	[5]
IFRS Based, Total assets	(57,199)	[5]	(75,139)	[5]	(57,199)	[5]	(75,139)	[5]
IFRS Based, Total loans, net	3,144	[5]	(1,995)	[5]	3,144	[5]	(1,995)	[5]
IFRS Based, Goodwill	484	[5]	484	[5]	484	[5]	484	[5]
IFRS Based, Total deposits	(5,047)	[5]	(6,229)	[5]	(5,047)	[5]	(6,229)	[5]
IFRS Reclassifications [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	4	[1],[6]	8	[1],[6]	5	[1],[6]	22	[1],[6]
IFRS Based, Other operating income	(1)	[6]	23	[6]	(4)	[6]	48	[6]
IFRS Based, Total operating income	3	[6]	31	[6]	1	[6]	70	[6]
IFRS Loan Impairment charges	20	[2],[6]	(7)	[2],[6]	14	[2],[6]	5	[2],[6]
IFRS Based,operating income, net	(17)	[6]	38	[6]	(13)	[6]	65	[6]
IFRS Based Operating expenses	(17)	[3],[6]	38	[3],[6]	(13)	[3],[6]	65	[3],[6]
IFRS Based, Profit before income tax expense	0	[6]	0	[6]	0	[6]	0	[6]
IFRS Based, Total assets	45	[6]	15	[6]	45	[6]	15	[6]
IFRS Based, Total loans, net	(493)	[6]	(15,419)	[6]	(493)	[6]	(15,419)	[6]
IFRS Based, Goodwill	0	[6]	0	[6]	0	[6]	0	[6]
IFRS Based, Total deposits	$ 3,424	[6]	$ 16,763	[6]	$ 3,424	[6]	$ 16,763	[6]

[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 June 30, 2013 and 2012 which are consolidated on our balance sheet. Assets and liabilities exclude intercompany balances that eliminate in consolidation. Assets: Interest bearing deposits with banks, $221 and $216, Other assets $544 and $533, Total assets $983 and $749 respectively. Liabilities: Long-term debt $92 and $92, Interest, taxes and other liabilities $122 and $152. Total liabilities $614 and $244, respectively.

[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.