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, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Operating Statistics [Line Items]
US GAAP Based, Net Interest Income	$ 510	$ 621	$ 1,632	$ 1,794
US GAAP Based, Other Operating Income	397	667	1,627	1,790
US GAAP Based, Total operating income	907	1,288	3,259	3,584
US GAAP Based, Loan impairment charges	84	78	173	171
US GAAP Based, Operating Income, Net	823	1,210	3,086	3,413
US GAAP Based, Operating Expenses	1,617	921	4,024	2,742
Income (loss) from continuing operations before income tax expense	(794)	289	(938)	671
US GAAP Based, Total Assets	203,132	188,442	203,132	188,442	210,280
US GAAP Based, Total loans, net	60,815	48,851	60,815	48,851	51,124
US GAAP Based, Goodwill	2,228	2,228	2,228	2,228	2,228
US GAAP Based, Deposits	121,335	132,841	121,335	132,841	139,729
RBWM [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	209	259	653	756
IFRS Based, Other Operating Income	138	148	497	337
IFRS Based, Total operating income	347	407	1,150	1,093
IFRS Based, Loan impairment charges	72	76	174	166
IFRS Based, Operating Income, Net	275	331	976	927
IFRS Based, Operating Expenses	368	368	1,010	1,187
IFRS Based, Profit Before Income Tax Expense	(93)	(37)	(34)	(260)
IFRS Based, Total Assets	23,726	25,629	23,726	25,629
IFRS Based, Total loans, net	16,334	16,118	16,334	16,118
IFRS Based, Goodwill	581	581	581	581
IFRS Based, Deposits	35,494	47,314	35,494	47,314
CMB [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	168	180	490	527
IFRS Based, Other Operating Income	173	114	578	325
IFRS Based, Total operating income	341	294	1,068	852
IFRS Based, Loan impairment charges	6	(5)	(3)	7
IFRS Based, Operating Income, Net	335	299	1,071	845
IFRS Based, Operating Expenses	175	177	550	553
IFRS Based, Profit Before Income Tax Expense	160	122	521	292
IFRS Based, Total Assets	24,012	20,144	24,012	20,144
IFRS Based, Total loans, net	19,066	16,173	19,066	16,173
IFRS Based, Goodwill	357	357	357	357
IFRS Based, Deposits	22,012	27,215	22,012	27,215
GBM [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	129	120	439	382
IFRS Based, Other Operating Income	251	67	742	756
IFRS Based, Total operating income	380	187	1,181	1,138
IFRS Based, Loan impairment charges	6	28	(2)	1
IFRS Based, Operating Income, Net	374	159	1,183	1,137
IFRS Based, Operating Expenses	249	270	744	735
IFRS Based, Profit Before Income Tax Expense	125	(111)	439	402
IFRS Based, Total Assets	221,734	232,769	221,734	232,769
IFRS Based, Total loans, net	32,559	25,592	32,559	25,592
IFRS Based, Goodwill	480	480	480	480
IFRS Based, Deposits	44,669	47,906	44,669	47,906
PB [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	45	44	137	134
IFRS Based, Other Operating Income	26	27	83	97
IFRS Based, Total operating income	71	71	220	231
IFRS Based, Loan impairment charges	2	(24)	(3)	(34)
IFRS Based, Operating Income, Net	69	95	223	265
IFRS Based, Operating Expenses	57	65	178	194
IFRS Based, Profit Before Income Tax Expense	12	30	45	71
IFRS Based, Total Assets	7,093	5,946	7,093	5,946
IFRS Based, Total loans, net	5,290	4,462	5,290	4,462
IFRS Based, Goodwill	326	326	326	326
IFRS Based, Deposits	12,319	11,929	12,319	11,929
Other [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	(9)	(6)	(19)	(73)
IFRS Based, Other Operating Income	(201)	380	(341)	363
IFRS Based, Total operating income	(210)	374	(360)	290
IFRS Based, Operating Income, Net	(210)	374	(360)	290
IFRS Based, Operating Expenses	823	14	1,565	51
IFRS Based, Profit Before Income Tax Expense	(1,033)	360	(1,925)	239
IFRS Based, Total Assets	92	92	92	92
Adjustments Or Reconciling Items [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	(3)	(11)	(10)	(26)
IFRS Based, Other Operating Income	3	11	10	26
Aggregate [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	539	586	1,690	1,700
IFRS Based, Other Operating Income	390	747	1,569	1,904
IFRS Based, Total operating income	929	1,333	3,259	3,604
IFRS Based, Loan impairment charges	86	75	166	140
IFRS Based, Operating Income, Net	843	1,258	3,093	3,464
IFRS Based, Operating Expenses	1,672	894	4,047	2,720
IFRS Based, Profit Before Income Tax Expense	(829)	364	(954)	744
IFRS Based, Total Assets	276,657	284,580	276,657	284,580
IFRS Based, Total loans, net	73,249	62,345	73,249	62,345
IFRS Based, Goodwill	1,744	1,744	1,744	1,744
IFRS Based, Deposits	114,494	134,364	114,494	134,364
IFRS Adjustments [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	(22)	(71)	(73)	(104)
IFRS Based, Other Operating Income	5	10	41	34
IFRS Based, Total operating income	(17)	(61)	(32)	(70)
IFRS Based, Loan impairment charges	(4)	1		6
IFRS Based, Operating Income, Net	(13)	(62)	(32)	(76)
IFRS Based, Operating Expenses	(48)	13	(48)	(3)
IFRS Based, Profit Before Income Tax Expense	35	(75)	16	(73)
IFRS Based, Total Assets	(73,460)	(96,198)	(73,460)	(96,198)
IFRS Based, Total loans, net	(1,124)	(5,880)	(1,124)	(5,880)
IFRS Based, Goodwill	484	485	484	485
IFRS Based, Deposits	(5,897)	(5,029)	(5,897)	(5,029)
IFRS Reclassifications [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	(7)	106	15	198
IFRS Based, Other Operating Income	2	(90)	17	(148)
IFRS Based, Total operating income	(5)	16	32	50
IFRS Based, Loan impairment charges	2	2	7	25
IFRS Based, Operating Income, Net	(7)	14	25	25
IFRS Based, Operating Expenses	(7)	14	25	25
IFRS Based, Total Assets	(65)	60	(65)	60
IFRS Based, Total loans, net	(11,310)	(7,614)	(11,310)	(7,614)
IFRS Based, Deposits	$ 12,738	$ 3,506	$ 12,738	$ 3,506