Business Segments - Summary on Reconciliation of Results Under Ifrs to Us Gaap (Detail) - USD ($) $ in Millions		3 Months Ended			6 Months Ended
		Jun. 30, 2016		Jun. 30, 2015	Jun. 30, 2016		Jun. 30, 2015	Dec. 31, 2015
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]	$ 643		$ 580	$ 1,277		$ 1,134
Group Reporting Basis Other operating income		325		481	899		1,022
Group Reporting Basis Total operating income		968		1,061	2,176		2,156
Group Reporting Basis Loan impairment charges		177		22	409		62
Group Reporting Basis Revenues		791		1,039	1,767		2,094
Group Reporting Basis Operating expenses	[2]	805		857	1,534		1,651
Group Reporting Basis Income (loss) from continuing operations before income tax		(14)		182	233		443
Group Reporting Basis Total assets		262,583		242,421	262,583		242,421
Group Reporting Basis Total loans, net		75,158		78,809	75,158		78,809
Group Reporting Basis Goodwill		1,264		1,264	1,264		1,264
Group Reporting Basis Total deposits		97,802		95,457	97,802		95,457
Net interest income	[1]	638		626	1,292		1,232
Other operating income		293		403	755		867
Total operating income		931		1,029	2,047		2,099
Loan impairment charges		134		(6)	291		47
Total income		797		1,035	1,756		2,052
Operating expenses	[2]	823		850	1,549		1,627
Income (loss) before income tax		(26)		185	207		425
Total assets		210,873	[3]	196,618	210,873	[3]	196,618	$ 188,278	[3]
Total loans, net		78,747		82,969	78,747		82,969	82,005
Goodwill		1,612		1,612	1,612		1,612	1,612
Total deposits		132,819		122,547	132,819		122,547	$ 118,579
Group Reporting Basis Adjustments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1],[4]	(22)		(18)	(41)		(32)
Group Reporting Basis Other operating income	[4]	(14)		(15)	(84)		(25)
Group Reporting Basis Total operating income	[4]	(36)		(33)	(125)		(57)
Group Reporting Basis Loan impairment charges	[4]	(19)		(27)	(88)		(13)
Group Reporting Basis Revenues	[4]	(17)		(6)	(37)		(44)
Group Reporting Basis Operating expenses	[2],[4]	(5)		(9)	(11)		(26)
Group Reporting Basis Income (loss) from continuing operations before income tax	[4]	(12)		3	(26)		(18)
Group Reporting Basis Total assets	[4]	(51,717)		(45,816)	(51,717)		(45,816)
Group Reporting Basis Total loans, net	[4]	(192)		906	(192)		906
Group Reporting Basis Goodwill	[4]	348		348	348		348
Group Reporting Basis Total deposits	[4]	(4,994)		(4,512)	(4,994)		(4,512)
Group Reporting Basis Reclassifications [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1],[5]	17		64	56		130
Group Reporting Basis Other operating income	[5]	(18)		(63)	(60)		(130)
Group Reporting Basis Total operating income	[5]	(1)		1	(4)		0
Group Reporting Basis Loan impairment charges	[5]	(24)		(1)	(30)		(2)
Group Reporting Basis Revenues	[5]	23		2	26		2
Group Reporting Basis Operating expenses	[2],[5]	23		2	26		2
Group Reporting Basis Income (loss) from continuing operations before income tax	[5]	0		0	0		0
Group Reporting Basis Total assets	[5]	7		13	7		13
Group Reporting Basis Total loans, net	[5]	3,781		3,254	3,781		3,254
Group Reporting Basis Goodwill	[5]	0		0	0		0
Group Reporting Basis Total deposits	[5]	40,011		31,602	40,011		31,602
Adjustments/Reconciling Items [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]	0		(3)	(2)		(8)
Group Reporting Basis Other operating income		0		3	2		8
Group Reporting Basis Total operating income		0		0	0		0
Group Reporting Basis Loan impairment charges		0		0	0		0
Group Reporting Basis Revenues		0		0	0		0
Group Reporting Basis Operating expenses	[2]	0		0	0		0
Group Reporting Basis Income (loss) from continuing operations before income tax		0		0	0		0
Group Reporting Basis Total assets		0		0	0		0
Group Reporting Basis Total loans, net		0		0	0		0
Group Reporting Basis Goodwill		0		0	0		0
Group Reporting Basis Total deposits		0		0	0		0
RBWM [Member] | Operating Segments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]	204		199	405		400
Group Reporting Basis Other operating income		77		87	157		175
Group Reporting Basis Total operating income		281		286	562		575
Group Reporting Basis Loan impairment charges		9		15	25		37
Group Reporting Basis Revenues		272		271	537		538
Group Reporting Basis Operating expenses	[2]	268		313	527		607
Group Reporting Basis Income (loss) from continuing operations before income tax		4		(42)	10		(69)
Group Reporting Basis Total assets		20,899		20,059	20,899		20,059
Group Reporting Basis Total loans, net		17,791		17,111	17,791		17,111
Group Reporting Basis Goodwill		581		581	581		581
Group Reporting Basis Total deposits		31,854		31,139	31,854		31,139
CMB [Member] | Operating Segments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]	205		207	418		404
Group Reporting Basis Other operating income		67		70	140		146
Group Reporting Basis Total operating income		272		277	558		550
Group Reporting Basis Loan impairment charges		18		4	31		14
Group Reporting Basis Revenues		254		273	527		536
Group Reporting Basis Operating expenses	[2]	166		172	328		328
Group Reporting Basis Income (loss) from continuing operations before income tax		88		101	199		208
Group Reporting Basis Total assets		30,240		31,868	30,240		31,868
Group Reporting Basis Total loans, net		29,025		30,711	29,025		30,711
Group Reporting Basis Goodwill		358		358	358		358
Group Reporting Basis Total deposits		23,685		21,209	23,685		21,209
GBM [Member] | Operating Segments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]	190		132	366		250
Group Reporting Basis Other operating income		178		219	397		485
Group Reporting Basis Total operating income		368		351	763		735
Group Reporting Basis Loan impairment charges		150		4	354		12
Group Reporting Basis Revenues		218		347	409		723
Group Reporting Basis Operating expenses	[2]	249		264	473		523
Group Reporting Basis Income (loss) from continuing operations before income tax		(31)		83	(64)		200
Group Reporting Basis Total assets		202,708		181,541	202,708		181,541
Group Reporting Basis Total loans, net		21,787		24,489	21,787		24,489
Group Reporting Basis Goodwill		0		0	0		0
Group Reporting Basis Total deposits		28,593		30,343	28,593		30,343
PB [Member] | Operating Segments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]	49		50	100		99
Group Reporting Basis Other operating income		22		27	45		51
Group Reporting Basis Total operating income		71		77	145		150
Group Reporting Basis Loan impairment charges		0		(1)	(1)		(1)
Group Reporting Basis Revenues		71		78	146		151
Group Reporting Basis Operating expenses	[2]	59		58	117		116
Group Reporting Basis Income (loss) from continuing operations before income tax		12		20	29		35
Group Reporting Basis Total assets		8,244		8,174	8,244		8,174
Group Reporting Basis Total loans, net		6,555		6,498	6,555		6,498
Group Reporting Basis Goodwill		325		325	325		325
Group Reporting Basis Total deposits		13,670		12,766	13,670		12,766
Other [Member] | Operating Segments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]	(5)		(5)	(10)		(11)
Group Reporting Basis Other operating income		(19)		75	158		157
Group Reporting Basis Total operating income		(24)		70	148		146
Group Reporting Basis Loan impairment charges		0		0	0		0
Group Reporting Basis Revenues		(24)		70	148		146
Group Reporting Basis Operating expenses	[2]	63		50	89		77
Group Reporting Basis Income (loss) from continuing operations before income tax		(87)		20	59		69
Group Reporting Basis Total assets		492		779	492		779
Group Reporting Basis Total loans, net		0		0	0		0
Group Reporting Basis Goodwill		0		0	0		0
Group Reporting Basis Total deposits		$ 0		$ 0	$ 0		$ 0

[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 Balance Sheet Management and more appropriately reflect the profitability of segments.

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

[3] The following table summarizes assets and liabilities related to our consolidated variable interest entities ("VIEs") at June 30, 2016 and December 31, 2015 which are consolidated on our balance sheet. Assets and liabilities exclude intercompany balances that eliminate in consolidation. See Note 17, "Variable Interest Entities," for additional information. Assets: Other assets $280 million and $320 million. Total assets $280 million and $320 million respectively. Liabilities: Long-term debt $92 million and $92 million, Interest, taxes and other liabilities $68 million and $68 million. Total liabilities $160 million and $160 million, respectively.

[4] Represents adjustments associated with differences between the Group Reporting Basis and the U.S. GAAP basis of accounting.

[5] Represents differences in financial statement presentation between Group Reporting Basis and U.S. GAAP.