Business Segments - Summary on Reconciliation of Results Under Ifrs to Us Gaap (Detail) - USD ($) $ in Millions		3 Months Ended			9 Months Ended
		Sep. 30, 2016		Sep. 30, 2015	Sep. 30, 2016		Sep. 30, 2015	Dec. 31, 2015
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]	$ 608		$ 591	$ 1,885		$ 1,725
Group Reporting Basis Other operating income		357		590	1,256		1,612
Group Reporting Basis Total operating income		965		1,181	3,141		3,337
Group Reporting Basis Loan impairment charges		42		42	451		104
Group Reporting Basis Revenues		923		1,139	2,690		3,233
Group Reporting Basis Operating expenses	[2]	814		797	2,348		2,448
Group Reporting Basis Income (loss) from continuing operations before income tax		109		342	342		785
Group Reporting Basis Total assets		253,974		258,133	253,974		258,133
Group Reporting Basis Total loans, net		73,630		79,858	73,630		79,858
Group Reporting Basis Goodwill		1,264		1,264	1,264		1,264
Group Reporting Basis Total deposits		99,995		98,598	99,995		98,598
Net interest income	[1]	604		617	1,896		1,849
Other operating income		320		531	1,075		1,398
Total operating income		924		1,148	2,971		3,247
Loan impairment charges		62	[3]	47	353	[3]	94
Total income		862		1,101	2,618		3,153
Operating expenses	[2]	803		786	2,352		2,413
Income before income tax		59		315	266		740
Total assets		208,310	[4]	204,366	208,310	[4]	204,366	$ 188,278	[4]
Total loans, net		76,565		84,264	76,565		84,264	82,005
Goodwill		1,612		1,612	1,612		1,612	1,612
Total deposits		131,082		131,450	131,082		131,450	$ 118,579
Group Reporting Basis Adjustments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1],[5]	(18)		(19)	(59)		(51)
Group Reporting Basis Other operating income	[5]	(27)		(11)	(111)		(36)
Group Reporting Basis Total operating income	[5]	(45)		(30)	(170)		(87)
Group Reporting Basis Loan impairment charges	[5]	16		4	(72)		(9)
Group Reporting Basis Revenues	[5]	(61)		(34)	(98)		(78)
Group Reporting Basis Operating expenses	[2],[5]	(11)		(7)	(22)		(33)
Group Reporting Basis Income (loss) from continuing operations before income tax	[5]	(50)		(27)	(76)		(45)
Group Reporting Basis Total assets	[5]	(45,673)		(54,496)	(45,673)		(54,496)
Group Reporting Basis Total loans, net	[5]	(447)		286	(447)		286
Group Reporting Basis Goodwill	[5]	348		348	348		348
Group Reporting Basis Total deposits	[5]	(4,919)		(5,167)	(4,919)		(5,167)
Group Reporting Basis Reclassifications [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1],[6]	14		45	70		175
Group Reporting Basis Other operating income	[6]	(10)		(48)	(70)		(178)
Group Reporting Basis Total operating income	[6]	4		(3)	0		(3)
Group Reporting Basis Loan impairment charges	[6]	4		1	(26)		(1)
Group Reporting Basis Revenues	[6]	0		(4)	26		(2)
Group Reporting Basis Operating expenses	[2],[6]	0		(4)	26		(2)
Group Reporting Basis Income (loss) from continuing operations before income tax	[6]	0		0	0		0
Group Reporting Basis Total assets	[6]	9		729	9		729
Group Reporting Basis Total loans, net	[6]	3,382		4,120	3,382		4,120
Group Reporting Basis Goodwill	[6]	0		0	0		0
Group Reporting Basis Total deposits	[6]	36,006		38,019	36,006		38,019
Adjustments/Reconciling Items [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]	0		(1)	(2)		(9)
Group Reporting Basis Other operating income		0		1	2		9
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		197	609		597
Group Reporting Basis Other operating income		72		85	229		260
Group Reporting Basis Total operating income		276		282	838		857
Group Reporting Basis Loan impairment charges		27		15	52		52
Group Reporting Basis Revenues		249		267	786		805
Group Reporting Basis Operating expenses	[2]	283		280	810		887
Group Reporting Basis Income (loss) from continuing operations before income tax		(34)		(13)	(24)		(82)
Group Reporting Basis Total assets		20,719		20,177	20,719		20,177
Group Reporting Basis Total loans, net		17,727		17,217	17,727		17,217
Group Reporting Basis Goodwill		581		581	581		581
Group Reporting Basis Total deposits		31,702		31,260	31,702		31,260
CMB [Member] | Operating Segments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]	205		209	623		613
Group Reporting Basis Other operating income		66		82	206		228
Group Reporting Basis Total operating income		271		291	829		841
Group Reporting Basis Loan impairment charges		(19)		23	12		37
Group Reporting Basis Revenues		290		268	817		804
Group Reporting Basis Operating expenses	[2]	167		171	495		499
Group Reporting Basis Income (loss) from continuing operations before income tax		123		97	322		305
Group Reporting Basis Total assets		28,832		32,143	28,832		32,143
Group Reporting Basis Total loans, net		27,740		30,905	27,740		30,905
Group Reporting Basis Goodwill		358		358	358		358
Group Reporting Basis Total deposits		24,926		22,580	24,926		22,580
GBM [Member] | Operating Segments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]	156		142	522		392
Group Reporting Basis Other operating income		188		287	585		772
Group Reporting Basis Total operating income		344		429	1,107		1,164
Group Reporting Basis Loan impairment charges		33		5	387		17
Group Reporting Basis Revenues		311		424	720		1,147
Group Reporting Basis Operating expenses	[2]	241		247	714		770
Group Reporting Basis Income (loss) from continuing operations before income tax		70		177	6		377
Group Reporting Basis Total assets		195,803		196,535	195,803		196,535
Group Reporting Basis Total loans, net		21,730		25,025	21,730		25,025
Group Reporting Basis Goodwill		0		0	0		0
Group Reporting Basis Total deposits		30,151		31,621	30,151		31,621
PB [Member] | Operating Segments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]	53		49	153		148
Group Reporting Basis Other operating income		22		26	67		77
Group Reporting Basis Total operating income		75		75	220		225
Group Reporting Basis Loan impairment charges		1		(1)	0		(2)
Group Reporting Basis Revenues		74		76	220		227
Group Reporting Basis Operating expenses	[2]	56		62	173		178
Group Reporting Basis Income (loss) from continuing operations before income tax		18		14	47		49
Group Reporting Basis Total assets		8,149		8,491	8,149		8,491
Group Reporting Basis Total loans, net		6,433		6,711	6,433		6,711
Group Reporting Basis Goodwill		325		325	325		325
Group Reporting Basis Total deposits		13,216		13,137	13,216		13,137
Other [Member] | Operating Segments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]	(10)		(5)	(20)		(16)
Group Reporting Basis Other operating income		9		109	167		266
Group Reporting Basis Total operating income		(1)		104	147		250
Group Reporting Basis Loan impairment charges		0		0	0		0
Group Reporting Basis Revenues		(1)		104	147		250
Group Reporting Basis Operating expenses	[2]	67		37	156		114
Group Reporting Basis Income (loss) from continuing operations before income tax		(68)		67	(9)		136
Group Reporting Basis Total assets		471		787	471		787
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 provision for credit losses and charge-offs for residential mortgage loans during both the three and nine months ended September 30, 2016 includes $11 million related to the lower of amortized cost or fair value adjustment attributable to credit factors for loans transferred to held for sale. See Note 6, "Loans Held for Sale," for additional information.

[4] The following table summarizes assets and liabilities related to our consolidated variable interest entities ("VIEs") at September 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 $248 million and $320 million. Total assets $248 million and $320 million respectively. Liabilities: Long-term debt $79 million and $92 million, Interest, taxes and other liabilities $55 million and $68 million. Total liabilities $134 million and $160 million, respectively.

[5] Represents adjustments associated with differences between U.S. GAAP and the Group Reporting Basis.

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