Business Segments - Summary on Reconciliation of Results Under Ifrs to Us Gaap (Detail) - USD ($) $ in Millions		3 Months Ended				9 Months Ended
		Sep. 30, 2015		Sep. 30, 2014		Sep. 30, 2015		Sep. 30, 2014		Dec. 31, 2014
Operating Statistics [Line Items]
Net interest income	[1]	$ 617		$ 543		$ 1,849		$ 1,735
Other operating income		531		386		1,398		1,147
Total operating income		1,148		929		3,247		2,882
Loan impairment charges		47		23		94		124
Total income		1,101		906		3,153		2,758
Operating expenses	[2]	786		934		2,413		2,560
Income (loss) before income tax		315		(28)		740		198
Total assets		204,366	[3]	175,012		204,366	[3]	175,012		$ 185,539	[3]
Total loans, net		84,264		72,808		84,264		72,808		77,061
Goodwill		1,612		1,612		1,612		1,612		1,612
Total deposits		131,450	[3],[4]	108,677	[4]	131,450	[3],[4]	108,677	[4]	$ 116,118	[3]
Group Reporting Basis Adjustments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1],[5]	(19)		(20)		(51)		(51)
Group Reporting Basis Other operating income	[5]	(11)		7		(36)		(3)
Group Reporting Basis Total operating income	[5]	(30)		(13)		(87)		(54)
Group Reporting Basis Loan impairment charges	[5]	4		(14)		(9)		(62)
Group Reporting Basis Revenues	[5]	(34)		1		(78)		8
Group Reporting Basis Operating expenses	[2],[5]	(7)		(222)		(33)		(154)
Group Reporting Basis Income (loss) from continuing operations before income tax	[5]	(27)		223		(45)		162
Group Reporting Basis Total assets	[5]	(54,496)		(50,353)		(54,496)		(50,353)
Group Reporting Basis Total loans, net	[5]	286		1,224		286		1,224
Group Reporting Basis Goodwill	[5]	348		348		348		348
Group Reporting Basis Total deposits	[4],[5]	(5,167)		(3,758)		(5,167)		(3,758)
Group Reporting Basis Reclassifications [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1],[6]	45		36		175		93
Group Reporting Basis Other operating income	[6]	(48)		(43)		(178)		(112)
Group Reporting Basis Total operating income	[6]	(3)		(7)		(3)		(19)
Group Reporting Basis Loan impairment charges	[6]	1		(10)		(1)		(24)
Group Reporting Basis Revenues	[6]	(4)		3		(2)		5
Group Reporting Basis Operating expenses	[2],[6]	(4)		3		(2)		5
Group Reporting Basis Income (loss) from continuing operations before income tax	[6]	0		0		0		0
Group Reporting Basis Total assets	[6]	729		62		729		62
Group Reporting Basis Total loans, net	[6]	4,120		2,430		4,120		2,430
Group Reporting Basis Goodwill	[6]	0		0		0		0
Group Reporting Basis Total deposits	[4],[6]	38,019		19,420		38,019		19,420
Aggregate [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]	591		527		1,725		1,693
Group Reporting Basis Other operating income		590		422		1,612		1,262
Group Reporting Basis Total operating income		1,181		949		3,337		2,955
Group Reporting Basis Loan impairment charges		42		47		104		210
Group Reporting Basis Revenues		1,139		902		3,233		2,745
Group Reporting Basis Operating expenses	[2]	797		1,153		2,448		2,709
Group Reporting Basis Income (loss) from continuing operations before income tax		342		(251)		785		36
Group Reporting Basis Total assets		258,133		225,303		258,133		225,303
Group Reporting Basis Total loans, net		79,858		69,154		79,858		69,154
Group Reporting Basis Goodwill		1,264		1,264		1,264		1,264
Group Reporting Basis Total deposits	[4]	98,598		93,015		98,598		93,015
Segment Reconciling Items [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]	(1)		8		(9)		(1)
Group Reporting Basis Other operating income		1		(8)		9		1
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	[4]	0		0		0		0
RBWM [Member] | Operating Segments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]	192		196		584		606
Group Reporting Basis Other operating income		85		98		258		315
Group Reporting Basis Total operating income		277		294		842		921
Group Reporting Basis Loan impairment charges		14		11		51		34
Group Reporting Basis Revenues		263		283		791		887
Group Reporting Basis Operating expenses	[2]	267		343		848		920
Group Reporting Basis Income (loss) from continuing operations before income tax		(4)		(60)		(57)		(33)
Group Reporting Basis Total assets		20,106		19,339		20,106		19,339
Group Reporting Basis Total loans, net		17,146		16,491		17,146		16,491
Group Reporting Basis Goodwill		581		581		581		581
Group Reporting Basis Total deposits	[4]	30,631		28,515		30,631		28,515
CMB [Member] | Operating Segments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]	214		204		626		593
Group Reporting Basis Other operating income		82		90		230		222
Group Reporting Basis Total operating income		296		294		856		815
Group Reporting Basis Loan impairment charges		24		29		38		119
Group Reporting Basis Revenues		272		265		818		696
Group Reporting Basis Operating expenses	[2]	184		169		538		501
Group Reporting Basis Income (loss) from continuing operations before income tax		88		96		280		195
Group Reporting Basis Total assets		32,214		27,769		32,214		27,769
Group Reporting Basis Total loans, net		30,976		26,626		30,976		26,626
Group Reporting Basis Goodwill		358		358		358		358
Group Reporting Basis Total deposits	[4]	23,209		22,616		23,209		22,616
GBM [Member] | Operating Segments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]	142		74		392		280
Group Reporting Basis Other operating income		287		191		772		636
Group Reporting Basis Total operating income		429		265		1,164		916
Group Reporting Basis Loan impairment charges		5		11		17		66
Group Reporting Basis Revenues		424		254		1,147		850
Group Reporting Basis Operating expenses	[2]	247		553		770		1,031
Group Reporting Basis Income (loss) from continuing operations before income tax		177		(299)		377		(181)
Group Reporting Basis Total assets		196,535		169,686		196,535		169,686
Group Reporting Basis Total loans, net		25,025		20,056		25,025		20,056
Group Reporting Basis Goodwill		0		0		0		0
Group Reporting Basis Total deposits	[4]	31,621		30,663		31,621		30,663
Group Reporting Basis Brokered Deposits				2,100				2,100
PB [Member] | Operating Segments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]	49		47		148		152
Group Reporting Basis Other operating income		26		28		77		78
Group Reporting Basis Total operating income		75		75		225		230
Group Reporting Basis Loan impairment charges		(1)		(4)		(2)		(9)
Group Reporting Basis Revenues		76		79		227		239
Group Reporting Basis Operating expenses	[2]	62		58		178		174
Group Reporting Basis Income (loss) from continuing operations before income tax		14		21		49		65
Group Reporting Basis Total assets		8,491		7,670		8,491		7,670
Group Reporting Basis Total loans, net		6,711		5,981		6,711		5,981
Group Reporting Basis Goodwill		325		325		325		325
Group Reporting Basis Total deposits	[4]	13,137		11,221		13,137		11,221
Other [Member] | Operating Segments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]	(5)		(2)		(16)		63
Group Reporting Basis Other operating income		109		23		266		10
Group Reporting Basis Total operating income		104		21		250		73
Group Reporting Basis Loan impairment charges		0		0		0		0
Group Reporting Basis Revenues		104		21		250		73
Group Reporting Basis Operating expenses	[2]	37		30		114		83
Group Reporting Basis Income (loss) from continuing operations before income tax		67		(9)		136		(10)
Group Reporting Basis Total assets		787		839		787		839
Group Reporting Basis Total loans, net		0		0		0		0
Group Reporting Basis Goodwill		0		0		0		0
Group Reporting Basis Total deposits	[4]	$ 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") as of September 30, 2015 and December 31, 2014 which are consolidated on our balance sheet. Assets and liabilities exclude intercompany balances that eliminate in consolidation. See Note 216, "Variable Interest Entities," for additional information. Assets: Other assets $338 million and $380 million. Total assets $338 million and $380 million respectively. Liabilities: Long-term debt $92 million and $92 million, Interest, taxes and other liabilities $69 million and $75 million. Total liabilities $161 million and $167 million, respectively.

[4] During the second quarter of 2015, we concluded that brokered deposits would be better presented as debt under the Group Reporting Basis. As a result, we reclassified $2.1 billion of brokered deposits in the GB&M segment to debt at September 30, 2014 to conform with current year presentation.

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

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