Business Segments - Summary on Reconciliation of Results Under Ifrs to Us Gaap (Detail) - USD ($) $ in Millions		3 Months Ended										12 Months Ended
		Dec. 31, 2015		Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014		Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Operating Statistics [Line Items]
Net interest income		$ 621		$ 617	$ 626	$ 606	$ 569		$ 543	$ 673	$ 519	$ 2,470	[1]	$ 2,304	[1]	$ 2,041	[1]
Other operating income		274		531	403	464	459		386	261	500	1,672		1,606		1,857
Total operating income												4,142		3,910		3,898
Loan impairment charges		267		47	(6)	53	64		23	85	16	361		188		193
Total income												3,781		3,722		3,705
Operating expenses		808		786	850	777	864		934	876	750	3,221	[2]	3,424	[2]	3,887	[2]
Income (loss) before income tax		(180)		$ 315	$ 185	$ 240	100		(28)	$ (27)	$ 253	560		298		(182)
Total assets		188,278	[3]				185,539	[3]				188,278	[3]	185,539	[3]	185,487
Total loans, net		82,005					77,061					82,005		77,061		67,089
Goodwill		1,612					1,612					1,612		1,612		1,612
Total deposits		118,579	[4]				116,118	[4]				118,579	[4]	116,118	[4]	112,608
Segment Reconciling Items [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]											(12)		(3)		(13)
Group Reporting Basis Other operating income												12		3		13
Group Reporting Basis Total operating income												0		0		0
Group Reporting Basis Loan impairment charges												0		0		0
Group Reporting Basis Revenues												0		0		0
Group Reporting Basis Operating expenses	[2]											0		0		0
Group Reporting Basis Income (loss) from continuing operations before income tax												0		0		0
Group Reporting Basis Total assets		0					0					0		0		0
Group Reporting Basis Total loans, net		0					0					0		0		0
Group Reporting Basis Goodwill		0					0					0		0		0
Group Reporting Basis Total deposits		0	[4]				0	[4]				0	[4]	0	[4]	0
Aggregate [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]											2,317		2,236		2,101
Group Reporting Basis Other operating income												1,947		1,899		1,849
Group Reporting Basis Total operating income												4,264		4,135		3,950
Group Reporting Basis Loan impairment charges												264		127		175
Group Reporting Basis Revenues												4,000		4,008		3,775
Group Reporting Basis Operating expenses	[2]											3,245		3,582		3,702
Group Reporting Basis Income (loss) from continuing operations before income tax												755		426		73
Group Reporting Basis Total assets		234,530					239,636					234,530		239,636		232,359
Group Reporting Basis Total loans, net		78,214					73,702					78,214		73,702		63,029
Group Reporting Basis Goodwill		1,264					1,264					1,264		1,264		1,264
Group Reporting Basis Total deposits		94,145	[4]				92,711	[4]				94,145	[4]	92,711	[4]	97,088
Group Reporting Basis Adjustments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]											(78)	[5]	(74)	[5]	(76)
Group Reporting Basis Other operating income												(39)	[5]	(132)	[5]	22
Group Reporting Basis Total operating income												(117)	[5]	(206)	[5]	(54)
Group Reporting Basis Loan impairment charges												130	[5]	80	[5]	0
Group Reporting Basis Revenues												(247)	[5]	(286)	[5]	(54)
Group Reporting Basis Operating expenses	[2]											(52)	[5]	(158)	[5]	201
Group Reporting Basis Income (loss) from continuing operations before income tax												(195)	[5]	(128)	[5]	(255)
Group Reporting Basis Total assets		(46,569)	[5]				(54,138)	[5]				(46,569)	[5]	(54,138)	[5]	(49,879)
Group Reporting Basis Total loans, net		317	[5]				1,032	[5]				317	[5]	1,032	[5]	1,503
Group Reporting Basis Goodwill		348	[5]				348	[5]				348	[5]	348	[5]	348
Group Reporting Basis Total deposits		(4,097)	[4],[5]				(4,811)	[4],[5]				(4,097)	[4],[5]	(4,811)	[4],[5]	(3,869)
Group Reporting Basis Reclassifications [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]											231	[6]	142	[6]	16
Group Reporting Basis Other operating income												(236)	[6]	(161)	[6]	(14)
Group Reporting Basis Total operating income												(5)	[6]	(19)	[6]	2
Group Reporting Basis Loan impairment charges												(33)	[6]	(19)	[6]	18
Group Reporting Basis Revenues												28	[6]	0	[6]	(16)
Group Reporting Basis Operating expenses	[2]											28	[6]	0	[6]	(16)
Group Reporting Basis Income (loss) from continuing operations before income tax												0	[6]	0	[6]	0
Group Reporting Basis Total assets		317	[6]				41	[6]				317	[6]	41	[6]	3,007
Group Reporting Basis Total loans, net		3,474	[6]				2,327	[6]				3,474	[6]	2,327	[6]	2,557
Group Reporting Basis Goodwill		0	[6]				0	[6]				0	[6]	0	[6]	0
Group Reporting Basis Total deposits		28,531	[4],[6]				28,218	[4],[6]				28,531	[4],[6]	28,218	[4],[6]	19,389
RBWM [Member] | Operating Segments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]											776		802		842
Group Reporting Basis Other operating income												333		414		347
Group Reporting Basis Total operating income												1,109		1,216		1,189
Group Reporting Basis Loan impairment charges												64		27		129
Group Reporting Basis Revenues												1,045		1,189		1,060
Group Reporting Basis Operating expenses	[2]											1,133		1,227		1,206
Group Reporting Basis Income (loss) from continuing operations before income tax												(88)		(38)		(146)
Group Reporting Basis Total assets		20,325					19,648					20,325		19,648		19,267
Group Reporting Basis Total loans, net		17,325					16,704					17,325		16,704		16,233
Group Reporting Basis Goodwill		581					581					581		581		581
Group Reporting Basis Total deposits		31,191	[4]				28,323	[4]				31,191	[4]	28,323	[4]	30,220
CMB [Member] | Operating Segments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]											847		800		706
Group Reporting Basis Other operating income												298		308		293
Group Reporting Basis Total operating income												1,145		1,108		999
Group Reporting Basis Loan impairment charges												141		42		45
Group Reporting Basis Revenues												1,004		1,066		954
Group Reporting Basis Operating expenses	[2]											721		683		680
Group Reporting Basis Income (loss) from continuing operations before income tax												283		383		274
Group Reporting Basis Total assets		31,656					29,009					31,656		29,009		23,427
Group Reporting Basis Total loans, net		28,431					27,777					28,431		27,777		22,254
Group Reporting Basis Goodwill		358					358					358		358		358
Group Reporting Basis Total deposits		24,001	[4]				22,086	[4]				24,001	[4]	22,086	[4]	21,601
GBM [Member] | Operating Segments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]											527		378		423
Group Reporting Basis Other operating income												966		1,034		1,165
Group Reporting Basis Total operating income												1,493		1,412		1,588
Group Reporting Basis Loan impairment charges												64		66		(4)
Group Reporting Basis Revenues												1,429		1,346		1,592
Group Reporting Basis Operating expenses	[2]											994		1,308		1,464
Group Reporting Basis Income (loss) from continuing operations before income tax												435		38		128
Group Reporting Basis Total assets		173,321					181,946					173,321		181,946		180,559
Group Reporting Basis Total loans, net		25,743					22,693					25,743		22,693		18,336
Group Reporting Basis Goodwill		0					0					0		0		0
Group Reporting Basis Total deposits		25,142	[4]				31,484	[4]				25,142	[4]	31,484	[4]	33,231
Group Reporting Basis Brokered Deposits									$ 3,700
PB [Member] | Operating Segments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]											201		199		189
Group Reporting Basis Other operating income												99		104		109
Group Reporting Basis Total operating income												300		303		298
Group Reporting Basis Loan impairment charges												(5)		(8)		5
Group Reporting Basis Revenues												305		311		293
Group Reporting Basis Operating expenses	[2]											245		238		254
Group Reporting Basis Income (loss) from continuing operations before income tax												60		73		39
Group Reporting Basis Total assets		8,428					8,184					8,428		8,184		8,340
Group Reporting Basis Total loans, net		6,715					6,528					6,715		6,528		6,206
Group Reporting Basis Goodwill		325					325					325		325		325
Group Reporting Basis Total deposits		13,811	[4]				10,818	[4]				13,811	[4]	10,818	[4]	12,036
Other [Member] | Operating Segments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]											(22)		60		(46)
Group Reporting Basis Other operating income												239		36		(78)
Group Reporting Basis Total operating income												217		96		(124)
Group Reporting Basis Loan impairment charges												0		0		0
Group Reporting Basis Revenues												217		96		(124)
Group Reporting Basis Operating expenses	[2]											152		126		98
Group Reporting Basis Income (loss) from continuing operations before income tax												65		(30)		(222)
Group Reporting Basis Total assets		800					849					800		849		766
Group Reporting Basis Total loans, net		0					0					0		0		0
Group Reporting Basis Goodwill		0					0					0		0		0
Group Reporting Basis Total deposits		$ 0	[4]				$ 0	[4]				$ 0	[4]	$ 0	[4]	$ 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 December 31, 2015 and December 31, 2014 which are consolidated on our balance sheet. Assets and liabilities exclude intercompany balances that eliminate in consolidation. See Note 24, "Variable Interest Entities," for additional information. Assets: Other assets $320 million and $380 million. Total assets $320 million and $380 million respectively. Liabilities: Long-term debt $92 million and $92 million, Interest, taxes and other liabilities $68 million and $75 million. Total liabilities $160 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 $3.7 billion of brokered deposits in the GB&M segment to debt at December 31, 2014 to conform with the current year presentation. There was no impact at December 31, 2013.

[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.