Business Segments - Summary on Reconciliation of Results Under Ifrs to Us Gaap (Detail) - USD ($) $ in Millions		3 Months Ended										12 Months Ended
		Dec. 31, 2016		Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015		Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]											$ 2,471		$ 2,317		$ 2,236
Group Reporting Basis Other operating income												1,523		1,947		1,899
Group Reporting Basis Total operating income												3,994		4,264		4,135
Group Reporting Basis Loan impairment charges												494		264		127
Group Reporting Basis Revenues												3,500		4,000		4,008
Group Reporting Basis Operating expenses	[2]											3,206		3,245		3,582
Group Reporting Basis Income (loss) from continuing operations before income tax												294		755		426
Group Reporting Basis Total assets		$ 246,506					$ 234,530					246,506		234,530		239,636
Group Reporting Basis Total loans, net		72,464					78,214					72,464		78,214		73,702
Group Reporting Basis Goodwill		1,264					1,264					1,264		1,264		1,264
Group Reporting Basis Total deposits		95,344					94,145					95,344		94,145		92,711
Net interest income		588		$ 604	$ 638	$ 654	621		$ 617	$ 626	$ 606	2,484	[1]	2,470	[1]	2,304	[1]
Other operating income		257		320	293	462	274		531	403	464	1,332		1,672		1,606
Total operating income												3,816		4,142		3,910
Loan impairment charges		19		62	134	157	267		47	(6)	53	372	[3]	361		188
Total income												3,444		3,781		3,722
Operating expenses		874		803	823	726	808		786	850	777	3,226	[2]	3,221	[2]	3,424	[2]
Income before income tax		(48)		$ 59	$ (26)	$ 233	(180)		$ 315	$ 185	$ 240	218		560		298
Total assets		201,301	[4]				188,278	[4]				201,301	[4]	188,278	[4]	185,539
Total loans, net		72,858					82,005					72,858		82,005		77,061
Goodwill		1,612					1,612					1,612		1,612		1,612
Total deposits		129,248					118,579					129,248		118,579		116,118
Group Reporting Basis Adjustments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1],[5]											(76)		(78)		(74)
Group Reporting Basis Other operating income	[5]											(104)		(39)		(132)
Group Reporting Basis Total operating income	[5]											(180)		(117)		(206)
Group Reporting Basis Loan impairment charges	[5]											(78)		130		80
Group Reporting Basis Revenues	[5]											(102)		(247)		(286)
Group Reporting Basis Operating expenses	[2],[5]											(26)		(52)		(158)
Group Reporting Basis Income (loss) from continuing operations before income tax	[5]											(76)		(195)		(128)
Group Reporting Basis Total assets	[5]	(45,234)					(46,569)					(45,234)		(46,569)		(54,138)
Group Reporting Basis Total loans, net	[5]	(405)					317					(405)		317		1,032
Group Reporting Basis Goodwill	[5]	348					348					348		348		348
Group Reporting Basis Total deposits	[5]	(4,379)					(4,097)					(4,379)		(4,097)		(4,811)
Group Reporting Basis Reclassifications [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1],[6]											89		231		142
Group Reporting Basis Other operating income	[6]											(87)		(236)		(161)
Group Reporting Basis Total operating income	[6]											2		(5)		(19)
Group Reporting Basis Loan impairment charges	[6]											(44)		(33)		(19)
Group Reporting Basis Revenues	[6]											46		28		0
Group Reporting Basis Operating expenses	[2],[6]											46		28		0
Group Reporting Basis Income (loss) from continuing operations before income tax	[6]											0		0		0
Group Reporting Basis Total assets	[6]	29					317					29		317		41
Group Reporting Basis Total loans, net	[6]	799					3,474					799		3,474		2,327
Group Reporting Basis Goodwill	[6]	0					0					0		0		0
Group Reporting Basis Total deposits	[6]	38,283					28,531					38,283		28,531		28,218
Adjustments/Reconciling Items [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]											(2)		(12)		(3)
Group Reporting Basis Other operating income												2		12		3
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					0					0		0		0
RBWM [Member] | Operating Segments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]											807		793		820
Group Reporting Basis Other operating income												370		336		417
Group Reporting Basis Total operating income												1,177		1,129		1,237
Group Reporting Basis Loan impairment charges												60		65		29
Group Reporting Basis Revenues												1,117		1,064		1,208
Group Reporting Basis Operating expenses	[2]											1,144		1,185		1,294
Group Reporting Basis Income (loss) from continuing operations before income tax												(27)		(121)		(86)
Group Reporting Basis Total assets		20,203					20,396					20,203		20,396		19,731
Group Reporting Basis Total loans, net		17,473					17,396					17,473		17,396		16,787
Group Reporting Basis Goodwill		581					581					581		581		581
Group Reporting Basis Total deposits		32,472					31,814					32,472		31,814		29,005
CMB [Member] | Operating Segments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]											735		736		703
Group Reporting Basis Other operating income												227		244		272
Group Reporting Basis Total operating income												962		980		975
Group Reporting Basis Loan impairment charges												50		139		36
Group Reporting Basis Revenues												912		841		939
Group Reporting Basis Operating expenses	[2]											588		608		561
Group Reporting Basis Income (loss) from continuing operations before income tax												324		233		378
Group Reporting Basis Total assets		25,082					26,763					25,082		26,763		25,122
Group Reporting Basis Total loans, net		24,125					23,538					24,125		23,538		23,890
Group Reporting Basis Goodwill		358					358					358		358		358
Group Reporting Basis Total deposits		22,005					20,599					22,005		20,599		20,275
GBM [Member] | Operating Segments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]											780		621		457
Group Reporting Basis Other operating income												766		1,017		1,067
Group Reporting Basis Total operating income												1,546		1,638		1,524
Group Reporting Basis Loan impairment charges												384		65		70
Group Reporting Basis Revenues												1,162		1,573		1,454
Group Reporting Basis Operating expenses	[2]											987		1,055		1,363
Group Reporting Basis Income (loss) from continuing operations before income tax												175		518		91
Group Reporting Basis Total assets		192,995					178,143					192,995		178,143		185,750
Group Reporting Basis Total loans, net		24,842					30,565					24,842		30,565		26,497
Group Reporting Basis Goodwill		0					0					0		0		0
Group Reporting Basis Total deposits		29,249					27,921					29,249		27,921		32,613
PB [Member] | Operating Segments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]											202		201		199
Group Reporting Basis Other operating income												89		99		104
Group Reporting Basis Total operating income												291		300		303
Group Reporting Basis Loan impairment charges												0		(5)		(8)
Group Reporting Basis Revenues												291		305		311
Group Reporting Basis Operating expenses	[2]											232		245		238
Group Reporting Basis Income (loss) from continuing operations before income tax												59		60		73
Group Reporting Basis Total assets		7,714					8,428					7,714		8,428		8,184
Group Reporting Basis Total loans, net		6,024					6,715					6,024		6,715		6,528
Group Reporting Basis Goodwill		325					325					325		325		325
Group Reporting Basis Total deposits		11,618					13,811					11,618		13,811		10,818
Other [Member] | Operating Segments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income	[1]											(51)		(22)		60
Group Reporting Basis Other operating income												69		239		36
Group Reporting Basis Total operating income												18		217		96
Group Reporting Basis Loan impairment charges												0		0		0
Group Reporting Basis Revenues												18		217		96
Group Reporting Basis Operating expenses	[2]											255		152		126
Group Reporting Basis Income (loss) from continuing operations before income tax												(237)		65		(30)
Group Reporting Basis Total assets		512					800					512		800		849
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					$ 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 the 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 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 7, "Loans Held for Sale," for additional information.

[4] The following table summarizes assets and liabilities related to our consolidated variable interest entities ("VIEs") at December 31, 2016 and December 31, 2015 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 $231 million and $320 million. Total assets $231 million and $320 million respectively. Liabilities: Long-term debt $79 million and $92 million, Interest, taxes and other liabilities $60 million and $68 million. Total liabilities $139 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.