Business Segments - Summary on Reconciliation of Results Under Ifrs to Us Gaap (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended										12 Months Ended
	Dec. 31, 2014		Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013		Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Operating Statistics [Line Items]
Net interest income	$ 569		$ 543	$ 673	$ 519	$ 526		$ 492	$ 518	$ 505	$ 2,304	[1]	$ 2,041	[1]	$ 2,158	[1]
Other operating income	459		386	261	500	267		432	566	592	1,606		1,857		1,973
Total operating income											3,910		3,898		4,131
Loan impairment charges	64		23	85	16	51		54	67	21	188		193		293
Total income											3,722		3,705		3,838
Operating expenses	864		934	876	750	1,519		834	766	768	3,424	[2]	3,887	[2]	4,664	[2]
Income (loss) from continuing operations before income tax	100		(28)	(27)	253	(777)		36	251	308	298		(182)		(826)
Total assets	185,539	[3]				185,487	[3]				185,539	[3]	185,487	[3]	191,446
Total loans, net	77,061					67,089					77,061		67,089		62,611
Goodwill	1,612					1,612					1,612		1,612		2,228
Total deposits	116,118					112,608					116,118		112,608		117,671
Group Reporting Basis Adjustments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income											(74)	[1]	(76)	[1]	(123)	[1]
Group Reporting Basis Other operating income											(132)		22		43
Group Reporting Basis Total operating income											(206)		(54)		(80)
Group Reporting Basis Loan impairment charges											80		0		73
Group Reporting Basis Revenues											(286)		(54)		(153)
Group Reporting Basis Operating expenses											(158)	[2]	201	[2]	(36)	[2]
Group Reporting Basis Income (loss) from continuing operations before income tax											(128)		(255)		(117)
Group Reporting Basis Total assets	(54,138)					(49,879)					(54,138)		(49,879)		(67,543)
Group Reporting Basis Total loans, net	1,032					1,503					1,032		1,503		3,495
Group Reporting Basis Goodwill	348					348					348		348		484
Group Reporting Basis Total deposits	(4,811)					(3,869)					(4,811)		(3,869)		(5,122)
Group Reporting Basis Reclassifications [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income											142	[1]	16	[1]	22	[1]
Group Reporting Basis Other operating income											(161)		(14)		68
Group Reporting Basis Total operating income											(19)		2		90
Group Reporting Basis Loan impairment charges											(19)		18		16
Group Reporting Basis Revenues											0		(16)		74
Group Reporting Basis Operating expenses											0	[2]	(16)	[2]	74	[2]
Group Reporting Basis Income (loss) from continuing operations before income tax											0		0		0
Group Reporting Basis Total assets	41					3,007					41		3,007		94
Group Reporting Basis Total loans, net	2,327					2,557					2,327		2,557		(297)
Group Reporting Basis Goodwill	0					0					0		0		0
Group Reporting Basis Total deposits	24,559					19,389					24,559		19,389		16,353
Aggregate [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income											2,236	[1]	2,101	[1]	2,259	[1]
Group Reporting Basis Other operating income											1,899		1,849		1,862
Group Reporting Basis Total operating income											4,135		3,950		4,121
Group Reporting Basis Loan impairment charges											127		175		204
Group Reporting Basis Revenues											4,008		3,775		3,917
Group Reporting Basis Operating expenses											3,582	[2]	3,702	[2]	4,626	[2]
Group Reporting Basis Income (loss) from continuing operations before income tax											426		73		(709)
Group Reporting Basis Total assets	239,636					232,359					239,636		232,359		258,895
Group Reporting Basis Total loans, net	73,702					63,029					73,702		63,029		59,413
Group Reporting Basis Goodwill	1,264					1,264					1,264		1,264		1,744
Group Reporting Basis Total deposits	96,370					97,088					96,370		97,088		106,440
Segment Reconciling Items [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income											(3)	[1]	(13)	[1]	(15)	[1]
Group Reporting Basis Other operating income											3		13		15
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											0	[2]	0	[2]	0	[2]
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											802	[1]	842	[1]	854	[1]
Group Reporting Basis Other operating income											414		347		555
Group Reporting Basis Total operating income											1,216		1,189		1,409
Group Reporting Basis Loan impairment charges											27		129		204
Group Reporting Basis Revenues											1,189		1,060		1,205
Group Reporting Basis Operating expenses											1,227	[2]	1,206	[2]	1,301	[2]
Group Reporting Basis Income (loss) from continuing operations before income tax											(38)		(146)		(96)
Group Reporting Basis Total assets	19,648					19,267					19,648		19,267		22,789
Group Reporting Basis Total loans, net	16,704					16,233					16,704		16,233		16,422
Group Reporting Basis Goodwill	581					581					581		581		581
Group Reporting Basis Total deposits	28,323					30,220					28,323		30,220		35,406
CMB [Member] | Operating Segments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income											800	[1]	706	[1]	673	[1]
Group Reporting Basis Other operating income											308		293		539
Group Reporting Basis Total operating income											1,108		999		1,212
Group Reporting Basis Loan impairment charges											42		45		4
Group Reporting Basis Revenues											1,066		954		1,208
Group Reporting Basis Operating expenses											683	[2]	680	[2]	631	[2]
Group Reporting Basis Income (loss) from continuing operations before income tax											383		274		577
Group Reporting Basis Total assets	29,009					23,427					29,009		23,427		23,585
Group Reporting Basis Total loans, net	27,777					22,254					27,777		22,254		19,754
Group Reporting Basis Goodwill	358					358					358		358		358
Group Reporting Basis Total deposits	22,086					21,601					22,086		21,601		21,759
GBM [Member] | Operating Segments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income											378	[1]	423	[1]	606	[1]
Group Reporting Basis Other operating income											1,034		1,165		916
Group Reporting Basis Total operating income											1,412		1,588		1,522
Group Reporting Basis Loan impairment charges											66		(4)		(1)
Group Reporting Basis Revenues											1,346		1,592		1,523
Group Reporting Basis Operating expenses											1,308	[2]	1,464	[2]	997	[2]
Group Reporting Basis Income (loss) from continuing operations before income tax											38		128		526
Group Reporting Basis Total assets	181,946					180,559					181,946		180,559		203,680
Group Reporting Basis Total loans, net	22,693					18,336					22,693		18,336		17,530
Group Reporting Basis Goodwill	0					0					0		0		480
Group Reporting Basis Total deposits	35,143					33,231					35,143		33,231		37,134
PB [Member] | Operating Segments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income											199	[1]	189	[1]	184	[1]
Group Reporting Basis Other operating income											104		109		106
Group Reporting Basis Total operating income											303		298		290
Group Reporting Basis Loan impairment charges											(8)		5		(3)
Group Reporting Basis Revenues											311		293		293
Group Reporting Basis Operating expenses											238	[2]	254	[2]	232	[2]
Group Reporting Basis Income (loss) from continuing operations before income tax											73		39		61
Group Reporting Basis Total assets	8,184					8,340					8,184		8,340		8,208
Group Reporting Basis Total loans, net	6,528					6,206					6,528		6,206		5,707
Group Reporting Basis Goodwill	325					325					325		325		325
Group Reporting Basis Total deposits	10,818					12,036					10,818		12,036		12,141
Other [Member] | Operating Segments [Member]
Operating Statistics [Line Items]
Group Reporting Basis Net interest income											60	[1]	(46)	[1]	(43)	[1]
Group Reporting Basis Other operating income											36		(78)		(269)
Group Reporting Basis Total operating income											96		(124)		(312)
Group Reporting Basis Loan impairment charges											0		0		0
Group Reporting Basis Revenues											96		(124)		(312)
Group Reporting Basis Operating expenses											126	[2]	98	[2]	1,465	[2]
Group Reporting Basis Income (loss) from continuing operations before income tax											(30)		(222)		(1,777)
Group Reporting Basis Total assets	849					766					849		766		633
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 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, 2014 and December 31, 2013 which are consolidated on our balance sheet. Assets and liabilities exclude intercompany balances that eliminate in consolidation. See Note 25, "Variable Interest Entities," for additional information. Assets: Interest bearing deposits with banks, $0 million and $5 million, Securities held-to-maturity, $0 million and $200 million Other assets $380 million and $502 million. Total assets $380 million and $707 million respectively. Liabilities: Long-term debt $92 million and $92 million, Interest, taxes and other liabilities $75 million and $93 million. Total liabilities $167 million and $185 million, respectively.