Commitments and Contingent Liabilities - Additional Information (Detail)				3 Months Ended
		May. 21, 2015 USD ($)	Mar. 19, 2015 USD ($)	Mar. 31, 2016 USD ($) LegalMatter	Feb. 29, 2016 LegalMatter	Dec. 31, 2015 USD ($)	Dec. 17, 2015 LegalMatter	Jun. 18, 2014 trust	Jan. 18, 2008 USD ($)
Commitments and Contingencies Disclosure [Line Items]
Lending commitment maturing in less than one year				$ 31,300,000,000
Lending commitment maturing in one to five years				22,600,000,000
Lending commitment maturing over five years				$ 223,000,000
Maximum maturities of prearranged contract for a securities lending transaction (in days)				90 days
Cash collateralization percentage generally required for a securities lending transaction with indemnification against broker default (percent)				102.00%
Securities lending indemnifications, secured amount of collateral				$ 334,000,000,000		$ 306,000,000,000
Securities lending indemnifications joint venture				55,000,000,000		54,000,000,000
Securities Lending Indemnifications Collateral Joint Venture				$ 58,000,000,000		56,000,000,000
Bank filed a proof of claim on Jan. 18, 2008 in the Chapter 11 bankruptcy of Sentinel Management Group, Inc. (Sentinel), seeking to recover approximate amount loaned to Sentinel									$ 312,000,000
FX-related settlements			$ 714,000,000
FX Settlement SEC penalty		$ 30,000,000
Loss contingency, number of MBS trusts | trust								260
Number of lawsuits pending related to Stanford Matter (legal matters) | LegalMatter				13
Arbitration claims related to Stanford matter pending | LegalMatter				5
Brazil Matter -Number of Lawsuits filed | LegalMatter							3
DR Matters -Number of Class Action Lawsuits filed | LegalMatter					4
Standby letters of credit
Commitments and Contingencies Disclosure [Line Items]
Off balance sheet credit risk	[1]			$ 4,767,000,000		4,915,000,000
SBLCs collateralized with cash and securities				354,000,000		299,000,000
SBLCs expiring within one year				3,100,000,000
SBLCs expiring within one to five years				1,700,000,000
Commercial letters of credit
Commitments and Contingencies Disclosure [Line Items]
Off balance sheet credit risk				226,000,000		303,000,000
Operations
Commitments and Contingencies Disclosure [Line Items]
Allowance for lending related commitments				125,000,000		$ 118,000,000
Maximum
Commitments and Contingencies Disclosure [Line Items]
Loss contingency, aggregate range of reasonable loss (up to)				$ 710,000,000

[1] Net of participations totaling $864 million at March 31, 2016 and $809 million at Dec. 31, 2015.