Regulation and Capital Adequacy - Consolidated Regulatory Capital Ratios (Detail) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016	Jan. 01, 2016
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Preferred stock	$ 11,203	$ 11,203
Tier 1 leverage ratio	9.50%	9.40%
Standardized Capital Rules [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common shareholders' equity	$ 75,714	$ 75,690
Deductions for goodwill and identifiable intangible assets, net of deferred tax liabilities	(2,923)	(2,874)
Deductions for investments in nonconsolidated financial institutions	(461)	(424)
Other adjustments	(493)	(346)
Total Common Equity Tier 1	71,837	72,046	$ 71,363
Preferred stock	11,203	11,203
Deduction for investments in covered funds	(328)	(445)
Other adjustments	(199)	(364)
Tier 1 capital	82,513	82,440	81,511
Qualifying subordinated debt	14,336	14,566
Junior subordinated debt issued to trusts	660	792
Allowance for losses on loans and lending commitments	791	722
Other adjustments	(6)	(6)
Tier 2 capital	15,781	16,074	16,705
Total capital	98,294	98,514
RWAs	$ 507,401	$ 496,676	524,107
CET1 ratio	14.20%	14.50%
Tier 1 capital ratio	16.30%	16.60%
Total capital ratio	19.40%	19.80%
Basel III Advanced Transitional [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Common Equity Tier 1	$ 71,837	$ 72,046	71,363
Tier 1 capital	82,513	82,440	81,511
Allowance for losses on loans and lending commitments	(791)	(722)
Tier 2 capital	14,990	15,352	16,103
Total capital	97,503	97,792
Standardized Tier 2 capital	15,781	16,074
RWAs	$ 558,276	$ 549,650	$ 577,651
CET1 ratio	12.90%	13.10%
Tier 1 capital ratio	14.80%	15.00%
Total capital ratio	17.50%	17.80%