Fair Value Measurements - Financial Assets Liabilities Summary (Detail) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total financial assets at fair value	$ 508,954	$ 497,693
Total assets	$ 894,069	$ 860,165	$ 878,036
Total level 3 financial assets as a percentage of total assets	2.60%	2.70%
Total level 3 financial assets as a percentage of total financial assets at fair value	4.60%	4.70%
Total financial liabilities at fair value	$ 297,084	$ 271,284
Total level 3 financial liabilities as a percentage of total financial liabilities at fair value	7.10%	7.90%
Counterparty and Cash Collateral Netting [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total financial assets at fair value	$ (78,540)	$ (87,038)
Total financial liabilities at fair value	(37,802)	(44,695)
Investments in funds at NAV [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total financial assets at fair value	6,183	6,465
Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total financial assets at fair value	151,691	135,401
Total financial liabilities at fair value	67,732	62,504
Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total financial assets at fair value	406,332	419,585
Total financial liabilities at fair value	246,087	232,027
Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total financial assets at fair value	23,288	23,280
Total financial liabilities at fair value	$ 21,067	$ 21,448