Fair Value Option - Financial Assets and Financial Liabilities by Level (Detail) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities purchased under agreements to resell	$ 116,546	$ 116,077
Securities borrowed	79,893	82,398
Receivables from customers and counterparties	3,644	3,266
Total financial assets at fair value	200,083	201,741
Deposits	(19,480)	(13,782)
Securities sold under agreements to repurchase	(88,533)	(71,816)
Securities loaned	(4,403)	(2,647)
Other secured financings	(21,960)	(21,073)
Unsecured borrowings Short-term	(13,900)	(14,792)
Unsecured borrowings Long-term	(32,075)	(29,410)
Other liabilities and accrued expenses	(806)	(621)
Total financial liabilities at fair value	(181,157)	(154,141)
Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities purchased under agreements to resell	116,546	116,077
Securities borrowed	79,893	82,398
Receivables from customers and counterparties	3,630	3,211
Total financial assets at fair value	200,069	201,686
Deposits	(16,132)	(10,609)
Securities sold under agreements to repurchase	(88,469)	(71,750)
Securities loaned	(4,403)	(2,647)
Other secured financings	(21,392)	(20,516)
Unsecured borrowings Short-term	(9,656)	(10,896)
Unsecured borrowings Long-term	(24,197)	(22,185)
Other liabilities and accrued expenses	(743)	(559)
Total financial liabilities at fair value	(164,992)	(139,162)
Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Receivables from customers and counterparties	14	55
Total financial assets at fair value	14	55
Deposits	(3,348)	(3,173)
Securities sold under agreements to repurchase	(64)	(66)
Other secured financings	(568)	(557)
Unsecured borrowings Short-term	(4,244)	(3,896)
Unsecured borrowings Long-term	(7,878)	(7,225)
Other liabilities and accrued expenses	(63)	(62)
Total financial liabilities at fair value	$ (16,165)	$ (14,979)