Derivatives and Hedging Activities - Fair Value of Derivatives by Level (Detail) - USD ($) $ in Millions	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015
Derivative [Line Items]
Total financial assets at fair value	$ 503,915	$ 509,779	$ 526,687
Fair value included in financial instruments owned	292,420		293,940
Total financial liabilities at fair value	(274,802)	(287,653)	(280,939)
Fair value included in financial instruments sold, but not yet purchased	(115,154)		(115,248)
Level 1 [Member]
Derivative [Line Items]
Total financial assets at fair value	146,775	129,627	153,051
Total financial liabilities at fair value	(62,631)	(62,841)	(59,798)
Level 2 [Member]
Derivative [Line Items]
Total financial assets at fair value	426,203	451,127	432,445
Total financial liabilities at fair value	(243,800)	(256,973)	(245,759)
Level 3 [Member]
Derivative [Line Items]
Total financial assets at fair value	24,289	24,732	24,046
Total financial liabilities at fair value	(19,021)	(19,335)	(16,812)
Derivatives [Member]
Derivative [Line Items]
Total financial assets at fair value	154,955		144,502
Fair value included in financial instruments owned	54,744		53,890
Total financial liabilities at fair value	(95,089)		(88,201)
Fair value included in financial instruments sold, but not yet purchased	(44,439)		(46,771)
Derivatives [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Total financial assets at fair value	753,057		568,325
Total financial liabilities at fair value	(697,099)		(514,244)
Derivatives [Member] | Credit Risk Contract [Member]
Derivative [Line Items]
Total financial assets at fair value	30,651		40,882
Total financial liabilities at fair value	(27,306)		(36,775)
Derivatives [Member] | Foreign Exchange Contract [Member]
Derivative [Line Items]
Total financial assets at fair value	82,707		97,148
Total financial liabilities at fair value	(79,914)		(99,600)
Derivatives [Member] | Commodity Contract [Member]
Derivative [Line Items]
Total financial assets at fair value	13,871		20,674
Total financial liabilities at fair value	(14,983)		(21,071)
Derivatives [Member] | Equity Contract [Member]
Derivative [Line Items]
Total financial assets at fair value	47,257		47,160
Total financial liabilities at fair value	(48,375)		(46,198)
Derivatives [Member] | Gross Fair Value Of Derivative [Member]
Derivative [Line Items]
Total financial assets at fair value	927,543		774,189
Total financial liabilities at fair value	(867,677)		(717,888)
Derivatives [Member] | Counterparty Netting With in Levels [Member]
Derivative [Line Items]
Total financial assets at fair value	(772,588)		(629,687)
Total financial liabilities at fair value	772,588		629,687
Derivatives [Member] | Cross Level Counterparty Netting Adjustment [Member]
Derivative [Line Items]
Total financial assets at fair value	(1,603)		(1,480)
Total financial liabilities at fair value	1,603		1,480
Derivatives [Member] | Cash Collateral Netting [Member]
Derivative [Line Items]
Cash collateral netting	(98,608)		(89,132)
Cash collateral netting	49,047		39,950
Derivatives [Member] | Level 1 [Member]
Derivative [Line Items]
Total financial assets at fair value	19		50
Total financial liabilities at fair value	(575)		(29)
Derivatives [Member] | Level 1 [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Total financial assets at fair value	9		4
Total financial liabilities at fair value	(22)		(11)
Derivatives [Member] | Level 1 [Member] | Equity Contract [Member]
Derivative [Line Items]
Total financial assets at fair value	11		46
Total financial liabilities at fair value	(554)		(18)
Derivatives [Member] | Level 1 [Member] | Gross Fair Value Of Derivative [Member]
Derivative [Line Items]
Total financial assets at fair value	20		50
Total financial liabilities at fair value	(576)		(29)
Derivatives [Member] | Level 1 [Member] | Counterparty Netting With in Levels [Member]
Derivative [Line Items]
Total financial assets at fair value	(1)
Total financial liabilities at fair value	1
Derivatives [Member] | Level 2 [Member]
Derivative [Line Items]
Total financial assets at fair value	148,843		138,582
Total financial liabilities at fair value	(90,713)		(82,797)
Derivatives [Member] | Level 2 [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Total financial assets at fair value	752,087		567,761
Total financial liabilities at fair value	(696,170)		(513,275)
Derivatives [Member] | Level 2 [Member] | Credit Risk Contract [Member]
Derivative [Line Items]
Total financial assets at fair value	24,863		34,832
Total financial liabilities at fair value	(24,429)		(33,518)
Derivatives [Member] | Level 2 [Member] | Foreign Exchange Contract [Member]
Derivative [Line Items]
Total financial assets at fair value	82,474		96,959
Total financial liabilities at fair value	(79,713)		(99,377)
Derivatives [Member] | Level 2 [Member] | Commodity Contract [Member]
Derivative [Line Items]
Total financial assets at fair value	13,469		20,087
Total financial liabilities at fair value	(14,579)		(20,222)
Derivatives [Member] | Level 2 [Member] | Equity Contract [Member]
Derivative [Line Items]
Total financial assets at fair value	46,612		46,491
Total financial liabilities at fair value	(46,484)		(43,953)
Derivatives [Member] | Level 2 [Member] | Gross Fair Value Of Derivative [Member]
Derivative [Line Items]
Total financial assets at fair value	919,505		766,130
Total financial liabilities at fair value	(861,375)		(710,345)
Derivatives [Member] | Level 2 [Member] | Counterparty Netting With in Levels [Member]
Derivative [Line Items]
Total financial assets at fair value	(770,662)		(627,548)
Total financial liabilities at fair value	770,662		627,548
Derivatives [Member] | Level 3 [Member]
Derivative [Line Items]
Total financial assets at fair value	6,093	$ 6,553	5,870
Total financial liabilities at fair value	(3,801)		(5,375)
Derivatives [Member] | Level 3 [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Total financial assets at fair value	961		560
Total financial liabilities at fair value	(907)		(958)
Derivatives [Member] | Level 3 [Member] | Credit Risk Contract [Member]
Derivative [Line Items]
Total financial assets at fair value	5,788		6,050
Total financial liabilities at fair value	(2,877)		(3,257)
Derivatives [Member] | Level 3 [Member] | Foreign Exchange Contract [Member]
Derivative [Line Items]
Total financial assets at fair value	233		189
Total financial liabilities at fair value	(201)		(223)
Derivatives [Member] | Level 3 [Member] | Commodity Contract [Member]
Derivative [Line Items]
Total financial assets at fair value	402		587
Total financial liabilities at fair value	(404)		(849)
Derivatives [Member] | Level 3 [Member] | Equity Contract [Member]
Derivative [Line Items]
Total financial assets at fair value	634		623
Total financial liabilities at fair value	(1,337)		(2,227)
Derivatives [Member] | Level 3 [Member] | Gross Fair Value Of Derivative [Member]
Derivative [Line Items]
Total financial assets at fair value	8,018		8,009
Total financial liabilities at fair value	(5,726)		(7,514)
Derivatives [Member] | Level 3 [Member] | Counterparty Netting With in Levels [Member]
Derivative [Line Items]
Total financial assets at fair value	(1,925)		(2,139)
Total financial liabilities at fair value	$ 1,925		$ 2,139