Fair Value Measurements - Changes in Fair Value of Level 3 Assets and Liabilities (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance	$ 3,181		$ 3,884		$ 3,690		$ 4,157
Fair Value Assets, Trading Revenue (Loss)	(124)	[1]	22	[1]	(38)	[1]	(204)	[1]
Fair Value Assets, Other Revenue	24	[1]	(44)	[1]	39	[1]	(44)	[1]
Fair Value Assets, Purchases	232		432		268		515
Fair Value Assets, Issuances	5		1		11		9
Fair Value Assets, Settlements	(688)		(294)		(1,288)		(417)
Transfers Into Level 3	0		(1)		(46)		(4)
Fair Value Assets, Transfers Out of Level 3	(15)		6		(21)		(6)
Fair Value Assets, Ending Balance	2,615		4,006		2,615		4,006
Fair Value Assets, Current Period Unrealized Gains (Losses)	(127)		(49)		(96)		(286)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Liability, Beginning Balance	(3,494)		(3,124)		(3,065)		(2,953)
Fair Value Liability, Trading Revenue (Loss)	169	[1]	(11)	[1]	97	[1]	(68)	[1]
Fair Value Liability, Purchases	0		0		0		0
Fair Value Liability, Issuances	(140)		(401)		(755)		(777)
Fair Value Liability, Settlements	178		80		338		165
Fair Value Liability, Transfers Into Level 3	(177)		(53)		(160)		(50)
Fair Value Liability, Transfers Out of Level 3	344		314		425		488
Fair Value Liability, Ending Balance	(3,120)		(3,195)		(3,120)		(3,195)
Fair Value Liability, Current Period Unrealized Gains (Losses)	193		(9)		156		(46)
Interest rate contracts [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance	6	[2]	9	[2]	7	[2]	9	[2]
Fair Value Assets, Trading Revenue (Loss)	(1)	[1],[2]	0	[1],[2]	(1)	[1],[2]	0	[1],[2]
Fair Value Assets, Other Revenue	(6)	[1],[2]	3	[1],[2]	(7)	[1],[2]	3	[1],[2]
Fair Value Assets, Purchases	0	[2]	0	[2]	0	[2]	0	[2]
Fair Value Assets, Issuances	0	[2]	0	[2]	0	[2]	0	[2]
Fair Value Assets, Settlements	0	[2]	0	[2]	0	[2]	0	[2]
Transfers Into Level 3	0	[2]	0	[2]	0	[2]	0	[2]
Fair Value Assets, Transfers Out of Level 3	0	[2]	0	[2]	0	[2]	0	[2]
Fair Value Assets, Ending Balance	(1)	[2]	12	[2]	(1)	[2]	12	[2]
Fair Value Assets, Current Period Unrealized Gains (Losses)	(7)	[2]	3	[2]	(8)	[2]	3	[2]
Foreign exchange contracts [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance	134	[2]	(5)	[2]	5	[2]	(1)	[2]
Fair Value Assets, Trading Revenue (Loss)	(18)	[1],[2]	(18)	[1],[2]	(4)	[1],[2]	(19)	[1],[2]
Fair Value Assets, Other Revenue	0	[1],[2]	0	[1],[2]	0	[1],[2]	0	[1],[2]
Fair Value Assets, Purchases	0	[2]	0	[2]	0	[2]	0	[2]
Fair Value Assets, Issuances	0	[2]	(5)	[2]	0	[2]	(5)	[2]
Fair Value Assets, Settlements	(6)	[2]	2	[2]	116	[2]	2	[2]
Transfers Into Level 3	(6)	[2]	0	[2]	(13)	[2]	(3)	[2]
Fair Value Assets, Transfers Out of Level 3	0	[2]	1	[2]	0	[2]	1	[2]
Fair Value Assets, Ending Balance	104	[2]	(25)	[2]	104	[2]	(25)	[2]
Fair Value Assets, Current Period Unrealized Gains (Losses)	(28)	[2]	(17)	[2]	106	[2]	(19)	[2]
Equity contracts [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance	34	[2]	(53)	[2]	(7)	[2]	(83)	[2]
Fair Value Assets, Trading Revenue (Loss)	(81)	[1],[2]	13	[1],[2]	(20)	[1],[2]	63	[1],[2]
Fair Value Assets, Other Revenue	0	[1],[2]	0	[1],[2]	0	[1],[2]	0	[1],[2]
Fair Value Assets, Purchases	0	[2]	0	[2]	0	[2]	0	[2]
Fair Value Assets, Issuances	0	[2]	0	[2]	0	[2]	0	[2]
Fair Value Assets, Settlements	(27)	[2]	(10)	[2]	(48)	[2]	(29)	[2]
Transfers Into Level 3	6	[2]	(1)	[2]	13	[2]	(1)	[2]
Fair Value Assets, Transfers Out of Level 3	(15)	[2]	5	[2]	(21)	[2]	4	[2]
Fair Value Assets, Ending Balance	(83)	[2]	(46)	[2]	(83)	[2]	(46)	[2]
Fair Value Assets, Current Period Unrealized Gains (Losses)	(92)	[2]	(1)	[2]	(73)	[2]	22	[2]
Credit contracts [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance	364	[2]	984	[2]	571	[2]	1,353	[2]
Fair Value Assets, Trading Revenue (Loss)	(105)	[1],[2]	(13)	[1],[2]	(155)	[1],[2]	(388)	[1],[2]
Fair Value Assets, Other Revenue	0	[1],[2]	0	[1],[2]	0	[1],[2]	0	[1],[2]
Fair Value Assets, Purchases	0	[2]	0	[2]	0	[2]	0	[2]
Fair Value Assets, Issuances	0	[2]	0	[2]	0	[2]	0	[2]
Fair Value Assets, Settlements	(34)	[2]	(50)	[2]	(145)	[2]	(44)	[2]
Transfers Into Level 3	0	[2]	0	[2]	46	[2]	0	[2]
Fair Value Assets, Transfers Out of Level 3	0	[2]	0	[2]	0	[2]	0	[2]
Fair Value Assets, Ending Balance	225	[2]	921	[2]	225	[2]	921	[2]
Fair Value Assets, Current Period Unrealized Gains (Losses)	(82)	[2]	(22)	[2]	(274)	[2]	(355)	[2]
Collateralized debt obligations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance	481		661		466		703
Fair Value Assets, Trading Revenue (Loss)	83	[1]	18	[1]	118	[1]	57	[1]
Fair Value Assets, Other Revenue	0	[1]	0	[1]	0	[1]	0	[1]
Fair Value Assets, Purchases	216		24		237		25
Fair Value Assets, Issuances	0		0		0		0
Fair Value Assets, Settlements	(553)		(45)		(594)		(127)
Transfers Into Level 3	0		0		0		0
Fair Value Assets, Transfers Out of Level 3	0		0		0		0
Fair Value Assets, Ending Balance	227		658		227		658
Fair Value Assets, Current Period Unrealized Gains (Losses)	56		16		87		49
Corporate and other domestic [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance	1,524		1,753		1,861		1,679
Fair Value Assets, Trading Revenue (Loss)	21	[1]	(2)	[1]	28	[1]	18	[1]
Fair Value Assets, Other Revenue	0	[1]	0	[1]	0	[1]	0	[1]
Fair Value Assets, Purchases	16		19		31		101
Fair Value Assets, Issuances	0		0		0		0
Fair Value Assets, Settlements	(63)		(171)		(422)		(199)
Transfers Into Level 3	0		0		0		0
Fair Value Assets, Transfers Out of Level 3	0		0		0		0
Fair Value Assets, Ending Balance	1,498		1,599		1,498		1,599
Fair Value Assets, Current Period Unrealized Gains (Losses)	21		(6)		24		8
Foreign debt securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance	294		294		299		253
Fair Value Assets, Trading Revenue (Loss)	(9)	[1]	25	[1]	(14)	[1]	66	[1]
Fair Value Assets, Other Revenue	0	[1]	0	[1]	0	[1]	0	[1]
Fair Value Assets, Purchases	0		389		0		389
Fair Value Assets, Issuances	0		0		0		0
Fair Value Assets, Settlements	0		(20)		0		(20)
Transfers Into Level 3	0		0		0		0
Fair Value Assets, Transfers Out of Level 3	0		0		0		0
Fair Value Assets, Ending Balance	285		688		285		688
Fair Value Assets, Current Period Unrealized Gains (Losses)	(9)		25		(14)		66
Government debt securities issued by foreign entities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance	143				311
Fair Value Assets, Trading Revenue (Loss)	(7)	[1]			15	[1]
Fair Value Assets, Other Revenue	0	[1]			0	[1]
Fair Value Assets, Purchases	0				0
Fair Value Assets, Issuances	0				0
Fair Value Assets, Settlements	(1)				(191)
Transfers Into Level 3	0				0
Fair Value Assets, Transfers Out of Level 3	0				0
Fair Value Assets, Ending Balance	135				135
Fair Value Assets, Current Period Unrealized Gains (Losses)	(9)				10
Equity securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance	11		13		9		13
Fair Value Assets, Trading Revenue (Loss)	(7)	[1]	(1)	[1]	(5)	[1]	(1)	[1]
Fair Value Assets, Other Revenue	0	[1]	0	[1]	0	[1]	0	[1]
Fair Value Assets, Purchases	0		0		0		0
Fair Value Assets, Issuances	0		0		0		0
Fair Value Assets, Settlements	(4)		0		(4)		0
Transfers Into Level 3	0		0		0		0
Fair Value Assets, Transfers Out of Level 3	0		0		0		0
Fair Value Assets, Ending Balance	0		12		0		12
Fair Value Assets, Current Period Unrealized Gains (Losses)	(7)		(1)		(5)		(1)
Mortgage servicing rights [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance	190	[3]	228	[3]	168	[3]	220	[3]
Fair Value Assets, Trading Revenue (Loss)	0	[1],[2]	0	[1],[2]	0	[1],[2]	0	[1],[2]
Fair Value Assets, Other Revenue	30	[1],[2]	(47)	[1],[2]	46	[1],[2]	(47)	[1],[2]
Fair Value Assets, Purchases	0	[2]	0	[2]	0	[2]	0	[2]
Fair Value Assets, Issuances	5	[2],[3]	6	[2],[3]	11	[2],[3]	14	[2],[3]
Fair Value Assets, Settlements	0	[2]	0	[2]	0	[2]	0	[2]
Transfers Into Level 3	0	[2]	0	[2]	0	[2]	0	[2]
Fair Value Assets, Transfers Out of Level 3	0	[2]	0	[2]	0	[2]	0	[2]
Fair Value Assets, Ending Balance	225	[3]	187	[3]	225	[3]	187	[3]
Fair Value Assets, Current Period Unrealized Gains (Losses)	30	[3]	(46)	[3]	51	[2],[3]	(47)	[3]
Deposits In Domestic Office [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Liability, Beginning Balance	(2,876)		(2,964)		(2,636)		(2,867)
Fair Value Liability, Trading Revenue (Loss)	154	[1]	(21)	[1]	113	[1]	(77)	[1]
Fair Value Liability, Purchases	0		0		0		0
Fair Value Liability, Issuances	(81)		(269)		(485)		(556)
Fair Value Liability, Settlements	110		79		219		160
Fair Value Liability, Transfers Into Level 3	(177)		(46)		(160)		(43)
Fair Value Liability, Transfers Out of Level 3	208		313		287		475
Fair Value Liability, Ending Balance	(2,662)		(2,908)		(2,662)		(2,908)
Fair Value Liability, Current Period Unrealized Gains (Losses)	175		(14)		149		(50)
Long-term Debt [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance							11	[2]
Fair Value Assets, Trading Revenue (Loss)							0	[1],[2]
Fair Value Assets, Other Revenue							0	[1],[2]
Fair Value Assets, Purchases							0	[2]
Fair Value Assets, Issuances							0	[2]
Fair Value Assets, Settlements							0	[2]
Transfers Into Level 3	177				160		0	[2]
Fair Value Assets, Transfers Out of Level 3							(11)	[2]
Fair Value Assets, Ending Balance			0	[4]			0	[4]
Fair Value Assets, Current Period Unrealized Gains (Losses)							(12)	[4]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Liability, Beginning Balance	(618)		(160)		(429)		(86)
Fair Value Liability, Trading Revenue (Loss)	15	[1]	10	[1]	(16)	[1]	9	[1]
Fair Value Liability, Purchases	0		0		0		0
Fair Value Liability, Issuances	(59)		(132)		(270)		(221)
Fair Value Liability, Settlements	68		1		119		5
Fair Value Liability, Transfers Into Level 3	0		(7)		0		(7)
Fair Value Liability, Transfers Out of Level 3	136		1		138		13
Fair Value Liability, Ending Balance	(458)		(287)		(458)		(287)
Fair Value Liability, Current Period Unrealized Gains (Losses)	$ 18		$ 5		$ 7		$ 4

[1] Includes realized and unrealized gains and losses.

[2] Level 3 net derivatives included derivative assets of $1.0 billion and derivative liabilities of $740 million as of June 30, 2013 and derivative assets of $2.4 billion and derivative liabilities of $2.2 billion as of June 30, 2012.

[3] See Note 8, “Intangible Assets,” for additional information.

[4] Includes Level 3 corporate lending activities risk-managed on a fair value basis for which we have elected the fair value option.