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, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance	$ 3,690		$ 3,181		$ 3,150		$ 3,690
Fair Value Assets, Trading Revenue (Loss)	43	[1]	(124)	[1]	57	[1]	(38)	[1]
Fair Value Assets, Other Revenue	(13)	[1]	24	[1]	(25)	[1]	39	[1]
Fair Value Assets, Purchases	11		232		564		268
Fair Value Assets, Issuances	0		5		0		11
Fair Value Assets, Settlements	(45)		(688)		(73)		(1,288)
Transfers Into Level 3	2		0		6		(46)
Fair Value Assets, Transfers Out of Level 3	(107)		(15)		(98)		(21)
Fair Value Assets, Ending Balance	3,581		2,615		3,581		2,615
Fair Value Assets, Current Period Unrealized Gains (Losses)	(2)		(127)		(61)		(96)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Liability, Beginning Balance	(2,976)		(3,494)		(3,234)		(3,065)
Fair Value Liability, Trading Revenue (Loss)	(81)	[1]	169	[1]	(113)	[1]	97	[1]
Fair Value Liability, Purchases	0		0		0		0
Fair Value Liability, Issuances	(245)		(140)		(313)		(755)
Fair Value Liability, Settlements	203		178		418		338
Transfers into level 3	(27)		(177)		(95)		(160)
Fair Value Liability, Transfers Out of Level 3	131		344		342		425
Fair Value Liability, Ending Balance	(2,995)		(3,120)		(2,995)		(3,120)
Fair Value Liability, Current Period Unrealized Gains (Losses)	(56)		193		(74)		156
Interest rate contracts [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance	1	[2]	6	[2]	1	[2]	7	[2]
Fair Value Assets, Trading Revenue (Loss)	0	[1],[2]	(1)	[1],[2]	0	[1],[2]	(1)	[1],[2]
Fair Value Assets, Other Revenue	(1)	[1],[2]	(6)	[1],[2]	(1)	[1],[2]	(7)	[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	0	[2]	(1)	[2]	0	[2]	(1)	[2]
Fair Value Assets, Current Period Unrealized Gains (Losses)	0	[2]	(7)	[2]	(1)	[2]	(8)	[2]
Foreign exchange contracts [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance	96	[2]	134	[2]	95	[2]	5	[2]
Fair Value Assets, Trading Revenue (Loss)	8	[1],[2]	(18)	[1],[2]	10	[1],[2]	(4)	[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	(6)	[2]	(6)	[2]	(12)	[2]	116	[2]
Transfers Into Level 3	0	[2]	(6)	[2]	0	[2]	(13)	[2]
Fair Value Assets, Transfers Out of Level 3	(98)	[2]	0	[2]	(93)	[2]	0	[2]
Fair Value Assets, Ending Balance	0	[2]	104	[2]	0	[2]	104	[2]
Fair Value Assets, Current Period Unrealized Gains (Losses)	4	[2]	(28)	[2]	5	[2]	106	[2]
Equity contracts [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance	24	[2]	34	[2]	3	[2]	(7)	[2]
Fair Value Assets, Trading Revenue (Loss)	66	[1],[2]	(81)	[1],[2]	86	[1],[2]	(20)	[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	(29)	[2]	(27)	[2]	(36)	[2]	(48)	[2]
Transfers Into Level 3	2	[2]	6	[2]	6	[2]	13	[2]
Fair Value Assets, Transfers Out of Level 3	(4)	[2]	(15)	[2]	0	[2]	(21)	[2]
Fair Value Assets, Ending Balance	59	[2]	(83)	[2]	59	[2]	(83)	[2]
Fair Value Assets, Current Period Unrealized Gains (Losses)	41	[2]	(92)	[2]	49	[2]	(73)	[2]
Precious metals contracts [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance	0	[2]			(2)	[2]
Fair Value Assets, Trading Revenue (Loss)	0	[1],[2]			2	[1],[2]
Fair Value Assets, Other Revenue	0	[1],[2]			0	[1],[2]
Fair Value Assets, Purchases	0	[2]			0	[2]
Fair Value Assets, Issuances	0	[2]			0	[2]
Fair Value Assets, Settlements	0	[2]			0	[2]
Transfers Into Level 3	0	[2]			0	[2]
Fair Value Assets, Transfers Out of Level 3	0	[2]			0	[2]
Fair Value Assets, Ending Balance	0	[2]			0	[2]
Fair Value Assets, Current Period Unrealized Gains (Losses)	0	[2]			0	[2]
Credit contracts [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance	181	[2]	364	[2]	191	[2]	571	[2]
Fair Value Assets, Trading Revenue (Loss)	(41)	[1],[2]	(105)	[1],[2]	(55)	[1],[2]	(155)	[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	3	[2]	(34)	[2]	7	[2]	(145)	[2]
Transfers Into Level 3	0	[2]	0	[2]	0	[2]	(46)	[2]
Fair Value Assets, Transfers Out of Level 3	114	[2]	0	[2]	114	[2]	0	[2]
Fair Value Assets, Ending Balance	257		225	[2]	257		225	[2]
Fair Value Assets, Current Period Unrealized Gains (Losses)	(42)	[2]	(82)	[2]	(98)	[2]	(274)	[2]
Collateralized debt obligations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance	258		481		254		466
Fair Value Assets, Trading Revenue (Loss)	7	[1]	83	[1]	14	[1]	118	[1]
Fair Value Assets, Other Revenue	0	[1]	0	[1]	0	[1]	0	[1]
Fair Value Assets, Purchases	0		216		0		237
Fair Value Assets, Issuances	0		0		0		0
Fair Value Assets, Settlements	(5)		(553)		(8)		(594)
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	260		227		260		227
Fair Value Assets, Current Period Unrealized Gains (Losses)	7		56		14		87
Corporate and other domestic [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance	2,808		1,524		2,260		1,861
Fair Value Assets, Trading Revenue (Loss)	0	[1]	21	[1]	(5)	[1]	28	[1]
Fair Value Assets, Other Revenue	0	[1]	0	[1]	0	[1]	0	[1]
Fair Value Assets, Purchases	11		16		564		31
Fair Value Assets, Issuances	0		0		0		0
Fair Value Assets, Settlements	0		(63)		0		(422)
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	2,819		1,498		2,819		1,498
Fair Value Assets, Current Period Unrealized Gains (Losses)	0		21		(6)		24
Foreign debt securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance	0		294		0		299
Fair Value Assets, Trading Revenue (Loss)	0	[1]	(9)	[1]	0	[1]	(14)	[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	0		0		0		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		285		0		285
Fair Value Assets, Current Period Unrealized Gains (Losses)	0		(9)		0		(14)
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	117		143		121		311
Fair Value Assets, Trading Revenue (Loss)	3	[1]	(7)	[1]	5	[1]	15	[1]
Fair Value Assets, Other Revenue	0	[1]	0		0	[1]	0
Fair Value Assets, Purchases	0		0		0		0
Fair Value Assets, Issuances	0		0		0		0
Fair Value Assets, Settlements	(1)		(1)		(7)		(191)
Transfers Into Level 3	0		0		0		0
Fair Value Assets, Transfers Out of Level 3	(119)		0		(119)		0
Fair Value Assets, Ending Balance	0		135		0		135
Fair Value Assets, Current Period Unrealized Gains (Losses)	0		(9)		0		10
Equity securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance	0		11		0		9
Fair Value Assets, Trading Revenue (Loss)	0	[1]	(7)	[1]	0	[1]	(5)	[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	0		(4)		0		(4)
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		0		0		0
Fair Value Assets, Current Period Unrealized Gains (Losses)	0		(7)		0		(5)
Mortgage servicing rights [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance	205	[2],[3]	190	[2],[4]	227	[2],[3]	168	[2],[3]
Fair Value Assets, Trading Revenue (Loss)	0	[1],[2],[3]	0	[1],[2]	0	[1],[2],[3]	0	[1],[2],[3]
Fair Value Assets, Other Revenue	(12)	[1],[2],[3]	30	[1],[2]	(24)	[1],[2],[3]	46	[1],[2],[3]
Fair Value Assets, Purchases	0	[2],[3]	0	[2],[4]	0	[2],[3]	0	[2],[3]
Fair Value Assets, Issuances	0	[2],[3]	5	[2],[4]	0	[2],[3]	11	[2],[3]
Fair Value Assets, Settlements	(7)	[2],[3]	0	[2],[4]	(17)	[2],[3]	0	[2],[3]
Transfers Into Level 3	0	[2],[3]	0	[2],[4]	0	[2],[3]	0	[2],[3]
Fair Value Assets, Transfers Out of Level 3	0	[2],[3]	0	[2],[4]	0	[2],[3]	0	[2],[3]
Fair Value Assets, Ending Balance	186	[2],[3]	225	[2],[3],[4]	186	[2],[3]	225	[2],[3],[4]
Fair Value Assets, Current Period Unrealized Gains (Losses)	(12)	[2],[3]	30	[2],[4]	(24)	[2],[3]	51	[2],[3]
Deposits In Domestic Office [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Transfers Into Level 3			(177)				(160)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Liability, Beginning Balance	(2,244)		(2,876)		(2,334)		(2,636)
Fair Value Liability, Trading Revenue (Loss)	(85)	[1]	411	[1]	(210)	[1]	370	[1]
Fair Value Liability, Purchases	0		0		0		0
Fair Value Liability, Issuances	(135)		(81)		(160)		(485)
Fair Value Liability, Settlements	130		110		298		219
Transfers into level 3	(27)				(95)
Fair Value Liability, Transfers Out of Level 3	104		165		244		244
Fair Value Liability, Ending Balance	(2,257)		(2,448)		(2,257)		(2,448)
Fair Value Liability, Current Period Unrealized Gains (Losses)	(34)		432		(51)		406
Long-term Debt [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Liability, Beginning Balance	(732)		(618)		(900)		(429)
Fair Value Liability, Trading Revenue (Loss)	4	[1]	(242)	[1]	97	[1]	(273)	[1]
Fair Value Liability, Purchases	0		0		0		0
Fair Value Liability, Issuances	(110)		(59)		(153)		(270)
Fair Value Liability, Settlements	73		68		120		119
Transfers into level 3	0		0		0		0
Fair Value Liability, Transfers Out of Level 3	27		179		98		181
Fair Value Liability, Ending Balance	(738)		(672)		(738)		(672)
Fair Value Liability, Current Period Unrealized Gains (Losses)	$ (22)		$ (239)		$ (23)		$ (250)

[1] Includes realized and unrealized gains and losses.

[2] Level 3 net derivatives included derivative assets of $538 million and derivative liabilities of $222 million as of June 30, 2014 and derivative assets of $985 million and derivative liabilities of $740 million as of June 30, 2013.

[3] See Note 7, "Intangible Assets," for additional information.

[4] Includes certain commercial loans held for sale which we have elected to apply the fair value option. See Note 6, "Loans Held for Sale," for further information.