Fair Value Measurements - Changes in Fair Value of Level 3 Assets and Liabilities (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Assets, Beginning Balance	$ 4,006	$ 4,090	$ 4,157	$ 3,500
Fair Value Assets, Trading Revenue (Loss)	(44)	366	(248)	450
Fair Value Assets, Other Revenue	(18)	(125)	(62)	(176)
Fair Value Assets, Other Comprehensive Income
Fair Value Assets, Purchases	19	29	534	914
Fair Value Assets, Issuances	5		14
Fair Value Assets, Settlements	(98)	(66)	(515)	(493)
Fair Value Assets, Transfers Into Level 3	25	(18)	21	33
Fair Value Assets, Transfers Out of Level 3	(340)	94	(346)	142
Fair Value Assets, Ending Balance	3,555	4,370	3,555	4,370
Fair Value Assets, Current Period Unrealized Gains (Losses)	(86)	353	(372)	120
Fair Value Liability, Beginning Balance	(3,195)	(5,404)	(2,953)	(3,913)
Fair Value Liability, Trading Revenue (Loss)	(103)	175	(171)	72
Fair Value Liability, Other Comprehensive Income
Fair Value Liability, Purchases
Fair Value Liability, Issuances	(178)	610	(955)	2,486
Fair Value Liability, Settlements	96	153	261	537
Fair Value Liability, Transfers Into Level 3	2		(48)	28
Fair Value Liability, Transfers Out of Level 3	(177)	642	(665)	773
Fair Value Liability, Ending Balance	(3,201)	(5,044)	(3,201)	(5,044)
Fair Value Liability, Current Period Unrealized Gains (Losses)	(99)	78	(145)	79
Interest rate contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Assets, Beginning Balance	12	3	9	(1)
Fair Value Assets, Other Revenue	2	9	5	13
Fair Value Assets, Other Comprehensive Income
Fair Value Assets, Ending Balance	14	12	14	12
Fair Value Assets, Current Period Unrealized Gains (Losses)	1	9	4	13
Foreign exchange contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Assets, Beginning Balance	(25)	1	(1)	(4)
Fair Value Assets, Trading Revenue (Loss)	(12)	(2)	(31)	3
Fair Value Assets, Other Comprehensive Income
Fair Value Assets, Issuances	(1)		(6)
Fair Value Assets, Settlements	9		11
Fair Value Assets, Transfers Into Level 3			(3)
Fair Value Assets, Transfers Out of Level 3	32		33
Fair Value Assets, Ending Balance	3	(1)	3	(1)
Fair Value Assets, Current Period Unrealized Gains (Losses)	20	(1)	1	3
Equity contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Assets, Beginning Balance	(46)	(29)	(83)	12
Fair Value Assets, Trading Revenue (Loss)	84	(173)	147	(93)
Fair Value Assets, Other Comprehensive Income
Fair Value Assets, Settlements	(6)	(30)	(35)	(188)
Fair Value Assets, Transfers Into Level 3	1	(18)		33
Fair Value Assets, Transfers Out of Level 3	(2)	94	2	80
Fair Value Assets, Ending Balance	31	(156)	31	(156)
Fair Value Assets, Current Period Unrealized Gains (Losses)	71	(33)	93	(109)
Precious metals contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Assets, Trading Revenue (Loss)	1		1
Fair Value Assets, Other Comprehensive Income
Fair Value Assets, Ending Balance	1		1
Fair Value Assets, Current Period Unrealized Gains (Losses)	1		1
Credit contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Assets, Beginning Balance	921	1,069	1,353	1,202
Fair Value Assets, Trading Revenue (Loss)	(227)	613	(615)	562
Fair Value Assets, Other Comprehensive Income
Fair Value Assets, Settlements	(7)	(13)	(51)	(157)
Fair Value Assets, Transfers Into Level 3	(16)		(16)
Fair Value Assets, Transfers Out of Level 3	(370)		(370)	62
Fair Value Assets, Ending Balance	301	1,669	301	1,669
Fair Value Assets, Current Period Unrealized Gains (Losses)	(250)	598	(605)	441
Collateralized debt obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Assets, Beginning Balance	658	770	703	793
Fair Value Assets, Trading Revenue (Loss)	44	(41)	101	(14)
Fair Value Assets, Other Comprehensive Income
Fair Value Assets, Purchases	20	7	45	100
Fair Value Assets, Settlements	(84)	(29)	(211)	(172)
Fair Value Assets, Transfers Into Level 3	40		40
Fair Value Assets, Ending Balance	678	707	678	707
Fair Value Assets, Current Period Unrealized Gains (Losses)	30	(48)	79	(31)
Corporate and other domestic [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Assets, Beginning Balance	1,599	1,615	1,679	833
Fair Value Assets, Trading Revenue (Loss)	24	5	42
Fair Value Assets, Other Comprehensive Income
Fair Value Assets, Purchases		22	101	814
Fair Value Assets, Settlements	(5)		(204)	(5)
Fair Value Assets, Ending Balance	1,618	1,642	1,618	1,642
Fair Value Assets, Current Period Unrealized Gains (Losses)	24	(5)	32
Foreign debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Assets, Beginning Balance	688	271	253	243
Fair Value Assets, Trading Revenue (Loss)	41	(34)	107	(6)
Fair Value Assets, Other Comprehensive Income
Fair Value Assets, Purchases	(1)		388
Fair Value Assets, Settlements	(4)		(24)
Fair Value Assets, Ending Balance	724	237	724	237
Fair Value Assets, Current Period Unrealized Gains (Losses)	35	(33)	101	(6)
Equity securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Assets, Beginning Balance	12	16	13	17
Fair Value Assets, Trading Revenue (Loss)	1	(2)		(2)
Fair Value Assets, Other Comprehensive Income
Fair Value Assets, Settlements	(1)	(2)	(1)	(3)
Fair Value Assets, Ending Balance	12	12	12	12
Fair Value Assets, Current Period Unrealized Gains (Losses)	1	(1)		(2)
Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Assets, Beginning Balance		11	11	11
Fair Value Assets, Other Comprehensive Income
Fair Value Assets, Transfers Out of Level 3			(11)
Fair Value Assets, Ending Balance		11		11
Fair Value Assets, Current Period Unrealized Gains (Losses)			(12)
Mortgage servicing rights [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Assets, Beginning Balance	187	363	220	394
Fair Value Assets, Other Revenue	(20)	(134)	(67)	(189)
Fair Value Assets, Other Comprehensive Income
Fair Value Assets, Issuances	6		20
Fair Value Assets, Settlements		8		32
Fair Value Assets, Ending Balance	173	237	173	237
Fair Value Assets, Current Period Unrealized Gains (Losses)	(19)	(133)	(66)	(189)
Deposits In Domestic Office
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Liability, Beginning Balance	(2,908)	(4,719)	(2,867)	(3,612)
Fair Value Liability, Trading Revenue (Loss)	(81)	62	(158)	(29)
Fair Value Liability, Other Comprehensive Income
Fair Value Liability, Purchases
Fair Value Liability, Issuances	(119)	588	(675)	1,865
Fair Value Liability, Settlements	94	107	254	348
Fair Value Liability, Transfers Into Level 3	2		(41)	25
Fair Value Liability, Transfers Out of Level 3	(132)	207	(607)	252
Fair Value Liability, Ending Balance	(2,880)	(4,931)	(2,880)	(4,931)
Fair Value Liability, Current Period Unrealized Gains (Losses)	(79)	68	(129)	67
Long-term Debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Liability, Beginning Balance	(287)	(685)	(86)	(301)
Fair Value Liability, Trading Revenue (Loss)	(22)	113	(13)	101
Fair Value Liability, Other Comprehensive Income
Fair Value Liability, Purchases
Fair Value Liability, Issuances	(59)	22	(280)	621
Fair Value Liability, Settlements	2	46	7	189
Fair Value Liability, Transfers Into Level 3			(7)	3
Fair Value Liability, Transfers Out of Level 3	(45)	435	(58)	521
Fair Value Liability, Ending Balance	(321)	(113)	(321)	(113)
Fair Value Liability, Current Period Unrealized Gains (Losses)	$ (20)	$ 10	$ (16)	$ 12