Fair Value Option - Changes in fair value under the fair value option (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	$ (88)	$ (226)
Debit Valuation Adjustment
Changes in fair value under the fair value option election
Structured note credit adjustments	108	(115)
Federal funds sold and securities purchased under resale agreements
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	73	(40)
Federal funds sold and securities purchased under resale agreements | Principal transactions
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	73	(40)
Federal funds sold and securities purchased under resale agreements | All other income
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	0	0
Securities borrowed
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	(2)	(3)
Securities borrowed | Principal transactions
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	(2)	(3)
Securities borrowed | All other income
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	0	0
Debt and Equity Instruments, Excluding Loans [Member]
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	380	228
Debt and Equity Instruments, Excluding Loans [Member] | Principal transactions
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	380	230
Debt and Equity Instruments, Excluding Loans [Member] | All other income
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	0	(2)
Loans reported as trading assets: Changes in instrument-specific credit risk
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	155	372
Loans reported as trading assets: Changes in instrument-specific credit risk | Principal transactions
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	152	363
Loans reported as trading assets: Changes in instrument-specific credit risk | All other income
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	3	9
Loans reported as trading assets: Other changes in fair value
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	407	356
Loans reported as trading assets: Other changes in fair value | Principal transactions
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	127	64
Loans reported as trading assets: Other changes in fair value | All other income
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	280	292
Loans: Changes in instrument-specific credit risk
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	1	8
Loans: Changes in instrument-specific credit risk | Principal transactions
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	1	8
Loans: Changes in instrument-specific credit risk | All other income
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	0	0
Loans: Other changes in fair value
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	0	7
Loans: Other changes in fair value | Principal transactions
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	0	7
Loans: Other changes in fair value | All other income
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	0	0
Other assets
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	66	(68)
Other assets | Principal transactions
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	60	5
Other assets | All other income
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	6	(73)
Deposits
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	(125)	(104)
Deposits | Principal transactions
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	(125)	(104)
Deposits | All other income
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	0	0
Federal funds purchased and securities loaned or sold under repurchase agreements
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	(9)	(16)
Federal funds purchased and securities loaned or sold under repurchase agreements | Principal transactions
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	(9)	(16)
Federal funds purchased and securities loaned or sold under repurchase agreements | All other income
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	0	0
Other borrowed funds
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	(9)	(260)
Other borrowed funds | Principal transactions
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	(9)	(260)
Other borrowed funds | All other income
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	0	0
Trading liabilities
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	(2)	(6)
Trading liabilities | Principal transactions
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	(2)	(6)
Trading liabilities | All other income
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	0	0
Beneficial interests issued by consolidated VIEs
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	18	(89)
Beneficial interests issued by consolidated VIEs | Principal transactions
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	18	(89)
Beneficial interests issued by consolidated VIEs | All other income
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	0	0
Other liabilities
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	0	0
Other liabilities | Principal transactions
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	0	0
Other liabilities | All other income
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	0	0
Long-term debt: Changes in instrument-specific credit risk
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	116	(77)
Long-term debt: Changes in instrument-specific credit risk | Principal transactions
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	116	(77)
Long-term debt: Changes in instrument-specific credit risk | All other income
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	0	0
Long-term debt: Other changes in fair value
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	(378)	(18)
Long-term debt: Other changes in fair value | Principal transactions
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	(378)	(18)
Long-term debt: Other changes in fair value | All other income
Changes in fair value under the fair value option election
Fair value option, changes in fair value gain (loss)	$ 0	$ 0