Guarantee Arrangements and Pledged Assets and Collateral - Offsetting of Resale and Repurchase Agreements and Securities Borrowing and Lending Agreements (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013
Offsetting [Abstract]
Securities purchased under agreements to resell, Gross Amounts Recognized	$ 5,635		$ 4,187
Securities sold under repurchase agreements, Gross Amounts Offset in the Balance Sheet	4,283	[1]	2,068	[1]
Securities purchased under agreements to resell, Net Amounts Presented in the Balance Sheet	1,352		2,119
Securities purchased under agreements to resell, Gross Amounts Not Offset in the Balance Sheet, Financial Instruments	1,352	[2]	2,118	[2]
Securities purchased under agreements to resell, Gross Amounts Not Offset in the Balance Sheet, Cash Collateral Receive / Pledged	0		0
Securities purchased under agreements to resell, Net amount	0	[3]	1	[3]
Securities sold under repurchase agreements, Gross Amounts Recognized	23,537		14,989
Securities sold under repurchase agreements, Gross Amounts Offset in the Balance Sheet	4,283	[1]	2,068	[1]
Securities sold under repurchase agreements, Net Amounts Presented in the Balance Sheet	19,254		12,921
Securities sold under repurchase agreements, Gross Amounts Not Offset in the Balance sheet, Financial Instruments	19,254	[2]	12,913	[2]
Securities sold under repurchase agreements, Gross Amounts Not Offset in the Balance Sheet, Cash Collateral Received / Pledged	0		0
Securities sold under repurchase agreements, Net amount	$ 0	[3]	$ 8	[3]

[1] Represents recognized amount of resale and repurchase agreements with counterparties subject to legally enforceable netting agreements that meet the applicable netting criteria as permitted by generally accepted accounting principles.

[2] Represents securities received or pledged to cover financing transaction exposures.

[3] Represents the amount of our exposure that is not collateralized / covered by pledged collateral.