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	Dec. 31, 2014		Dec. 31, 2013
Commitments and Contingencies Disclosure [Abstract]
Securities purchased under agreements to resell, Gross Amounts Recognized	$ 7,165		$ 4,187
Securities purchased under agreements to resell, Gross Amounts Offset in the Balance Sheet	5,752	[1]	2,068	[1]
Securities Purchased under Agreements to Resell	1,413		2,119
Securities purchased under agreements to resell, Gross Amounts Not Offset in the Balance Sheet, Financial Instruments	1,413	[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	13,459		14,989
Securities sold under repurchase agreements, Gross Amounts Offset in the Balance Sheet	5,752	[1]	2,068	[1]
Securities sold under repurchase agreements, Net Amounts Presented in the Balance Sheet	7,707		12,921
Securities sold under repurchase agreements, Gross Amounts Not Offset in the Balance sheet, Financial Instruments	7,707	[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.