Derivative Instruments Derivatives 2 - FV Gains and Losses (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Derivative fair value gains (losses), net	$ 1,188		$ (2,383)		$ 1,750		$ (2,409)
Risk Management Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative fair value gains (losses), net	691		(1,821)		1,122		(1,642)
Mortgage commitment derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative fair value gains (losses), net	497		(562)		628		(767)
Pay-fixed Swap [Member] | Risk Management Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative fair value gains (losses), net	7,102		(5,858)		8,494		(4,683)
Receive-fixed Swap [Member] | Risk Management Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative fair value gains (losses), net	(6,111)		3,592		(7,039)		2,674
Basis Swap [Member] | Risk Management Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative fair value gains (losses), net	(33)		18		(50)		56
Foreign Currency Swap [Member] | Risk Management Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative fair value gains (losses), net	(59)		8		(125)		9
Pay-fixed Swaption [Member] | Risk Management Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative fair value gains (losses), net	(468)		79		(451)		57
Receive-fixed Swaption [Member] | Risk Management Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative fair value gains (losses), net	247		345		268		251
Other [Member] | Risk Management Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative fair value gains (losses), net	$ 13	[1]	$ (5)	[1]	$ 25	[1]	$ (6)	[1]

[1] Includes interest rate caps, futures, swap credit enhancements and mortgage insurance contracts.