Derivative Instruments Derivatives 2 - FV Gains and Losses (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Derivative fair value gains (losses), net	$ 544		$ (1,324)		$ 2,294		$ (3,733)
Risk Management Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative fair value gains (losses), net	713		(508)		1,835		(2,150)
Mortgage commitment derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative fair value gains (losses), net	(169)		(816)		459		(1,583)
Pay-fixed Swap [Member] | Risk Management Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative fair value gains (losses), net	(166)		(2,272)		8,328		(6,955)
Receive-fixed Swap [Member] | Risk Management Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative fair value gains (losses), net	680		1,511		(6,359)		4,185
Basis Swap [Member] | Risk Management Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative fair value gains (losses), net	(2)		42		(52)		98
Foreign Currency Swap [Member] | Risk Management Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative fair value gains (losses), net	58		61		(67)		70
Pay-fixed Swaption [Member] | Risk Management Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative fair value gains (losses), net	148		51		(303)		108
Receive-fixed Swaption [Member] | Risk Management Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative fair value gains (losses), net	(3)		123		265		374
Other [Member] | Risk Management Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative fair value gains (losses), net	$ (2)	[1]	$ (24)	[1]	$ 23	[1]	$ (30)	[1]

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