Investment Securities (Rollforward of Cumulative OTTI Credit Losses Recognized in Earnings) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Beginning balance	$ (1,157)	$ (1,165)	$ (1,160)	$ (1,201)
Additional loss where credit impairment was previously recognized	(1)	(4)	(3)	(14)
Reduction due to credit impaired securities sold or matured		5	5	51
Ending balance	$ (1,158)	$ (1,164)	$ (1,158)	$ (1,164)