Investment Securities, Credit Loss Component (Details) - Total debt securities [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Schedule of Marketable Securities [Line Items]
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Additions, No Previous Impairment	$ 0	$ 3	$ 0	$ 3
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Credit loss recognized, beginning of period	1,029	1,143	1,025	1,171
Additions:
For securities with previous credit impairments	19	6	39	13
Total additions	19	9	39	16
Reductions:
For securities sold, matured, or intended/required to be sold	(52)	(40)	(66)	(69)
For recoveries of previous credit impairments	(3)	(5)	(5)	(11)
Total reductions	(55)	(45)	(71)	(80)
Credit loss recognized, end of period	$ 993	$ 1,107	$ 993	$ 1,107