Investment Securities - Schedule of Credit Losses Related to Debt Securities Recognized in Earnings (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Credit loss component, beginning of period	$ 165	$ 149	$ 160	$ 120
Additions:
Initial credit impairment	1	3	2	14
Subsequent credit impairment	2	8	6	26
Total additions	3	11	8	40
Reduction due to payoffs, disposals, transfers & other	(2)	0	(2)	0
Credit loss component, end of period	$ 166	$ 160	$ 166	$ 160