Investment Securities (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014 country	Sep. 30, 2013	Sep. 30, 2014 security country	Sep. 30, 2013	Dec. 31, 2013
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Pledged Financial Instruments, Not Separately Reported, Securities	$ 44,770,000,000		$ 44,770,000,000		$ 46,990,000,000
Other-than-temporary impairment recorded	0	10,000,000	11,000,000	20,000,000
Number of peripheral european countries	4		4
Impairment associated with adverse changes in timing of expected future cash flows	0	2,000,000	1,000,000	6,000,000
Gross pre-tax unrealized losses on securities			(759,000,000)
Number of available for sale and held to maturity securities in gross pre-tax unrealized loss position			1,459
Minimum
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Percentage change in additional house price declines			9.00%
Maximum
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Percentage change in additional house price declines			15.00%
Agency Securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Other-than-temporary impairment recorded	0	0	0	0
Asset-backed securities, student loans
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Other-than-temporary impairment recorded	0	0	0	0
Federal Family Education Loan Program
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Federal government credit support guarantee, percentage minimum			97.00%
Other-than-temporary impairment recorded	0	0	0	0
Collective credit support, percentage minimum			100.00%
Average remaining term			4 years 7 months 1 day
Maximum concentration risk on credit instruments (less than)			800,000,000
U.S. Non-Agency Residential Mortgage-Backed Securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Other-than-temporary impairment recorded	0	0	0	0
Non-U.S. debt securities, mortgage-backed securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Other-than-temporary impairment recorded	1,000,000		1,000,000	6,000,000
Non-U.S. debt securities, mortgage-backed securities | European Periphery
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Other-than-temporary impairment recorded		6,000,000		6,000,000
Total exposure to asset backed securities	910,000,000		910,000,000
Aggregate pre-tax gross unrealized gain (loss) on available for sale securities			125,000,000
Available for sale, gross unrealized gains			126,000,000
Available for sale, gross unrealized losses			(1,000,000)
Non-U.S. debt securities, mortgage-backed securities | Spain
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Total exposure to asset backed securities	173,000,000		173,000,000
Non-U.S. debt securities, mortgage-backed securities | Italy
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Total exposure to asset backed securities	555,000,000		555,000,000
Non-U.S. debt securities, mortgage-backed securities | Ireland
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Total exposure to asset backed securities	109,000,000		109,000,000
Non-U.S. debt securities, mortgage-backed securities | Portugal
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Total exposure to asset backed securities	73,000,000		73,000,000
Direct sovereign debt
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Total exposure to asset backed securities	0		0
State and political subdivisions
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Other-than-temporary impairment recorded	0	0	0	0
Collateralized mortgage obligations
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Other-than-temporary impairment recorded			$ 10,000,000	$ 8,000,000