Fair Value (Schedule of Availability of Significant Unobservable Inputs by Balance Sheet Classification) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Assets:
Investment securities available for sale	$ 96,552		$ 99,174
Asset-backed securities, student loans
Assets:
Investment securities available for sale	12,806	[1]	14,542	[1]
Asset-backed securities, credit cards
Assets:
Investment securities available for sale	3,111		8,210
Asset-backed securities, other
Assets:
Investment securities available for sale	4,343		5,064
Non-U.S. debt securities, mortgage-backed securities
Assets:
Investment securities available for sale	10,239		11,029
Non-U.S. debt securities, asset-backed securities
Assets:
Investment securities available for sale	3,447		5,390
Non-U.S. debt securities, other
Assets:
Investment securities available for sale	5,849		4,727
State and political subdivisions
Assets:
Investment securities available for sale	10,645		10,263
Collateralized mortgage obligations
Assets:
Investment securities available for sale	4,671		5,269
Other U.S. debt securities
Assets:
Investment securities available for sale	4,284		4,980
Pricing Methods with Significant Unobservable Market Inputs (Level 3)
Assets:
Assets, fair value disclosure	5,543		7,564
Liabilities:
Liabilities, fair value disclosure	68		26
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Derivative instruments, liabilities
Liabilities:
Derivative instruments, foreign exchange contracts, liabilities	59		17
Derivative instruments, other, liabilities	9		9
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Derivative instruments, assets
Assets:
Derivative instruments, foreign exchange contracts, assets	68		19
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | U.S. Treasury and federal agencies, mortgage-backed securities
Assets:
Investment securities available for sale	260		716
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Asset-backed securities, student loans
Assets:
Investment securities available for sale	266		423
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Asset-backed securities, credit cards
Assets:
Investment securities available for sale			24
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Asset-backed securities, other
Assets:
Investment securities available for sale	3,944		4,532
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Non-U.S. debt securities, mortgage-backed securities
Assets:
Investment securities available for sale			375
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Non-U.S. debt securities, asset-backed securities
Assets:
Investment securities available for sale	424		798
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Non-U.S. debt securities, other
Assets:
Investment securities available for sale	298		464
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | State and political subdivisions
Assets:
Investment securities available for sale	41		43
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Collateralized mortgage obligations
Assets:
Investment securities available for sale	234		162
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Other U.S. debt securities
Assets:
Investment securities available for sale	8		8
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Readily Available [Member]
Assets:
Assets, fair value disclosure	175	[2]	191	[2]
Liabilities:
Liabilities, fair value disclosure	68	[2]	26	[2]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Readily Available [Member] | Derivative instruments, liabilities
Liabilities:
Derivative instruments, foreign exchange contracts, liabilities	59	[2]	17	[2]
Derivative instruments, other, liabilities	9	[2],[3]	9	[2],[3]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Readily Available [Member] | Derivative instruments, assets
Assets:
Derivative instruments, foreign exchange contracts, assets	68	[2]	19	[2]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Readily Available [Member] | U.S. Treasury and federal agencies, mortgage-backed securities
Assets:
Investment securities available for sale	0	[2]	0	[2]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Readily Available [Member] | Asset-backed securities, student loans
Assets:
Investment securities available for sale	0	[2]	13	[2]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Readily Available [Member] | Asset-backed securities, credit cards
Assets:
Investment securities available for sale	0		24	[2]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Readily Available [Member] | Asset-backed securities, other
Assets:
Investment securities available for sale	66	[2]	92	[2]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Readily Available [Member] | Non-U.S. debt securities, mortgage-backed securities
Assets:
Investment securities available for sale			0	[2]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Readily Available [Member] | Non-U.S. debt securities, asset-backed securities
Assets:
Investment securities available for sale	0	[2]	0	[2]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Readily Available [Member] | Non-U.S. debt securities, other
Assets:
Investment securities available for sale	0	[2]	0	[2]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Readily Available [Member] | State and political subdivisions
Assets:
Investment securities available for sale	41	[2]	43	[2]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Readily Available [Member] | Collateralized mortgage obligations
Assets:
Investment securities available for sale	0	[2]	0	[2]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Readily Available [Member] | Other U.S. debt securities
Assets:
Investment securities available for sale	0	[2]	0	[2]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Not Readily Available [Member]
Assets:
Assets, fair value disclosure	5,368	[4]	7,373	[4]
Liabilities:
Liabilities, fair value disclosure	0	[4]	0	[4]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Not Readily Available [Member] | Derivative instruments, liabilities
Liabilities:
Derivative instruments, foreign exchange contracts, liabilities	0	[4]	0	[4]
Derivative instruments, other, liabilities	0	[4]	0	[4]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Not Readily Available [Member] | Derivative instruments, assets
Assets:
Derivative instruments, foreign exchange contracts, assets	0	[4]	0	[4]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Not Readily Available [Member] | U.S. Treasury and federal agencies, mortgage-backed securities
Assets:
Investment securities available for sale	260	[4]	716	[4]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Not Readily Available [Member] | Asset-backed securities, student loans
Assets:
Investment securities available for sale	266	[4]	410	[4]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Not Readily Available [Member] | Asset-backed securities, credit cards
Assets:
Investment securities available for sale			0	[4]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Not Readily Available [Member] | Asset-backed securities, other
Assets:
Investment securities available for sale	3,878	[4]	4,440	[4]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Not Readily Available [Member] | Non-U.S. debt securities, mortgage-backed securities
Assets:
Investment securities available for sale			375	[4]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Not Readily Available [Member] | Non-U.S. debt securities, asset-backed securities
Assets:
Investment securities available for sale	424	[4]	798	[4]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Not Readily Available [Member] | Non-U.S. debt securities, other
Assets:
Investment securities available for sale	298	[4]	464	[4]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Not Readily Available [Member] | State and political subdivisions
Assets:
Investment securities available for sale	0	[4]	0	[4]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Not Readily Available [Member] | Collateralized mortgage obligations
Assets:
Investment securities available for sale	234	[4]	162	[4]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Not Readily Available [Member] | Other U.S. debt securities
Assets:
Investment securities available for sale	$ 8	[4]	$ 8	[4]

[1] Substantially composed of securities guaranteed by the federal government with respect to at least 97% of defaulted principal and accrued interest on the underlying loans.

[2] Information with respect to these model-priced financial assets and liabilities is provided above in a separate table.

[3] Relates to stable value wrap contracts; refer to the sensitivity discussion following the tables presented below, and to note 7.

[4] Fair value for these financial assets is measured using non-binding broker or dealer quotes.