Fair Value (Fair Value Inputs, Assets and Liabilities, Quantitative Information) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended		12 Months Ended
	Jun. 30, 2014		Dec. 31, 2013
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investment securities available for sale	$ 98,546		$ 99,174
Asset-backed securities, student loans
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investment securities available for sale	13,962	[1]	14,542	[1]
Asset-backed securities, credit cards
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investment securities available for sale	6,566		8,210
Asset-backed securities, other
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investment securities available for sale	4,635		5,064
Non-U.S. debt securities, other
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investment securities available for sale	5,757		4,727
State and political subdivisions
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investment securities available for sale	10,617		10,263
Pricing Methods with Significant Unobservable Market Inputs (Level 3)
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Assets, fair value disclosure	5,756		7,564
Liabilities, fair value disclosure	19		26
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Derivative instruments, liabilities
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative instruments, foreign exchange contracts, liabilities	10		17
Derivative instruments, other, liabilities	9		9
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Derivative instruments, assets
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative instruments, foreign exchange contracts, assets	10		19
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Asset-backed securities, student loans
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investment securities available for sale	322		423
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Asset-backed securities, credit cards
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investment securities available for sale			24
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Asset-backed securities, other
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investment securities available for sale	4,061		4,532
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Non-U.S. debt securities, other
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investment securities available for sale	515		464
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | State and political subdivisions
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investment securities available for sale	41		43
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Discounted cash flows | Derivative instruments, liabilities | Weighted average
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Participant redemptions	4.90%	[2]	7.50%	[2]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Discounted cash flows | Asset-backed securities, student loans | Weighted average
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Credit spread	2.20%		3.50%
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Discounted cash flows | Asset-backed securities, credit cards | Weighted average
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Credit spread	0.00%		2.00%
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Discounted cash flows | Asset-backed securities, other | Weighted average
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Credit spread	1.00%		1.50%
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Discounted cash flows | State and political subdivisions | Weighted average
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Credit spread	1.60%		1.70%
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Option model | Derivative instruments, liabilities | Weighted average
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Volatility	5.80%		11.20%
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Option model | Derivative instruments, assets | Weighted average
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Volatility	6.00%		11.40%
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Readily Available [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Assets, fair value disclosure	141	[3]	191	[3]
Liabilities, fair value disclosure	19	[3]	26	[3]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Readily Available [Member] | Derivative instruments, liabilities
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative instruments, foreign exchange contracts, liabilities	10	[3]	17	[3]
Derivative instruments, other, liabilities	9	[3]	9	[3]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Readily Available [Member] | Derivative instruments, assets
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative instruments, foreign exchange contracts, assets	10	[3]	19	[3]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Readily Available [Member] | Asset-backed securities, student loans
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investment securities available for sale	14	[3]	13	[3]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Readily Available [Member] | Asset-backed securities, credit cards
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investment securities available for sale	0	[3]	24	[3]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Readily Available [Member] | Asset-backed securities, other
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investment securities available for sale	76	[3]	92	[3]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Readily Available [Member] | Non-U.S. debt securities, other
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investment securities available for sale	0	[3]	0	[3]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Readily Available [Member] | State and political subdivisions
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investment securities available for sale	41	[3]	43	[3]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Readily Available [Member] | Discounted cash flows | Derivative instruments, liabilities
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative instruments, other, liabilities	9	[2]	9	[2]
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Readily Available [Member] | Discounted cash flows | Asset-backed securities, student loans
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investment securities available for sale			13
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Readily Available [Member] | Discounted cash flows | Asset-backed securities, credit cards
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investment securities available for sale			24
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Readily Available [Member] | Discounted cash flows | Asset-backed securities, other
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investment securities available for sale			92
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Readily Available [Member] | Discounted cash flows | State and political subdivisions
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investment securities available for sale			43
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Readily Available [Member] | Option model | Derivative instruments, liabilities
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative instruments, foreign exchange contracts, liabilities	10		17
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Significant Unobservable Inputs Readily Available [Member] | Option model | Derivative instruments, assets
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative instruments, foreign exchange contracts, assets	$ 10		$ 19

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

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