Fair Value (Schedule of Fair Value Measurements, Assets, Using Significant Unobservable Inputs) (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Assets	$ 6,568,000,000	$ 6,820,000,000	$ 6,980,000,000	$ 8,691,000,000
Transfers into Level 3, Assets	139,000,000	95,000,000	139,000,000	116,000,000
Transfers out of Level 3, Assets	(76,000,000)	(1,188,000,000)	(500,000,000)	(4,218,000,000)
Recorded in Revenue, Assets	48,000,000	3,000,000	166,000,000	108,000,000
Recorded in Other Comprehensive Income, Assets	8,000,000	(3,000,000)	40,000,000	12,000,000
Purchases, Assets	812,000,000	1,691,000,000	1,242,000,000	3,094,000,000
Issuances, Assets	0	0	0	0
Sales, Assets	0	0	(36,000,000)	(73,000,000)
Settlements, Assets	(605,000,000)	(487,000,000)	(1,137,000,000)	(799,000,000)
Fair Value, ending balance, Assets	6,894,000,000	6,931,000,000	6,894,000,000	6,931,000,000
Change in Unrealized Gains (Losses) Related to Financial Instruments, Assets, Held at Period End	34,000,000	(52,000,000)	56,000,000	(73,000,000)
Derivative instruments, assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Assets				178,000,000
Transfers into Level 3, Assets				0
Transfers out of Level 3, Assets				0
Recorded in Revenue, Assets				(118,000,000)
Recorded in Other Comprehensive Income, Assets				0
Purchases, Assets				198,000,000
Sales, Assets				1,000,000
Settlements, Assets				(99,000,000)
Fair Value, ending balance, Assets		160,000,000		160,000,000
Change in Unrealized Gains (Losses) Related to Financial Instruments, Assets, Held at Period End				(73,000,000)
Foreign exchange contracts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Assets	172,000,000	127,000,000	113,000,000	168,000,000
Transfers into Level 3, Assets	0	0	0	0
Transfers out of Level 3, Assets	0	0	0	0
Recorded in Revenue, Assets	31,000,000	(77,000,000)	134,000,000	(108,000,000)
Recorded in Other Comprehensive Income, Assets	0	0	0	0
Purchases, Assets	12,000,000	157,000,000	32,000,000	198,000,000
Sales, Assets			0	0
Settlements, Assets	(94,000,000)	(47,000,000)	(158,000,000)	(98,000,000)
Fair Value, ending balance, Assets	121,000,000	160,000,000	121,000,000	160,000,000
Change in Unrealized Gains (Losses) Related to Financial Instruments, Assets, Held at Period End	34,000,000	(52,000,000)	56,000,000	(73,000,000)
Interest-rate contracts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Assets				10,000,000
Transfers into Level 3, Assets				0
Transfers out of Level 3, Assets				0
Recorded in Revenue, Assets				(10,000,000)
Recorded in Other Comprehensive Income, Assets				0
Purchases, Assets				0
Sales, Assets				1,000,000
Settlements, Assets				(1,000,000)
Fair Value, ending balance, Assets		0		0
Change in Unrealized Gains (Losses) Related to Financial Instruments, Assets, Held at Period End				0
Categories of investments, marketable securities, available-for-sale securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Assets	6,396,000,000	6,693,000,000	6,867,000,000	8,513,000,000
Transfers into Level 3, Assets	139,000,000	95,000,000	139,000,000	116,000,000
Transfers out of Level 3, Assets	(76,000,000)	(1,188,000,000)	(500,000,000)	(4,218,000,000)
Recorded in Revenue, Assets	17,000,000	80,000,000	32,000,000	226,000,000
Recorded in Other Comprehensive Income, Assets	8,000,000	(3,000,000)	40,000,000	12,000,000
Purchases, Assets	800,000,000	1,534,000,000	1,210,000,000	2,896,000,000
Sales, Assets			(36,000,000)	(74,000,000)
Settlements, Assets	(511,000,000)	(440,000,000)	(979,000,000)	(700,000,000)
Fair Value, ending balance, Assets	6,773,000,000	6,771,000,000	6,773,000,000	6,771,000,000
Categories of investments, marketable securities, available-for-sale securities | US Treasury and federal agencies, mortgage-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Assets	798,000,000	912,000,000	825,000,000	1,189,000,000
Transfers into Level 3, Assets		50,000,000		50,000,000
Transfers out of Level 3, Assets				(251,000,000)
Recorded in Other Comprehensive Income, Assets			1,000,000
Purchases, Assets	92,000,000		92,000,000
Settlements, Assets	(26,000,000)	(29,000,000)	(54,000,000)	(55,000,000)
Fair Value, ending balance, Assets	864,000,000	933,000,000	864,000,000	933,000,000
Categories of investments, marketable securities, available-for-sale securities | Total asset-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Assets	4,357,000,000	3,720,000,000	4,649,000,000	3,749,000,000
Transfers into Level 3, Assets		0		21,000,000
Transfers out of Level 3, Assets	(76,000,000)	0	(175,000,000)	(341,000,000)
Recorded in Revenue, Assets	16,000,000	14,000,000	29,000,000	25,000,000
Recorded in Other Comprehensive Income, Assets	11,000,000	(3,000,000)	38,000,000	12,000,000
Purchases, Assets	385,000,000	370,000,000	565,000,000	793,000,000
Sales, Assets			(36,000,000)	(74,000,000)
Settlements, Assets	(441,000,000)	(249,000,000)	(818,000,000)	(333,000,000)
Fair Value, ending balance, Assets	4,252,000,000	3,852,000,000	4,252,000,000	3,852,000,000
Categories of investments, marketable securities, available-for-sale securities | Asset-backed securities, student loans
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Assets	461,000,000	511,000,000	588,000,000	860,000,000
Transfers into Level 3, Assets		0		0
Transfers out of Level 3, Assets	(76,000,000)		(175,000,000)	(341,000,000)
Recorded in Revenue, Assets	1,000,000	1,000,000	1,000,000	1,000,000
Recorded in Other Comprehensive Income, Assets	2,000,000	(8,000,000)	8,000,000	(10,000,000)
Purchases, Assets	0		0
Sales, Assets			(26,000,000)
Settlements, Assets	(8,000,000)	(20,000,000)	(16,000,000)	(26,000,000)
Fair Value, ending balance, Assets	380,000,000	484,000,000	380,000,000	484,000,000
Categories of investments, marketable securities, available-for-sale securities | Asset-backed securities, credit cards
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Assets	24,000,000	119,000,000	67,000,000	91,000,000
Transfers into Level 3, Assets		0		21,000,000
Transfers out of Level 3, Assets	0		0	0
Recorded in Revenue, Assets	0	2,000,000	0	3,000,000
Recorded in Other Comprehensive Income, Assets	0	(4,000,000)	0	(3,000,000)
Purchases, Assets	0	157,000,000	0	224,000,000
Sales, Assets			0	(62,000,000)
Settlements, Assets	0	0	(43,000,000)	0
Fair Value, ending balance, Assets	24,000,000	274,000,000	24,000,000	274,000,000
Categories of investments, marketable securities, available-for-sale securities | Asset-backed securities, other
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Assets	3,872,000,000	3,090,000,000	3,994,000,000	2,798,000,000
Transfers into Level 3, Assets		0		0
Transfers out of Level 3, Assets	0		0	0
Recorded in Revenue, Assets	15,000,000	11,000,000	28,000,000	21,000,000
Recorded in Other Comprehensive Income, Assets	9,000,000	9,000,000	30,000,000	25,000,000
Purchases, Assets	385,000,000	213,000,000	565,000,000	569,000,000
Sales, Assets			(10,000,000)	(12,000,000)
Settlements, Assets	(433,000,000)	(229,000,000)	(759,000,000)	(307,000,000)
Fair Value, ending balance, Assets	3,848,000,000	3,094,000,000	3,848,000,000	3,094,000,000
Categories of investments, marketable securities, available-for-sale securities | Total non-U.S. debt securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Assets	1,077,000,000	1,818,000,000	1,219,000,000	3,296,000,000
Transfers into Level 3, Assets	139,000,000	0	139,000,000	0
Transfers out of Level 3, Assets	0	(1,129,000,000)	(325,000,000)	(3,435,000,000)
Recorded in Revenue, Assets	1,000,000	0	3,000,000	0
Recorded in Other Comprehensive Income, Assets	(2,000,000)	0	2,000,000	0
Purchases, Assets	183,000,000	987,000,000	413,000,000	1,821,000,000
Sales, Assets			0	0
Settlements, Assets	(33,000,000)	(40,000,000)	(86,000,000)	(46,000,000)
Fair Value, ending balance, Assets	1,365,000,000	1,636,000,000	1,365,000,000	1,636,000,000
Categories of investments, marketable securities, available-for-sale securities | Non-U.S. debt securities, mortgage-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Assets	331,000,000	469,000,000	555,000,000	1,457,000,000
Transfers into Level 3, Assets				0
Transfers out of Level 3, Assets	0	(338,000,000)	(208,000,000)	(1,495,000,000)
Recorded in Revenue, Assets	0		0	0
Recorded in Other Comprehensive Income, Assets	(1,000,000)	3,000,000	0	4,000,000
Purchases, Assets	0	147,000,000	0	306,000,000
Sales, Assets			0	0
Settlements, Assets	(2,000,000)	(8,000,000)	(19,000,000)	1,000,000
Fair Value, ending balance, Assets	328,000,000	273,000,000	328,000,000	273,000,000
Categories of investments, marketable securities, available-for-sale securities | Non-U.S. debt securities, asset-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Assets	470,000,000	1,035,000,000	524,000,000	1,768,000,000
Transfers into Level 3, Assets	139,000,000		139,000,000	0
Transfers out of Level 3, Assets	0	(483,000,000)	(77,000,000)	(1,568,000,000)
Recorded in Revenue, Assets	1,000,000		3,000,000	0
Recorded in Other Comprehensive Income, Assets	(2,000,000)	1,000,000	1,000,000	0
Purchases, Assets	183,000,000	840,000,000	234,000,000	1,207,000,000
Sales, Assets			0	0
Settlements, Assets	(35,000,000)	(31,000,000)	(68,000,000)	(45,000,000)
Fair Value, ending balance, Assets	756,000,000	1,362,000,000	756,000,000	1,362,000,000
Categories of investments, marketable securities, available-for-sale securities | Non-U.S. debt securities, other
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Assets	276,000,000	314,000,000	140,000,000	71,000,000
Transfers into Level 3, Assets	0		0	0
Transfers out of Level 3, Assets	0	(308,000,000)	(40,000,000)	(372,000,000)
Recorded in Revenue, Assets	0		0	0
Recorded in Other Comprehensive Income, Assets	1,000,000	(4,000,000)	1,000,000	(4,000,000)
Purchases, Assets	0	0	179,000,000	308,000,000
Sales, Assets			0	0
Settlements, Assets	4,000,000	(1,000,000)	1,000,000	(2,000,000)
Fair Value, ending balance, Assets	281,000,000	1,000,000	281,000,000	1,000,000
Categories of investments, marketable securities, available-for-sale securities | State and political subdivisions
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Assets	47,000,000	50,000,000	48,000,000	50,000,000
Transfers into Level 3, Assets	0	0	0	0
Transfers out of Level 3, Assets	0	0	0	0
Recorded in Revenue, Assets	0	0	0	0
Recorded in Other Comprehensive Income, Assets	(1,000,000)	0	(1,000,000)	0
Purchases, Assets	0	0	0	0
Sales, Assets			0
Settlements, Assets	(1,000,000)	(1,000,000)	(2,000,000)	(1,000,000)
Fair Value, ending balance, Assets	45,000,000	49,000,000	45,000,000	49,000,000
Categories of investments, marketable securities, available-for-sale securities | Collateralized mortgage obligations
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Assets	108,000,000	193,000,000	117,000,000	227,000,000
Transfers into Level 3, Assets	0	45,000,000	0	45,000,000
Transfers out of Level 3, Assets	0	(59,000,000)	0	(191,000,000)
Recorded in Revenue, Assets	0	66,000,000	0	201,000,000
Recorded in Other Comprehensive Income, Assets	0	0	0	0
Purchases, Assets	140,000,000	177,000,000	140,000,000	282,000,000
Sales, Assets			0	0
Settlements, Assets	(10,000,000)	(121,000,000)	(19,000,000)	(263,000,000)
Fair Value, ending balance, Assets	238,000,000	301,000,000	238,000,000	301,000,000
Categories of investments, marketable securities, available-for-sale securities | Other U.S.debt securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Assets	9,000,000		9,000,000	2,000,000
Transfers into Level 3, Assets	0		0	0
Transfers out of Level 3, Assets	0		0	0
Recorded in Revenue, Assets	0		0	0
Recorded in Other Comprehensive Income, Assets	0		0	0
Purchases, Assets	0		0	0
Sales, Assets			0	0
Settlements, Assets	0		0	(2,000,000)
Fair Value, ending balance, Assets	$ 9,000,000	$ 0	$ 9,000,000	$ 0