Fair Value (Schedule of Fair Value Measurements, Assets, Using Significant Unobservable Inputs) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value as of beginning of period	$ 5,756	$ 6,894	$ 7,564	$ 6,980
Recorded in Revenue, Assets	64	(7)	79	165
Recorded in Other Comprehensive Income, Assets	(10)	(15)	(12)	25
Purchases, Assets	614	1,163	766	2,392
Issuances, Assets	0	0	0	0
Sales, Assets	(74)	(24)	(81)	(59)
Settlements, Assets	(551)	(349)	(1,249)	(1,481)
Transfers into Level 3, Assets	76	15	76	154
Transfers out of Level 3, Assets	(332)	(297)	(1,600)	(796)
Fair value as of end of period	5,543	7,380	5,543	7,380
Change in Unrealized Gains (Losses) Related to Financial Instruments Held as of period end	40	(16)	35	29
Derivative instruments, assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value as of beginning of period	10	121	19	113
Recorded in Revenue, Assets	44	(21)	26	119
Recorded in Other Comprehensive Income, Assets	0	0	0	0
Purchases, Assets	22	7	32	25
Issuances, Assets	0	0	0	0
Sales, Assets	0	0	0	0
Settlements, Assets	(8)	(30)	(9)	(180)
Transfers into Level 3, Assets	0	0	0	0
Transfers out of Level 3, Assets	0	0	0	0
Fair value as of end of period	68	77	68	77
Change in Unrealized Gains (Losses) Related to Financial Instruments Held as of period end	40	(16)	35	29
Foreign exchange contracts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value as of beginning of period	10	121	19	113
Recorded in Revenue, Assets	44	(21)	26	119
Recorded in Other Comprehensive Income, Assets	0	0	0	0
Purchases, Assets	22	7	32	25
Issuances, Assets	0	0	0	0
Sales, Assets	0	0	0	0
Settlements, Assets	(8)	(30)	(9)	(180)
Transfers into Level 3, Assets	0	0	0	0
Transfers out of Level 3, Assets	0	0	0	0
Fair value as of end of period	68	77	68	77
Change in Unrealized Gains (Losses) Related to Financial Instruments Held as of period end	40	(16)	35	29
Categories of investments, marketable securities, available-for-sale securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value as of beginning of period	5,746	6,773	7,545	6,867
Recorded in Revenue, Assets	20	14	53	46
Recorded in Other Comprehensive Income, Assets	(10)	(15)	(12)	25
Purchases, Assets	592	1,156	734	2,367
Issuances, Assets	0	0	0	0
Sales, Assets	(74)	(24)	(81)	(59)
Settlements, Assets	(543)	(319)	(1,240)	(1,301)
Transfers into Level 3, Assets	76	15	76	154
Transfers out of Level 3, Assets	(332)	(297)	(1,600)	(796)
Fair value as of end of period	5,475	7,303	5,475	7,303
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 as of beginning of period	96	864	716	825
Recorded in Revenue, Assets	0	0	0	0
Recorded in Other Comprehensive Income, Assets	0	(1)	0	(1)
Purchases, Assets	168	0	168	92
Issuances, Assets	0	0	0	0
Sales, Assets	0	0	0	0
Settlements, Assets	(4)	(29)	(14)	(83)
Transfers into Level 3, Assets	0	0	0	0
Transfers out of Level 3, Assets	0	(93)	(610)	(92)
Fair value as of end of period	260	741	260	741
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 as of beginning of period	4,383	4,252	4,979	4,649
Recorded in Revenue, Assets	18	13	47	41
Recorded in Other Comprehensive Income, Assets	(9)	(7)	(12)	31
Purchases, Assets	299	793	306	1,358
Issuances, Assets	0	0	0	0
Sales, Assets	(74)	(24)	(74)	(59)
Settlements, Assets	(407)	(285)	(957)	(1,103)
Transfers into Level 3, Assets	0	0	0	0
Transfers out of Level 3, Assets	0	0	(79)	(175)
Fair value as of end of period	4,210	4,742	4,210	4,742
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 as of beginning of period	322	380	423	588
Recorded in Revenue, Assets	0	0	1	1
Recorded in Other Comprehensive Income, Assets	(1)	(2)	2	6
Purchases, Assets	24	0	24	0
Issuances, Assets	0	0	0	0
Sales, Assets	(74)	0	(74)	(26)
Settlements, Assets	(5)	(10)	(31)	(26)
Transfers into Level 3, Assets	0	0	0	0
Transfers out of Level 3, Assets	0	0	(79)	(175)
Fair value as of end of period	266	368	266	368
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 as of beginning of period		24	24	67
Recorded in Revenue, Assets		0	0	0
Recorded in Other Comprehensive Income, Assets		0	0	0
Purchases, Assets		0	0	0
Issuances, Assets		0	0	0
Sales, Assets		0	0	0
Settlements, Assets		0	(24)	(43)
Transfers into Level 3, Assets		0	0	0
Transfers out of Level 3, Assets		0	0	0
Fair value as of end of period	0	24	0	24
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 as of beginning of period	4,061	3,848	4,532	3,994
Recorded in Revenue, Assets	18	13	46	40
Recorded in Other Comprehensive Income, Assets	(8)	(5)	(14)	25
Purchases, Assets	275	793	282	1,358
Issuances, Assets	0	0	0	0
Sales, Assets	0	(24)	0	(33)
Settlements, Assets	(402)	(275)	(902)	(1,034)
Transfers into Level 3, Assets	0	0	0	0
Transfers out of Level 3, Assets	0	0	0	0
Fair value as of end of period	3,944	4,350	3,944	4,350
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 as of beginning of period	1,021	1,365	1,637	1,219
Recorded in Revenue, Assets	2	1	5	4
Recorded in Other Comprehensive Income, Assets	(1)	(1)	0	1
Purchases, Assets	0	313	55	727
Issuances, Assets	0	0	0	0
Sales, Assets	0	0	(1)	0
Settlements, Assets	(124)	6	(247)	(81)
Transfers into Level 3, Assets	76	0	76	139
Transfers out of Level 3, Assets	(252)	(104)	(803)	(429)
Fair value as of end of period	722	1,580	722	1,580
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 as of beginning of period		328	375	555
Recorded in Revenue, Assets		0	0	0
Recorded in Other Comprehensive Income, Assets		(1)	0	(1)
Purchases, Assets		0	0	0
Issuances, Assets		0	0	0
Sales, Assets		0	0	0
Settlements, Assets		13	0	(6)
Transfers into Level 3, Assets		0	0	0
Transfers out of Level 3, Assets		0	(375)	(208)
Fair value as of end of period	0	340	0	340
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 as of beginning of period	506	756	798	524
Recorded in Revenue, Assets	2	1	5	4
Recorded in Other Comprehensive Income, Assets	(1)	1	0	2
Purchases, Assets	0	164	0	399
Issuances, Assets	0	0	0	0
Sales, Assets	0	0	0	0
Settlements, Assets	(99)	(19)	(219)	(88)
Transfers into Level 3, Assets	76	0	76	139
Transfers out of Level 3, Assets	(60)	(104)	(236)	(181)
Fair value as of end of period	424	799	424	799
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 as of beginning of period	515	281	464	140
Recorded in Revenue, Assets	0	0	0	0
Recorded in Other Comprehensive Income, Assets	0	(1)	0	0
Purchases, Assets	0	149	55	328
Issuances, Assets	0	0	0	0
Sales, Assets	0	0	(1)	0
Settlements, Assets	(25)	12	(28)	13
Transfers into Level 3, Assets	0	0	0	0
Transfers out of Level 3, Assets	(192)	0	(192)	(40)
Fair value as of end of period	298	441	298	441
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 as of beginning of period	41	45	43	48
Recorded in Revenue, Assets	0	0	1	0
Recorded in Other Comprehensive Income, Assets	0	(1)	(1)	(1)
Purchases, Assets	0	0	0	0
Issuances, Assets	0	0	0	0
Sales, Assets	0	0	0	0
Settlements, Assets	0	0	(2)	(3)
Transfers into Level 3, Assets	0	0	0	0
Transfers out of Level 3, Assets	0	0	0	0
Fair value as of end of period	41	44	41	44
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 as of beginning of period	196	238	162	117
Recorded in Revenue, Assets	0	0	0	1
Recorded in Other Comprehensive Income, Assets	0	(5)	1	(5)
Purchases, Assets	125	50	205	190
Issuances, Assets	0	0	0	0
Sales, Assets	0	0	(6)	0
Settlements, Assets	(7)	(11)	(20)	(31)
Transfers into Level 3, Assets	0	15	0	15
Transfers out of Level 3, Assets	(80)	(100)	(108)	(100)
Fair value as of end of period	234	187	234	187
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 as of beginning of period	9	9	8	9
Recorded in Revenue, Assets	0	0	0	0
Recorded in Other Comprehensive Income, Assets	0	0	0	0
Purchases, Assets	0	0	0	0
Issuances, Assets	0	0	0	0
Sales, Assets	0	0	0	0
Settlements, Assets	(1)	0	0	0
Transfers into Level 3, Assets	0	0	0	0
Transfers out of Level 3, Assets	0	0	0	0
Fair value as of end of period	$ 8	$ 9	$ 8	$ 9