Fair Value (Schedule of Fair Value Measurements, Assets, Using Significant Unobservable Inputs) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value as of December 31, 2012	$ 6,980	$ 8,691
Transfers into Level 3, Assets	174	137
Transfers out of Level 3, Assets	(1,045)	(5,815)
Recorded in Revenue, Assets	165	325
Recorded in Other Comprehensive Income, Assets	16	93
Purchases, Assets	3,091	5,334
Issuances, Assets	0	0
Sales, Assets	(60)	(119)
Settlements, Assets	(1,757)	(1,666)
Fair value as of December 31, 2013	7,564	6,980
Change in Unrealized Gains (Losses) Related to Financial Instruments Held as of period end	(2)	(24)
Derivative instruments, assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value as of December 31, 2012	113	178
Recorded in Revenue, Assets	103	(95)
Recorded in Other Comprehensive Income, Assets	0	0
Purchases, Assets	20	137
Sales, Assets	0	0
Settlements, Assets	(217)	(107)
Fair value as of December 31, 2013	19	113
Change in Unrealized Gains (Losses) Related to Financial Instruments Held as of period end	(2)	(24)
Foreign exchange contracts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value as of December 31, 2012	113	168
Transfers into Level 3, Assets	0	0
Transfers out of Level 3, Assets	0	0
Recorded in Revenue, Assets	103	(85)
Recorded in Other Comprehensive Income, Assets	0	0
Purchases, Assets	20	137
Sales, Assets	0	0
Settlements, Assets	(217)	(107)
Fair value as of December 31, 2013	19	113
Change in Unrealized Gains (Losses) Related to Financial Instruments Held as of period end	(2)	(24)
Interest-rate contracts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value as of December 31, 2012		10
Transfers into Level 3, Assets		0
Transfers out of Level 3, Assets		0
Recorded in Revenue, Assets		(10)
Recorded in Other Comprehensive Income, Assets		0
Purchases, Assets		0
Sales, Assets		0
Settlements, Assets		0
Fair value as of December 31, 2013		0
Change in Unrealized Gains (Losses) Related to Financial Instruments Held as of 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 as of December 31, 2012	6,867	8,513
Transfers into Level 3, Assets		137
Transfers out of Level 3, Assets		(5,815)
Recorded in Revenue, Assets	62	420
Recorded in Other Comprehensive Income, Assets	16	93
Purchases, Assets	3,071	5,197
Sales, Assets	(60)	(119)
Settlements, Assets	(1,540)	(1,559)
Fair value as of December 31, 2013	7,545	6,867
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 December 31, 2012	825	1,189
Transfers into Level 3, Assets		50
Transfers out of Level 3, Assets	(92)	(301)
Recorded in Other Comprehensive Income, Assets		2
Purchases, Assets	92
Issuances, Assets
Settlements, Assets	(109)	(115)
Fair value as of December 31, 2013	716	825
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 December 31, 2012	4,649	3,749
Transfers into Level 3, Assets		33
Transfers out of Level 3, Assets		(523)
Recorded in Revenue, Assets	55	49
Recorded in Other Comprehensive Income, Assets	21	78
Purchases, Assets	1,800	2,259
Sales, Assets	(60)	(74)
Settlements, Assets	(1,262)	(922)
Fair value as of December 31, 2013	4,979	4,649
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 December 31, 2012	588	860
Transfers into Level 3, Assets		0
Transfers out of Level 3, Assets	(201)	(341)
Recorded in Revenue, Assets	2	2
Recorded in Other Comprehensive Income, Assets	12	15
Purchases, Assets	79	100
Sales, Assets	(26)
Settlements, Assets	(31)	(48)
Fair value as of December 31, 2013	423	588
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 December 31, 2012	67	91
Transfers into Level 3, Assets		21
Transfers out of Level 3, Assets	0	(136)
Recorded in Revenue, Assets	0	6
Recorded in Other Comprehensive Income, Assets	0	(6)
Purchases, Assets	0	239
Sales, Assets	0	(62)
Settlements, Assets	(43)	(86)
Fair value as of December 31, 2013	24	67
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 December 31, 2012	3,994	2,798
Transfers into Level 3, Assets		12
Transfers out of Level 3, Assets	(23)	(46)
Recorded in Revenue, Assets	53	41
Recorded in Other Comprehensive Income, Assets	9	69
Purchases, Assets	1,721	1,920
Sales, Assets	(34)	(12)
Settlements, Assets	(1,188)	(788)
Fair value as of December 31, 2013	4,532	3,994
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 December 31, 2012	1,219	3,296
Transfers into Level 3, Assets	160	0
Transfers out of Level 3, Assets	(585)	(4,677)
Recorded in Revenue, Assets	5	2
Recorded in Other Comprehensive Income, Assets	3	11
Purchases, Assets	961	2,655
Sales, Assets	0	0
Settlements, Assets	(126)	(68)
Fair value as of December 31, 2013	1,637	1,219
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 December 31, 2012	555	1,457
Transfers into Level 3, Assets		0
Transfers out of Level 3, Assets	(208)	(1,715)
Recorded in Revenue, Assets	0	0
Recorded in Other Comprehensive Income, Assets	(1)	5
Purchases, Assets	33	799
Sales, Assets	0	0
Settlements, Assets	(4)	9
Fair value as of December 31, 2013	375	555
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 December 31, 2012	524	1,768
Transfers into Level 3, Assets	160	0
Transfers out of Level 3, Assets	(283)	(2,493)
Recorded in Revenue, Assets	5	2
Recorded in Other Comprehensive Income, Assets	3	8
Purchases, Assets	531	1,317
Sales, Assets	0	0
Settlements, Assets	(142)	(78)
Fair value as of December 31, 2013	798	524
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 December 31, 2012	140	71
Transfers into Level 3, Assets	0	0
Transfers out of Level 3, Assets	(94)	(469)
Recorded in Revenue, Assets	0	0
Recorded in Other Comprehensive Income, Assets	1	(2)
Purchases, Assets	397	539
Sales, Assets	0	0
Settlements, Assets	20	1
Fair value as of December 31, 2013	464	140
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 December 31, 2012	48	50
Transfers into Level 3, Assets	0	0
Transfers out of Level 3, Assets	0	0
Recorded in Revenue, Assets	1	0
Recorded in Other Comprehensive Income, Assets	(2)	(1)
Purchases, Assets	0	0
Sales, Assets	0
Settlements, Assets	(4)	(1)
Fair value as of December 31, 2013	43	48
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 December 31, 2012	117	227
Transfers into Level 3, Assets	14	45
Transfers out of Level 3, Assets	(144)	(314)
Recorded in Revenue, Assets	1	369
Recorded in Other Comprehensive Income, Assets	(5)	3
Purchases, Assets	218	283
Sales, Assets	0	(45)
Settlements, Assets	(39)	(451)
Fair value as of December 31, 2013	162	117
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 December 31, 2012	9	2
Transfers into Level 3, Assets	0	9
Transfers out of Level 3, Assets	0	0
Recorded in Revenue, Assets	0	0
Recorded in Other Comprehensive Income, Assets	(1)	0
Purchases, Assets	0	0
Sales, Assets	0	0
Settlements, Assets	0	(2)
Fair value as of December 31, 2013	$ 8	$ 9