Fair Value (Schedule of Fair Value Measurements, Assets, Using Significant Unobservable Inputs) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value as of beginning of period	$ 7,564	$ 6,980
Recorded in Revenue, Assets	7	110
Recorded in Other Comprehensive Income, Assets	(5)	32
Purchases, Assets	93	463
Issuances, Assets	0	0
Sales, Assets	(7)	(36)
Settlements, Assets	366	557
Transfers into Level 3, Assets	0	0
Transfers out of Level 3, Assets	(1,217)	(424)
Fair value as of end of period	6,069	6,568
Change in Unrealized Gains (Losses) Related to Financial Instruments Held as of period end	(7)	53
Derivative instruments, assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value as of beginning of period	19	113
Recorded in Revenue, Assets	(11)	95
Recorded in Other Comprehensive Income, Assets	0	0
Purchases, Assets	7	53
Issuances, Assets	0	0
Sales, Assets	0	0
Settlements, Assets	9	89
Transfers into Level 3, Assets	0	0
Transfers out of Level 3, Assets	0	0
Fair value as of end of period	6	172
Change in Unrealized Gains (Losses) Related to Financial Instruments Held as of period end	(7)	53
Foreign exchange contracts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value as of beginning of period	19	113
Recorded in Revenue, Assets	(11)	95
Recorded in Other Comprehensive Income, Assets	0	0
Purchases, Assets	7	53
Issuances, Assets	0	0
Sales, Assets	0	0
Settlements, Assets	9	89
Transfers into Level 3, Assets	0	0
Transfers out of Level 3, Assets	0	0
Fair value as of end of period	6	172
Change in Unrealized Gains (Losses) Related to Financial Instruments Held as of period end	(7)	53
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	7,545	6,867
Recorded in Revenue, Assets	18	15
Recorded in Other Comprehensive Income, Assets	(5)	32
Purchases, Assets	86	410
Issuances, Assets	0	0
Sales, Assets	(7)	(36)
Settlements, Assets	357	468
Transfers into Level 3, Assets	0	0
Transfers out of Level 3, Assets	(1,217)	(424)
Fair value as of end of period	6,063	6,396
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	716	825
Recorded in Revenue, Assets	0	0
Recorded in Other Comprehensive Income, Assets	0	0
Purchases, Assets	0	0
Issuances, Assets	0	0
Sales, Assets	0	0
Settlements, Assets	5	27
Transfers into Level 3, Assets	0	0
Transfers out of Level 3, Assets	(611)	0
Fair value as of end of period	100	798
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	4,979	4,649
Recorded in Revenue, Assets	16	13
Recorded in Other Comprehensive Income, Assets	(3)	28
Purchases, Assets	6	180
Issuances, Assets	0	0
Sales, Assets	0	(36)
Settlements, Assets	282	(377)
Transfers into Level 3, Assets	0	0
Transfers out of Level 3, Assets	(79)	(100)
Fair value as of end of period	4,637	4,357
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	423	588
Recorded in Revenue, Assets	1	0
Recorded in Other Comprehensive Income, Assets	1	7
Purchases, Assets	0	0
Issuances, Assets	0	0
Sales, Assets	0	(26)
Settlements, Assets	13	8
Transfers into Level 3, Assets	0	0
Transfers out of Level 3, Assets	(79)	(100)
Fair value as of end of period	333	461
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	67
Recorded in Revenue, Assets	0	0
Recorded in Other Comprehensive Income, Assets	0	0
Purchases, Assets	0	0
Issuances, Assets	0	0
Sales, Assets	0	0
Settlements, Assets	24	43
Transfers into Level 3, Assets	0	0
Transfers out of Level 3, Assets	0	0
Fair value as of end of period	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	4,532	3,994
Recorded in Revenue, Assets	15	13
Recorded in Other Comprehensive Income, Assets	(4)	21
Purchases, Assets	6	180
Issuances, Assets	0	0
Sales, Assets	0	(10)
Settlements, Assets	245	326
Transfers into Level 3, Assets	0	0
Transfers out of Level 3, Assets	0	0
Fair value as of end of period	4,304	3,872
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	1,637	1,219
Recorded in Revenue, Assets	2	2
Recorded in Other Comprehensive Income, Assets	(2)	3
Purchases, Assets	0	230
Issuances, Assets	0	0
Sales, Assets	(1)	0
Settlements, Assets	63	53
Transfers into Level 3, Assets	0	0
Transfers out of Level 3, Assets	(499)	(324)
Fair value as of end of period	1,074	1,077
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	375	555
Recorded in Revenue, Assets	0	0
Recorded in Other Comprehensive Income, Assets	0	0
Purchases, Assets	0	0
Issuances, Assets	0	0
Sales, Assets	0	0
Settlements, Assets	0	17
Transfers into Level 3, Assets	0	0
Transfers out of Level 3, Assets	(375)	(207)
Fair value as of end of period	0	331
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	798	524
Recorded in Revenue, Assets	2	2
Recorded in Other Comprehensive Income, Assets	(1)	3
Purchases, Assets	0	51
Issuances, Assets	0	0
Sales, Assets	0	0
Settlements, Assets	63	33
Transfers into Level 3, Assets	0	0
Transfers out of Level 3, Assets	(124)	(77)
Fair value as of end of period	612	470
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	464	140
Recorded in Revenue, Assets	0	0
Recorded in Other Comprehensive Income, Assets	(1)	0
Purchases, Assets	0	179
Issuances, Assets	0	0
Sales, Assets	(1)	0
Settlements, Assets	0	3
Transfers into Level 3, Assets	0	0
Transfers out of Level 3, Assets	0	(40)
Fair value as of end of period	462	276
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	43	48
Recorded in Revenue, Assets	0	0
Recorded in Other Comprehensive Income, Assets	0	1
Purchases, Assets	0	0
Issuances, Assets	0	0
Sales, Assets	0	0
Settlements, Assets	(1)	2
Transfers into Level 3, Assets	0	0
Transfers out of Level 3, Assets	0	0
Fair value as of end of period	42	47
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	162	117
Recorded in Revenue, Assets	0	0
Recorded in Other Comprehensive Income, Assets	0	0
Purchases, Assets	80	0
Issuances, Assets	0	0
Sales, Assets	(6)	0
Settlements, Assets	(6)	9
Transfers into Level 3, Assets	0	0
Transfers out of Level 3, Assets	(28)	0
Fair value as of end of period	202	108
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	8	9
Recorded in Revenue, Assets	0	0
Recorded in Other Comprehensive Income, Assets	0	0
Purchases, Assets	0	0
Issuances, Assets	0	0
Sales, Assets	0	0
Settlements, Assets	0	0
Transfers into Level 3, Assets	0	0
Transfers out of Level 3, Assets	0	0
Fair value as of end of period	$ 8	$ 9