Fair Value Measurements (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Jun. 30, 2012 Securitizations credit_rating	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Debt Security, Maturity Period for Classification as Cash Equivalent	90 days or less
Investment Security, Maturity Period for Classification as Marketable Security	greater than 90 days
Securities Purchased under Agreements to Resell Gross	$ 70,000,000		$ 25,000,000
Securitizations, Number of Transactions		2
Number of investment grade credit ratings, Number		2
Fair Value Measurement, Period After Which Fair Value of Collateral is Adjusted	greater than 120 days past due
Fair Value of Derivative Assets	1,275,000,000		1,256,000,000
Fair Value of Derivative Liabilities	251,000,000		400,000,000
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents - financial instruments	183,000,000		324,000,000
Marketable securities	2,331,000,000		2,106,000,000
Fair Value of Derivative Assets	1,275,000,000		1,256,000,000
Total assets at fair value	3,789,000,000		3,686,000,000
Fair Value of Derivative Liabilities	251,000,000		400,000,000
Total liabilities at fair value	251,000,000		400,000,000
Fair Value, Measurements, Recurring [Member] | Cash Equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Par value assets excluded from fair value by input	5,300,000,000		6,300,000,000
Fair Value, Measurements, Recurring [Member] | Cash [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Par value assets excluded from fair value by input	2,100,000,000		2,600,000,000
Fair Value, Measurements, Recurring [Member] | U.S. Government [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents - financial instruments	2,000,000		200,000,000
Marketable securities	629,000,000		620,000,000
Fair Value, Measurements, Recurring [Member] | U.S. government-sponsored enterprises [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents - financial instruments	136,000,000		20,000,000
Marketable securities	297,000,000		12,000,000
Fair Value, Measurements, Recurring [Member] | Non-U.S. government agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable securities	182,000,000		95,000,000
Fair Value, Measurements, Recurring [Member] | Corporate debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents - financial instruments	3,000,000		1,000,000
Marketable securities	1,120,000,000		1,155,000,000
Fair Value, Measurements, Recurring [Member] | Mortgage-backed and other asset-backed [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable securities	54,000,000		67,000,000
Fair Value, Measurements, Recurring [Member] | Non-U.S. government [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents - financial instruments	42,000,000		103,000,000
Marketable securities	39,000,000		142,000,000
Fair Value, Measurements, Recurring [Member] | Other liquid investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable securities	10,000,000		15,000,000
Fair Value, Measurements, Recurring [Member] | Interest rate contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair Value of Derivative Assets	1,181,000,000		1,247,000,000
Fair Value of Derivative Liabilities	215,000,000		256,000,000
Fair Value, Measurements, Recurring [Member] | Foreign currency exchange contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair Value of Derivative Assets	49,000,000		9,000,000
Fair Value of Derivative Liabilities	10,000,000		27,000,000
Fair Value, Measurements, Recurring [Member] | Cross-currency interest rate swap contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair Value of Derivative Assets	45,000,000		0
Fair Value of Derivative Liabilities	26,000,000		117,000,000
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents - financial instruments	2,000,000		200,000,000
Marketable securities	629,000,000		620,000,000
Fair Value of Derivative Assets	0		0
Total assets at fair value	631,000,000		820,000,000
Fair Value of Derivative Liabilities	0		0
Total liabilities at fair value	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | U.S. Government [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents - financial instruments	2,000,000		200,000,000
Marketable securities	629,000,000		620,000,000
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | U.S. government-sponsored enterprises [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents - financial instruments	0		0
Marketable securities	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Non-U.S. government agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable securities	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Corporate debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents - financial instruments	0		0
Marketable securities	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Mortgage-backed and other asset-backed [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable securities	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Non-U.S. government [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents - financial instruments	0		0
Marketable securities	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Other liquid investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable securities	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Interest rate contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair Value of Derivative Assets	0		0
Fair Value of Derivative Liabilities	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Foreign currency exchange contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair Value of Derivative Assets	0		0
Fair Value of Derivative Liabilities	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Cross-currency interest rate swap contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair Value of Derivative Assets	0		0
Fair Value of Derivative Liabilities	0		0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents - financial instruments	181,000,000		124,000,000
Marketable securities	1,702,000,000		1,486,000,000
Fair Value of Derivative Assets	1,275,000,000		1,256,000,000
Total assets at fair value	3,158,000,000		2,866,000,000
Fair Value of Derivative Liabilities	251,000,000		400,000,000
Total liabilities at fair value	251,000,000		400,000,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | U.S. Government [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents - financial instruments	0		0
Marketable securities	0		0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | U.S. government-sponsored enterprises [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents - financial instruments	136,000,000		20,000,000
Marketable securities	297,000,000		12,000,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Non-U.S. government agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable securities	182,000,000		95,000,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Corporate debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents - financial instruments	3,000,000		1,000,000
Marketable securities	1,120,000,000		1,155,000,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Mortgage-backed and other asset-backed [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable securities	54,000,000		67,000,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Non-U.S. government [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents - financial instruments	42,000,000		103,000,000
Marketable securities	39,000,000		142,000,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Other liquid investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable securities	10,000,000		15,000,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Interest rate contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair Value of Derivative Assets	1,181,000,000		1,247,000,000
Fair Value of Derivative Liabilities	215,000,000		256,000,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Foreign currency exchange contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair Value of Derivative Assets	49,000,000		9,000,000
Fair Value of Derivative Liabilities	10,000,000		27,000,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Cross-currency interest rate swap contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair Value of Derivative Assets	45,000,000		0
Fair Value of Derivative Liabilities	26,000,000		117,000,000
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents - financial instruments	0		0
Marketable securities	0		0
Fair Value of Derivative Assets	0		0
Total assets at fair value	0		0
Fair Value of Derivative Liabilities	0		0
Total liabilities at fair value	0		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | U.S. Government [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents - financial instruments	0		0
Marketable securities	0		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | U.S. government-sponsored enterprises [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents - financial instruments	0		0
Marketable securities	0		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Non-U.S. government agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable securities	0		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Corporate debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents - financial instruments	0		0
Marketable securities	0		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Mortgage-backed and other asset-backed [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable securities	0		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Non-U.S. government [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents - financial instruments	0		0
Marketable securities	0		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Other liquid investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable securities	0		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Interest rate contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair Value of Derivative Assets	0		0
Fair Value of Derivative Liabilities	0		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Foreign currency exchange contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair Value of Derivative Assets	0		0
Fair Value of Derivative Liabilities	0		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Cross-currency interest rate swap contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair Value of Derivative Assets	0		0
Fair Value of Derivative Liabilities	$ 0		$ 0