Fair Value Measurements (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair Value of Derivative Assets	$ 751,000,000	$ 585,000,000
Fair Value of Derivative Liabilities	291,000,000	506,000,000
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents - financial instruments	441,000,000	24,000,000
Marketable securities	3,767,000,000	1,943,000,000
Fair Value of Derivative Assets	751,000,000	585,000,000
Total assets at fair value	4,959,000,000	2,552,000,000
Fair Value of Derivative Liabilities	291,000,000	506,000,000
Total liabilities at fair value	291,000,000	506,000,000
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	4,200,000,000	6,600,000,000
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	2,700,000,000	2,800,000,000
Fair Value, Measurements, Recurring [Member] | US Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents - financial instruments	40,000,000	0
Fair Value, Measurements, Recurring [Member] | Corporate debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents - financial instruments	60,000,000	0
Marketable securities	1,525,000,000	1,273,000,000
Fair Value, Measurements, Recurring [Member] | Other Marketable Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable securities	35,000,000	43,000,000
Fair Value, Measurements, Recurring [Member] | Foreign Government and Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents - financial instruments	341,000,000	24,000,000
Marketable securities	644,000,000	184,000,000
Fair Value, Measurements, Recurring [Member] | US Treasury and Government [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable securities	1,563,000,000	443,000,000
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents - financial instruments	40,000,000	0
Marketable securities	341,000,000	418,000,000
Fair Value of Derivative Assets	0	0
Total assets at fair value	381,000,000	418,000,000
Fair Value of Derivative Liabilities	0	0
Total liabilities at fair value	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | US Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents - financial instruments	40,000,000	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] | Other Marketable Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable securities	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Foreign Government and Agencies [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] | US Treasury and Government [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable securities	341,000,000	418,000,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents - financial instruments	401,000,000	24,000,000
Marketable securities	3,426,000,000	1,525,000,000
Fair Value of Derivative Assets	751,000,000	585,000,000
Total assets at fair value	4,578,000,000	2,134,000,000
Fair Value of Derivative Liabilities	291,000,000	506,000,000
Total liabilities at fair value	291,000,000	506,000,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | US Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents - financial instruments	0	0
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	60,000,000	0
Marketable securities	1,525,000,000	1,273,000,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Other Marketable Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable securities	35,000,000	43,000,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Foreign Government and Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents - financial instruments	341,000,000	24,000,000
Marketable securities	644,000,000	184,000,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | US Treasury and Government [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable securities	$ 1,222,000,000	$ 25,000,000