Fair Value Measurements (Details) (USD $)	3 Months Ended
	Mar. 31, 2014 investment	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross Unrealized Losses	$ (1,000,000)
Cash and cash equivalents	2,254,000,000	1,657,000,000	1,742,000,000	1,617,000,000
Short-term marketable securities	679,000,000	775,000,000
Long-term marketable securities	2,008,000,000	1,939,000,000
Fair Value, Assets, Level 1 to Level 2 Transfers, Amount	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net	0
Available for Sale Debt maturities min date	1 year
Available for sale securities max maturity	3 years
Number of investments in unrealized loss position	92
Fair market value of investments	675,000,000
Fair Value Measurements, Valuation Techniques	based primarily on quoted market prices for the same or similar issues
Long-term Debt, Fair Value	1,380,000,000	1,370,000,000
Fair Value, Measurements, Recurring [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Cost	4,937,000,000	4,368,000,000
Gross Unrealized Gains	4,000,000	4,000,000
Gross Unrealized Losses	0	(1,000,000)
Fair Value	4,941,000,000	4,371,000,000
Cash and cash equivalents	2,254,000,000	1,657,000,000
Short-term marketable securities	679,000,000	775,000,000
Long-term marketable securities	2,008,000,000	1,939,000,000
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Cost	2,612,000,000	1,756,000,000
Gross Unrealized Gains	1,000,000	1,000,000
Gross Unrealized Losses	0	0
Fair Value	2,613,000,000	1,757,000,000
Cash and cash equivalents	1,531,000,000	751,000,000
Short-term marketable securities	169,000,000	205,000,000
Long-term marketable securities	913,000,000	801,000,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Cost	1,788,000,000	2,305,000,000
Gross Unrealized Gains	3,000,000	3,000,000
Gross Unrealized Losses	0	(1,000,000)
Fair Value	1,791,000,000	2,307,000,000
Cash and cash equivalents	186,000,000	599,000,000
Short-term marketable securities	510,000,000	570,000,000
Long-term marketable securities	1,095,000,000	1,138,000,000
Fair Value, Measurements, Recurring [Member] | Asset-backed securities and other | Level 2 [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Cost	34,000,000	24,000,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	34,000,000	24,000,000
Cash and cash equivalents	0	0
Short-term marketable securities	3,000,000	2,000,000
Long-term marketable securities	31,000,000	22,000,000
Fair Value, Measurements, Recurring [Member] | Cash
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Cost	537,000,000	307,000,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	537,000,000	307,000,000
Cash and cash equivalents	537,000,000	307,000,000
Short-term marketable securities	0	0
Long-term marketable securities	0	0
Fair Value, Measurements, Recurring [Member] | Bank and time deposits | Level 1 [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Cost	1,063,000,000	474,000,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	1,063,000,000	474,000,000
Cash and cash equivalents	1,063,000,000	474,000,000
Short-term marketable securities	0	0
Long-term marketable securities	0	0
Fair Value, Measurements, Recurring [Member] | Money market funds | Level 1 [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Cost	463,000,000	277,000,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	463,000,000	277,000,000
Cash and cash equivalents	463,000,000	277,000,000
Short-term marketable securities	0	0
Long-term marketable securities	0	0
Fair Value, Measurements, Recurring [Member] | U.S. treasury and agency obligations | Level 1 [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Cost	1,086,000,000	1,005,000,000
Gross Unrealized Gains	1,000,000	1,000,000
Gross Unrealized Losses	0	0
Fair Value	1,087,000,000	1,006,000,000
Cash and cash equivalents	5,000,000	0
Short-term marketable securities	169,000,000	205,000,000
Long-term marketable securities	913,000,000	801,000,000
Fair Value, Measurements, Recurring [Member] | Corporate bonds | Level 2 [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Cost	1,566,000,000	1,591,000,000
Gross Unrealized Gains	3,000,000	3,000,000
Gross Unrealized Losses	0	(1,000,000)
Fair Value	1,569,000,000	1,593,000,000
Cash and cash equivalents	20,000,000	0
Short-term marketable securities	485,000,000	477,000,000
Long-term marketable securities	1,064,000,000	1,116,000,000
Fair Value, Measurements, Recurring [Member] | Commercial paper | Level 2 [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Cost	188,000,000	690,000,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	188,000,000	690,000,000
Cash and cash equivalents	166,000,000	599,000,000
Short-term marketable securities	22,000,000	91,000,000
Long-term marketable securities	0	0
Fair Value, Measurements, Recurring [Member] | None [Member] | Fair Value, Inputs, Level 3 [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Cost	0	0
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	0	0
Cash and cash equivalents	0	0
Short-term marketable securities	0	0
Long-term marketable securities	0	0
UNITED STATES
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investments and Cash	2,210,000,000
Foreign Countries [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investments and Cash	$ 2,730,000,000