Fair Value Measurements (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011	Dec. 31, 2010
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Cost	$ 3,187	$ 5,206
Gross Unrealized Gains	3	1
Gross unrealized losses		(2)
Fair Value	3,190	5,205
Cash and cash equivalents	1,416	4,146	2,333	1,622
Short-term marketable securities	735	383
Long-term marketable securities	1,039	676
Level 1 [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Cost	1,575	4,107
Gross Unrealized Gains	1
Fair Value	1,576	4,107
Cash and cash equivalents	709	3,630
Short-term marketable securities	251	97
Long-term marketable securities	616	380
Level 2 [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Cost	1,406	945
Gross Unrealized Gains	2	1
Gross unrealized losses		(2)
Fair Value	1,408	944
Cash and cash equivalents	501	362
Short-term marketable securities	484	286
Long-term marketable securities	423	296
Cash [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Cost	206	154
Fair Value	206	154
Cash and cash equivalents	206	154
Bank and time deposits [Member] | Level 1 [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Cost	386	2,717
Fair Value	386	2,717
Cash and cash equivalents	385	2,716
Short-term marketable securities	1
Long-term marketable securities		1
Money market funds [Member] | Level 1 [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Cost	286	914
Fair Value	286	914
Cash and cash equivalents	286	914
Short-term marketable securities	0
U.S. treasury and agency obligations [Member] | Level 1 [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Cost	893	469
Gross Unrealized Gains	1
Fair Value	894	469
Cash and cash equivalents	38
Short-term marketable securities	240	90
Long-term marketable securities	616	379
Corporate bonds [Member] | Level 1 [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Cost	10	7
Fair Value	10	7
Short-term marketable securities	10	7
Corporate bonds [Member] | Level 2 [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Cost	746	543
Gross Unrealized Gains	2	1
Gross unrealized losses		(2)
Fair Value	748	542
Cash and cash equivalents	5	51
Short-term marketable securities	360	211
Long-term marketable securities	383	280
Commercial Paper [Member] | Level 2 [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Cost	597	381
Fair Value	597	381
Cash and cash equivalents	496	311
Short-term marketable securities	101	70
Asset-backed securities and other [Member] | Level 2 [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Cost	63	21
Fair Value	63	21
Short-term marketable securities	23	5
Long-term marketable securities	40	16
None [Member] | Level 3 [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Cost	0
Fair Value	0
Cash and cash equivalents	0
Long-term marketable securities	$ 0