Cash, Cash Equivalents and Marketable Securities (Details 2) (USD $) In Millions	Jun. 30, 2011	Dec. 31, 2010
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	$ 3,800	$ 4,058
Level 1 [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	2,370	3,169
Level 1 [Member] | Cash [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	104	103
Level 1 [Member] | Bank Deposits [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	812	455
Level 1 [Member] | Certificates of Deposits [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	9
Level 1 [Member] | Money market funds [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	212	641
Level 1 [Member] | U.S. treasury and agency obligations [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	1,216	1,950
Level 1 [Member] | Foreign government and agency obligations [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	0
Level 1 [Member] | Commercial Paper [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	0	0
Level 1 [Member] | Corporate bonds [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	17	20
Level 1 [Member] | Asset-backed Securities and other [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	0
Level 2 [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	1,430	889
Level 2 [Member] | Cash [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	0	0
Level 2 [Member] | Bank Deposits [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	0	0
Level 2 [Member] | Certificates of Deposits [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	0
Level 2 [Member] | Money market funds [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	0	0
Level 2 [Member] | U.S. treasury and agency obligations [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	0	0
Level 2 [Member] | Foreign government and agency obligations [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	6
Level 2 [Member] | Commercial Paper [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	1,007	782
Level 2 [Member] | Corporate bonds [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	400	107
Level 2 [Member] | Asset-backed Securities and other [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	17
Level 3 [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	0	0
Level 3 [Member] | Cash [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	0	0
Level 3 [Member] | Bank Deposits [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	0	0
Level 3 [Member] | Certificates of Deposits [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	0
Level 3 [Member] | Money market funds [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	0	0
Level 3 [Member] | U.S. treasury and agency obligations [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	0	0
Level 3 [Member] | Foreign government and agency obligations [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	0
Level 3 [Member] | Commercial Paper [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	0	0
Level 3 [Member] | Corporate bonds [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	0	0
Level 3 [Member] | Asset-backed Securities and other [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	0
Cash [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	104	103
Bank Deposits [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	812	455
Certificates of Deposits [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	9
Money market funds [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	212	641
U.S. treasury and agency obligations [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	1,216	1,950
Foreign government and agency obligations [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	6
Commercial Paper [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	1,007	782
Corporate bonds [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	417	127
Asset-backed Securities and other [Member]
Fair value measurements for investments aggregated by major security type
Fair value measurements for investments aggregated by major security type	$ 17