Fair Value Measurements (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Trading securities	$ 3,401	$ 2,895
Available-for-sale securities	141	131
Equity warrants	2	2
Interest rate swap agreements	234	246
Foreign exchange contracts	13	10
Fair value, assets measured on recurring basis, total	3,791	3,284
Derivative component of prepaid forward sale agreements and indexed debt instruments	1,704	1,234
Contractual obligations	984	1,004
Contingent consideration	579	583
Fair value liabilities measured on recurring basis	3,315	2,898
Fair Value, Inputs, Level 1 [Member]
Trading securities	3,401
Available-for-sale securities	100
Fair value, assets measured on recurring basis, total	3,501
Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities	20
Interest rate swap agreements	234
Foreign exchange contracts	13
Fair value, assets measured on recurring basis, total	267
Derivative component of prepaid forward sale agreements and indexed debt instruments	1,704
Fair value liabilities measured on recurring basis	1,752
Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities	21
Equity warrants	2
Fair value, assets measured on recurring basis, total	23
Contractual obligations	984
Contingent consideration	579
Fair value liabilities measured on recurring basis	1,563
Cross Currency Swap Agreements [Member]
Foreign currency contracts	35	69
Cross Currency Swap Agreements [Member] | Fair Value, Inputs, Level 2 [Member]
Foreign currency contracts	35
Foreign Exchange Contracts [Member]
Foreign currency contracts	13	8
Foreign Exchange Contracts [Member] | Fair Value, Inputs, Level 2 [Member]
Foreign currency contracts	$ 13