Acquisitions (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Business Acquisition [Line Items]
Maximum future contingent consideration for acquisitions completed after January 1, 2009	$ 2,300,000,000
Benefit related to change in fair value of contingent liability	23,000,000
Contingent payment related to business combination	0
Accrued Contingent Consideration	(642,000,000)	(663,000,000)
Business Combination, Liabilities Arising from Contingencies, Amount Recognized	(2,000,000)
R&D- and commercialization-based milestones [Member]
Business Acquisition [Line Items]
Fair value of contingent consideration	(199,000,000)
Discounted cash flow [Member] | revenue-based payments [Member]
Business Acquisition [Line Items]
Fair value of contingent consideration	(203,000,000)
Monte Carlo [Member] | revenue-based payments [Member]
Business Acquisition [Line Items]
Fair value of contingent consideration	$ (240,000,000)