Intangible Assets and Goodwill Intangible Assets and Goodwill Narrative (Details) (USD $)	12 Months Ended								12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Jan. 17, 2012 Pharmasset [Member]	Jan. 17, 2012 Pharmasset [Member] In-Process Reseach and Development [Member]	Dec. 31, 2011 CV Therapeutics [Member]	Jan. 14, 2011 Arresto Biosciences Inc [Member] In-Process Reseach and Development [Member]	Apr. 02, 2011 Calistoga Pharmaceuticals Inc [Member] In-Process Reseach and Development [Member]	Dec. 31, 2011 CGI Pharmaceuticals [Member]	Jul. 08, 2010 CGI Pharmaceuticals [Member]
Goodwill [Line Items]
Finite-Lived Intangible Asset, Useful Life	11 years
Amortization of Intangible Assets	$ 63,300,000	$ 69,600,000	$ 59,900,000
Indefinite-Lived Intangible Assets (Excluding Goodwill)	10,986,200,000	266,200,000
Acquired Indefinite-lived Intangible Asset, Amount				10,720,000,000	10,738,000,000		117,000,000	149,200,000		26,630,000
Impairment of Intangible Assets (Excluding Goodwill)									26,600,000
Gross carrying amount						$ 2,900,000