Quarterly Financial Data (Unaudited) (Details Textual) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule Of Development Milestone And Collaboration [Line Items]
Research and development									$ 2,012.8	$ 1,893.4	$ 1,444.1
Net income attributable to noncontrolling interests, net of tax									46.2	6.8	0.0
Restructuring charges	$ 93.4								93.4	0.0	0.0
Product, net	2,425.9	$ 2,391.7	$ 2,198.6	$ 2,172.3	$ 2,287.0	$ 2,117.3	$ 2,056.3	$ 1,742.8	9,188.5	$ 8,203.4	$ 5,542.3
AGTC
Schedule Of Development Milestone And Collaboration [Line Items]
Research and development		48.1							$ 54.5
Mitsubishi Tanabe Pharma Corporation
Schedule Of Development Milestone And Collaboration [Line Items]
Research and development	$ 60.0
Eisai
Schedule Of Development Milestone And Collaboration [Line Items]
Research and development							21.6	$ 117.7
Neurimmune
Schedule Of Development Milestone And Collaboration [Line Items]
Net income attributable to noncontrolling interests, net of tax		$ 60.0
ITALY
Schedule Of Development Milestone And Collaboration [Line Items]
Product, net							$ 53.5