Intangible Assets (Summary of Intangible Assets) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross acquired intangible assets	$ 38,225.5	$ 37,923.3
Accumulated amortization	(5,361.2)	(4,877.2)
Intangible assets, net	32,864.3	33,046.1	$ 32,834.1	$ 34,697.5
Currently marketed products
Finite-Lived Intangible Assets [Line Items]
Gross acquired intangible assets	32,274.8	31,973.5
Accumulated amortization	(5,000.6)	(4,549.2)
Intangible assets, net	27,274.2	27,424.3
IPR&D
Finite-Lived Intangible Assets [Line Items]
Gross acquired intangible assets	5,114.8	5,113.9
Accumulated amortization	0.0	0.0
Intangible assets, net	5,114.8	5,113.9
Other intangible assets
Finite-Lived Intangible Assets [Line Items]
Gross acquired intangible assets	835.9	835.9
Accumulated amortization	(360.6)	(328.0)
Intangible assets, net	$ 475.3	$ 507.9