Intangible Assets (Narrative) (Details) - USD ($) $ in Millions			12 Months Ended
	Jun. 03, 2016	Jan. 22, 2016	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Acquisitions			$ (1,385.0)	$ 27,462.8
Baxalta | Currently marketed products
Finite-Lived Intangible Assets [Line Items]
Acquisitions	$ 21,165.0
Baxalta | In-Process Research and Development (IPR&D)
Finite-Lived Intangible Assets [Line Items]
Acquisitions	160.0
Baxalta | Other contract rights
Finite-Lived Intangible Assets [Line Items]
Acquisitions	$ 42.2
Dyax | Currently marketed products
Finite-Lived Intangible Assets [Line Items]
Acquisitions		$ 135.0
Dyax | In-Process Research and Development (IPR&D)
Finite-Lived Intangible Assets [Line Items]
Acquisitions		4,100.0
Dyax | Royalty rights
Finite-Lived Intangible Assets [Line Items]
Acquisitions		$ 425.0