Segment Reporting (Revenue by Product) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenue from External Customer [Line Items]
Product sales	$ 10,885.8	$ 6,099.9	$ 5,830.4
Hematology
Revenue from External Customer [Line Items]
Product sales	2,240.8	0.0	0.0
HEMOPHILIA
Revenue from External Customer [Line Items]
Product sales	1,789.0	0.0	0.0
INHIBITOR THERAPIES
Revenue from External Customer [Line Items]
Product sales	451.8	0.0	0.0
Genetic Diseases
Revenue from External Customer [Line Items]
Product sales	2,698.0	2,398.9	2,327.1
CINRYZE
Revenue from External Customer [Line Items]
Product sales	680.2	617.7	503.0
ELAPRASE
Revenue from External Customer [Line Items]
Product sales	589.0	552.6	592.8
FIRAZYR
Revenue from External Customer [Line Items]
Product sales	578.5	445.0	364.2
REPLAGAL
Revenue from External Customer [Line Items]
Product sales	452.4	441.2	500.4
VPRIV
Revenue from External Customer [Line Items]
Product sales	345.7	342.4	366.7
KALBITOR
Revenue from External Customer [Line Items]
Product sales	52.2	0.0	0.0
Neuroscience
Revenue from External Customer [Line Items]
Product sales	2,490.5	2,200.4	2,204.5
VYVANSE
Revenue from External Customer [Line Items]
Product sales	2,013.9	1,722.2	1,449.0
ADDERALL XR
Revenue from External Customer [Line Items]
Product sales	363.8	362.8	383.2
Other Neuroscience
Revenue from External Customer [Line Items]
Product sales	112.8	115.4	372.3
Immunology
Revenue from External Customer [Line Items]
Product sales	1,516.1	0.0	0.0
IMMUNOGLOBULIN THERAPIES
Revenue from External Customer [Line Items]
Product sales	1,143.9	0.0	0.0
BIO THERAPEUTICS
Revenue from External Customer [Line Items]
Product sales	372.2	0.0	0.0
Internal Medicine
Revenue from External Customer [Line Items]
Product sales	1,755.5	1,500.6	1,298.8
LIALDA/MEZAVANT
Revenue from External Customer [Line Items]
Product sales	792.1	684.4	633.8
PENTASA
Revenue from External Customer [Line Items]
Product sales	309.4	305.8	289.7
GATTEX/REVESTIVE
Revenue from External Customer [Line Items]
Product sales	219.4	141.7	0.0
NATPARA
Revenue from External Customer [Line Items]
Product sales	85.3	24.4	0.0
Other Internal Medicine
Revenue from External Customer [Line Items]
Product sales	349.3	344.3	375.3
Oncology
Revenue from External Customer [Line Items]
Product sales	130.5	0.0	0.0
Opthalmology
Revenue from External Customer [Line Items]
Product sales	$ 54.4	$ 0.0	$ 0.0