Acquisitions - Acquisition of ACAM2000 Narrative (Details) - USD ($) $ in Millions	Oct. 06, 2017	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Goodwill		$ 266.6	$ 259.7
ACAM2000
Business Acquisition [Line Items]
Term of contract under acquisition	10 years
Value of contract	$ 425.0
Amount for deliveries of product	160.0
Upfront payments	97.5
Amount of payment for manufacturing related milestones	20.0
Cash	117.5
Amount of payment for regulatory related milestones		$ 7.5	$ 7.5
Fair value of contingent purchase consideration	$ 2.2
Present value discount rate	15.50%
Amortization period of intangible assets	10 years
Goodwill	$ 8.1