Acquisitions - PaxVax Preliminary Allocation of Purchase Price (Details) - USD ($) $ in Millions		9 Months Ended	12 Months Ended
	Oct. 04, 2018	Sep. 30, 2019	Sep. 30, 2019	Dec. 31, 2018
Estimated fair value of tangible assets acquired and liabilities assumed:
Goodwill		$ 268.6	$ 268.6	$ 259.7
Measurement Period Adjustments
Goodwill, measurement period adjustments		8.9
Total purchase price		$ 0.0
PaxVax
Estimated fair value of tangible assets acquired and liabilities assumed:
Cash	$ 9.0
Accounts receivable	4.1
Inventory	19.7
Prepaid expenses and other assets	11.9
Prepaid expenses and other assets, measurements period adjustments			(0.3)
Property, plant and equipment	57.8
Deferred tax assets	3.6
Deferred tax assets, measurement period adjustments			(0.2)
Accounts payable	(3.5)
Accrued expenses and other liabilities	(34.0)
Total fair value of tangible assets acquired and liabilities assumed	68.6
Acquired in-process research and development	0.0
Acquired intangible assets	133.0
Goodwill	71.5
Total purchase price	273.1
Measurement Period Adjustments
Accrued expenses and other liabilities, measurement period adjustment			(0.4)
Total fair value of tangible assets acquired and liabilities assumed, measurement period adjustments			(0.9)
Acquired in-process research and development, measurement period adjustment			(9.0)
Goodwill, measurement period adjustments			$ 9.9
PaxVax | Previously Reported
Estimated fair value of tangible assets acquired and liabilities assumed:
Cash	9.0
Accounts receivable	4.1
Inventory	19.7
Prepaid expenses and other assets	12.2
Property, plant and equipment	57.8
Deferred tax assets	3.8
Accounts payable	(3.5)
Accrued expenses and other liabilities	(33.6)
Total fair value of tangible assets acquired and liabilities assumed	69.5
Acquired in-process research and development	9.0
Acquired intangible assets	133.0
Goodwill	61.6
Total purchase price	$ 273.1