Acquisitions - PaxVax Preliminary Allocation of Purchase Price (Details) - USD ($) $ in Millions		6 Months Ended
	Oct. 04, 2018	Mar. 31, 2019	Dec. 31, 2018
Estimated fair value of tangible assets acquired and liabilities assumed:
Goodwill		$ 267.7	$ 259.7
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	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	0.0
Acquired in-process research and development, measurement period adjustment		(9.0)
Acquired intangible assets	133.0
Goodwill	70.6
Goodwill, measurement period adjustments		$ 9.0
Total purchase price	273.1
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)
Acquired in-process research and development	9.0
Acquired intangible assets	133.0
Goodwill	61.6
Total purchase price	$ 273.1