Acquisitions - Summary of Changes to Goodwill Balance (Detail) - USD ($) $ in Millions	3 Months Ended	18 Months Ended
	Dec. 31, 2018	Mar. 31, 2020
Goodwill [Line Items]
Ending balance		$ 327.1
Counsyl Inc [Member]
Goodwill [Line Items]
Beginning balance	$ 94.9	94.9
Fair value adjustment to equipment		0.7
Intangible adjustment		2.9
Working capital adjustment	$ (1.1)	(1.1)
Change in deferred tax liability		1.9
Ending balance		$ 99.3