Income Taxes - Schedule of Unrecognized Tax Benefit (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Beginning balance	$ 29.6	$ 26.9	$ 14.2
Increases in tax positions for prior years	2.8	0.3	1.7
Decreases in tax positions for prior years	(2.9)	(1.0)
Purchase Accounting		0.3
Increases in tax positions for current year	4.6	4.0	11.9
Settlements	(0.3)	(0.2)
Lapse in statutes of limitation	(3.3)	(0.7)	(0.9)
Ending balance	$ 30.5	$ 29.6	$ 26.9