Income Taxes - Schedule of Unrecognized Tax Benefit (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Beginning balance	$ 12.2	$ 14.9	$ 14.9
Increases in tax positions for prior years	2.0		0.7
Decreases in tax positions for prior years	(1.4)	(4.3)	(0.5)
Acquisition related:
Purchase Accounting			0.3
Increases in tax positions for current year	1.9	1.9	3.4
Settlements	(0.2)		(1.3)
Lapse in statutes of limitation	(0.3)	(0.3)	(2.6)
Ending balance	$ 14.2	$ 12.2	$ 14.9