Income Taxes - Summary of Changes in Gross Unrecognized Tax Benefits (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of period	$ 30.4	$ 39.7	$ 45.2
Additions based on tax positions related to current year	4.0	5.0	5.6
Reductions based on tax positions related to prior years	(0.9)	(0.2)	(1.8)
Settlements	0.0	(12.3)	(6.5)
Statute expirations	(2.9)	(0.6)	0.0
Foreign currency translation	(1.1)	(1.2)	(2.8)
Balance at end of period	$ 29.5	$ 30.4	$ 39.7