Other Comprehensive (Loss) Income - Schedule of Components of Other Comprehensive (Loss) Income and Income Tax (Benefit) Expense Allocated to Each Component (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Accumulated Other Comprehensive Income Loss [Line Items]
Other comprehensive (loss) income, Before Tax Amount	$ (25.3)	$ 23.1
Other comprehensive (loss) income, Income Tax Expense	(2.7)	5.8
Other comprehensive (loss) income	(22.6)	17.3
Translation adjustments
Accumulated Other Comprehensive Income Loss [Line Items]
Other comprehensive (loss) income, Before Tax Amount	9.0	17.9
Other comprehensive (loss) income, Income Tax Expense	0.0	0.0
Other comprehensive (loss) income	9.0	17.9
Adjustment for net periodic pension and other postretirement benefits plan cost
Accumulated Other Comprehensive Income Loss [Line Items]
Other comprehensive (loss) income, Before Tax Amount	1.0	5.2
Other comprehensive (loss) income, Income Tax Expense	0.3	5.8
Other comprehensive (loss) income	0.7	(0.6)
Unrealized loss on available-for-sale securities
Accumulated Other Comprehensive Income Loss [Line Items]
Other comprehensive (loss) income, Before Tax Amount	(35.3)	0.0
Other comprehensive (loss) income, Income Tax Expense	(3.0)	0.0
Other comprehensive (loss) income	$ (32.3)	$ 0.0