Other Income, Net - Schedule of Components of Other Income (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Securities earnings:
Dividends and interest			$ 14.2	$ 13.6
Securities transactions, net				0.1
Total	$ 7.2	$ 6.9	14.2	13.7
Currency transactions, net			(3.7)	4.2
Insurance recoveries		0.2	0.1	0.3
Business interruption insurance proceeds				3.4
Termination fee	4.0		4.0
Other, net			0.7	0.5
Total	$ 7.7	$ 10.7	$ 15.3	$ 22.1