Other Income, Net - Schedule of Components of Other Income (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Securities earnings:
Dividends and interest	$ 7.0	$ 6.7
Securities transactions, net		0.1
Total	7.0	6.8
Currency transactions, net	(0.2)	2.3
Insurance recoveries	0.1	0.1
Business interruption insurance proceeds		2.0
Other, net	0.7	0.2
Total	$ 7.6	$ 11.4