Other Income, Net - Schedule of Components of Other Income (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Securities earnings:
Dividends and interest	$ 8.3	$ 7.0
Currency transactions, net	(5.0)	(0.2)
Insurance recoveries	0.2	0.1
Infrastructure reimbursement	3.8	0.2
Gain on land sales	12.5
Other, net	0.6	0.7
Total	$ 20.4	$ 7.6