Other Income, Net - Schedule of Components of Other Income (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Securities earnings:
Dividends and interest			$ 8.7	$ 23.5
Securities transactions, net			0.3	12.6
Total	$ 2.6	$ 19.3	9.0	36.1
Currency transactions, net			5.6	4.2
Insurance recoveries	0.2	0.5	5.2	0.9
Infrastructure reimbursement			9.2	4.3
Gain on land sales			4.4	12.5
Other, net			2.1	1.8
Total	$ 13.6	$ 20.1	$ 35.5	$ 59.8