Other Income, Net - Schedule of Components of Other Income (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Securities earnings:
Dividends and interest				$ 10.9	$ 26.1	$ 29.4
Securities transactions, net				0.3	12.4	0.1
Total				11.2	38.5	29.5
Gain on land sales	$ 4.4		$ 12.5	4.4	12.5
Gain on sale of business	$ 3.0			3.0	58.4
Insurance recoveries		$ 7.7		7.7	1.3	0.4
Currency transactions, net				2.0	10.1	(7.5)
Disposal of property and equipment, net				(0.3)	(0.3)	(0.5)
Infrastructure reimbursement		$ 8.8		9.2	4.3	1.0
Other, net				3.7	2.8	2.3
Total				$ 40.9	$ 69.2	$ 25.2

Amount of unrealized and realized gain (loss) on investment in debt and equity securities.

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