Revenue Recognition - Schedule of Disaggregates of Net Sales of our Component Products and Real Estate Management and Development Segments (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation Of Revenue [Line Items]
Net sales	$ 455.2	$ 496.5	$ 1,431.4	$ 1,383.6
Component Products
Disaggregation Of Revenue [Line Items]
Net sales	30.0	26.9	90.8	86.9
Component Products | Security Products
Disaggregation Of Revenue [Line Items]
Net sales	24.5	22.8	75.8	74.9
Component Products | Marine Components
Disaggregation Of Revenue [Line Items]
Net sales	5.5	4.1	15.0	12.0
Real Estate Management And Development
Disaggregation Of Revenue [Line Items]
Net sales	14.9	5.1	28.1	21.0
Real Estate Management And Development | Land Sales
Disaggregation Of Revenue [Line Items]
Net sales	13.4	2.7	23.0	14.8
Real Estate Management And Development | Water Delivery
Disaggregation Of Revenue [Line Items]
Net sales	0.9	1.8	3.7	4.5
Real Estate Management And Development | Utility and Other
Disaggregation Of Revenue [Line Items]
Net sales	$ 0.6	$ 0.6	$ 1.4	$ 1.7