Revenue - Disaggregation of Sales - 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, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation Of Revenue [Line Items]
Net sales	$ 475.2	$ 455.2	$ 1,483.5	$ 1,431.4
Component Products
Disaggregation Of Revenue [Line Items]
Net sales	29.7	30.0	94.6	90.8
Component Products | Security Products
Disaggregation Of Revenue [Line Items]
Net sales	23.4	24.5	75.0	75.8
Component Products | Marine Components
Disaggregation Of Revenue [Line Items]
Net sales	6.3	5.5	19.6	15.0
Real Estate Management And Development
Disaggregation Of Revenue [Line Items]
Net sales	8.1	14.9	30.5	28.1
Real Estate Management And Development | Land Sales
Disaggregation Of Revenue [Line Items]
Net sales	6.3	13.4	24.3	23.0
Real Estate Management And Development | Water Delivery
Disaggregation Of Revenue [Line Items]
Net sales	1.4	0.9	4.9	3.7
Real Estate Management And Development | Utility and Other
Disaggregation Of Revenue [Line Items]
Net sales	$ 0.4	$ 0.6	$ 1.3	$ 1.4