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
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation Of Revenue [Line Items]
Net sales	$ 479.6	$ 466.0
Component Products
Disaggregation Of Revenue [Line Items]
Net sales	31.2	28.4
Component Products | Security Products
Disaggregation Of Revenue [Line Items]
Net sales	24.7	24.1
Component Products | Marine Components
Disaggregation Of Revenue [Line Items]
Net sales	6.5	4.3
Real Estate Management And Development
Disaggregation Of Revenue [Line Items]
Net sales	11.9	7.2
Real Estate Management And Development | Land Sales
Disaggregation Of Revenue [Line Items]
Net sales	9.5	5.8
Real Estate Management And Development | Water Delivery
Disaggregation Of Revenue [Line Items]
Net sales	1.9	0.9
Real Estate Management And Development | Utility and Other
Disaggregation Of Revenue [Line Items]
Net sales	$ 0.5	$ 0.5