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
	Mar. 31, 2018	Mar. 31, 2017
Component Products
Disaggregation Of Revenue [Line Items]
Net sales	$ 28.4	$ 29.9
Component Products | Security Products
Disaggregation Of Revenue [Line Items]
Net sales	24.1	26.0
Component Products | Marine Components
Disaggregation Of Revenue [Line Items]
Net sales	4.3	3.9
Real Estate Management And Development
Disaggregation Of Revenue [Line Items]
Net sales	5.6	7.2
Real Estate Management And Development | Land Sales
Disaggregation Of Revenue [Line Items]
Net sales	3.7	5.8
Real Estate Management And Development | Water Delivery
Disaggregation Of Revenue [Line Items]
Net sales	1.3	0.9
Real Estate Management And Development | Utility and Other
Disaggregation Of Revenue [Line Items]
Net sales	$ 0.6	$ 0.5