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								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation Of Revenue [Line Items]
Net sales	$ 414.1	$ 475.2	$ 528.6	$ 479.6	$ 388.7	$ 455.2	$ 510.2	$ 466.0	$ 1,897.5	$ 1,820.1	$ 1,879.4
Component Products
Disaggregation Of Revenue [Line Items]
Net sales									124.2	118.2	112.0
Component Products | Security Products
Disaggregation Of Revenue [Line Items]
Net sales									99.3	98.4	96.6
Component Products | Marine Components
Disaggregation Of Revenue [Line Items]
Net sales									24.9	19.8	15.4
Real Estate Management And Development
Disaggregation Of Revenue [Line Items]
Net sales									42.1	40.0	38.4
Real Estate Management And Development | Land Sales
Disaggregation Of Revenue [Line Items]
Net sales									33.5	32.3	30.2
Real Estate Management And Development | Water Delivery
Disaggregation Of Revenue [Line Items]
Net sales									6.8	5.6	6.0
Real Estate Management And Development | Utility and Other
Disaggregation Of Revenue [Line Items]
Net sales									$ 1.8	$ 2.1	$ 2.2