Restructuring - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($) Person	Dec. 31, 2017 USD ($) Person	Dec. 31, 2016 USD ($) Person
Restructuring Cost and Reserve [Line Items]
Number of employees | Person	300	250	300
Restructuring costs	$ 40.6	$ 28.2	$ 12.2
Aquatic Systems
Restructuring Cost and Reserve [Line Items]
Restructuring costs	15.3	3.6	1.8
Filtration Solutions
Restructuring Cost and Reserve [Line Items]
Restructuring costs	14.6	13.0	7.4
Flow Technologies
Restructuring Cost and Reserve [Line Items]
Restructuring costs	9.3	7.0	1.3
Other
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 1.4	$ 4.6	$ 1.7