Restructuring - Additional Information (Detail) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) Person	Sep. 30, 2019 USD ($)	Dec. 31, 2019 Person
Restructuring Cost and Reserve [Line Items]
Number of employees | Person			150		375
Total restructuring costs	$ 1.8	$ 2.9	$ 5.6	$ 10.7
Aquatic Systems
Restructuring Cost and Reserve [Line Items]
Total restructuring costs	0.4	1.5	2.4	4.9
Filtration Solutions
Restructuring Cost and Reserve [Line Items]
Total restructuring costs	1.1	0.5	1.7	3.7
Flow Technologies
Restructuring Cost and Reserve [Line Items]
Total restructuring costs	$ 0.3	$ 0.9	$ 1.5	$ 2.1