Restructuring - Additional Information (Detail) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) Person	Jun. 30, 2018 USD ($)
Restructuring Cost and Reserve [Line Items]
Number of employees | Person			300
Total restructuring costs	$ 6.7	$ 25.0	$ 7.8	$ 30.6
Aquatic Systems
Restructuring Cost and Reserve [Line Items]
Total restructuring costs	2.0	1.2	2.9	3.0
Filtration Solutions
Restructuring Cost and Reserve [Line Items]
Total restructuring costs	1.2	11.5	1.6	13.5
Flow Technologies
Restructuring Cost and Reserve [Line Items]
Total restructuring costs	2.4	6.3	2.1	8.0
Other
Restructuring Cost and Reserve [Line Items]
Total restructuring costs	$ 1.1	$ 6.0	$ 1.2	$ 6.1