Segment Information - Financial Information By Reportable Segment (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Net sales	[1]	$ 2,957.2	$ 2,965.1	$ 2,845.7
Segment Income (Loss)		516.3	536.8	496.5
Identifiable assets		4,139.5	3,806.5	8,633.7
Capital expenditures		58.5	48.2	39.1
Depreciation		$ 48.3	$ 49.7	$ 50.8
Segment Reporting, Disclosure of Major Customers		1	1
Segment Reporting, Net sales associated with Major Customer (percent)		15.00%	15.00%	15.00%
Aquatic Systems
Segment Reporting Information [Line Items]
Net sales		$ 985.3	$ 1,026.1	$ 939.6
Segment Income (Loss)		268.9	277.6	254.1
Identifiable assets		1,340.1	1,304.2	1,323.0
Capital expenditures		11.1	10.6	9.6
Depreciation		8.3	8.1	10.6
Filtration Solutions
Segment Reporting Information [Line Items]
Net sales		1,066.9	1,001.0	990.6
Segment Income (Loss)		171.3	168.5	154.5
Identifiable assets		1,552.6	1,232.4	1,333.3
Capital expenditures		26.3	16.6	19.2
Depreciation		22.5	23.2	21.6
Flow Technologies
Segment Reporting Information [Line Items]
Net sales		903.6	936.7	914.2
Segment Income (Loss)		138.4	145.6	140.6
Identifiable assets		1,000.0	1,003.6	1,010.8
Capital expenditures		14.1	10.3	7.3
Depreciation		12.0	13.1	13.4
Other
Segment Reporting Information [Line Items]
Net sales		1.4	1.3	1.3
Segment Income (Loss)		(62.3)	(54.9)	(52.7)
Identifiable assets	[2]	246.8	266.3	4,966.6
Capital expenditures		7.0	10.7	3.0
Depreciation		$ 5.5	$ 5.3	$ 5.2

[1] ⁽¹⁾  One customer in the Aquatic Systems segment, Pool Corporation, represented approximately 15% of our consolidated net sales in 2019, 2018 and 2017.

[2] ⁽¹⁾   All cash and cash equivalents and assets held for sale are included in “Other.”