Segment Information (Details) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020 USD ($)	Sep. 27, 2020 USD ($)	Jun. 28, 2020 USD ($)	Mar. 29, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 29, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2020 USD ($) segment	Dec. 31, 2020 USD ($) item	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Segment information
Number of geographic segments										3	3
Net sales	$ 403.4	$ 383.9	$ 338.7	$ 382.6	$ 400.3	$ 394.7	$ 416.8	$ 388.7	$ 1,508.6			$ 1,600.5	$ 1,564.9
Operating income									181.1			197.1	188.4
Interest income									(0.2)			(0.4)	(0.8)
Interest expense									13.3			14.1	16.3
Other expense (income), net									1.0			(0.5)	(1.7)
INCOME BEFORE INCOME TAXES									167.0			183.9	174.6
Capital expenditures									43.8			29.2	35.9
Depreciation and amortization									46.5			46.6	48.5
Identifiable assets (at end of period)	1,738.2				1,723.1				1,738.2	$ 1,738.2	$ 1,738.2	1,723.1	1,653.7
Property, plant and equipment, net (at end of period)	212.3				200.0				212.3	212.3	212.3	200.0	201.9
Residential & Commercial Flow Control
Segment information
Net sales									786.5			827.5
HVAC & Gas Products
Segment information
Net sales									459.6			498.0
Drainage & Water Re-use Products
Segment information
Net sales									156.3			172.4
Water Quality Products
Segment information
Net sales									106.2			102.6
U.S.
Segment information
Net sales									956.5			1,014.0	964.2
Property, plant and equipment, net (at end of period)	118.9				112.6				118.9	118.9	118.9	112.6	111.0
Reportable segments
Segment information
Operating income									220.0			244.2	228.1
Corporate
Segment information
Operating income									(38.9)			(47.1)	(39.7)
Intersegment sales
Segment information
Net sales									99.0			95.0	115.3
Americas
Segment information
Net sales									1,025.7			1,084.1	1,032.1
Capital expenditures									31.2			18.3	21.5
Depreciation and amortization									29.7			29.3	29.1
Identifiable assets (at end of period)	1,075.1				1,102.9				1,075.1	1,075.1	1,075.1	1,102.9	1,028.1
Property, plant and equipment, net (at end of period)	122.9				116.7				122.9	122.9	122.9	116.7	115.0
Americas | Residential & Commercial Flow Control
Segment information
Net sales									584.6			610.5
Americas | HVAC & Gas Products
Segment information
Net sales									263.9			294.6
Americas | Drainage & Water Re-use Products
Segment information
Net sales									75.8			80.2
Americas | Water Quality Products
Segment information
Net sales									101.4			98.8
Americas | Reportable segments
Segment information
Operating income									166.3			187.4	171.1
Americas | Intersegment sales
Segment information
Net sales									8.7			12.1	12.7
Europe
Segment information
Net sales									424.9			451.0	467.0
Capital expenditures									11.4			10.3	12.7
Depreciation and amortization									14.3			14.6	16.7
Identifiable assets (at end of period)	537.2				515.2				537.2	537.2	537.2	515.2	510.2
Property, plant and equipment, net (at end of period)	83.8				77.5				83.8	83.8	83.8	77.5	80.0
Europe | Residential & Commercial Flow Control
Segment information
Net sales									157.8			171.3
Europe | HVAC & Gas Products
Segment information
Net sales									184.0			188.2
Europe | Drainage & Water Re-use Products
Segment information
Net sales									79.4			88.8
Europe | Water Quality Products
Segment information
Net sales									3.7			2.7
Europe | Reportable segments
Segment information
Operating income									50.2			49.9	49.8
Europe | Intersegment sales
Segment information
Net sales									18.9			15.2	14.2
APMEA
Segment information
Net sales									58.0			65.4	65.8
Capital expenditures									1.2			0.6	1.7
Depreciation and amortization									2.5			2.7	2.7
Identifiable assets (at end of period)	125.9				105.0				125.9	125.9	125.9	105.0	115.4
Property, plant and equipment, net (at end of period)	$ 5.6				$ 5.8				5.6	$ 5.6	$ 5.6	5.8	6.9
APMEA | Residential & Commercial Flow Control
Segment information
Net sales									44.1			45.7
APMEA | HVAC & Gas Products
Segment information
Net sales									11.7			15.2
APMEA | Drainage & Water Re-use Products
Segment information
Net sales									1.1			3.4
APMEA | Water Quality Products
Segment information
Net sales									1.1			1.1
APMEA | Reportable segments
Segment information
Operating income									3.5			6.9	7.2
APMEA | Intersegment sales
Segment information
Net sales									$ 71.4			$ 67.7	$ 88.4