Segment Information (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 26, 2021 USD ($)	Sep. 27, 2020 USD ($)	Sep. 26, 2021 USD ($)	Sep. 26, 2021 USD ($) segment	Sep. 26, 2021 USD ($) item	Sep. 27, 2020 USD ($)	Dec. 31, 2020 USD ($)
Segment information
Number of geographic segments				3	3
Net sales	$ 455.0	$ 383.9	$ 1,335.3			$ 1,105.2
Operating income	64.7	47.9	177.0			126.7
Interest income						(0.2)
Interest expense	1.4	3.0	4.9			10.0
Other (income) expense, net	(0.2)	1.1	(1.0)			1.0
INCOME BEFORE INCOME TAXES	63.5	43.8	173.1			115.9
Capital expenditures	6.6	10.0	19.6			33.8
Depreciation and amortization	10.7	11.8	34.0			34.7
Identifiable assets (at end of period)	1,863.2	1,709.0	1,863.2	$ 1,863.2	$ 1,863.2	1,709.0	$ 1,738.2
Property, plant and equipment, net (at end of period)	204.2	211.3	204.2	204.2	204.2	211.3	$ 212.3
Residential & Commercial Flow Control
Segment information
Net sales	235.5	205.3	707.2			573.5
HVAC & Gas Products
Segment information
Net sales	143.6	113.1	408.4			332.1
Drainage & Water Re-use Products
Segment information
Net sales	47.1	37.8	134.5			117.8
Water Quality Products
Segment information
Net sales	28.8	27.7	85.2			81.8
U.S.
Segment information
Net sales	288.7	242.5	828.1			711.8
Reportable segments
Segment information
Operating income	78.4	57.7	213.6			154.2
Corporate
Segment information
Operating income	(13.7)	(9.8)	(36.6)			(27.5)
Intersegment sales
Segment information
Net sales	41.4	25.0	125.9			74.5
Americas
Segment information
Net sales	309.1	261.5	889.0			761.3
Capital expenditures	5.3	6.9	12.6			24.5
Depreciation and amortization	7.3	7.5	22.4			22.4
Identifiable assets (at end of period)	1,150.0	1,105.8	1,150.0	1,150.0	1,150.0	1,105.8
Property, plant and equipment, net (at end of period)	120.9	125.6	120.9	120.9	120.9	125.6
Americas | Residential & Commercial Flow Control
Segment information
Net sales	173.5	151.1	513.0			430.5
Americas | HVAC & Gas Products
Segment information
Net sales	82.9	63.9	226.4			194.5
Americas | Drainage & Water Re-use Products
Segment information
Net sales	25.2	20.0	69.0			57.9
Americas | Water Quality Products
Segment information
Net sales	27.5	26.5	80.6			78.4
Americas | U.S.
Segment information
Property, plant and equipment, net (at end of period)	116.4	121.8	116.4	116.4	116.4	121.8
Americas | Reportable segments
Segment information
Operating income	55.9	47.3	159.6			120.2
Americas | Intersegment sales
Segment information
Net sales	2.5	1.6	7.4			7.1
Europe
Segment information
Net sales	124.1	106.7	383.8			305.0
Capital expenditures	1.3	2.5	6.6			8.5
Depreciation and amortization	3.2	3.7	9.5			10.5
Identifiable assets (at end of period)	571.0	494.1	571.0	571.0	571.0	494.1
Property, plant and equipment, net (at end of period)	78.4	80.3	78.4	78.4	78.4	80.3
Europe | Residential & Commercial Flow Control
Segment information
Net sales	44.5	42.2	143.4			113.9
Europe | HVAC & Gas Products
Segment information
Net sales	57.5	46.3	172.9			129.1
Europe | Drainage & Water Re-use Products
Segment information
Net sales	21.1	17.3	63.8			59.3
Europe | Water Quality Products
Segment information
Net sales	1.0	0.9	3.7			2.7
Europe | Reportable segments
Segment information
Operating income	18.3	10.4	43.2			33.3
Europe | Intersegment sales
Segment information
Net sales	6.7	4.2	22.9			13.7
APMEA
Segment information
Net sales	21.8	15.7	62.5			38.9
Capital expenditures		0.6	0.4			0.8
Depreciation and amortization	0.2	0.6	2.1			1.8
Identifiable assets (at end of period)	142.2	109.1	142.2	142.2	142.2	109.1
Property, plant and equipment, net (at end of period)	4.9	5.4	4.9	$ 4.9	$ 4.9	5.4
APMEA | Residential & Commercial Flow Control
Segment information
Net sales	17.5	12.0	50.8			29.1
APMEA | HVAC & Gas Products
Segment information
Net sales	3.2	2.9	9.1			8.5
APMEA | Drainage & Water Re-use Products
Segment information
Net sales	0.8	0.5	1.7			0.6
APMEA | Water Quality Products
Segment information
Net sales	0.3	0.3	0.9			0.7
APMEA | Reportable segments
Segment information
Operating income	4.2		10.8			0.7
APMEA | Intersegment sales
Segment information
Net sales	$ 32.2	$ 19.2	$ 95.6			$ 53.7