REVENUES FROM CONTRACTS - Disaggregated Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 03, 2021	Jun. 27, 2020	Jul. 03, 2021	Jun. 27, 2020
Disaggregation of Revenue [Line Items]
Revenues	$ 296.7	$ 258.0	$ 584.6	$ 514.8
Transferred at Point in Time
Disaggregation of Revenue [Line Items]
Revenues	267.8	227.2	518.7	438.4
Transferred over Time
Disaggregation of Revenue [Line Items]
Revenues	28.9	30.8	65.9	76.4
Package and process cooling equipment and services
Disaggregation of Revenue [Line Items]
Revenues	111.5	109.9	213.4	212.1
Boilers, comfort heating, and ventilation
Disaggregation of Revenue [Line Items]
Revenues	73.9	55.7	147.8	116.3
Underground locators, inspection and rehabilitation equipment, and robotic systems
Disaggregation of Revenue [Line Items]
Revenues	65.9	47.3	133.3	96.0
Signal monitoring, obstruction lighting, and bus fare collection systems
Disaggregation of Revenue [Line Items]
Revenues	45.3	44.8	89.5	88.0
South African projects
Disaggregation of Revenue [Line Items]
Revenues	0.1	0.3	0.6	2.4
HVAC
Disaggregation of Revenue [Line Items]
Revenues	185.4	165.2	361.0	328.0
HVAC \| Transferred at Point in Time
Disaggregation of Revenue [Line Items]
Revenues	166.3	141.5	320.7	269.0
HVAC \| Transferred over Time
Disaggregation of Revenue [Line Items]
Revenues	19.1	23.7	40.3	59.0
HVAC \| Package and process cooling equipment and services
Disaggregation of Revenue [Line Items]
Revenues	111.5	109.5	213.2	211.7
HVAC \| Boilers, comfort heating, and ventilation
Disaggregation of Revenue [Line Items]
Revenues	73.9	55.7	147.8	116.3
HVAC \| Underground locators, inspection and rehabilitation equipment, and robotic systems
Disaggregation of Revenue [Line Items]
Revenues	0.0	0.0	0.0	0.0
HVAC \| Signal monitoring, obstruction lighting, and bus fare collection systems
Disaggregation of Revenue [Line Items]
Revenues	0.0	0.0	0.0	0.0
HVAC \| South African projects
Disaggregation of Revenue [Line Items]
Revenues	0.0	0.0	0.0	0.0
Detection and Measurement
Disaggregation of Revenue [Line Items]
Revenues	111.2	92.1	222.8	184.0
Detection and Measurement \| Transferred at Point in Time
Disaggregation of Revenue [Line Items]
Revenues	101.5	85.7	198.0	169.2
Detection and Measurement \| Transferred over Time
Disaggregation of Revenue [Line Items]
Revenues	9.7	6.4	24.8	14.8
Detection and Measurement \| Package and process cooling equipment and services
Disaggregation of Revenue [Line Items]
Revenues	0.0	0.0	0.0	0.0
Detection and Measurement \| Boilers, comfort heating, and ventilation
Disaggregation of Revenue [Line Items]
Revenues	0.0	0.0	0.0	0.0
Detection and Measurement \| Underground locators, inspection and rehabilitation equipment, and robotic systems
Disaggregation of Revenue [Line Items]
Revenues	65.9	47.3	133.3	96.0
Detection and Measurement \| Signal monitoring, obstruction lighting, and bus fare collection systems
Disaggregation of Revenue [Line Items]
Revenues	45.3	44.8	89.5	88.0
Detection and Measurement \| South African projects
Disaggregation of Revenue [Line Items]
Revenues	0.0	0.0	0.0	0.0
Other
Disaggregation of Revenue [Line Items]
Revenues	0.1	0.7	0.8	2.8
Other \| Transferred at Point in Time
Disaggregation of Revenue [Line Items]
Revenues	0.0	0.0	0.0	0.2
Other \| Transferred over Time
Disaggregation of Revenue [Line Items]
Revenues	0.1	0.7	0.8	2.6
Other \| Package and process cooling equipment and services
Disaggregation of Revenue [Line Items]
Revenues	0.0	0.4	0.2	0.4
Other \| Boilers, comfort heating, and ventilation
Disaggregation of Revenue [Line Items]
Revenues	0.0	0.0	0.0	0.0
Other \| Underground locators, inspection and rehabilitation equipment, and robotic systems
Disaggregation of Revenue [Line Items]
Revenues	0.0	0.0	0.0	0.0
Other \| Signal monitoring, obstruction lighting, and bus fare collection systems
Disaggregation of Revenue [Line Items]
Revenues	0.0	0.0	0.0	0.0
Other \| South African projects
Disaggregation of Revenue [Line Items]
Revenues	$ 0.1	$ 0.3	$ 0.6	$ 2.4