Segment Information - Summary of Operations by Segment (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Customer revenue	$ 432.0	$ 435.9
Gross profit	139.2	113.1
DWS
Segment Reporting Information [Line Items]
Customer revenue	141.1	160.2
C&I
Segment Reporting Information [Line Items]
Customer revenue	123.3	104.0
CPF
Segment Reporting Information [Line Items]
Customer revenue	167.6	171.7
Intersegment
Segment Reporting Information [Line Items]
Customer revenue	1.0	0.1
Intersegment | DWS
Segment Reporting Information [Line Items]
Customer revenue	0.0	0.0
Intersegment | C&I
Segment Reporting Information [Line Items]
Customer revenue	0.0	0.0
Intersegment | CPF
Segment Reporting Information [Line Items]
Customer revenue	1.0	0.1
Operating Segments
Segment Reporting Information [Line Items]
Customer revenue	433.0	436.0
Gross profit	133.6	104.5
Operating Segments | DWS
Segment Reporting Information [Line Items]
Customer revenue	141.1	160.2
Gross profit	18.5	7.2
Operating Segments | C&I
Segment Reporting Information [Line Items]
Customer revenue	123.3	104.0
Gross profit	12.0	(2.8)
Operating Segments | CPF
Segment Reporting Information [Line Items]
Customer revenue	168.6	171.8
Gross profit	$ 103.1	$ 100.1