Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue
Sales	$ 289.3	$ 244.1
Point in time
Disaggregation of Revenue
Sales	242.4	164.2
Over time
Disaggregation of Revenue
Sales	46.9	79.9
Operating Segments | Energy & Chemicals
Disaggregation of Revenue
Sales	105.6	89.9
Operating Segments | Energy & Chemicals | Point in time
Disaggregation of Revenue
Sales	74.1	23.9
Operating Segments | Energy & Chemicals | Over time
Disaggregation of Revenue
Sales	31.5	66.0
Operating Segments | D&S West
Disaggregation of Revenue
Sales	118.0	100.6
Operating Segments | D&S West | Point in time
Disaggregation of Revenue
Sales	107.4	91.3
Operating Segments | D&S West | Over time
Disaggregation of Revenue
Sales	10.6	9.3
Operating Segments | D&S East
Disaggregation of Revenue
Sales	68.7	55.1
Operating Segments | D&S East | Point in time
Disaggregation of Revenue
Sales	63.9	50.5
Operating Segments | D&S East | Over time
Disaggregation of Revenue
Sales	4.8	4.6
Intersegment Eliminations
Disaggregation of Revenue
Sales	(3.0)	(1.5)
Intersegment Eliminations | Point in time
Disaggregation of Revenue
Sales	(3.0)	(1.5)
Intersegment Eliminations | Over time
Disaggregation of Revenue
Sales	$ 0.0	$ 0.0