Restructuring Activities - Restructuring Accruals (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restructuring Reserve
Restructuring Reserve Beginning	$ 2.7	$ 6.3	$ 2.6
Restructuring charges	4.4	11.2	9.5
Cash payments and other	(6.2)	(15.0)	(5.8)
Acquired restructuring reserve		0.2
Restructuring Reserve Ending	0.9	2.7	6.3
Operating Segments | Energy & Chemicals
Restructuring Reserve
Restructuring Reserve Beginning	0.2	0.1	1.1
Restructuring charges	0.7	2.4	1.0
Cash payments and other	(0.9)	(2.5)	(2.0)
Acquired restructuring reserve		0.2
Restructuring Reserve Ending	0.0	0.2	0.1
Operating Segments | D&S West
Restructuring Reserve
Restructuring Reserve Beginning	1.2	3.2	0.4
Restructuring charges	0.0	1.1	3.5
Cash payments and other	(1.2)	(3.1)	(0.7)
Acquired restructuring reserve		0.0
Restructuring Reserve Ending	0.0	1.2	3.2
Operating Segments | D&S East
Restructuring Reserve
Restructuring Reserve Beginning	0.2	0.0	0.2
Restructuring charges	1.4	1.7	0.8
Cash payments and other	(0.8)	(1.5)	(1.0)
Acquired restructuring reserve		0.0
Restructuring Reserve Ending	0.8	0.2	0.0
Corporate
Restructuring Reserve
Restructuring Reserve Beginning	1.1	3.0	0.9
Restructuring charges	2.3	6.0	4.2
Cash payments and other	(3.3)	(7.9)	(2.1)
Acquired restructuring reserve		0.0
Restructuring Reserve Ending	$ 0.1	$ 1.1	$ 3.0