Segment and Geographic Information - Assets (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Revenues from External Customers and Long-Lived Assets
Assets	$ 1,897.7	$ 1,724.7
Continuing Operations | Corporate
Revenues from External Customers and Long-Lived Assets
Assets	92.1	93.9
Continuing Operations | Energy & Chemicals | Operating Segments
Revenues from External Customers and Long-Lived Assets
Assets	889.2	782.9
Continuing Operations | D&S West | Operating Segments
Revenues from External Customers and Long-Lived Assets
Assets	420.3	415.7
Continuing Operations | D&S East | Operating Segments
Revenues from External Customers and Long-Lived Assets
Assets	496.1	327.3
Total assets of discontinued operations
Revenues from External Customers and Long-Lived Assets
Assets	$ 0.0	$ 104.9