Business Combinations, Intangible Assets Acquired (Details) $ in Millions	6 Months Ended
	Jun. 30, 2018 USD ($)
Finite-Lived Intangible Assets, Gross [Abstract]
Aggregate Acquisitions	$ 5.6
Customer relationships
Finite-Lived Intangible Assets, Gross [Abstract]
Weighted Average Useful Life	5 years
Estimated Useful Life	5 years
Aggregate Acquisitions	$ 4.6
Customer backlog
Finite-Lived Intangible Assets, Gross [Abstract]
Weighted Average Useful Life	1 year
Estimated Useful Life	1 year
Aggregate Acquisitions	$ 0.7
Non-compete agreements
Finite-Lived Intangible Assets, Gross [Abstract]
Weighted Average Useful Life	5 years
Estimated Useful Life	5 years
Aggregate Acquisitions	$ 0.2
Trade name
Finite-Lived Intangible Assets, Gross [Abstract]
Weighted Average Useful Life	1 year
Estimated Useful Life	1 year
Aggregate Acquisitions	$ 0.1