Goodwill and Intangible Assets - Estimated Useful Lives of Intangible Assets (Details)	12 Months Ended
	Dec. 31, 2018
Minimum
Intangible Assets, Gross (Excluding Goodwill) [Abstract]
Estimated useful lives	1 year
Maximum
Intangible Assets, Gross (Excluding Goodwill) [Abstract]
Estimated useful lives	10 years
Customer relationships | Minimum
Intangible Assets, Gross (Excluding Goodwill) [Abstract]
Estimated useful lives	5 years
Customer relationships | Maximum
Intangible Assets, Gross (Excluding Goodwill) [Abstract]
Estimated useful lives	10 years
Non-compete agreements | Minimum
Intangible Assets, Gross (Excluding Goodwill) [Abstract]
Estimated useful lives	3 years
Non-compete agreements | Maximum
Intangible Assets, Gross (Excluding Goodwill) [Abstract]
Estimated useful lives	5 years
Developed software | Minimum
Intangible Assets, Gross (Excluding Goodwill) [Abstract]
Estimated useful lives	2 years
Developed software | Maximum
Intangible Assets, Gross (Excluding Goodwill) [Abstract]
Estimated useful lives	7 years
Trade name
Intangible Assets, Gross (Excluding Goodwill) [Abstract]
Estimated useful lives	1 year
Customer Backlog | Minimum
Intangible Assets, Gross (Excluding Goodwill) [Abstract]
Estimated useful lives	1 year
Customer Backlog | Maximum
Intangible Assets, Gross (Excluding Goodwill) [Abstract]
Estimated useful lives	1 year 6 months