Business Combinations, Goodwill and Intangible Assets - Weighted Average Life of Intangible Assets (Details)	3 Months Ended
	Mar. 31, 2019
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average life of intangible assets	7 years 10 months 2 days
Leasehold benefits
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average life of intangible assets	2 months 1 day
Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average life of intangible assets	4 years 2 months 1 day
Non-compete agreements
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average life of intangible assets	5 months 19 days
Trade names and trademarks (Finite lived)
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average life of intangible assets	2 years 11 months 1 day