Acquisitions - Weighted Average Amortization Period (Details) - Adestra	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average amortization period	9 years 1 month 6 days	9 years 1 month 6 days
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average amortization period	9 years 6 months	9 years 9 months 18 days
Trade name
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average amortization period	9 years 1 month 6 days	8 years
Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average amortization period	7 years 6 months	6 years 8 months 12 days
Noncompete agreements
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average amortization period	0 years	3 years