Intangible Assets - Gross Carrying Amounts and Accumulated Amortization (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets
Total intangible assets, gross	$ 177,336	$ 172,178
Total accumulated amortization	(47,740)	(42,525)
Total intangible assets, net	129,596	129,653
Customer relationships
Finite-Lived Intangible Assets
Total intangible assets, gross	149,420	146,200
Total accumulated amortization	$ (38,270)	(24,870)
Weighted Average Life (years)	10 years 3 months 18 days
Technology including internally developed software
Finite-Lived Intangible Assets
Total intangible assets, gross	$ 21,892	18,078
Total accumulated amortization	$ (6,153)	(10,879)
Weighted Average Life (years)	6 years 8 months 12 days
Backlog
Finite-Lived Intangible Assets
Total intangible assets, gross	$ 3,100	6,860
Total accumulated amortization	$ (2,842)	(5,827)
Weighted Average Life (years)	4 years
Trade Names
Finite-Lived Intangible Assets
Total intangible assets, gross	$ 2,500	0
Total accumulated amortization	$ (138)	0
Weighted Average Life (years)	15 years
Covenants not to compete
Finite-Lived Intangible Assets
Total intangible assets, gross	$ 424	1,040
Total accumulated amortization	$ (337)	$ (949)
Weighted Average Life (years)	4 years 8 months 12 days