Other intangible assets (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Intangible assets, net (excluding goodwill)	$ 15,246	$ 10,815
Amortization of intangible assets	2,400	1,200	$ 2,000
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	17,958	22,720
Intangible assets, less accumulated amortization	6,268	13,535
Intangible assets, net (excluding goodwill)	11,690	9,185
Noncompete agreements
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	3,439	2,605
Intangible assets, less accumulated amortization	1,957	1,956
Intangible assets, net (excluding goodwill)	1,482	649
Other intangible assets
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	8,094	6,458
Intangible assets, less accumulated amortization	6,020	5,477
Intangible assets, net (excluding goodwill)	2,074	981
Series of Individually Immaterial Business Acquisitions
Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired	$ 6,800	$ 8,200