Other intangible assets (Details 2) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Intangible assets, net (excluding goodwill)	$ 26,376,000	$ 15,511,000	$ 26,376,000	$ 15,511,000	$ 15,246,000
Amortization of intangible assets	2,100,000	500,000	6,800,000	1,600,000
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	27,551,000	18,011,000	27,551,000	18,011,000	17,958,000
Intangible assets, less accumulated amortization	5,958,000	5,823,000	5,958,000	5,823,000	6,268,000
Intangible assets, net (excluding goodwill)	21,593,000	12,188,000	21,593,000	12,188,000	11,690,000
Noncompete agreements
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	3,941,000	3,419,000	3,941,000	3,419,000	3,439,000
Intangible assets, less accumulated amortization	2,176,000	1,868,000	2,176,000	1,868,000	1,957,000
Intangible assets, net (excluding goodwill)	1,765,000	1,551,000	1,765,000	1,551,000	1,482,000
Other intangible assets
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	12,853,000	7,488,000	12,853,000	7,488,000	8,094,000
Intangible assets, less accumulated amortization	9,835,000	5,716,000	9,835,000	5,716,000	6,020,000
Intangible assets, net (excluding goodwill)	$ 3,018,000	$ 1,772,000	$ 3,018,000	$ 1,772,000	$ 2,074,000