Other intangible assets (Details 2) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Intangible assets, net (excluding goodwill)	$ 34,250,000	$ 11,680,000	$ 15,246,000
Amortization of intangible assets	2,000,000.0	600,000
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	30,087,000	14,471,000	17,958,000
Intangible assets, less accumulated amortization	4,138,000	5,156,000	6,268,000
Intangible assets, net (excluding goodwill)	25,949,000	9,315,000	11,690,000
Noncompete agreements
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	4,229,000	3,179,000	3,439,000
Intangible assets, less accumulated amortization	1,928,000	1,730,000	1,957,000
Intangible assets, net (excluding goodwill)	2,301,000	1,449,000	1,482,000
Other intangible assets
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	13,060,000	6,458,000	8,094,000
Intangible assets, less accumulated amortization	7,060,000	5,542,000	6,020,000
Intangible assets, net (excluding goodwill)	6,000,000	$ 916,000	$ 2,074,000
Series of individually immaterial business combinations
Finite-Lived Intangible Assets [Line Items]
Other intangible assets acquired	$ 21,000,000.0