Goodwill and intangible assets Schedule of Finite-Lived Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Accumulated amortization	$ 18,479	$ 14,870
Finite-Lived Intangible Assets, Net	5,461
Intangible Assets, Gross (Excluding Goodwill)	23,940	23,940
Intangible assets, net	5,461	9,070
Goodwill [Abstract]
Goodwill	49,246	49,246
Impairment and Amortization [Abstract]
Goodwill, Impairment Loss	0	0	$ 0
Impairment of Intangibles (Excl. Goodwill)	0	0	0
Amortization expense	3,600	4,500	$ 4,600
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	10,920	10,920
Accumulated amortization	5,819	4,645
Finite-Lived Intangible Assets, Net	5,101	6,275
Technology-Based Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	10,050	10,050
Accumulated amortization	9,803	7,731
Finite-Lived Intangible Assets, Net	247	2,319
Trademarks and Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	1,110	1,110
Accumulated amortization	1,110	831
Finite-Lived Intangible Assets, Net	0	279
Backlog
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	1,400	1,400
Accumulated amortization	1,287	1,203
Finite-Lived Intangible Assets, Net	113	197
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	460	460
Accumulated amortization	460	460
Finite-Lived Intangible Assets, Net	$ 0	$ 0
Minimum [Member] | Customer relationships
Finite-Lived Intangible Assets [Line Items]
Weighted average useful life (years)	7 years
Minimum [Member] | Technology-Based Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted average useful life (years)	3 years
Minimum [Member] | Trademarks and Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted average useful life (years)	3 years
Minimum [Member] | Backlog
Finite-Lived Intangible Assets [Line Items]
Weighted average useful life (years)	3 years
Minimum [Member] | Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Weighted average useful life (years)	2 years
Maximum [Member] | Customer relationships
Finite-Lived Intangible Assets [Line Items]
Weighted average useful life (years)	9 years
Maximum [Member] | Technology-Based Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted average useful life (years)	7 years
Maximum [Member] | Trademarks and Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted average useful life (years)	7 years
Maximum [Member] | Backlog
Finite-Lived Intangible Assets [Line Items]
Weighted average useful life (years)	3 years
Maximum [Member] | Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Weighted average useful life (years)	4 years
Product Segment
Goodwill [Abstract]
Goodwill	$ 41,200
Service Segment
Goodwill [Abstract]
Goodwill	$ 8,000