Intangible assets (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Amortization of Intangible Assets	$ 200	$ 100
Finite-Lived Intangible Assets, Gross	12,791		$ 13,093
Finite-Lived Intangible Assets, Accumulated Amortization	(1,449)		(1,280)
Finite-Lived Intangible Assets, Net	11,342		11,813
Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	8,001		8,182
Finite-Lived Intangible Assets, Accumulated Amortization	(1,059)		(957)
Finite-Lived Intangible Assets, Net	6,942		7,225
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	4,790		4,911
Finite-Lived Intangible Assets, Accumulated Amortization	(390)		(323)
Finite-Lived Intangible Assets, Net	$ 4,400		$ 4,588