Property, plant and equipment (Tables)

12 Months Ended

Dec. 31, 2017

Property, plant and equipment

Summary of property, plant and equipment

	December 31,
	2017		2016
Land	$	2,378	$	2,378
Land improvements	4,357		4,357
Leasehold improvements		4,183		2,569
Buildings	26,846		26,058
Machinery and equipment	44,618		40,878
Furniture and fixtures	13,681		12,561
Mobile equipment and other	4,576		3,873
Construction-in-process	4,320		3,850
Total property, plant and equipment	104,959		96,524
Less accumulated depreciation	(50,997)		(44,383)
Net property, plant and equipment	$	53,962	$	52,141