Property, plant and equipment: (Tables)

12 Months Ended

Dec. 31, 2012

Property, plant and equipment:

Schedule of property, plant and equipment

December 31, 2012	Cost		Accumulated amortization		Net book value
Land and buildings	$	575	$	64	$	511
Computer equipment and software	11,529		8,140		3,389
Furniture and fixtures	4,032		1,913		2,119
Machinery and equipment	80,667		34,219		46,448
Leasehold improvements	15,602		9,875		5,727
	$	112,405	$	54,211	$	58,194

December 31, 2011	Cost		Accumulated amortization		Net book value
Land and buildings	$	668	$	124	$	544
Computer equipment and software	8,903		7,246		1,657
Furniture and fixtures	2,072		1,602		470
Machinery and equipment	54,156		27,288		26,868
Leasehold improvements	14,930		9,061		5,869
	$	80,729	$	45,321	$	35,408