Inventories (Tables)

3 Months Ended

Mar. 31, 2013

Inventories

Schedule of inventories

	December 31, 2012		March 31, 2013
Raw materials and spare parts	$	30,137	$	37,219
Work in process	5,835		3,988
Finished goods	2,180		3,011
Total	$	38,152	$	44,218