Inventories (Tables)

3 Months Ended

Mar. 31, 2013

Inventories [Abstract]

Summary of inventories

Inventories were comprised of the following at December 31, 2012 and March 31, 2013:

	December 31,		March 31,
	2012		2013
Finished goods	$	37,415	$	40,898
Work in process		32,383		35,638
Raw materials and supplies		73,455		86,384
Inventories	$	143,253	$	162,920