INVENTORIES (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Major classes of inventories
Raw materials	$ 144,140	$ 113,813
Work-in-progress and supplies	7,714	6,633
Finished goods	185,145	167,108
Inventories	$ 336,999	$ 287,554