SUPPLEMENTAL CASH FLOW FINANCIAL INFORMATION (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Cash paid during the period for:
Interest	$ 3,290	$ 3,278
Income taxes (net of refunds)	5,591	1,566
Non-cash financing and investing activities:
Purchase of property, plant and equipment in accounts payable	1,308	1,028
Capital lease obligations	65
Issuance of restricted stock units of common stock	$ 9,617	$ 8,419