SUPPLEMENTAL CASH FLOW DISCLOSURES (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
SUPPLEMENTAL CASH FLOW DISCLOSURES
Interest paid	$ 247,879	$ 37,719	$ 4,182
Income taxes paid	$ 45,399	$ 26,300	$ 12,139