Long-Term Debt (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Long-term debt
Total long-term debt	$ 426,770	$ 307,667
Less: Current maturities of long-term debt	(79,663)	(1,667)
Debt discount, net	(79)	(170)
Total long term debt	347,028	305,830
Facility Agreement [Member]
Long-term debt
Total long-term debt	40,000	141,667
Secured Reducing Revolving Loan Facility [Member]
Long-term debt
Total long-term debt	7,028	6,000
Senior Notes Due 2022 [Member]
Long-term debt
Total long-term debt	300,000
Senior Notes Due 2014 [Member]
Long-term debt
Total long-term debt	$ 79,742	$ 160,000