INDEBTEDNESS (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Long-term debt
Total	$ 212,000,000	$ 245,135,000
Less current maturities		(135,000)
Long-term debt	212,000,000	245,000,000
Interest paid	9,800,000	17,000,000	12,800,000
Aggregate maturities of the Company's indebtedness, excluding the impact of the amendment to the revolving credit facility
2013	212,000,000
Total	212,000,000	245,135,000
Credit agreement
Long-term debt
Increase in the available borrowing capacity subject to certain limitations and satisfaction of certain conditions	200,000,000
Outstanding letters of credit	3,000,000	3,000,000
Credit agreement | Amendment to existing credit facility
Long-term debt
Maximum borrowing capacity	450,000,000
Revolving credit facility
Long-term debt
Total	212,000,000	245,000,000
Maximum borrowing capacity	500,000,000
Variable rate (as a percent)	1.15%	1.55%
Aggregate maturities of the Company's indebtedness, excluding the impact of the amendment to the revolving credit facility
Total	212,000,000	245,000,000
Revolving credit facility | Amendment to existing credit facility
Long-term debt
Maximum borrowing capacity	450,000,000
Increase in the available borrowing capacity subject to certain limitations and satisfaction of certain conditions	200,000,000
Revolving credit facility | Federal funds rate
Long-term debt
Basis spread on federal funds rate (as a percent)	0.50%
Other
Long-term debt
Total		135,000
Aggregate maturities of the Company's indebtedness, excluding the impact of the amendment to the revolving credit facility
Total		135,000
Revolving credit agreements with various European financial institutions
Long-term debt
Maximum borrowing capacity	$ 12,200,000