|**LONG-TERM DEBT LONG-TERM DEBT (Tables)**                | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  
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|**Long-term Debt, Unclassified [Abstract]**               |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  
|Schedule of Long-term Debt Instruments [Table Text Block] | Long-term debt consists of the following:As of December 31,20122011(in thousands)Senior notes3.25% Convertible senior notes due 2016:Principal amount$115,000$115,000Unamortized discount(13,671)(17,079)3.25% Convertible senior notes due 2016, net of discount101,32997,9217.75% Senior notes due 2022:Principal amount500,000—12% Senior notes due 2018:Principal amount—203,000Unamortized discount—(1,764)12% Senior notes due 2018, net of discount—201,236Total senior notes601,329299,157Credit facilitiesCorporate49,000209,000PDCM26,25024,000Total credit facilities75,250233,000Total long-term debt$676,579$532,157
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|                                                          | As of December 31,                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               
|                                                          | 2012                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|                                                          | (in thousands)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   
|Senior notes                                              |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  
|3.25% Convertible senior notes due 2016:                  |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  
|Principal amount                                          | $                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                
|Unamortized discount                                      | (13,671                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
|3.25% Convertible senior notes due 2016, net of discount  | 101,329                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
|7.75% Senior notes due 2022:                              |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  
|Principal amount                                          | 500,000                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
|12% Senior notes due 2018:                                |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  
|Principal amount                                          | —                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                
|Unamortized discount                                      | —                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                
|12% Senior notes due 2018, net of discount                | —                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                
|Total senior notes                                        | 601,329                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
|Credit facilities                                         |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  
|Corporate                                                 | 49,000                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           
|PDCM                                                      | 26,250                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           
|Total credit facilities                                   | 75,250                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           
|Total long-term debt                                      | $                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                
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