|**BUSINESS COMBINATIONS BUSINESS COMBINATIONS (Notes)**                     | 12 Months Ended                                                                                                                                                                                                                                                                                        
|--------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|
|**Business Acquisition [Line Items]**                                       |                                                                                                                                                                                                                                                                                                        
|Schedule of Intangible Assets and Goodwill [Table Text Block]               | The following table presents the changes in goodwill from the preliminary allocation at December 31, 2016, and the final allocation determined during the third quarter of 2017:Amount(in thousands)Preliminary purchase price allocation$62,041Adjustments13,080Final purchase price allocation$75,121
|                                                                           
|                                                                            |                                                                                                                                                                                                                                                                                                        
|                                                                            | Amount                                                                                                                                                                                                                                                                                                 
|                                                                            | (in thousands)                                                                                                                                                                                                                                                                                         
|                                                                            |                                                                                                                                                                                                                                                                                                        
|Preliminary purchase price allocation                                       | $                                                                                                                                                                                                                                                                                                      
|Adjustments                                                                 | 13,080                                                                                                                                                                                                                                                                                                 
|Final purchase price allocation                                             | $                                                                                                                                                                                                                                                                                                      
|Business Acquisition, Pro Forma Information [Table Text Block]              |                                                                                                                                                                                                                                                                                                        
|                                                                           
|                                                                            |                                                                                                                                                                                                                                                                                                        
|                                                                            | Years Ended December 31,                                                                                                                                                                                                                                                                               
|                                                                            | 2016                                                                                                                                                                                                                                                                                                   
|                                                                            | (in thousands, except per share amounts)                                                                                                                                                                                                                                                               
|Total revenue                                                               | 412,746                                                                                                                                                                                                                                                                                                
|Net loss                                                                    | $                                                                                                                                                                                                                                                                                                      
|                                                                            |                                                                                                                                                                                                                                                                                                        
|Earnings per share:                                                         |                                                                                                                                                                                                                                                                                                        
|Basic and diluted                                                           | $                                                                                                                                                                                                                                                                                                      
|Business Combination Disclosure [Text Block]                                |                                                                                                                                                                                                                                                                                                        
|                                                                           
|                                                                            |                                                                                                                                                                                                                                                                                                        
|                                                                            | Year Ended December 31, 2016                                                                                                                                                                                                                                                                           
|Acquisition costs:                                                          |                                                                                                                                                                                                                                                                                                        
|Cash, net of cash acquired                                                  | $                                                                                                                                                                                                                                                                                                      
|Retirement of seller's debt                                                 | 40,000                                                                                                                                                                                                                                                                                                 
|Total cash consideration                                                    | 945,962                                                                                                                                                                                                                                                                                                
|Common stock                                                                | 690,702                                                                                                                                                                                                                                                                                                
|Other purchase price adjustments                                            | 426                                                                                                                                                                                                                                                                                                    
|Total acquisition costs                                                     | $                                                                                                                                                                                                                                                                                                      
|                                                                            |                                                                                                                                                                                                                                                                                                        
|Recognized amounts of identifiable assets acquired and liabilities assumed: |                                                                                                                                                                                                                                                                                                        
|Assets acquired:                                                            |                                                                                                                                                                                                                                                                                                        
|Current Assets                                                              | $                                                                                                                                                                                                                                                                                                      
|Crude oil and natural gas properties - proved                               | 216,000                                                                                                                                                                                                                                                                                                
|Crude oil and natural gas properties - unproved                             | 1,697,000                                                                                                                                                                                                                                                                                              
|Infrastructure, pipeline, and other                                         | 33,153                                                                                                                                                                                                                                                                                                 
|Construction in progress                                                    | 12,323                                                                                                                                                                                                                                                                                                 
|Goodwill                                                                    | 75,121                                                                                                                                                                                                                                                                                                 
|Total assets acquired                                                       | 2,039,998                                                                                                                                                                                                                                                                                              
|Liabilities assumed:                                                        |                                                                                                                                                                                                                                                                                                        
|Current liabilities                                                         | (24,496                                                                                                                                                                                                                                                                                                
|Asset retirement obligations                                                | (3,705                                                                                                                                                                                                                                                                                                 
|Deferred tax liabilities, net                                               | (374,707                                                                                                                                                                                                                                                                                               
|Total liabilities assumed                                                   | (402,908                                                                                                                                                                                                                                                                                               
|Total identifiable net assets acquired                                      | $                                                                                                                                                                                                                                                                                                      
|                                                                           
|                                                                            |                                                                                                                                                                                                                                                                                                        
|                                                                            | Years Ended December 31,                                                                                                                                                                                                                                                                               
|                                                                            | 2016                                                                                                                                                                                                                                                                                                   
|                                                                            | (in thousands, except per share amounts)                                                                                                                                                                                                                                                               
|Total revenue                                                               | 412,746                                                                                                                                                                                                                                                                                                
|Net loss                                                                    | $                                                                                                                                                                                                                                                                                                      
|                                                                            |                                                                                                                                                                                                                                                                                                        
|Earnings per share:                                                         |                                                                                                                                                                                                                                                                                                        
|Basic and diluted                                                           | $                                                                                                                                                                                                                                                                                                      
|                                                                           
|                                                                            |                                                                                                                                                                                                                                                                                                        
|                                                                            | Amount                                                                                                                                                                                                                                                                                                 
|                                                                            | (in thousands)                                                                                                                                                                                                                                                                                         
|                                                                            |                                                                                                                                                                                                                                                                                                        
|Preliminary purchase price allocation                                       | $                                                                                                                                                                                                                                                                                                      
|Adjustments                                                                 | 13,080                                                                                                                                                                                                                                                                                                 
|Final purchase price allocation                                             | $                                                                                                                                                                                                                                                                                                      

X- DefinitionLine items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.
+ ReferencesNo definition available.
+ Details**Name:**
us-gaap_BusinessAcquisitionLineItems**Namespace Prefix:**
us-gaap_**Data Type:**
xbrli:stringItemType**Balance Type:**
na**Period Type:**
duration X- DefinitionTabular disclosure of pro forma results of operations for a material business acquisition or series of individually immaterial business acquisitions that are material in the aggregate.
+ ReferencesReference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(2)-(3) -URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463
+ Details**Name:**
us-gaap_BusinessAcquisitionProFormaInformationTextBlock**Namespace Prefix:**
us-gaap_**Data Type:**
nonnum:textBlockItemType**Balance Type:**
na**Period Type:**
duration X- DefinitionThe entire disclosure for a business combination (or series of individually immaterial business combinations) completed during the period, including background, timing, and recognized assets and liabilities. The disclosure may include leverage buyout transactions (as applicable).
+ ReferencesReference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -URI http://asc.fasb.org/topic&trid=2303972
+ Details**Name:**
us-gaap_BusinessCombinationDisclosureTextBlock**Namespace Prefix:**
us-gaap_**Data Type:**
nonnum:textBlockItemType**Balance Type:**
na**Period Type:**
duration X- DefinitionTabular disclosure of goodwill and intangible assets, which may be broken down by segment or major class.
+ ReferencesReference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267
+ Details**Name:**
us-gaap_ScheduleOfIntangibleAssetsAndGoodwillTableTextBlock**Namespace Prefix:**
us-gaap_**Data Type:**
nonnum:textBlockItemType**Balance Type:**
na**Period Type:**
duration