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Acquisitions (Details) $ / shares in Units, $ in Thousands, shares in Millions |  |  | 3 Months Ended | 9 Months Ended | 12 Months Ended | 15 Months Ended
--- | --- | --- | --- | --- | --- | ---
Dec. 21, 2016 USD ($) shares | Oct. 04, 2016 USD ($) | Sep. 30, 2017 USD ($) | Sep. 30, 2017 USD ($) | Dec. 31, 2017 USD ($) a $ / shares | Dec. 31, 2016 USD ($) $ / shares | Dec. 31, 2015 USD ($) | Dec. 31, 2017 USD ($) $ / shares
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |
Payments to acquire oil and gas property and equipment |  |  |  |  |  | $ 89,896 | $ 2,183,790 | $ 7,984 |
Carrying value of properties exchanged |  |  |  |  |  | 293,963 | 733 | $ 0 |
Wells in progress |  |  |  |  |  | 321,347 | 235,147 |  | $ 321,347
Proved oil and gas properties |  |  |  |  |  | 6,139,379 | 5,700,418 |  | 6,139,379
Unproved oil and gas properties |  |  |  |  |  | $ 2,047,203 | $ 2,471,947 |  | $ 2,047,203
Common Stock, par value per share | $ / shares |  |  |  |  |  | $ 0.01 | $ 0.01 |  | $ 0.01
Other Howard and Martin Counties acquisitions 2017 [Member] |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |
Net acres acquired | a |  |  |  |  |  | 3,600 |  |  |
Payments to acquire oil and gas property and equipment |  |  |  |  |  | $ 76,500 |  |  |
QStar Acquisition 2016 [Member] |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |
Payments to acquire oil and gas property and equipment |  | $ 1,200,000 |  | $ 7,300 | $ 1,174,628 |  |  |  |
Wells in progress |  | 21,812 |  |  |  |  |  |  |
Proved oil and gas properties |  | 61,239 |  |  |  |  |  |  |
Unproved oil and gas properties |  | 1,538,264 |  |  |  |  |  |  |
Working capital acquired |  | (1,852) |  |  |  |  |  |  |
Asset retirement obligations |  | $ (7,641) |  |  |  |  |  |  |
Acquisition of oil and gas properties, consideration paid |  |  |  |  | $ 1,600,000 |  |  |  |
Private issuance of Common Stock for an acquisition | shares |  | 13.4 |  |  |  |  |  |  |
Fair value of equity consideration | [1] | $ 437,194 |  |  |  |  |  |  |
Total consideration |  | 1,611,822 |  |  |  |  |  |  |
Total oil and gas properties acquired |  | $ 1,621,315 |  |  |  |  |  |  |
Rock Oil Acquisition 2016 [Member] |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |
Payments to acquire a business, gross |  |  | $ 991,000 |  |  | $ 7,700 |  |  | $ 998,691
Wells in progress |  |  | 5,672 |  |  |  |  |  |
Proved oil and gas properties |  |  | 82,584 |  |  |  |  |  |
Unproved oil and gas properties |  |  | 913,819 |  |  |  |  |  |
Other assets |  |  | 5,338 |  |  |  |  |  |
Total fair value of oil and gas properties acquired |  |  | 1,007,413 |  |  |  |  |  |
Working capital acquired |  |  | (1,127) |  |  |  |  |  |
Asset retirement obligations |  |  | (7,595) |  |  |  |  |  |
Total fair value of net assets acquired |  |  | $ 998,691 |  |  |  |  |  |
Other Howard and Martin Counties trades [Member] |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |
Non-monetary trade, acreage acquired | a |  |  |  |  |  | 8,125 |  |  |
Non-monetary trade, acreage exchanged | a |  |  |  |  |  | 7,580 |  |  |
Carrying value of properties exchanged |  |  |  |  |  | $ 294,000 |  |  |
[1] | The Company issued approximately 13.4 million shares of common stock, par value $0.01 per share, in a private placement to the sellers in the QStar Acquisition on December 21, 2016. The equity consideration was valued on this date using Level 1 and Level 2 inputs with a discount applied due to the lack of marketability in the near term in accordance with the Lock-Up and Registration Rights Agreement that prohibited the sale of such stock until no earlier than the 90th day after issuance.

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