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LONG-TERM DEBT (Narrative) (Details) |  |  |  |  | 3 Months Ended | 9 Months Ended |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Sep. 30, 2021 | Nov. 02, 2020 USD ($) | Oct. 15, 2020 USD ($) | May 01, 2020 USD ($) | Sep. 30, 2020 USD ($) | Sep. 30, 2019 USD ($) | Sep. 30, 2020 USD ($) | Sep. 30, 2019 USD ($) | Nov. 05, 2020 USD ($) | Oct. 08, 2020 USD ($) | Jul. 27, 2020 USD ($) | Mar. 31, 2020 USD ($) | Dec. 31, 2019 USD ($) | Nov. 25, 2019 USD ($)
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt issuance costs, net |  |  |  |  | $ 19,772,000 |  | $ 19,772,000 |  |  |  |  |  | $ 23,751,000 |
Capitalized interest expense, undeveloped properties |  |  |  |  | 200,000 | $ 1,000,000.0 | 900,000 | $ 2,800,000 |  |  |  |  |  |
Amount of debt to be repurchased |  |  |  |  |  |  |  |  |  |  |  |  | 200,000,000 |
Repayments of debt |  |  |  |  |  |  | 372,484,000 | 550,500,000 |  |  |  |  |  |
Gain on debt extinguishment |  |  |  |  | 0 | $ 23,600,000 | 49,579,000 | $ 23,600,000 |  |  |  |  |  |
Subsequent Event |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
cash on hand |  |  |  |  |  |  |  |  | $ 61,700,000 |  |  |  |  |
Senior Notes | Carry Value |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Carrying value of notes |  |  |  |  | 1,800,000,000 |  | 1,800,000,000 |  |  |  |  |  |  |
Senior Notes | Fair Value | Level 1 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Carrying value of notes |  |  |  |  | 1,100,000,000 |  | 1,100,000,000 |  |  |  |  |  |  |
Construction Loan |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt issuance costs, net |  |  |  |  | 100,000 |  | 100,000 |  |  |  |  |  |  |
Revolving Credit Facility |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount of principal repurchased |  |  |  |  | 0 |  | 73,300,000 |  |  |  |  |  |  |
Repayments of debt |  |  |  |  |  |  | 22,800,000 |  |  |  |  |  |  |
Gain on debt extinguishment |  |  |  |  |  |  | 49,600,000 |  |  |  |  |  |  |
6.625% senior unsecured notes due 2023 | Senior Notes |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  | $ 324,583,000 |  | $ 324,583,000 |  |  |  |  |  | 329,467,000 |
Stated interest rate, percent |  |  |  |  | 6.625% |  | 6.625% |  |  |  |  |  |  |
Debt issuance costs, net |  |  |  |  | $ 2,600,000 |  | $ 2,600,000 |  |  |  |  |  |  |
6.625% senior unsecured notes due 2023 | Senior Notes | Subsequent Event |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stated interest rate, percent |  | 6.625% |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest |  | $ 10,800,000 |  |  |  |  |  |  |  |  |  |  |  |
6.000% senior unsecured notes due 2024 | Senior Notes |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  | $ 579,568,000 |  | $ 579,568,000 |  |  |  |  |  | 603,428,000 |
Stated interest rate, percent |  |  |  |  | 6.00% |  | 6.00% |  |  |  |  |  |  |
Debt issuance costs, net |  |  |  |  | $ 5,700,000 |  | $ 5,700,000 |  |  |  |  |  |  |
6.000% senior unsecured notes due 2024 | Senior Notes | Subsequent Event |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stated interest rate, percent |  |  | 6.00% |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest |  |  | $ 17,400,000 |  |  |  |  |  |  |  |  |  |  |
6.375% senior unsecured notes due 2025 | Senior Notes |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  | $ 507,870,000 |  | $ 507,870,000 |  |  |  |  |  | 529,525,000 |
Stated interest rate, percent |  |  |  |  | 6.375% |  | 6.375% |  |  |  |  |  |  |
Debt issuance costs, net |  |  |  |  | $ 8,100,000 |  | $ 8,100,000 |  |  |  |  |  |  |
6.375% senior unsecured notes due 2026 | Senior Notes |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  | $ 374,617,000 |  | $ 374,617,000 |  |  |  |  |  | 397,529,000 |
Stated interest rate, percent |  |  |  |  | 6.375% |  | 6.375% |  |  |  |  |  |  |
Debt issuance costs, net |  |  |  |  | $ 3,300,000 |  | $ 3,300,000 |  |  |  |  |  |  |
Revolving Credit Agreement | Revolving Credit Agreement |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Elected commitment amount |  |  |  |  | 700,000,000 |  | 700,000,000 |  |  |  |  |  |  |
Maximum repayment amount |  |  |  |  |  |  |  |  |  |  | $ 750,000,000 |  |  |
Revolving Credit Agreement | Revolving Credit Agreement | Subsequent Event |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Elected commitment amount |  |  |  |  |  |  |  |  |  | $ 580,000,000 |  |  |  |
Nova Scotia, Amegy, KeyBank | Revolving Credit Agreement | Revolving Credit Agreement |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Line of credit facility, maximum borrowing capacity |  |  |  |  | 1,500,000,000 |  | 1,500,000,000 |  |  |  |  |  |  |
Elected commitment amount |  |  |  | $ 700,000,000.0 |  |  |  |  |  |  |  | $ 1,000,000,000.0 |  | $ 1,200,000,000
Maximum net secured debt to EBITDAX ratio |  |  |  | 2.00 |  |  |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  | 279,857,000 |  | 279,857,000 |  |  |  |  |  | $ 120,000,000 |
Remaining borrowing capacity |  |  |  |  | 100,100,000 |  | $ 100,100,000 |  |  |  |  |  |  |
Nova Scotia, Amegy, KeyBank | Revolving Credit Agreement | Revolving Credit Agreement | Subsequent Event |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |  | 355,500,000 |  |  |  |  |
Remaining borrowing capacity |  |  |  |  |  |  |  |  | 0 |  |  |  |  |
Nova Scotia, Amegy, KeyBank | Revolving Credit Agreement | Revolving Credit Agreement | Forecast |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net funded debt to EBITDAX ratio | 4.00 |  |  |  |  |  |  |  |  |  |  |  |  |
Nova Scotia, Amegy, KeyBank | Letter of Credit |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Credit facility interest rate at the eurodollar rate |  |  |  |  |  |  | 2.90% |  |  |  |  |  |  |
Nova Scotia, Amegy, KeyBank | Letter of Credit | Revolving Credit Agreement |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Credit facility outstanding |  |  |  |  | $ 320,000,000.0 |  | $ 320,000,000.0 |  |  |  |  |  |  |
Nova Scotia, Amegy, KeyBank | Letter of Credit | Revolving Credit Agreement | Subsequent Event |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Credit facility outstanding |  |  |  |  |  |  |  |  | $ 243,700,000 |  |  |  |  |

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- Definition Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Excludes cash and cash equivalents within disposal group and discontinued operation. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 210 -Section 45 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=118262064&loc=SL116631418-115840 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.1) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 210 -Section 45 -Paragraph 21 -URI http://asc.fasb.org/extlink&oid=118262064&loc=SL116631419-115840 + Details
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- Definition Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=120520924&loc=SL6031897-161870 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(16)) -URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 + Details
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- Definition The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(16)) -URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910 + Details
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