XML 58 R47.htm IDEA: XBRL DOCUMENT
v3.25.3

Long-Term Debt - Narrative (Details) $ in Thousands |  |  | 3 Months Ended | 9 Months Ended |
--- | --- | --- | --- | --- | ---
Apr. 18, 2025 USD ($) | Apr. 17, 2025 USD ($) | Sep. 30, 2025 USD ($) | Sep. 30, 2025 USD ($) | Dec. 31, 2024 USD ($)
Line of Credit Facility [Line Items] |  |  |  |  |
Interest rate | 0.50% |  |  |  |
Variable rate | 0.75% |  |  |  |
Debt instrument, fee amount | $ 1,300 |  |  |  |
Credit facility |  |  | $ 208,000 | $ 208,000 | $ 170,000
Credit facility |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |
Borrowing base amount available | 400,000 | $ 300,000 | 400,000 | 400,000 |
Potential increase in borrowing capacity | $ 100,000 | $ 50,000 |  | 100,000 |
Potential maximum borrowing capacity |  |  | 500,000 | 500,000 |
Credit facility |  |  | 208,000 | $ 208,000 |
Weighted average interest rate |  |  |  | 7.04% |
Outstanding credit facility |  |  | $ 163,000 | $ 163,000 |
Percentage of eligible non investment grade decors |  |  | 85.00% | 85.00% |
Percentage of eligible inventory |  |  | 50.00% | 50.00% |
Line of credit facility, non exceeding cap of components |  |  | $ 2,500 | $ 2,500 |
Percentage of eligible compressors for extension of credit |  |  | 95.00% | 95.00% |
Term for depreciation |  |  |  | 25 years |
Percentage of net liquidation value of eligible compressors for extension of credit |  |  | 80.00% | 80.00% |
Percentage of eligible value at cost |  |  | 80.00% | 80.00% |
Unused commitment fee, rate |  |  |  | 0.375% |
Maximum leverage ratio allowed |  |  | 3.50 |  |
Fixed charge coverage ratio |  |  |  | 1.25 |
Credit facility | Maximum |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |
Default trigger, certain defaults of other company indebtedness, amount |  |  | $ 1,000 | $ 1,000 |
Default trigger, rendering of certain judgments, amount |  |  | $ 1,000 | $ 1,000 |
Credit facility | Federal Fund Rate |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |
Variable rate |  |  |  | 0.50% |
Credit facility | Secured Overnight Financing Rate (SOFR) |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |
Variable rate |  |  |  | 1.00% |
Credit facility | Secured Overnight Financing Rate (SOFR) | Minimum |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |
Variable rate |  |  |  | 2.50% |
Credit facility | Secured Overnight Financing Rate (SOFR) | Maximum |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |
Variable rate |  |  |  | 3.25% |
Credit facility | Base Rate | Minimum |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |
Variable rate |  |  |  | 1.50% |
Credit facility | Base Rate | Maximum |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |
Variable rate |  |  |  | 2.25% |

X
- Definition Line Of Credit Facility, Current Borrowing Capacity Component, Percent Of Eligible Accounts Receivable Owing By Non-Investment Grade Debtors + References No definition available. + Details
Name: | ngs_LineOfCreditFacilityCurrentBorrowingCapacityComponentPercentOfEligibleAccountsReceivableOwingByNonInvestmentGradeDebtors
Namespace Prefix: | ngs_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Line Of Credit Facility, Current Borrowing Capacity, Component, Percentage Of Eligible Compressors For Extension Of Credit + References No definition available. + Details
Name: | ngs_LineOfCreditFacilityCurrentBorrowingCapacityComponentPercentageOfEligibleCompressorsForExtensionOfCredit
Namespace Prefix: | ngs_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Line Of Credit Facility, Current Borrowing Capacity Component Percentage Of Eligible Inventory + References No definition available. + Details
Name: | ngs_LineOfCreditFacilityCurrentBorrowingCapacityComponentPercentageOfEligibleInventory
Namespace Prefix: | ngs_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Line Of Credit Facility Current Borrowing Capacity Component Percentage Of Eligible Value At Cost Excluding Any Cost for Capitalized Interest Or Other Non Cash Capitalized Costs + References No definition available. + Details
Name: | ngs_LineOfCreditFacilityCurrentBorrowingCapacityComponentPercentageOfEligibleValueAtCostExcludingAnyCostForCapitalizedInterestOrOtherNonCashCapitalizedCosts
Namespace Prefix: | ngs_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Line Of Credit Facility, Current Borrowing Capacity, Net Liquidation Value Of Percentage Of Eligible Compressors For Extension Of Credit + References No definition available. + Details
Name: | ngs_LineOfCreditFacilityCurrentBorrowingCapacityNetLiquidationValueOfPercentageOfEligibleCompressorsForExtensionOfCredit
Namespace Prefix: | ngs_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- References No definition available. + Details
Name: | ngs_LineOfCreditFacilityDefaultTriggerCertainDefaultsOfOtherCompanyIndebtednessAmount
Namespace Prefix: | ngs_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- References No definition available. + Details
Name: | ngs_LineOfCreditFacilityDefaultTriggerRenderingOfCertainJudgmentsAmount
Namespace Prefix: | ngs_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Line Of Credit Facility Fixed Charge Coverage Ratio + References No definition available. + Details
Name: | ngs_LineOfCreditFacilityFixedChargeCoverageRatio
Namespace Prefix: | ngs_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | duration

X
- Definition Line Of Credit Facility Leverage Ratio + References No definition available. + Details
Name: | ngs_LineOfCreditFacilityLeverageRatio
Namespace Prefix: | ngs_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | duration

X
- Definition Line Of Credit Facility, Non Exceeding Cap Of Component Capacity + References No definition available. + Details
Name: | ngs_LineOfCreditFacilityNonExceedingCapOfComponentCapacity
Namespace Prefix: | ngs_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- References No definition available. + Details
Name: | ngs_LineOfCreditFacilityPotentialIncreaseInBorrowingCapacity
Namespace Prefix: | ngs_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- References No definition available. + Details
Name: | ngs_LineOfCreditFacilityPotentialMaximumBorrowingCapacity
Namespace Prefix: | ngs_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Line Of Credit Facility, Term For Depreciation + References No definition available. + Details
Name: | ngs_LineOfCreditFacilityTermForDepreciation
Namespace Prefix: | ngs_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage points added to the reference rate to compute the variable rate on the debt instrument. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of the fee that accompanies borrowing money under the debt instrument. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)(b)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 + Details
Name: | us-gaap_DebtInstrumentFeeAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Incremental percentage increase (decrease) in the stated rate on a debt instrument. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentInterestRateIncreaseDecrease
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- 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 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -SubTopic 10 -Topic 210 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 944 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(16)(a)(2)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1 + Details
Name: | us-gaap_LineOfCredit
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)(b)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(19)(b)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 + Details
Name: | us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Line 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. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 235 -SubTopic 10 -Name Accounting Standards Codification -Section S50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480738/235-10-S50-1 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 235 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08(f)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481544/470-10-50-6 Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 470 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481544/470-10-50-6 + Details
Name: | us-gaap_LineOfCreditFacilityLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481544/470-10-50-6 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)(b)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(19)(b)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 + Details
Name: | us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility. + References No definition available. + Details
Name: | us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Weighted average interest rate of long-term debt outstanding calculated over time. + References No definition available. + Details
Name: | us-gaap_LongTermDebtWeightedAverageInterestRateOverTime
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VariableRateAxis=ngs_FederalFundRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VariableRateAxis=us-gaap_SecuredOvernightFinancingRateSofrMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VariableRateAxis=ngs_BaseRateLoansMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |