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FAIR VALUE OF FINANCIAL INSTRUMENTS - Valuation of UNG's securities using the fair value hierarchy (Details) - USD ($) | Sep. 30, 2023 | Dec. 31, 2022
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Short-Term Investments |  |
FAIR VALUE OF FINANCIAL INSTRUMENTS |  |
Fair value of securities | $ 190,950,000 | $ 317,800,000
Exchange-Traded Futures Contracts | United States Contracts |  |
FAIR VALUE OF FINANCIAL INSTRUMENTS |  |
Fair value of securities | (11,838,000) | (144,765,937)
Exchange-Traded Futures Contracts | OTC Commodity Swap Contracts |  |
FAIR VALUE OF FINANCIAL INSTRUMENTS |  |
Fair value of securities | (7,028,587) |
Level 1 | Short-Term Investments |  |
FAIR VALUE OF FINANCIAL INSTRUMENTS |  |
Fair value of securities | 190,950,000 | 317,800,000
Level 1 | Exchange-Traded Futures Contracts | United States Contracts |  |
FAIR VALUE OF FINANCIAL INSTRUMENTS |  |
Fair value of securities | (11,838,000) | $ (144,765,937)
Level 1 | Exchange-Traded Futures Contracts | OTC Commodity Swap Contracts |  |
FAIR VALUE OF FINANCIAL INSTRUMENTS |  |
Fair value of securities | $ (7,028,587) |

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- Definition Line items represents the information pertaining to fair value of financial instruments. + References No definition available. + Details
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- Definition Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482106/820-10-50-2 + Details
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