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FAIR VALUE OF FINANCIAL INSTRUMENTS - Valuation of UNG's securities using the fair value hierarchy (Details) - USD ($) | Sep. 30, 2025 | Dec. 31, 2024
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Short-Term Investments |  |
FAIR VALUE OF FINANCIAL INSTRUMENTS |  |
Fair value of securities | $ 305,950,000 | $ 532,370,156
United States Contracts |  |
FAIR VALUE OF FINANCIAL INSTRUMENTS |  |
Fair value of securities | 1,086,363 | 80,696,279
OTC Commodity Swap Contracts |  |
FAIR VALUE OF FINANCIAL INSTRUMENTS |  |
Fair value of securities | (970) | (2,205)
Level 1 | Short-Term Investments |  |
FAIR VALUE OF FINANCIAL INSTRUMENTS |  |
Fair value of securities | 305,950,000 | 532,370,156
Level 1 | United States Contracts |  |
FAIR VALUE OF FINANCIAL INSTRUMENTS |  |
Fair value of securities | 1,086,363 | 80,696,279
Level 1 | OTC Commodity Swap Contracts |  |
FAIR VALUE OF FINANCIAL INSTRUMENTS |  |
Fair value of securities | $ (970) |
Level 2 | OTC Commodity Swap Contracts |  |
FAIR VALUE OF FINANCIAL INSTRUMENTS |  |
Fair value of securities |  | $ (2,205)

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