XML 37 R20.htm IDEA: XBRL DOCUMENT
v3.8.0.1

CONTRACTS AND AGREEMENTS (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2017
Contractors [Abstract] |
Brokerage Commissions |
|  | For the Year Ended December 31, 2017 |  |  | For the Year Ended December 31, 2016 |  |  | For the Year Ended December 31, 2015 |
Total commissions accrued to brokers |  | $ | 1,728,440 |  |  | $ | 2,000,888 |  |  | $ | 2,371,433 |
Total commissions as annualized percentage of average total net assets |  |  | 0.35 | % |  |  | 0.37 | % |  |  | 0.39 | %
Commissions accrued as a result of rebalancing |  | $ | 1,420,519 |  |  | $ | 1,872,019 |  |  | $ | 2,089,974 |
Percentage of commissions accrued as a result of rebalancing |  |  | 82.19 | % |  |  | 93.56 | % |  |  | 88.13 | %
Commissions accrued as a result of creation and redemption activity |  | $ | 307,921 |  |  | $ | 128,869 |  |  | $ | 281,459 |
Percentage of commissions accrued as a result of creation and redemption activity |  |  | 17.81 | % |  |  | 6.44 | % |  |  | 11.87 | %

X
- Definition Brokerage Commissions + References No definition available. + Details
Name: | ung_BrokerageCommissionsTableTextBlock
Namespace Prefix: | ung_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_ContractorsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration