XML 43 R28.htm IDEA: XBRL DOCUMENT
v3.19.1

CONTRACTS AND AGREEMENTS (Brokerage Commissions) (Details) - USD ($) | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Total commissions accrued to brokers | $ 1,334 | $ 2,209 | $ 3,451
Total commissions as annualized percentage of average total net assets | 0.02% | 0.02% | 0.03%
Rebalancing Investments Transaction [Member] |  |  |
Total commissions accrued to brokers | $ 823 | $ 1,605 | $ 3,305
Total commissions as annualized percentage of average total net assets | 61.69% | 72.66% | 95.77%
Creation And Redemption Activity [Member] |  |  |
Total commissions accrued to brokers | $ 511 | $ 604 | $ 146
Total commissions as annualized percentage of average total net assets | 38.31% | 27.34% | 4.23%

X
- Definition Percentage of Average Daily Net Assets + References No definition available. + Details
Name: | unl_PercentageOfAverageDailyNetAssets
Namespace Prefix: | unl_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The amount of expense during the period for floor brokerage fees paid to other broker-dealers to execute trades on their behalf, stock exchange fees, order flow fees, and clearance fees. + References No definition available. + Details
Name: | us-gaap_FloorBrokerageExchangeAndClearanceFees
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_StatementClassOfStockAxis=unl_RebalancingInvestmentsTransactionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementClassOfStockAxis=unl_CreationAndRedemptionActivityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |