XML 19 R4.htm IDEA: XBRL DOCUMENT v3.7.0.1

Condensed Schedule of Investments (Parenthetical)	3 Months Ended
	Mar. 31, 2017 USD ($)
Collateral Amount On Open Futures Contracts	$ 44,975,772
United States [Member] | U.S. Treasury Bills 0.46%, 4/06/2017 [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	0.46%
Expiration date	4/06/2017
United States [Member] | U.S. Treasury Bills 0.47%, 4/13/2017 [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	0.47%
Expiration date	4/13/2017
United States [Member] | U.S. Treasury Bills 0.46%, 4/20/2017 [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	0.46%
Expiration date	4/20/2017
United States [Member] | U.S. Treasury Bills 0.47%, 4/27/2017 [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	0.47%
Expiration date	4/27/2017
United States [Member] | U.S. Treasury Bills 0.49%, 5/04/2017 [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	0.49%
Expiration date	5/04/2017
United States [Member] | U.S. Treasury Bills 0.55%, 5/11/2017 [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	0.55%
Expiration date	5/11/2017
United States [Member] | U.S. Treasury Bills 0.60%, 5/18/2017 [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	0.60%
Expiration date	5/18/2017
United States [Member] | U.S. Treasury Bills 0.61%, 5/25/2017[Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	0.61%
Expiration date	5/25/2017
United States [Member] | U.S. Treasury Bills 0.60%, 6/01/2017 [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	0.60%
Expiration date	6/01/2017
United States [Member] | U.S. Treasury Bills 0.62%, 6/08/2017 [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	0.62%
Expiration date	6/08/2017
United States [Member] | U.S. Treasury Bills 0.65%, 6/15/2017 [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	0.65%
Expiration date	6/15/2017
United States [Member] | U.S. Treasury Bills 0.64%, 6/22/2017 [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	0.64%
Expiration date	6/22/2017
United States [Member] | U.S. Treasury Bills 0.60%, 6/29/2017 [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	0.60%
Expiration date	6/29/2017
United States [Member] | U.S. Treasury Bills 0.62%, 7/06/2017 [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	0.62%
Expiration date	7/06/2017
United States [Member] | U.S. Treasury Bills 0.59%, 7/13/2017 [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	0.59%
Expiration date	7/13/2017
United States [Member] | U.S. Treasury Bills 0.61%, 7/20/2017 [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	0.61%
Expiration date	7/20/2017
United States [Member] | U.S. Treasury Bills 0.60%, 7/27/2017 [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	0.60%
Expiration date	7/27/2017
United States [Member] | U.S. Treasury Bills 0.61%, 8/10/2017 [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	0.61%
Expiration date	8/10/2017
United States [Member] | U.S. Treasury Bills 0.65%, 8/17/2017 [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	0.65%
Expiration date	8/17/2017
United States [Member] | U.S. Treasury Bills 0.67%, 8/24/2017 [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	0.67%
Expiration date	8/24/2017
United States [Member] | U.S. Treasury Bills 0.76%, 8/31/2017 [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	0.76%
Expiration date	8/31/2017
United States [Member] | U.S. Treasury Bills 0.84%, 9/07/2017 [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	0.84%
Expiration date	9/07/2017
United States [Member] | U.S. Treasury Bills 0.87%, 9/21/2017 [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	0.87%
Expiration date	9/21/2017
United States [Member] | U.S. Treasury Bills 0.89%, 9/28/2017 [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	0.89%
Expiration date	9/28/2017

X

- Definition

The collateral amount on open future contracts.

+ References

No definition available.

+ Details

Name:	ung_CollateralAmountOnOpenFuturesContracts
Namespace Prefix:	ung_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Definition

The list of dates or date range within which the options may be exercised of the investment subject to option.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 6
-Subparagraph (SX 210.12-14.4(b))
-URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611322-123010

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 5
-Subparagraph (SX 210.12-13.5(d))
-URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611282-123010

+ Details

Name:	us-gaap_InvestmentOwnedSubjectToOptionExerciseDates
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	invest_InvestmentGeographicRegionAxis=country_US
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesClassAxis=us-gaap_USTreasurySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentAxis=us-gaap_CashEquivalentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsFourMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsFiveMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsSixMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsSevenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillEightMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsNineMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsTenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsElevenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsTwelveMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsThirteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillFourteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsFifteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsSixteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsSeventeenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsEighteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsNineteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsTwentyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsTwentyOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsTwentyTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsTwentyThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsTwentyFourMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: