Mineral Property Transactions (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
Jun. 30, 2012 acre
Gas and Oil Acreage [Line Items]
Number of Projects	7
Percentage of initial working interest (in hundredths)	26.50%
Percentage of net revenue interest (in hundredths)	19.60%
Reduced percentage of net revenue interests after payout of initial well cost (in hundredths)	14.70%
Reduced percentage of working interests after payout of initial well cost (in hundredths)	19.80%
Gross acres acquired in Woodbine acquisition (in acres)	6,766
Net acres acquired in Woodbine acquisition (in acres)	1,274
Purchase price of Woodbine acquisition	$ 1.7
Bakken/Three Forks Shale [Member]
Gas and Oil Acreage [Line Items]
Percentage of undeveloped acreage sold (in hundredths)	75.00%
Proceeds from sale of undeveloped acreage	16.7
Proceeds from reimbursed well costs	1.4
Transfer of costs from unevaluated properties to proved properties	5.3
Percentage of interest in undeveloped acreage retained (in hundredths)	25.00%
Number of developed wells in which our original working interest is retained	10
Percentage of average working interest in the remaining locations (in hundredths)	8.75%
Montana Acreage [Member]
Gas and Oil Acreage [Line Items]
Percentage of undeveloped acreage sold (in hundredths)	87.50%
Transfer of costs from unevaluated properties to proved properties	$ 1.0
Percentage of interest in undeveloped acreage retained (in hundredths)	12.50%
Minimum percentage of net revenue interest in lease owned (in hundredths)	81.00%
Percentage of net revenue interest delivered to purchaser (in hundredths)	80.00%
Percentage of overriding royalty interest delivered to land broker (in hundredths)	1.00%
Percentage of commission paid to land broker (in hundredths)	10.00%
Minimum [Member] \| Bakken/Three Forks Shale [Member]
Gas and Oil Acreage [Line Items]
Expected net revenue interests in new wells after sale (in hundredths)	6.7375%
Maximum [Member] \| Bakken/Three Forks Shale [Member]
Gas and Oil Acreage [Line Items]
Expected net revenue interests in new wells after sale (in hundredths)	7.00%
GeoResources, Inc [Member] \| Bakken/Three Forks Shale [Member]
Gas and Oil Acreage [Line Items]
Percentage of undeveloped acreage sold (in hundredths)	56.25%
Yuma Exploration and Production Company, Inc [Member] \| Bakken/Three Forks Shale [Member]
Gas and Oil Acreage [Line Items]
Percentage of undeveloped acreage sold (in hundredths)	18.75%

Percentage of net revenue interests acquired in the business combination.

No definition available.

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- Definition

Represents the expected net revenue interests in new wells after sale.

+ References

No definition available.

+ Details

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Namespace Prefix:	useg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represent the minimum percentage of net revenue interest in lease owned as per the agreement.

+ References

No definition available.

+ Details

Name:	useg_MinimumPercentageOfNetRevenueInterestInLeasesOwned
Namespace Prefix:	useg_
Data Type:	num:percentItemType
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- Definition

Represents the number of projects.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Represents the percentage of acreage sold.

+ References

No definition available.

+ Details

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Namespace Prefix:	useg_
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Balance Type:	na
Period Type:	duration

- Definition

Represents the percentage of average working interest in the remaining locations.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
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- Definition

Represents the percentage of commission paid to the land broker for the cash consideration paid by purchaser.

+ References

No definition available.

+ Details

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Namespace Prefix:	useg_
Data Type:	num:percentItemType
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- Definition

Represents the percentage of interest in acreage retained.

+ References

No definition available.

+ Details

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Balance Type:	na
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- Definition

Represents the percentage of net revenue interest delivered to purchaser.

+ References

No definition available.

+ Details

Name:	useg_PercentageOfNetRevenueInterestDeliveredToPurchaser
Namespace Prefix:	useg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the percentage of overriding royalty interest delivered to land broker.

+ References

No definition available.

+ Details

Name:	useg_PercentageOfOverridingRoyaltyInterestDeliveredToLandBroker
Namespace Prefix:	useg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash inflow from reimbursed well costs.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- Definition

The cash inflow from sale of undeveloped acreage.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- Definition

Represents the reduced percentage of net revenue interests after payout of initial well cost.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
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Period Type:	instant

- Definition

Represents the reduced percentage of working interests after payout of initial well cost.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
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- Definition

Amount of transfer of costs from unevaluated properties to proved properties.

+ References

No definition available.

+ Details

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Namespace Prefix:	useg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

The total cost of the acquired entity including the cash paid to shareholders of acquired entities, fair value of debt and equity securities issued to shareholders of acquired entities, the fair value of the liabilities assumed, and direct costs of the acquisition.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141

-Paragraph 51

-Subparagraph d

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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Balance Type:	debit
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- Definition

Percentage of voting equity interests acquired in the business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=7659399&loc=d3e1392-128463

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141R

-Paragraph 68

-Subparagraph c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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- Details

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- Definition

Area spaced or assigned to productive wells in which a working interest is owned.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Industry Guide

-Number 2

-Paragraph 4

-Subparagraph A

+ Details

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Data Type:	num:areaItemType
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- Definition

Fractional interest owned based on working interests or other economic arrangements of area spaced or assigned to productive wells.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Industry Guide

-Number 2

-Paragraph 4

-Subparagraph A

+ Details

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Balance Type:	na
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- Definition

The total number of producing oil wells and oil wells capable of production, in which the entity owns an undivided working interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Industry Guide

-Number 2

-Paragraph 4

-Subparagraph A

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