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SHAREHOLDERS' EQUITY (Details) (USD $) | 12 Months Ended
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Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
Weighted Average Exercise Price [Roll Forward] |  |  |
Value of stock options exercised | $ (62,000)us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised |  | $ 0 us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised
Stock Options [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Percentage of outstanding shares reserved for issuance (in hundredths) | 25.00%useg_PercentageOfOutstandingSharesReservedForIssuance / us-gaap_AwardTypeAxis = useg_StockOption1Member |  |
Shares reserved for authorization (in shares) | 1,200,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized / us-gaap_AwardTypeAxis = useg_StockOption1Member |  |
Number of options available for grant and intrinsic value of options outstanding and exercisable [Abstract] |  |  |
Available for future grant (in shares) | 790,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant / us-gaap_AwardTypeAxis = useg_StockOption1Member | 790,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant / us-gaap_AwardTypeAxis = useg_StockOption1Member | 1,060,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant / us-gaap_AwardTypeAxis = useg_StockOption1Member
Aggregate intrinsic value of options outstanding | 0 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue / us-gaap_AwardTypeAxis = useg_StockOption1Member | 1,661,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue / us-gaap_AwardTypeAxis = useg_StockOption1Member | 0 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue / us-gaap_AwardTypeAxis = useg_StockOption1Member
Aggregate intrinsic value of options exercisable | 0 us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1 / us-gaap_AwardTypeAxis = useg_StockOption1Member | 1,073,000 us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1 / us-gaap_AwardTypeAxis = useg_StockOption1Member | 0 us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1 / us-gaap_AwardTypeAxis = useg_StockOption1Member
Employee Stock Options [Member] |  |  |
Options [Roll Forward] |  |  |
Outstanding at beginning of the year (in shares) | 2,500,949 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | 2,259,282 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | 2,318,399 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember
Granted (in shares) | 0 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | 270,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | 150,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember
Forfeited (in shares) | (3,333)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | 0 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | (10,000)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember
Expired (in shares) | 0 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | (28,333)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | (194,950)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember
Exercised (in shares) | (400,203)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | 0 us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | (4,167)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember
Outstanding at period end (in shares) | 2,097,413 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | 2,500,949 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | 2,259,282 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember
Exercisable at year end (in shares) | 1,949,080 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | 2,137,619 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | 2,119,282 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember
Weighted Average Exercise Price [Roll Forward] |  |  |
Beginning Balance (in dollars per share) | $ 3.60 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | $ 3.80 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | $ 3.94 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember
Granted (in dollars per share) | $ 0 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | $ 2.08 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | $ 2.32 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember
Forfeited (in dollars per share) | $ 2.08 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | $ 0 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | $ 2.32 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember
Expired (in dollar per share) | $ 0 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | $ 4.68 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | $ 4.47 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember
Exercised (in dollars per share) | $ 2.46 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | $ 0 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | $ 2.52 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember
Ending Balance (in dollars per share) | $ 3.82 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | $ 3.60 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | $ 3.80 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember
Exercisable (in dollars per share) | $ 3.95 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | $ 3.85 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | $ 3.90 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember
Weighted average fair value of options granted during the period (in dollars per share) | $ 0 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | $ 1.20 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | $ 1.30 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember
Employee Stock Options [Member] | Stock Options [Member] |  |  |
Weighted Average Exercise Price [Roll Forward] |  |  |
Proceeds from stock options exercised | 1,000 us-gaap_ProceedsFromStockOptionsExercised / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember |  |
Withholding of shares (in shares) | 14,206 useg_StockWithholdingOfSharesDuringPeriod / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember |  |
Withhold values of common stock | 63,000 useg_WithholdValuesOfCommonStock / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember |  |
Shares surrendered upon stock option exercise (in shares) | 228,047 us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember |  | 3,097 us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember
Value of stock options exercised | 982,000 us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember |  | 10,000 us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember
Intrinsic value of option exercised | 743,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | 0 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | 4,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember
Share-based compensation expense | 229,000 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | 120,000 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember | 33,000 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember
Total unrecognized expense for the option plan | 124,000 us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = us-gaap_EmployeeStockOptionMember |  |
Director Stock Options [Member] |  |  |
Options [Roll Forward] |  |  |
Outstanding at beginning of the year (in shares) | 146,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | 150,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | 210,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember
Granted (in shares) | 60,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | 36,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | 80,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember
Forfeited (in shares) | 0 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | 0 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | 0 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember
Expired (in shares) | 0 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | (40,000)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | (120,000)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember
Exercised (in shares) | (27,334)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | 0 us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | (20,000)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember
Outstanding at period end (in shares) | 178,666 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | 146,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | 150,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember
Exercisable at year end (in shares) | 82,333 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | 56,668 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | 63,335 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember
Weighted Average Exercise Price [Roll Forward] |  |  |
Beginning Balance (in dollars per share) | $ 2.93 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | $ 3.05 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | $ 3.10 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember
Granted (in dollars per share) | $ 3.77 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | $ 2.08 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | $ 2.78 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember
Forfeited (in dollars per share) | $ 0 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | $ 0 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | $ 0 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember
Expired (in dollar per share) | $ 0 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | $ 2.60 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | $ 3.05 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember
Exercised (in dollars per share) | $ 2.53 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | $ 0 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | $ 2.52 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember
Ending Balance (in dollars per share) | $ 3.28 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | $ 2.93 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | $ 3.05 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember
Exercisable (in dollars per share) | $ 3.30 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | $ 3.46 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | $ 3.01 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember
Weighted average fair value of options granted during the period (in dollars per share) | $ 2.27 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | $ 1.20 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | $ 1.59 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember
Director Stock Options [Member] | Stock Options [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Percentage of common stock (in hundredths) | 1.00%us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember |  |
Weighted Average Exercise Price [Roll Forward] |  |  |
Proceeds from stock options exercised | 8,000 us-gaap_ProceedsFromStockOptionsExercised / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | 50,000 us-gaap_ProceedsFromStockOptionsExercised / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember |
Shares surrendered upon stock option exercise (in shares) | 15,000 us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember |  |
Value of stock options exercised | 61,000 us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember |  |
Intrinsic value of option exercised | 45,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | 0 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | 17,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember
Share-based compensation expense | 89,000 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | 64,000 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | 69,000 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember
Total unrecognized expense for the option plan | 147,000 us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember |  |
Number of options available for grant and intrinsic value of options outstanding and exercisable [Abstract] |  |  |
Available for future grant (in shares) | 101,811 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | 131,359 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | 126,526 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember
Aggregate intrinsic value of options outstanding | 0 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | 142,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | 0 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember
Aggregate intrinsic value of options exercisable | $ 0 us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1 / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | $ 35,000 us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1 / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember | $ 0 us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1 / us-gaap_AwardTypeAxis = useg_StockOption1Member / us-gaap_PlanNameAxis = useg_DirectorStockOptionMember
2001 Incentive Stock Option Plan [Member] | Stock Options [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Term of the plan | 10 years |  |
2012 Equity Plan [Member] | Stock Options [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Term of the plan | 10 years |  |
2008 Stock Option Plan [Member] | Stock Options [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Term of the plan | 10 years |  |

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- Details
Name: | useg_NumberOfOptionsAvailableForGrantAndIntrinsicValueOfOptionsOutstandingAndExercisableAbstract
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- Definition The percentage of the maximum number of shares (or other type of equity) of common stock issued and outstanding at any time, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested). + References No definition available. + Details
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- Definition Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 14.F) -URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1)(i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 14 -Section F + Details
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- Definition Unrecognized cost of unvested options awarded to employees as compensation. + References No definition available. + Details
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- Definition The cash inflow associated with the amount received from holders exercising their stock options. This item inherently excludes any excess tax benefit, which the entity may have realized and reported separately. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Financing Activities -URI http://asc.fasb.org/extlink&oid=6513228 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (j) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3255-108585 + Details
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- Definition The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iv)(4) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iv)(3) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Gross number of share options (or share units) granted during the period. + References No definition available. + Details
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- Definition The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Number of options outstanding, including both vested and non-vested options. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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