XML 86 R49.htm IDEA: XBRL DOCUMENT v2.4.1.9

Equity - Additional Information (Detail) (USD $)	12 Months Ended			0 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	May 16, 2012	Jan. 26, 2015	Dec. 01, 2012
Class of Stock [Line Items]
Common stock, shares outstanding	13,916,026us-gaap_CommonStockSharesOutstanding	13,841,400us-gaap_CommonStockSharesOutstanding
Common stock, share authorized	25,000,000us-gaap_CommonStockSharesAuthorized	25,000,000us-gaap_CommonStockSharesAuthorized
Proceed from issuance of common stock	$ 1,200,000us-gaap_ProceedsFromIssuanceOfCommonStock	$ 1,100,000us-gaap_ProceedsFromIssuanceOfCommonStock	$ 66,800,000us-gaap_ProceedsFromIssuanceOfCommonStock
Common stock, share issued	38,020us-gaap_StockIssuedDuringPeriodSharesNewIssues	39,559us-gaap_StockIssuedDuringPeriodSharesNewIssues	41,752us-gaap_StockIssuedDuringPeriodSharesNewIssues
Common stock shares repurchase	2,763us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesPurchasedForAward	2,969us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesPurchasedForAward	6,368us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesPurchasedForAward
Repurchase expense	100,000utl_StockRepurchaseProgramFeesAndExpensesRelatedToTenderOffer	100,000utl_StockRepurchaseProgramFeesAndExpensesRelatedToTenderOffer	200,000utl_StockRepurchaseProgramFeesAndExpensesRelatedToTenderOffer
Share based compensation expense	1,400,000us-gaap_RestrictedStockExpense	700,000us-gaap_RestrictedStockExpense	1,300,000us-gaap_RestrictedStockExpense
Preferred Stock	200,000us-gaap_PreferredStockValue	200,000us-gaap_PreferredStockValue
Redeemable, Cumulative Preferred Stock	0us-gaap_TemporaryEquityCarryingAmountIncludingPortionAttributableToNoncontrollingInterests	0us-gaap_TemporaryEquityCarryingAmountIncludingPortionAttributableToNoncontrollingInterests	8,000us-gaap_TemporaryEquityCarryingAmountIncludingPortionAttributableToNoncontrollingInterests
Non Vested Restricted Stock
Class of Stock [Line Items]
Antidilutive securities excluded from computation of earnings per share	0us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount / us-gaap_RangeAxis = utl_NonVestedRestrictedStockMember	4,481us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount / us-gaap_RangeAxis = utl_NonVestedRestrictedStockMember	24,325us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount / us-gaap_RangeAxis = utl_NonVestedRestrictedStockMember
Restricted Stock Units
Class of Stock [Line Items]
Percentage of fully-vested restricted stock units that directors will receive in common shares when settled	70.00%utl_PercentageOfFullyVestedRestrictedStockUnitsThatDirectorsWillReceiveInCommonSharesWhenSettled / us-gaap_StatementClassOfStockAxis = utl_RestrictedStockUnitMember
Percentage of fully-vested restricted stock units that directors will receive in cash when settled	30.00%utl_PercentageOfFullyVestedRestrictedStockUnitsThatDirectorsWillReceiveInCashWhenSettled / us-gaap_StatementClassOfStockAxis = utl_RestrictedStockUnitMember
Fair value of liabilities associated with fully vested RSUs that will be settled in cash	400,000utl_FairValueOfRestrictedStockUnitsSettledInCash / us-gaap_StatementClassOfStockAxis = utl_RestrictedStockUnitMember	200,000utl_FairValueOfRestrictedStockUnitsSettledInCash / us-gaap_StatementClassOfStockAxis = utl_RestrictedStockUnitMember
Common Stock Offering
Class of Stock [Line Items]
Common stock, share issued				2,760,000us-gaap_CommonStockSharesIssued / us-gaap_StatementClassOfStockAxis = utl_CommonStockOfferingMember
Common stock price per share				$ 25.25us-gaap_EquityIssuancePerShareAmount / us-gaap_StatementClassOfStockAxis = utl_CommonStockOfferingMember
Proceed from issuance of common stock				65,700,000us-gaap_ProceedsFromIssuanceOfCommonStock / us-gaap_StatementClassOfStockAxis = utl_CommonStockOfferingMember
Dividend and Distribution Reinvestment and Share Purchase Plan
Class of Stock [Line Items]
Common stock price per share	$ 32.83us-gaap_EquityIssuancePerShareAmount / us-gaap_StatementClassOfStockAxis = utl_DividendAndDistributionReinvestmentAndSharePurchasePlanMember
Proceed from issuance of common stock	1,200,000us-gaap_ProceedsFromIssuanceOfCommonStock / us-gaap_StatementClassOfStockAxis = utl_DividendAndDistributionReinvestmentAndSharePurchasePlanMember	1,100,000us-gaap_ProceedsFromIssuanceOfCommonStock / us-gaap_StatementClassOfStockAxis = utl_DividendAndDistributionReinvestmentAndSharePurchasePlanMember	1,100,000us-gaap_ProceedsFromIssuanceOfCommonStock / us-gaap_StatementClassOfStockAxis = utl_DividendAndDistributionReinvestmentAndSharePurchasePlanMember
Dividend and Distribution Reinvestment and Share Purchase Plan | Common Stock
Class of Stock [Line Items]
Common stock, share issued	38,020us-gaap_StockIssuedDuringPeriodSharesNewIssues / us-gaap_StatementClassOfStockAxis = utl_DividendAndDistributionReinvestmentAndSharePurchasePlanMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember	39,559us-gaap_StockIssuedDuringPeriodSharesNewIssues / us-gaap_StatementClassOfStockAxis = utl_DividendAndDistributionReinvestmentAndSharePurchasePlanMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember	41,752us-gaap_StockIssuedDuringPeriodSharesNewIssues / us-gaap_StatementClassOfStockAxis = utl_DividendAndDistributionReinvestmentAndSharePurchasePlanMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember
Restricted Stock
Class of Stock [Line Items]
Restricted stock vesting period	4 years
Restricted stock vesting percentage annually	25.00%us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockMember
Restricted stock non-vested	67,334utl_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonvestedOptionsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockMember	53,480utl_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonvestedOptionsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockMember
Restricted stock weighted average grant date fair value	$ 28.51utl_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockMember	$ 25.99utl_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockMember
Unrecognized share based compensation	800,000us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockMember
Share compensation recognition period	2 years 6 months
Forfeitures or cancellations under the stock plan	0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockMember
Shares	9,078us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockMember	10,710us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockMember
Restricted Stock | Maximum
Class of Stock [Line Items]
Restricted stock available for awards	677,500us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockMember / us-gaap_RangeAxis = us-gaap_MaximumMember
Restricted stock that may be awarded in any one calendar year to any one participant	20,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockMember / us-gaap_RangeAxis = us-gaap_MaximumMember
Restricted Stock | Subsequent Event
Class of Stock [Line Items]
Shares					40,010us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockMember / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember
Aggregate Market Value					$ 1,500,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodIntrinsicValue / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockMember / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember
Unitil Energy Systems Inc | Series 6 | Nonredeemable Preferred Stock | Noncumulative Preferred Stock
Class of Stock [Line Items]
Preferred Stock	200,000us-gaap_PreferredStockValue / us-gaap_DebtConversionByUniqueDescriptionAxis = us-gaap_NoncumulativePreferredStockMember / us-gaap_ExtinguishmentOfDebtAxis = us-gaap_NonredeemablePreferredStockMember / dei_LegalEntityAxis = utl_UnitilEnergySystemsIncMember / us-gaap_StatementEquityComponentsAxis = utl_SeriesSixMember
Dividend rate	6.00%us-gaap_PreferredStockDividendRatePercentage / us-gaap_DebtConversionByUniqueDescriptionAxis = us-gaap_NoncumulativePreferredStockMember / us-gaap_ExtinguishmentOfDebtAxis = us-gaap_NonredeemablePreferredStockMember / dei_LegalEntityAxis = utl_UnitilEnergySystemsIncMember / us-gaap_StatementEquityComponentsAxis = utl_SeriesSixMember
Fitchburg Gas and Electric Light Company | Series 8
Class of Stock [Line Items]
Dividend rate						8.00%us-gaap_PreferredStockDividendRatePercentage / dei_LegalEntityAxis = utl_FitchburgGasAndElectricLightCompanyMember / us-gaap_StatementClassOfStockAxis = utl_SeriesEightMember
Redeemable, Cumulative Preferred Stock						1,000,000us-gaap_TemporaryEquityCarryingAmountIncludingPortionAttributableToNoncontrollingInterests / dei_LegalEntityAxis = utl_FitchburgGasAndElectricLightCompanyMember / us-gaap_StatementClassOfStockAxis = utl_SeriesEightMember
Fitchburg Gas and Electric Light Company | Series 5
Class of Stock [Line Items]
Dividend rate						5.125%us-gaap_PreferredStockDividendRatePercentage / dei_LegalEntityAxis = utl_FitchburgGasAndElectricLightCompanyMember / us-gaap_StatementClassOfStockAxis = utl_SeriesFiveMember
Redeemable, Cumulative Preferred Stock						$ 800,000us-gaap_TemporaryEquityCarryingAmountIncludingPortionAttributableToNoncontrollingInterests / dei_LegalEntityAxis = utl_FitchburgGasAndElectricLightCompanyMember / us-gaap_StatementClassOfStockAxis = utl_SeriesFiveMember
Preferred Stock premium percentage						1.28%utl_PreferredStockRedemptionPercentage / dei_LegalEntityAxis = utl_FitchburgGasAndElectricLightCompanyMember / us-gaap_StatementClassOfStockAxis = utl_SeriesFiveMember

X

- Definition

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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- Definition

The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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- Definition

Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Unrecognized cost of unvested options awarded to employees as compensation.

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- Definition

Amount per share or per unit assigned to the consideration received of equity securities issued for development stage entities.

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The percentage rate used to calculate dividend payments on preferred stock.

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Aggregate par or stated value of issued nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer). This item includes treasury stock repurchased by the entity. Note: elements for number of nonredeemable preferred shares, par value and other disclosure concepts are in another section within stockholders' equity.

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The cash inflow from the additional capital contribution to the entity.

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The noncash expense that represents the cost of restricted stock or unit distributed to employees as compensation.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Percentage of vesting of share-based compensation awards.

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- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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- Definition

Per share weighted average intrinsic value of equity-based compensation awards granted. Excludes stock and unit options.

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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).

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X

- 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.

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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.

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The number of shares purchased on the open market during the period for issuance to employees under the plan.

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Preferred Stock Redemption, Percentage

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Stock Repurchase Program Fees And Expenses Related To Tender Offer

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