Name:	nu_EmployeeServiceShareBasedCompenationEsppDisclosuresAbstract
Namespace Prefix:	nu_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Name:	nu_EmployeeServiceShareBasedCompensationAwardsOtherThanOptionsAbstract
Namespace Prefix:	nu_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	nu_EmployeeServiceShareBasedCompensationPerformanceShareDisclosuresAbstract
Namespace Prefix:	nu_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	nu_EmployeeServiceShareBasedCompensationStockOptionDisclosuresAbstract
Namespace Prefix:	nu_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Shares available remaining for future issuance under the ESPP, a noncompensatory plan.

+ References

No definition available.

+ Details

Name:	nu_EmployeeStockPurchasePlanSharesRemainingForFutureIssuance
Namespace Prefix:	nu_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The first purchase price at which employees are permitted to purchase NU common shares at six month intervals.

+ References

No definition available.

+ Details

Name:	nu_EsppDiscountedPurchasePriceFirstSixMonths
Namespace Prefix:	nu_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The second purchase price at which employees are permitted to purchase NU common shares at six month intervals.

+ References

No definition available.

+ Details

Name:	nu_EsppDiscountedPurchasePriceSecondSixMonths
Namespace Prefix:	nu_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Upon the merger with NSTAR, outstanding NSTAR stock options converted into NU stock options. Lower range of exercise prices applicable to these converted options.

+ References

No definition available.

+ Details

Name:	nu_ShareBaseCompensationConvertedNstarOptionsExercisePriceRangeLowerRangeLimit
Namespace Prefix:	nu_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Upon the merger with NSTAR, outstanding NSTAR stock options converted into NU stock options. Upper range of exercise prices applicable to these converted options.

+ References

No definition available.

+ Details

Name:	nu_ShareBaseCompensationConvertedNstarOptionsExercisePriceRangeUpperRangeLimit
Namespace Prefix:	nu_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of equity-based awards payment instruments, excluding options, that validly exist and are outstanding as of the payment date.

+ References

No definition available.

+ Details

Name:	nu_ShareBasedCompensationArragementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsBeginningBalance
Namespace Prefix:	nu_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of equity-based payment instruments, excluding options, that validly exist and are oustanding as of the balance sheet date.

+ References

No definition available.

+ Details

Name:	nu_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsEndingBalance
Namespace Prefix:	nu_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The weighted average grant-date fair value of the number of shares newly issued during the reporting period under the plan.

+ References

No definition available.

+ Details

Name:	nu_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsIssuedInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	nu_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

NU converted NSTAR Performance Shares and NSTAR Deferred Shares into NU RSU's as of the merger closing.

+ References

No definition available.

+ Details

Name:	nu_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNstarAwardsConvertedToNuRsusUponMerger
Namespace Prefix:	nu_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

No authoritative reference available.

+ References

No definition available.

+ Details

Name:	nu_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNstarAwardsConvertedToRsusUponMergerWeightedAverageGrantDateFairValue
Namespace Prefix:	nu_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Value of converted NSTAR Deferred and Performance Shares, upon the merger closing.

+ References

No definition available.

+ Details

Name:	nu_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNstarDeferredAndPerformanceAwardsConvertedToNuRsusUponMergerValue
Namespace Prefix:	nu_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Upon the merger with NSTAR, NU converted NSTAR Deferred Shares and NSTAR Performance Shares to NU RSU's.

+ References

No definition available.

+ Details

Name:	nu_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNstarDeferredAndPerformanceAwardsConvertedUponMerger
Namespace Prefix:	nu_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Value of converted NSTAR RSU Retention Awards, upon the merger closing.

+ References

No definition available.

+ Details

Name:	nu_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNstarRsuRetentionAwardsConvertedToNuRsuRetentionAwardsUponMergerValue
Namespace Prefix:	nu_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Upon the merger with NSTAR, NU converted NSTAR RSU Retention Awards to NU RSU Retention Awards.

+ References

No definition available.

+ Details

Name:	nu_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNstarRsuRetentionAwardsConvertedToNuRsusUponMerger
Namespace Prefix:	nu_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The weighted average fair value of awards on equity-based plans excluding option plans, for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain the title to proceeds from the sale of the award or underlying shares or units.

+ References

No definition available.

+ Details

Name:	nu_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageGrantDateFairValueBeginningBalance
Namespace Prefix:	nu_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

The weighted average fair value of awards on equity based plans excluding option plans for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

+ References

No definition available.

+ Details

Name:	nu_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageGrantDateFairValueEndingBalance
Namespace Prefix:	nu_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

No authoritative reference available.

+ References

No definition available.

+ Details

Name:	nu_ShareBasedCompensationArrangementByShareBasedPaymentAwardExpectedToVest
Namespace Prefix:	nu_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Upon the merger with NSTAR, outstanding NSTAR stock options converted into NU stock options.

+ References

No definition available.

+ Details

Name:	nu_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsConvertedNstarOptionsUponMerger
Namespace Prefix:	nu_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Value of converted NSTAR options, upon the merger closing.

+ References

No definition available.

+ Details

Name:	nu_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsConvertedNstarOptionsUponMergerTotalValue
Namespace Prefix:	nu_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Weighted Average Exercise Price of NSTAR Options Converted to NU Options during the period.

+ References

No definition available.

+ Details

Name:	nu_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsConvertedNstarOptionsUponMergerWeightedAverageExercisePrice
Namespace Prefix:	nu_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

As of June 30, 2012, 451,358 performance shares under the 2011 and 2012 Long-Term Incentive Programs converted to RSUs upon closing of the merger with NSTAR according to the terms of these programs. The remaining performance shares were measured based upon a modified performance period in accordance with the terms of the 2010 Incentive Program and fully vested, with distribution in 2013.

+ References

No definition available.

+ Details

Name:	nu_ShareBasedCompensationArrangementByShareBasedPaymentAwardPerformanceSharesConvertedToRsusUponMerger
Namespace Prefix:	nu_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

+ References

No definition available.

+ Details

Name:	nu_ShareBasedCompensationArrangementByShareBasedPaymentAwardPerformanceSharesConvertedToRsusUponMergerWeightedAverageGrantDateFairValue
Namespace Prefix:	nu_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

No authoritative reference available.

+ References

No definition available.

+ Details

Name:	nu_ShareBasedCompensationArrangementByShareBasedPaymentAwardVestedOutstandingNumber
Namespace Prefix:	nu_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Details

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

- Definition

Aggregate proceeds received by the entity during the annual period from exercises of stock or unit options and conversion of similar instruments granted under equity-based payment arrangements.

+ References

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationCashReceivedFromExerciseOfStockOptions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

As of the balance sheet date, the aggregate unrecognized cost of equity-based awards made to employees under equity-based compensation awards that have yet to vest.

+ References

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, using a decimal to express in number of years.

+ References

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

- Definition

The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

+ References

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Disclosure of the aggregate tax benefit realized from the exercise of stock options and the conversion of similar instruments during the annual period.

+ References

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitRealizedFromExerciseOfStockOptions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Reductions in the entity's income taxes that arise when compensation cost (from non-qualified share-based compensation) recognized on the entity's tax return exceeds compensation cost from equity-based compensation recognized in financial statements. This element represents the cash inflow reported in the enterprise's financing activities.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph i

-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.

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

-Publisher FASB

-Name Emerging Issues Task Force (EITF)

-Number 00-15

-Paragraph 3

-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.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 20

-Section 55

-Paragraph 24

-URI http://asc.fasb.org/extlink&oid=6576910&loc=d3e11374-113907

+ Details

Name:	us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Equity-based compensation cost during the period with respect to the award, which will be recognized in income (as well as the total recognized tax benefit) or capitalized as part of the cost of an asset.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 50

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6406099&loc=d3e25284-112666

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (h)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph 64, 65

-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.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph g(1)

-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.

Reference 5: 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

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardCompensationCost
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect during the reporting period as a result of the occurrence of a terminating event specified in the contractual agreement of the plan.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- 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).

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued 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).

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(2)(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.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph c(1)

-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.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(2)(iii)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(2)(a)

-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.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(2)(b)

-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.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(2)(i)-(ii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(2)(a)

-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.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(2)(b)

-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.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(2)(i)-(ii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- 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

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- 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

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The total accumulated difference between fair values of underlying shares on dates of exercise and exercise price on options which were exercised (or share units converted) into shares during the reporting period under the plan.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The weighted average price at which option holders acquired shares when converting their stock options into shares under the plan during the reporting period.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

For presentations that combine terminations, 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 or that expired.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The combined weighted average exercise price associated with stock options during the period that have either lapsed or been forfeited.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

The grant-date intrinsic value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGrantDateIntrinsicValue
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

The total dollar difference between fair values of the underlying shares reserved for issuance and exercise prices pertaining to options outstanding under the plan as of the balance sheet date.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including 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

-Subparagraph (c)(1)(i)-(ii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(1)(a)

-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.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(1)(b)

-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.

Reference 4: 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

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The weighted average price as of the beginning of the year at which grantees can acquire the shares reserved for issuance under the stock option plan.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

The weighted average period between the balance sheet date and expiration for all awards outstanding under the plan, which may be expressed in a decimal value for number of years.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Section 50

-Paragraph 2

-Subparagraph (e)(1)

-SubTopic 10

-Topic 718

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of shares newly issued during the reporting period under the plan.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph 65

-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.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-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.

Reference 3: 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

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The floor of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph 64

-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.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (g)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

The ceiling of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of shares issued during the period as a result of an employee stock purchase plan.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29, 30

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

-URI http://asc.fasb.org/extlink&oid=6959260&loc=d3e187085-122770

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 12

-Paragraph 10

-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.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 129

-Paragraph 5

-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.

+ Details

Name:	us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of share options (or share units) exercised during the current period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.28,29)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 4: 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)(2)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29, 30

-Article 5

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

-URI http://asc.fasb.org/extlink&oid=6959260&loc=d3e187085-122770

+ Details

Name:	us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

SHARE-BASED PAYMENTS (Details) (USD $)	0 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
SHARE-BASED PAYMENTS (Details) (USD $)	Apr. 09, 2012	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Excess Tax Benefit from Share-based Compensation, Financing Activities				$ 3.9	$ 1.4
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized		4,500,000		4,500,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		2,501,295		2,501,295		2,685,615
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost		4.8	3.2	21.6	9.3
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense		1.9	1.3	8.7	3.7
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized		30.3		30.3
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition				2.08
Employee Service Share Based Compensation Awards Other Than Options [Abstract]
Share-based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options NSTAR Deferred and Performance Awards Converted Upon Merger	421,775
Share-based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options NSTAR Deferred and Performance Awards Converted to NU RSU's Upon Merger, Value	15.5
Share-based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options NSTAR RSU Retention Awards Converted to NU RSU's Upon Merger	195,619
Share-based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options NSTAR RSU Retention Awards Converted to NU RSU Retention Awards Upon Merger, Value	7.2
Employee Service Share Based Compensation Stock Option Disclosures [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term		4.4		4.4
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number		2,306,717		2,306,717		47,374
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period				(405,551)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period				0
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit				$ 18.45		$ 18.58
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit				$ 28.12		$ 18.90
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price		$ 23.92		$ 23.92		$ 18.78
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price		$ 23.74		$ 23.74
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price				$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value				5.3
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value		34.0		34.0
Employee Service Share-based Compensation, Cash Received from Exercise of Stock Options				9.6
Employee Service Share-based Compensation, Tax Benefit Realized from Exercise of Stock Options				2.1
Share-base Compensation, Converted NSTAR Options, Exercise Price Range, Lower Range Limit				$ 0
Share-base Compensation, Converted NSTAR Options, Exercise Price Range, Upper Range Limit				$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Converted NSTAR Options Upon Merger	2,664,894
Share-based Compensation Arrangement by Share-based Payment Award, Options, Converted NSTAR Options Upon Merger, Weighted Average Exercise Price	$ 23.99
Share-based Compensation Arrangement by Share-based Payment Award, Options, Converted NSTAR Options Upon Merger, Total Value	30.5
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Grant Date Intrinsic Value				$ 34,100,000
Employee Service Share-based Compenation ESPP Disclosures [Abstract]
Stock Issued During Period, Shares, Employee Stock Purchase Plans				39,422		35,476
ESPP Discounted Purchase Price First Six Months				33.01	31.27
ESPP Discounted Purchase Price Second Six Months				37.89		32.30
Employee Stock Purchase Plan Shares Remaining For Future Issuance		857,280		857,280		896,702
The Connecticut Light And Power Company [Member]
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost		0.9	1.9	3.9	5.4
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense		0.4	0.8	1.6	2.2
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized		6.2		6.2
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition				2.17
NSTAR Electric Company [Member]
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost		0.5	1.9	5.4	5.8
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense		0.2	0.8	2.1	2.3
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized		8.6		8.6
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition				1.91
Nstar [Member]
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized		3,500,000		3,500,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		977,922		977,922
Public Service Company Of New Hampshire [Member]
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost		0.4	0.6	1.5	1.9
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense		0.1	0.3	0.6	0.7
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized		2.1		2.1
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition				1.97
Western Massachusetts Electric Company [Member]
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost		0.2	0.4	0.8	1.0
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense		0.1	0.1	0.3	0.4
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized		$ 1.3		$ 1.3
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition				1.96
Restricted Stock Units (RSUs) [Member]
Employee Service Share Based Compensation Awards Other Than Options [Abstract]
Share-based Compensation Arragement by Share-based Payment Award Equity Instruments Other Than Options Beginning Balance						959,920
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period				585,135
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period				(304,014)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period				(95,156)
Share-based Compensation Arrangement by Share-based Payment Award Equity Instruments Other Than Options Ending Balance				2,214,637
Share-based Compensation Arrangement by Share-based Payment Award Equity Instruments Other Than Options Weighted Average Grant Date Fair Value Beginning Balance						$ 26.36
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value				$ 32.98
Share-based Compensation Arrangement By Share-based Payment Award Equity Instruments Other Than Options Issued In Period Weighted Average Grant Date Fair Value				$ 27.96
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period, Weighted Average Grant Date Fair Value		$ 34.99		$ 34.99
Share-based Compensation Arrangement By Share-based Payment Award Equity Instruments Other Than Options Weighted Average Grant Date Fair Value Ending Balance		$ 32.07		$ 32.07
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number		1,402,517		1,402,517		403,108
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value		$ 34.69		$ 34.69		$ 28.70
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period				470,218
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value				$ 30.00
Share-based Compensation Arrangement By Share-based Payment Award Vested Outstanding Number				812,120
Share-based Compensation Arrangement By Share-based Payment Award Expected To Vest				1,332,391
Share-based Compensation Arrangement By Share-based Payment Award Equity Instruments Other Than Options NSTAR Awards Converted To NU RSU's Upon Merger	617,394
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, NSTAR Awards Converted to RSU's Upon Merger, Weighted Average Grant Date Fair Value	$ 36.79
Employee Service Share-based Compensation Performance Share Disclosures [Abstract]
Share-based Compensation Arrangement By Share-based Payment Award Performance Shares Converted to RSUs Upon Merger	451,358
Share-based Compensation Arrangement By Share-based Payment Award Performance Shares Converted to RSUs Upon Merger Weighted Average Grant-Date Fair Value	$ 34.32
Performance Shares [Member]
Employee Service Share Based Compensation Awards Other Than Options [Abstract]
Share-based Compensation Arragement by Share-based Payment Award Equity Instruments Other Than Options Beginning Balance						483,133
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period				227,683
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period				(106,773)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period				0
Share-based Compensation Arrangement by Share-based Payment Award Equity Instruments Other Than Options Ending Balance				152,685
Share-based Compensation Arrangement by Share-based Payment Award Equity Instruments Other Than Options Weighted Average Grant Date Fair Value Beginning Balance						$ 29.18
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value				$ 34.37
Share-based Compensation Arrangement By Share-based Payment Award Equity Instruments Other Than Options Issued In Period Weighted Average Grant Date Fair Value				$ 24.52
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period, Weighted Average Grant Date Fair Value		$ 0		$ 0
Share-based Compensation Arrangement By Share-based Payment Award Equity Instruments Other Than Options Weighted Average Grant Date Fair Value Ending Balance		$ 25.04		$ 25.04
Employee Service Share-based Compensation Performance Share Disclosures [Abstract]
Share-based Compensation Arrangement By Share-based Payment Award Performance Shares Converted to RSUs Upon Merger	(451,358)
Share-based Compensation Arrangement By Share-based Payment Award Performance Shares Converted to RSUs Upon Merger Weighted Average Grant-Date Fair Value	$ 34.32