Accounts receivable less allowance of $10,492 and $10,939, respectively
Accumulated other comprehensive income (loss)
Acquisition of gas companies, net of cash acquired
Payments to Acquire Businesses, Net of Cash Acquired
Paid-in capital
Total Amortization
Amortization
Deferred purchased gas
Stock-based compensation expense (Note A)
Unrealized (gains) and losses, net
Unrealized Gain (Loss) on Derivatives
Allowance for doubtful accounts receivable
Restricted Stock [Member]
Asset Retirement Obligation [Member]
Asset Retirement Obligation Costs [Member]
CONSOLIDATED BALANCE SHEET (Unaudited) [Abstract]
Basic
Earnings Per Share of Common Stock - Basic (Note A): (in dollars per share)
Unrestricted cash and temporary cash investments
Balance at beginning of period
Balance at end of period
Accounts receivable, net
Increase (Decrease) in Accounts Receivable
Natural gas in storage
Increase (Decrease) in Fuel Inventories
Taxes accrued/refundable, net
Interest accrued
Accrued pension
Prepayments
Increase (Decrease) in Prepaid Expense
Line of credit borrowings (repayments), net
Accounts payable
Unbilled revenues
Increase (Decrease) in Unbilled Receivables
Changes in:
Accrued liabilities
COMMITMENTS AND CONTINGENCIES
Commitments and Contingencies Disclosure [Text Block]
Common stock outstanding (in shares)
Common stock
Customer Rate Surcharge [Member]
Competitive Transition Charge [Member]
Comprehensive Income attributable to UIL Holdings
Comprehensive Income (Loss), Net of Tax, Attributable to Parent
Variable Interest Entities
Operating Expenses
Direct Operating Costs [Abstract]
Purchased power
Local real estate and personal property
Operating Expenses
Cost of Revenue [Abstract]
Transmission wholesale
Total Current Liabilities
Liabilities, Current
Current Liabilities
Long-term debt, net of unamortized discount and premium
Amount of note purchase agreement
Interest rate (in hundredths)
Maturity date
Debt Instrument, Name [Domain]
Debt Instrument [Axis]
Amortization of debt expense and redemption premiums
Title of Individual with Relationship to Entity [Domain]
Deferred Purchased Gas [Member]
Deferred Fuel Costs [Member]
Deferred income taxes
Deferred income taxes
Deferred Tax Assets, Net, Current
Deferred Income Taxes (future tax liabilities owed to taxing authorities)
Deferred Income Taxes [Member]
Deferred Income Tax Charges [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Domain]
Depreciation and amortization expense
Depreciation and amortization (Note F)
Depreciation and amortization
Total depreciation and amortization
Other amortization
Derivative, Name [Domain]
Gross derivative asset
Gross derivative liability
Total derivative assets/(liabilities)
Number of Contracts for Differences (CfDs) executed by UI
Number of Contracts for Differences (CfDs) executed by CL&P
Current portion of derivative assets (Note A)
Contract for differences
Derivative Assets
Derivative assets (Note A)
Derivative, by Nature [Axis]
Current portion of derivative liabilities (Note A)
Derivative liabilities (Note A)
Derivative [Line Items]
Derivative [Table]
Derivatives
Diluted
Earnings Per Share of Common Stock - Diluted (Note A): (in dollars per share)
Basis of Presentation
Income (loss) from equity investment
Income from Equity Investments
Income from Equity Investments
Effective book income tax rates (in hundredths)
Total stock-based compensation expense
Stock-Based Compensation [Abstract]
Environmental Remediation Costs [Member]
Environmental Restoration Costs [Member]
Carrying value of joint venture
Equity Method Investee, Name [Domain]
Restatement Adjustment [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Schedule of Error Corrections and Prior Period Adjustment Restatement [Table]
Entity's share of amount awarded to atomic power company
Derivatives [Abstract]
CONSOLIDATED STATEMENT OF INCOME (Unaudited) [Abstract]
Preferred Stock Dividends of Subsidiary, Noncontrolling Interests
Less: Preferred Stock Dividends of Subsidiary, Noncontrolling Interests
Less: Preferred Stock Dividends of Subsidiary, Noncontrolling Interests
INCOME TAXES
Income Tax Disclosure [Text Block]
Refundable taxes
Other assets
Increase (Decrease) in Other Operating Assets
Changes in restricted cash
Increase (Decrease) in Restricted Cash
Goodwill
Interest Charges, gross
Interest Expense
Interest Charges, net
Interest Expense [Abstract]
Interest on long-term debt
Other interest, net (Note F)
Equity Investments
Regulatory liabilities [Abstract]
Total Liabilities and Capitalization
Liabilities and Equity
LIABILITIES AND CAPITALIZATION
Taxes - other than income taxes (Note F)
Line of credit borrowings
Outstanding debt amount
Line of Credit Facility, Amount Outstanding
Maximum borrowing capacity
Available credit under the Credit Facility
Credit Agreement [Member]
Line of Credit [Member]
Current portion of long-term debt
Long-term debt
Total Other investments
Long-term Investments
Other investments
Other long-term receivable
Amount sought for change order requests
Unamortized Redemption Costs [Member]
Loss on Reacquired Debt [Member]
Redeemable preferred stock, noncontrolling interests
Hurricane Sandy [Member]
Related Party Transactions, by Related Party [Axis]
Net Cash (used in) Financing Activities
Net Cash Provided by (Used in) Financing Activities
Cash Flows from Financing Activities
Net Cash (used in) Investing Activities
Net Cash Provided by (Used in) Investing Activities
Cash Flows from Investing Activities
Net Cash provided by Operating Activities
Net Cash Provided by (Used in) Operating Activities
Cash Flows From Operating Activities
Net Income
Net Income attributable to UIL Holdings
Net income attributable to common shareholders
Net change for the period
Cash and Cash Equivalents, Period Increase (Decrease)
Net regulatory assets/(liabilities), December 31, 2011
Net regulatory assets/(liabilities), September 30, 2012
Net Regulatory Assets
Total Interest Charges, net
Interest Charges, net
Total Noncurrent Liabilities
Liabilities, Noncurrent
Noncurrent Liabilities
Operating Income
Operating Income (Loss)
Operating Revenues
Operating Revenues
Revenues
Other Comprehensive Income (Loss), net
Other
Other Assets, Current
Other
Payments for (Proceeds from) Other Investing Activities
Payroll taxes
Other
Other Long-term Investments
Other
Proceeds from (Payments for) Other Financing Activities
Other Income and (Deductions), net (Note F)
Other Income and (Deductions), net
Total Other Income and (Deductions), net
Payment of common stock dividend
Payments of Dividends, Common Stock
Pension contributions
Pension expense
PENSION AND OTHER BENEFITS
Pension and Other Postretirement Benefits Disclosure [Text Block]
Pension [Member]
Pension Plans, Defined Benefit [Member]
Actuarial loss
Defined Benefit Plan, Amortization of Gains (Losses)
Prior service costs
Transition obligation
Defined Benefit Plan, Amortization of Transition Obligations (Assets)
Components of net periodic benefit cost:
Expected return on plan assets
Defined Benefit Plan, Expected Return on Plan Assets
Composite health care trend rate (current year), minimum (in hundredths)
Defined Benefit Plan, Health Care Cost Trend Rate Assumed for Next Fiscal Year
Interest cost
Net periodic benefit cost
Defined Benefit Plan, Net Periodic Benefit Cost
Service cost
Composite health care trend rate (2018 forward), minimum (in hundredths)
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Axis]
Defined Benefit Plan Disclosure [Line Items]
Schedule of Defined Benefit Plans Disclosures [Table]
Prepayments
Issuance of common stock
Issuances of long term debt
Issuances of long-term debt
Cash distributions from GenConn
Net Property, Plant and Equipment
REGULATORY PROCEEDINGS
Public Utilities Disclosure [Text Block]
Investment in GenConn
Payments to Acquire Interest in Joint Venture
Plant expenditures including AFUDC debt
Payments to Acquire Property, Plant, and Equipment
Total Regulatory Assets
Regulatory Asset [Axis]
Regulatory Asset [Domain]
Pension and Other Post-Retirement Benefit Plans [Member]
Pension Costs [Member]
Less current portion of regulatory assets
Current regulatory assets (Note A)
Regulatory Assets, Net
Regulatory Assets (future amounts due from customers through the ratemaking process) (Note A)
Less current portion of regulatory liabilities
Current regulatory liabilities (Note A)
Total regulatory liabilities
Regulatory Liability [Axis]
Regulatory Liability [Domain]
Regulatory Liabilities, Net
Regulatory Liabilities (future amounts owed to customers through the ratemaking process) (Note A)
Related Party [Domain]
Cash distribution from related party
Related Party Transaction [Line Items]
RELATED PARTY TRANSACTIONS
Related Party Transactions Disclosure [Text Block]
Schedule of Related Party Transactions, by Related Party [Table]
Repayments of credit facility
Payments on long-term debt
Repayments of Long-term Debt
Restricted cash
Retained earnings
SHORT-TERM CREDIT ARRANGEMENTS
Schedule of Line of Credit Facilities [Table Text Block]
SEGMENT INFORMATION
Segment Reporting Disclosure [Text Block]
Reconciliation of Total Assets from Segments to Consolidated Financial Statements
Reconciliation of Assets from Segment to Consolidated [Table Text Block]
Reconciliation of Operating Profit (Loss) From Segments to Consolidated Financial Statements
Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Table Text Block]
Segment Reporting Information [Line Items]
Schedule of Segment Reporting Information, by Segment [Table]
Number of shares forfeited (in shares)
Number of shares granted (in shares)
Weighted average grant date fair value (in dollars per share)
Vesting rights
Schedule of Share-based Compensation Arrangement by Share-based Payment Award, Award Type and Plan Name [Axis]
Share-based Compensation Arrangements by Share-based Payment Award, Award Type and Plan Name [Domain]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table]
Short-term Debt, Type [Domain]
Short-term Debt, Type [Axis]
Short-term Debt [Line Items]
Schedule of Short-term Debt [Table]
Short-term borrowings outstanding
BUSINESS ORGANIZATION AND STATEMENT OF ACCOUNTING POLICIES
Significant Accounting Policies [Text Block]
Site contingency, liability accrued
Site Contingency, Nature of Contingency [Domain]
Site Contingency by Nature [Axis]
Site Contingency [Line Items]
Site Contingency [Table]
CONSOLIDATED STATEMENT OF CASH FLOWS (Unaudited) [Abstract]
CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME (Unaudited) [Abstract]
Stock-Based Compensation
Common Stock Equity
Storm Costs [Member]
Subsequent Event Type [Axis]
Subsequent Event [Line Items]
Subsequent Event [Table]
Subsequent Event Type [Domain]
Total Current Assets
Assets, Current
Current Assets
Unsecured Notes [Member]
Unsecured Debt [Member]
Principal amount of senior unsecured notes issued
Depreciation and amortization
Utilities Operating Expense, Depreciation and Amortization
Operation and maintenance
Diluted average number of shares outstanding
Average Number of Common Shares Outstanding - Diluted (in shares)
Weighted Average Number of Shares Outstanding, Diluted
Effect of dilutive securities
Basic average number of shares outstanding
Average Number of Common Shares Outstanding - Basic (in shares)
Management [Member]
President and Chief Executive Officer [Member]
Chief Executive Officer [Member]
Common Stock [Member]
Total Assets
Total Assets
Assets
Interest income
Equity Investments [Abstract]
Other
Other Liabilities, Noncurrent
Cash Dividends Declared per share of Common Stock (in dollars per share)
Scenario, Unspecified [Domain]
Statement, Scenario [Axis]
Supplemental retirement benefit trust life insurance policies
Contract for differences
Derivative Financial Instruments, Liabilities, Fair Value Disclosure
Regulatory assets [Abstract]
ASSETS
FAIR VALUE MEASUREMENTS
Fair Value, Measurement Inputs, Disclosure [Table Text Block]
Changes in fair value of assets and liabilities classified as level 3 [Roll Forward]
Discount rate, minimum (in hundredths)
Return on plan assets, minimum (in hundredths)
Average wage increase, minimum (in hundredths)
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Inputs, Level 1 [Member]
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Inputs, Level 2 [Member]
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Inputs, Level 3 [Member]
Class of Stock [Domain]
Other
Other Assets, Noncurrent
Total Operating Expenses
Operating Expenses
Number of shares of common stock outstanding with purchase options not included in diluted earnings per share (in shares)
Earnings per share [Abstract]
Earnings per Share
Other liabilities
Schedule of Equity Method Investments [Table]
Income Before Income Taxes and Equity Earnings
Income (Loss) Before Income Taxes and Equity Earnings
Schedule of Equity Method Investment, Equity Method Investee, Name [Axis]
Schedule of Equity Method Investments [Line Items]
Class of Stock [Axis]
Deferred Compensation Arrangement with Individual, Share-based Payments, by Title of Individual [Axis]
Net Common Stock Equity
Stockholders' Equity Attributable to Parent
Income Taxes (Note E)
Income Taxes
Allowance for funds used during construction (AFUDC) - equity
Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity
Unrestricted Cash and Temporary Cash Investments:
Plant expenditures included in ending accounts payable
Common stock par value (in dollars per share)
Lease payments for office space
Materials and supplies, at average cost
Unamortized debt issuance expenses
Statement, Business Segments [Axis]
Noncurrent investments available for sale
Net income
Net Income
Net Income
Taxes accrued
Accrued Income Taxes, Current
Denominator: [Abstract]
Taxes - other than income taxes
Total Taxes - Other than Income Taxes
Depreciation and Amortization
Commitments and Contingencies (Note J)
Regulatory Assets [Line Items]
Regulatory Liabilities [Line Items]
Adjustments to reconcile net income to net cash provided by operating activities:
Total Adjustments
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities
CAPITALIZATION
Schedule of Capitalization [Table Text Block]
Capitalization (Note B)
Total Capitalization
Capitalization, Long-term Debt and Equity
Long-term Debt, Type [Axis]
Accounts payable
Accounts Payable, Current
Accrued liabilities
Accrued Liabilities, Current
Dividends payable
Interest accrued
Interest Payable, Current
Schedule of Capitalization, Long-term Debt [Table]
Schedule of Capitalization, Long-term Debt [Line Items]
Comprehensive income
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent
Long-term Debt, Type [Domain]
Pension accrued
Other post-retirement benefits accrued
Numerator: [Abstract]
Temporary Equity, by Class of Stock [Table]
Temporary Equity [Line Items]
Total financial assets, fair value
Assets, Fair Value Disclosure
Total financial liabilities, fair value
Liabilities, Fair Value Disclosure
Segment [Domain]
Other [Member]
Unallocated Amount to Segment [Member]
Fair Value, Measurement Frequency [Domain]
Fair Value, Measurements, Fair Value Hierarchy [Domain]
Fair Value, Measurements, Recurring [Member]
Schedule of Regulatory Assets [Table]
Schedule of Regulatory Liabilities [Table]
Unbilled revenues
Settlements
Amount of pollution control revenue bonds required to either remarket or repay and cancel as per use of funds under credit facility
Other Income and (Deductions), net
Other Income and Expenses [Abstract]
Fair Value, Hierarchy [Axis]
Fair Value by Measurement Frequency [Axis]
COMMITMENTS AND CONTINGENCIES [Abstract]
INCOME TAXES [Abstract]
FAIR VALUE MEASUREMENTS [Abstract]
PENSION AND OTHER BENEFITS [Abstract]
Components of net Periodic Benefit Cost for Pension and Other Postretirement Benefits (OPEB)
Natural gas purchased
Standby letter of credit outstanding
SUPPLEMENTARY INFORMATION [Abstract]
Assets:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Table]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities:
Fair Value of Financial Assets and Liabilities
BUSINESS ORGANIZATION AND STATEMENT OF ACCOUNTING POLICIES [Abstract]
Rates [Abstract]
Equity Method Investments and Joint Ventures [Abstract]
SEGMENT INFORMATION [Abstract]
RELATED PARTY TRANSACTIONS [Abstract]
Other non-cash items, net
Other Noncash Income (Expense)
Range [Axis]
Range [Domain]
Maximum [Member]
Minimum [Member]
Earnings per share: [Abstract]
Earnings Per Share, Basic and Diluted [Abstract]
Non-cash investing activity:
Reconciliation of Basic and Diluted Earnings Per Share
Included in earnings
Cash distribution received
Derivatives, Fair Value, by Balance Sheet Location [Axis]
Balance Sheet Location [Domain]
Derivatives, Fair Value [Line Items]
Collateral required to be posted if the entity's credit rating declined two ratings to fall below investment grade
Unrealized Gains and Losses From Mark-To-Market Adjustments
Fair Value of Gross Derivative Assets and Liabilities
Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table]
Amendment Flag
Current Fiscal Year End Date
Document Period End Date
Entity [Domain]
Entity Well-known Seasoned Issuer
Entity Voluntary Filers
Entity Current Reporting Status
Entity Filer Category
Entity Registrant Name
Entity Central Index Key
Entity Common Stock, Shares Outstanding
Document Fiscal Year Focus
Document Fiscal Period Focus
Legal Entity [Axis]
Document Type
The estimated minimum amount of possible loss from the revised contingency.
Revised Amount Sought For Change Order Requests
Revised amount sought for change order requests
Number of subcontractors responsible for civil construction work in connection with the installation of UI's portion of the Middletown/Norwalk Transmission Project's underground electric cable system filed lawsuits in Connecticut state court.
Subcontractors responsible for civil construction
Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.
Net plant in service
Net plant in service segregated by segment [Abstract]
The number of reporting segments.
Number Of Reporting Segments
Number of reporting segments
Cost of electricity and natural gas purchased during the reporting period.
Cost of Purchased power and gas
Purchased power and gas
A component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.
Transmission Segment [Member]
A component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.
Distribution Segment [Member]
A component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.
Gas Distribution Reportable Segment [Member]
The total for the Electric Distribution and Electric Transmission reportable segments.
Total Electric Reportable Segments [Member]
A component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.
Electric Transmission Reportable Segment [Member]
A component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.
Electric Distribution Reportable Segment [Member]
Electric Distribution Reportable Segment [Member]
Refers to the amount transferred from CL&P associated with the Greater Springfield Reliability Project to UI.
Amount of transmission assets
Refers to the delivery terms according to REC purchase contracts.
Delivery terms of payment according to REC purchase contracts (in years)
Delivery terms of REC purchase contracts (in years)
Refers to the total amount of annual payments related to REC purchase contracts approved by PURA.
Total amount of annual payments related to REC purchase contracts approved by PURA
The amount of TSO incentives approved.
Amount of TSO incentives approved
Transitional Standard Offer Incentive (TSO) [Abstract]
The deferred transmission income (expense) regulatory assets during the period.
Deferred transmission income or expense [Member]
Deferred Transmission Income (Expense) [Member]
Incremental common shares attributable to unvested performance shares that were not included in diluted earnings per share (EPS) because to do so would increase EPS amounts or decrease loss per share amounts for the period presented. Performance shares vest upon achievement of certain target performance goals over a specified period of time.
Performance Shares [Member]
Non-employee directors stock-based compensation.
Non-employee directors [Member]
Maximum potential payment amount under weather insurance contract.
Maximum potential payment amount under weather insurance contract
Maximum payable amount allowed under weather insurance contract
The maximum amount to be paid to the entity under the weather insurance contract if temperatures are warmer than normal during the contract period.
Maximum potenial payment receivable under weather insurance contract
Maximum receivable amount allowed under weather insurance contract
The maximum delivery term for contracts for differences.
Delivery term of related contracts for differences, maximum
Delivery term of related contracts for differences, maximum (in years)
The minimum delivery term for contracts for differences.
Delivery term of related contracts for differences, minimum
Delivery term of related contracts for differences, minimum (in years)
Regulatory accounting [Abstract]
Derivatives [Abstract]
Financial instruments that can be used by organizations or individuals as part of a risk management strategy to reduce risk associated with adverse or unexpected weather conditions. The difference from other derivatives is that the underlying asset (rain/temperature/snow) has no direct value to price the weather derivative.
Weather Insurance Contracts SCG and CNG [Member]
Financial instruments that can be used by organizations or individuals as part of a risk management strategy to reduce risk associated with adverse or unexpected weather conditions. The difference from other derivatives is that the underlying asset (rain/temperature/snow) has no direct value to price the weather derivative.
Berkshire Weather Insurance [Member]
UIL's portion of another entity's derivative liabilities included as a gross derivative liability.
Gross derivative liability, UIL's portion of entity
The amount for regulatory asset for contracts for differences as itemized in a table of regulatory assets as of the end of the period
Regulatory assets contracts for differences
Regulatory asset
The percentage of cost borne by customers of entity two, as per the cost-sharing agreement set forth by the Contracts for Differences (CfDs).
Percentage of cost borne by Entity Two
Percentage of cost borne by CL&P customers (in hundredths)
The percentage of cost borne by customers of entity one, as per the cost-sharing agreement set forth by the Contracts for Differences (CfDs).
Percentage of cost borne by Entity One
Percentage of cost borne by UI customers for CFDs (in hundredths)
The number of Contracts for Differences (CfDs) approved by Public Utility Regulatory Authority (PURA), each of which specifies a capacity quantity and a monthly settlement that reflects the difference between a forward market price and the contract price.
Number of Contracts for Differences approved by Public Utility Regulatory Authority
Number of Contracts for Differences (CfDs) approved by Public Utility Regulatory Authority (PURA)
The number of new capacity resources selected related to Public Utility Regulatory Authority initiation process to solicit bids to create new or incremental capacity resources in order to reduce federally mandated congestion charges.
Number of new capacity resources selected
The percentage of ownership in a joint venture project selected to build and operate new peaking generation plants.
Ownership percentage in joint venture
Ownership percentage in joint venture (in hundredths)
Ownership percentage in joint venture [Abstract]
Ownership percentage in GenConn [Abstract]
The maximum amortization period (in years) for recovery of the individual regulatory liability in a schedule of regulatory liabilities.
Regulatory Liability Remaining Period Maximum
Remaining period, maximum (in years)
The minimum amortization period (in years) for recovery of the individual regulatory liability in a schedule of regulatory liabilities.
Regulatory Liability Remaining Period Minimum
Remaining period, minimum (in years)
The amortization period (in years) for recovery of the individual regulatory liability in a schedule of regulatory liabilities.
Regulatory Liability Remaining Period
Remaining period (in years)
Other regulatory liability.
Other Regulatory Liability [Member]
Deferred transmission expense regulatory liability.
Deferred Transmission Expense [Member]
Asset removal costs regulatory liability.
Asset Removal Costs [Member]
Deferred purchased gas regulatory liability.
Deferred Purchased Gas [Member]
Discloses the amount of regulatory liabilities arising from the difference between net periodic pension cost, according to US GAAP, and the amount of pension cost considered for rate-making purposes, according the actions of the regulator, and the amount of regulatory liabilities related to postretirement benefit costs.
Pension And Other Post Retirement Benefit Plans [Member]
Pension And Other Post-Retirement Benefit Plans [Member]
Middletown/Norwalk local transmission network service collections regulatory liability.
Middletown Norwalk Local Transmission Network Service Collections [Member]
Middletown/Norwalk Local Transmission Network Service Collections [Member]
Deferred gain on sale of property regulatory liability.
Deferred Gain on Sale of Property [Member]
Income taxes due principally to book-tax differences regulatory asset.
Income Taxes Due Principally To Book Tax Differences Liabilities [Member]
Accumulated deferred investment tax credits regulatory liability.
Accumulated Deferred Investment Tax Credits [Member]
The maximum amortization period (in years) for recovery of the individual regulatory asset in a schedule of regulatory assets.
Regulatory Asset Remaining Period Maximum
Remaining period, maximum (in years)
The minimum amortization period (in years) for recovery of the individual regulatory asset in a schedule of regulatory assets.
Regulatory Asset Remaining Period Minimum
Remaining period, minimum (in years)
The amortization period (in years) for recovery of the individual regulatory asset in a schedule of regulatory assets.
Regulatory Asset Remaining Period
Remaining period (in years)
Other regulatory asset.
Other Regulatory Asset [Member]
Excess generation service charge regulatory asset.
Excess Generation Service Charge [Member]
Contracts for differences regulatory asset.
Contracts For Differences Regulatory Asset [Member]
Unfunded future income taxes regulatory asset.
Unfunded Future Income Taxes [Member]
Debt premium regulatory asset.
Debt Premium [Member]
Deferred transmission income/expense regulatory asset.
Deferred transmission income/expense [Member]
Deferred Transmission Income (Expense) [Member]
Low income program regulatory asset.
Low Income Program [Member]
Hardship programs [Member]
Connecticut Yankee regulatory asset.
Connecticut Yankee [Member]
Nuclear plant investment - above market regulatory asset.
Nuclear Plant Investments Above Market [Member]
Nuclear Plant Investments - Above Market [Member]
The amount of net income allocated to unvested units, deducted from net income (loss) to arrive at net income attributable to common shareholders.
Net income allocated to unvested units
Less: Net income allocated to unvested units
Derivative liabilities, weather insurance contract.
Derivative Liabilities, Weather Insurance Contracts
Weather insurance contracts
Derivative liabilities contracts for difference.
Contracts for differences
Contracts for differences
Derivative assets contracts for difference.
Contract for differences
Contracts for differences
Unrealized gains (losses) from mark-to-market adjustments to derivative assets recorded in regulatory liabilities for the period.
Unrealized Gains Losses From Mark To Market Adjustments of Derivative Assets
Regulatory Liabilities - Derivative assets
Unrealized gains (losses) from mark-to-market adjustments to derivative liabilities recorded in regulatory assets for the period.
Unrealized Gains Losses From Mark To Market Adjustments of Derivative Liabilities
Regulatory Assets - Derivative liabilities
Unrealized gains and losses from mark to market adjustments [Abstract]
Unrealized gain and losses from mark-to-market adjustments [Abstract]
Line item in the statement of financial position in which the fair value amounts of the derivative instruments are included.
Noncurrent Portion Derivative Liabilities [Member]
Line item in the statement of financial position in which the fair value amounts of the derivative instruments are included.
Current Portion Derivative Liabilities [Member]
Line item in the statement of financial position in which the fair value amounts of the derivative instruments are included.
Noncurrent Portion Derivative Assets [Member]
Line item in the statement of financial position in which the fair value amounts of the derivative instruments are included.
Current Portion Derivative Assets [Member]
Tabular information about regulatory assets and liabilities, including current and noncurrent assets created when regulatory agencies permit the deferral of costs to the balance sheet that would otherwise be required to appear on the company's income statement and would be charged against current expenses or revenues, as well as current and noncurrent liabilities created when regulatory agencies permit.
Regulatory Assets and Liabilities [Table Text Block]
Regulatory Assets and Liabilities
The increase (decrease) during the reporting period in the value of assets that are created when regulatory agencies permits public utilities to defer costs (revenues) to the balance sheet. This element is a the increase (decrease) of regulatory assets and liabilities combined.
Change in regulatory asset/liability balances [Roll Forward]
This item represents the amount of the total change in unrealized (holding) gains or losses for the period. Such unrealized (holding) gains or losses relate to those net assets and liabilities still held at the reporting date for which fair value is measured on a recurring basis using significant unobservable inputs (Level 3).
Fair Value Net Assets And Liabilities Measured On Recurring Basis Change In Unrealized Gain Loss
Change in unrealized gains (losses) net relating to net derivative assets/(liabilities), still held as of September 30, 2012
This element represents total gains or losses for the period (realized and unrealized), arising from net assets and liabilities measured at fair value on a recurring basis using unobservable inputs (Level 3), which are included in regulatory assets and liabilities.
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Net Asset And Liability Gain Loss Included In Regulatory Assets Liabilities
Included in regulatory assets/(liabilities)
Unrealized gains and (losses), net [Abstract]
This element represents a net asset (liability) measured at fair value using significant unobservable inputs (Level 3) which is required for reconciliation purposes of beginning and ending balances.
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Net Asset And Liability Value
Net fair value assets/(liabilities), December 31, 2011
Net fair value assets/(liabilities), September 30, 2012
The upper range of the heating degree days.
Heating degree days, upper range
Heating degree days, upper range
The upper range of contract pricing.
Contract term pricing, upper range
Forward pricing, upper range (in dollars per MW)
The lower range of contract pricing.
Contract term pricing, lower range
Forward pricing, lower range (in dollars per MW)
The upper range percentage discount rate.
Discount rate, upper range
Discount rate, upper range (in hundredths)
The lower range percentage discount rate.
Discount rate, lower range
Discount rate, lower range (in hundredths)
Upper range percentage adjustment for non-performance risk using credit default swap rates.
Risk of non performance upper limit
Risk of non-performance, upper range (in hundredths)
Lower range percentage adjustment for non-performance risk using credit default swap rates.
Risk of non performance lower limit
Risk of non-performance, lower range (in hundredths)
Unobservable input [Abstract]
Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.
Fair Value, Net Assets And Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative assets and liabilities for weather insurance contract.
Weather Insurance Contract [Member]
Derivative assets and liabilities contract.
Contract For Difference [Member]
Represents classes of net assets and liabilities measured and disclosed at fair value.
Fair Value, Net Assets And Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, by Asset Class [Domain]
Fair value information by class of asset.
Fair Value by Net Asset and Liability Class [Axis]
Fair Value, Net Assets And Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table]
Fair values as of the balance sheet date of the net amount of all financial assets and liabilities.
Net assets liabilities fair value disclosure
Net fair value assets/(liabilities)
Under the UIL Deferred Compensation Plan (DCP), directors, named executive officers and certain other executives may elect to defer certain elements of compensation. Participants in the DCP are permitted to direct investments of their elective deferral accounts into 'deemed' investments consisting of non-publicly traded mutual funds available through variable insurance products, and Company common stock equivalents.
Deferred Compensation Plan Fair Value Disclosure
Deferred Compensation Plan
Weather insurance contract.
Weather insurance contracts
Weather insurance contracts
Tabular disclosure of the fair value measurement of net regulatory assets and liabilities that were established to recover any unrealized gains/(losses) associated with the contracts for differences. The table is a reconciliation of the beginning and ending balances, separately presenting changes during the period attributable to unrealized gains and (losses), net.
Change in Net Regulatory Asset Liability Balance [Table Text Block]
Change in Regulatory Asset/(Liability) Balance
Tabular disclosure of the fair value measurement of net assets and liabilities using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances, separately presenting changes during the period.
Fair Value Net Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Table Text Block]
Changes in Fair Value of Assets and Liabilities Classified as level 3
Tabular disclosure of additional quantitative information about level 3 fair value measurement.
Additional quantitative information about Level 3 fair value measurements [Table Text Block]
Additional quantitative information about Level 3 fair value measurements
The net book value of Electric System Work Center (ESWC) for which UI entered into a Purchase and Sale Agreement as part of its plan to consolidated operations and office personnel.
Original purchase price of business
Net book value of ESWC
The sale price of Electric System Work Center (ESWC) for which UI entered into a Purchase and Sale Agreement as part of its plan to consolidated operations and office personnel.
Sale price of business
Sales price of Electric System Work Center (ESWC)
Purchase and sales agreement [Abstract]
Amount of general contractor mark-up on approved subcontractor change order claims related to the Middletown/Norwalk Transmission Project.
Amount of general contractor mark up on approved subcontractor change order claims
Percentage of general contractor mark-up on approved subcontractor change order claims related to the Middletown/Norwalk Transmission Project.
Percentage of general contractor mark up on approved subcontractor change order claims
Percentage of general contractor mark-up on approved subcontractor change order claims (in hundredths)
The remaining amount of escrow with the purpose of bringing soil and groundwater on the site into compliance with applicable environmental laws.
Remaining amount of escrow
Remaining amount of escrow
Middletown/Norwalk Transmission Project [Abstract]
Site Contingency
The entity's share of the second set of damage claims which, if awarded, would be refunded to customers.
Entitys share of second set of damage claims
Entity's share of second set of damage claims
Amount of second set of damage claims filed by atomic power company relating to failure to remove spent atomic fuel.
Second set of damage claims relating to failure to remove spent atomic fuel
Amount of damages awarded to atomic power company for its spent fuel-related costs, resulting from breach of contracts by the DOE.
Damages awarded for spent fuel related costs
DOE spent fuel litigation [Abstract]
The amount demanded by GE from Berkshire for Berkshire's share of response costs.
Amount demanded as share of response costs
Regulatory asset related to atomic power company, for which the entity has regulatory approval to recover in future rates over a term ending in 2015.
Regulatory asset related to atomic power company
The entity's carrying value of stock in atomic power company.
Carrying value of stock in atomic power company
The entity's percentage stock ownership in atomic power company.
Percentage stock ownership in atomic power company
Percentage stock ownership share in atomic power company (in hundredths)
East Street Site in Pittsfield Massachusetts formerly owned by Berkshire that was used for coal and water gas manufacturing operations.
East Street Site Pittsfield Massachusetts [Member]
The environmental remediation obligation or asset related to an individual site.
Mill Street Greenfield Massachusetts Site [Member]
The environmental remediation obligation or asset related to an individual site.
Pine Street Bridgeport Connecticut Site [Member]
The environmental remediation obligation or asset related to an individual site.
New Haven Harbor Station Site [Member]
The environmental remediation obligation or asset related to an individual site.
Mill River New Haven Connecticut Site [Member]
Connecticut Yankee Atomic Power Company
Connecticut Yankee Atomic Power Company [Member]
GenConn Energy LLC, a joint venture, together with an affiliate of NRG Energy, Inc. (NRG).
GenConn [Member]
Percentage of revised return on equity sought by complainants.
Revised return on equity sought by complainants (in hundredths)
Refers to the preceding number of years for average interest rate.
Preceding number of years for average interest rates
Refers to the average interest rate used to estimate pension liabilities.
Average interest rate used to estimate pension liabilities
Represents the number of years on which average of interest rate is based.
Number of years on which average of interest rate is based
The maximum ultimate trend rate for health care costs.
Composite health care trend rate (2018 forward), maximum
Composite health care trend rate (2018 forward), maximum (in hundredths)
The maximum assumed health care cost trend rate for the next year used to measure the expected cost of benefits covered by the plan (gross eligible charges).
Composite health care trend rate (current year), maximum
Composite health care trend rate (current year), maximum (in hundredths)
An assumption as to the maximum rate of return on plan assets reflecting the average rate of earnings expected on the funds invested or to be invested to provide for the benefits included in the benefit obligation.
Return on plan assets, maximum
Return on plan assets, maximum (in hundredths)
The maximum expected rate of compensation increases (for pay-related plans).
Average wage increase, maximum
Average wage increase, maximum (in hundredths)
The maximum interest rate used to adjust for the time value of money
Discount rate, maximum
Discount rate, maximum (in hundredths)
Amortization of: [Abstract]
Amortization of:
Pension plan beginning in 2016 [Member]
Pension plan beginning in 2012 [Member]
Benefits provided to former or inactive employees, their beneficiaries, and covered dependents after employment but before retirement, except for: a) benefits provided through a pension or postretirement benefit plan, b) individual deferred compensation arrangements, c) termination benefits pertaining to exit or disposal activities, and d) stock compensation plans. Benefits may be provided in cash or in kind and may be paid as a result of disability, layoff, death, or other event.
Other Postemployment Benefit [Member]
OPEB [Member]
Disclosure of miscellaneous other nonoperating income and expense items, net not otherwise specified.
Miscellaneous Other income and deductions net
Miscellaneous other income and (deductions) - net
ISO load response, net.
ISO load response net
ISO load response, net
Conservation and Load Management incentive.
Conservation and Load Management incentive
Conservation & Load Management incentive
The offsetting entry to other income when an enterprise capitalizes, as part of the cost of plant and equipment, the cost of financing construction as financed partially by debt.
Allowance for funds used during construction debt
Allowance for funds used during construction - debt
The offsetting entry to other income when an enterprise capitalizes, as part of the cost of plant and equipment, the cost of financing construction as financed partially by equity.
Allowance for funds used during construction equity
Allowance for funds used during construction - equity
Other taxes
Other taxes
Other
Taxes attributable to Connecticut gross earnings.
Gross earnings taxes
Connecticut gross earnings
Taxes Other than Income Taxes Operating: [Abstract]
Taxes - Other than Income Taxes - Operating:
The expense charged against earnings during the period to allocate the capitalized costs of other regulatory assets over the periods expected to benefit from such costs.
Amortization of other regulatory assets
The expense charged against earnings during the period to allocate the capitalized costs of nuclear plant regulatory assets over the periods expected to benefit from such costs.
Amortization of nuclear plant regulatory assets
The current period total expense charged against earnings on long-lived, physical assets used in production, and which are not intended for resale, to allocate or recognize the cost of such assets over their useful lives; or to record the reduction in book value of an intangible asset over the benefit period of such asset; or to reflect consumption during the period of an asset that is not used in production.
Total Depreciation
Property, plant and equipment depreciation
Tabular disclosure of supplemental income statement information for the periods presented.
Supplementary Information [Table Text Block]
Supplementary Information
Document and Entity Information [Abstract]
Increase in statutory rate of Connecticut corporation business tax due to additional surcharge.
Increase in statutory rate of the Connecticut corporation business tax
Increase in statutory rate of the Connecticut corporation business tax (in hundredths)
The percentage increase in the combined federal and state income tax rate due to additional surcharge on corporation business tax.
Surcharge on the corporation business tax
Surcharge on the corporation business tax (in hundredths)
The combined statutory federal and state income tax rate applicable under enacted tax laws to the Company's pretax income from continuing operations for the period.
Statutory federal and state income tax rates
Combined statutory federal and state income tax rates (in hundredths)
The borrowing limit under credit agreement for the purpose of additional liquidity of the entity.
Line of Credit Facility Additional Amount
Additional liquidity amount
An arrangement in which loan proceeds can continuously be obtained following repayments, but the total amount borrowed cannot exceed a specified maximum amount.
Revolving Credit Facility [Member]
A document typically issued by a financial institution which acts as a guarantee of payment to a beneficiary, or as the source of payment for a specific transaction (for example, wiring funds to a foreign exporter if and when specified merchandise is accepted pursuant to the terms of the letter of credit).
Standby Letter of Credit Due 2012 [Member]
UIL Standby Letter of Credit Due 2013 [Member]
A document typically issued by a financial institution which acts as a guarantee of payment to a beneficiary, or as the source of payment for a specific transaction (for example, wiring funds to a foreign exporter if and when specified merchandise is accepted pursuant to the terms of the letter of credit).
Standby Letter of Credit Due 2011 [Member]
UI Standby Letter of Credit Due 2012 [Member]
The cash inflow from the amounts received by the insured upon the expiration of weather insurance contracts.
Payment received under weather insurance contract
Represents the number of fuel cell facilities approved by PURA.
Number of fuel cell facilities approved by PURA
Represents the number of solar facilities approved by PURA.
Number of solar facilities approved by PURA
Reduction in annual net income.
Reduction in annual net income
Reduction in weighted average return on equity in basis points.
Reduction in weighted average return on equity in basis points
Percentage return on equity sought by complainants.
Return on equity sought by complainants
Current approved base return on equity.
Current approved base return on equity
Current approved base return on equity (in hundredths)
Renewable generation capacity for recovery on a cost of service basis.
Renewable generation capacity for recovery
Renewable generation capacity for recovery (in MW)
Mega watts of solar projects selected.
Mega watts of solar projects selected by DEEP
Mega watts of solar projects selected by DEEP (in MW)
Number of solar projects selected.
Number of mega watts solar projects selected by DEEP
Number of solar projects selected by DEEP
Mega watts of grid connected renewable energy solicited from market from Department of Energy and Environmental Protection (DEEP).
Amount Of Grid Connected Renewable Energy Solicited By DEEP From Market
Amount of grid connected renewable energy solicited by DEEP from market
Number of mega watts of grid connected renewable energy allowed to be developed by each company.
Number Of Mega Watts Of Grid Connected Renewable Energy Allowed To Be Developed By Each Company
Number of mega watts of grid connected renewable energy allowed to be developed by each company (in MW)
Number of mega watts of grid connected renewable energy allowed to be developed per Connecticut Public Act 11-80
Number Of Mega Watts Of Grid Connected Renewable Energy Allowed To Be Developed Per Connecticut Public Act11 80
Number of mega watts of grid connected renewable energy allowed to be developed per Connecticut Public Act 11-80 (in MW)
Maximum annual commitment level obligation that are expected to peak after year six.
Maximum annual commitment level obligation after year six
Solicitation period that obligation will phase-in.
Solicitation period obligations will phase in
Solicitation period obligations will phase-in
Period of commitment to purchase Renewable Energy Credits (REC's).
Period of commitment to purchase Renewable Energy Credits
Period of commitment to purchase Renewable Energy Credits (RECs)
Maximum amount of commitment to purchase Renewable Energy Credits (REC's).
Maximum Amount Of Commitment To Purchase Renewable Energy Credits Recs From New Facilities Behind Distribution Customer Meters
Maximum amount of commitment to purchase Renewable Energy Credits (RECs) from new facilities behind distribution customer meters
Terminated contract which company was a direct party.
Contracts terminated
Number of new renewable source generation megawatts having the capability of achieving commercial operations.
Number of new renewable source generation megawatts having the capability of achieving commercial operation
Number of new renewable source generation megawatts having the capability of achieving commercial operation (in MW).
Company is party to contracts relating to project approved by PURA.
Company is party to contracts related to project approved by PURA
Percentage of benefit from contract executed.
Percentage of benefit from contract executed with CL&P
Percentage of benefit from contract executed with CL&P (in hundredths)
This element represent percentage of cost paid according to sharing agreement.
Sharing agreement executed with CL&P to share cost
Sharing agreement executed with CL&P to share cost (in hundredths)
Electric distribution required to purchase mega watts of new renewable generation according to Connecticut law.
Statutory requirements to purchase output of new renewable generation
Statutory requirements to purchase output of new renewable generation (in MW)
New Renewable Source Generation [Abstract]
Represents the maturity period of long term debt.
Maturity period of long term debt
The principal amount of debt securities approved by DPU for the company to issue.
Principal Amount Of Debt Securities DPU Approved For Issuance
Principal amount of debt securities DPU approved for issuance
The duration (in years) of the rate plan approved by the Massachusetts Department of Public Utilities.
Duration of approved rate plan
Duration of approved rate plan
The entity's approved return on equity, as per the relevant regulatory commission.
Approved return on equity
Approved return on equity (in hundredths)
Weighted average return on equity.
Weighted average return on equity
Weighted average return on equity (in hundredths)
Pre-tax income earned on each deposit in New England East-West Solution (NEEWS) Project.
Pre tax income earned on each deposits
Pre-tax income earned on each deposits in NEEWS project.
The maximum period over which the entity expects to make remaining investments.
Maximum period over which remaining investments are expected to be made
Maximum period over which remaining investments are expected to be made
The minimum period over which the entity expects to make remaining investments.
Minimum period over which remaining investments are expected to be made
Minimum period over which remaining investments are expected to be made
The cumulative amount of deposits made by the entity, through the balance sheet date, in projects to improve regional energy reliability.
Cumulative amount of deposits in projects to improve regional energy reliability
Cumulative amount of deposits
The expected amount of investment for ownership of specific transmission assets as they are placed in service, based on previously projected costs.
Expected amount of investment
The threshold percentage of another entity's costs for the Connecticut portions of the projects, by which the entity has the right to invest up to this amount, given that it is greater than the defined minimum amount.
Threshold percentage of costs for the Connecticut portions of projects
Threshold percentage of CL&P's costs for the Connecticut portions of projects (in hundredths)
The minimum amount of investment for ownership of specific transmission assets as they are placed in service.
Minimum amount of entitys investment for ownership of specific transmission assets
Minimum amount of entity's investment for ownership of specific transmission assets
The number of inter-related transmission projects to improve regional energy reliability, with portions sited in Connecticut.
Number of inter related transmission projects with portions sited
Number of inter-related transmission projects with portions sited in Connecticut
The number of inter-related transmission projects to improve regional energy reliability.
Number of inte related transmission projects
Projects to improve regional energy reliability [Abstract]
New England East-West Solution [Abstract]
The percentage of standard service customers with wholesale power supply agreements in place, for the second twelve month period following the end of the current fiscal year.
Percentage of standard service customers with wholesale power supply agreements in place for year two
Percentage of standard service customers with wholesale power supply agreements in place for 2013 (in hundredths)
Power Supply Arrangements [Abstract]
Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.
Schedule of Regulatory Proceedings [Line Items]
A utility business consisting of natural gas transportation, distribution and sales.
Berkshire Gas Company [Member]
The Berkshire Gas Company [Member]
Southern Connecticut Gas Company (SCG).
Southern Connecticut Gas Company (SCG) [Member]
The Southern Connecticut Gas Company (SCG) [Member]
Connecticut Natural Gas Corporation (CNG).
Connecticut Natural Gas Corporation (CNG) [Member]
Schedule of Regulatory Proceedings [Table]
The approximate number of customer outages caused by extensive damage to the electric system in the company's service territory due to a natural disaster.
Approximate number of customer outages
Transmission Return of Equity (ROE) [Abstract]
Gross amount of additional senior unsecured debt to be issued in next fiscal year.
Additional principal amount of unsecured debt to be issued
Additional principal amount of unsecured debt issued
Carrying value as of the balance sheet date of uncollateralized debt obligation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion.
Principal amount outstanding of pollution control revenue bonds remarketed
The principal amount of debt securities approved by PURA for the company to issue.
Principal amount of debt securities PURA approved for issuance
Approval for Issuance of Debt [Abstract]
Approval for issuance of Debt [Abstract]
The amount of decoupling charge to be approved by PURA.
Decoupling charge approved by PURA
Decoupling charge to be approved by PURA
The percentage of earnings retained by company.
Percentage of earnings returned to customers
Percentage of earnings retained by company (in hundredths)
The allowed distribution return on equity resulting from the final decision issued by the State of Connecticut's Department of Public Utility Control.
Allowed distribution return on equity
Allowed distribution return on equity (in hundredths)
Requested allowed distribution return on equity.
Requested allowed distribution return on equity
Requested allowed distribution return on equity (in hundredths)
Electric Distribution and Transmission Rates [Abstract]
Rates [Abstract]
Maximum number of hours to serve a customers.
Maximum number of hours to serve a customers
Maximum number of hours to serve a customers (in hours)
Percentage of Customers to establish standards for acceptable performance.
Percentage of Customers to establish standards for acceptable performance
Percentage of Customers to establish standards for acceptable performance (in hundredths)
The carrying amount of debt instrument at the end of the period.
Remaining amount of note purchase agreement
The amount of principal balance on note outstanding.
Debt Instrument, Principal amount of note outstanding
Principal amount of note outstanding
The aggregate principal amount outstanding on bonds that were refinanced.
Bonds refinanced, aggregate principal amount outstanding
A senior note is a bond that takes priority over other debt securities sold by the issuer. In the event the issuer goes bankrupt, senior debt holders receive priority for [must receive] repayment [prior] relative to junior and unsecured (general) creditors.
Series E Senior Notes [Member]
A senior note is a bond that takes priority over other debt securities sold by the issuer. In the event the issuer goes bankrupt, senior debt holders receive priority for [must receive] repayment [prior] relative to junior and unsecured (general) creditors.
Series D Senior Notes [Member]
A senior note is a bond that takes priority over other debt securities sold by the issuer. In the event the issuer goes bankrupt, senior debt holders receive priority for [must receive] repayment [prior] relative to junior and unsecured (general) creditors.
Series C Senior Notes [Member]
A senior note is a bond that takes priority over other debt securities sold by the issuer. In the event the issuer goes bankrupt, senior debt holders receive priority for [must receive] repayment [prior] relative to junior and unsecured (general) creditors.
Series A Senior Notes [Member]
A senior note is a bond that takes priority over other debt securities sold by the issuer. In the event the issuer goes bankrupt, senior debt holders receive priority for [must receive] repayment [prior] relative to junior and unsecured (general) creditors.
Series B Senior Notes [Member]
Represents the current and noncurrent portions of a debt security issued by a state, certain agencies or authorities, a local government, or development corporation to finance the construction of air- or water-pollution control facilities or sewage or solid waste disposal facilities pursuant to federal law.
Pollution Controlled Revenue Bonds [Member]
A utility business consisting of electric distribution and transmission operations.
United Illuminating Company (UI) [Member]
Supplementary Information
Supplementary Information [Text Block]
SUPPLEMENTARY INFORMATION
SHORT-TERM CREDIT ARRANGEMENTS [Abstract]
REGULATORY PROCEEDINGS [Abstract]
CAPITALIZATION [Abstract]
Represents deposits arrangements with industry participants during the period.
Deposits arrangements with industry participants
Deposits in New England East West Solution (NEEWS)
Represents plant expenditures including debt during the period.
Plant expenditures including debt
Plant expenditures funded by deposits in NEEWS
Represents equity investment in related parties including affiliates, employees, joint ventures, officers and stockholders, immediate families thereof, and pension funds.
Equity investment in related party
Equity investment in related party
Represents notes receivable due from related parties including affiliates, employees, joint ventures, officers and stockholders, immediate families thereof, and pension funds.
Related party note receivable
Related party note receivable
Cash outflow associated with investment in New England East West Solution (NEEWS) projects to improve regional energy reliability
Investment in NEEWS
Deposits in New England East West Solution (NEEWS) (Note C)
The cash inflow or outflow associated with loans for related parties where one party can exercise control or significant influence over another party, including affiliates, owners or officers and their immediate families, pension trusts, and so forth.
Proceeds from Payments for Loans for Related Parties
Related party note receivable
Cash distributions received from a related party entity.
Cash Distributions Received
Cash distributions from GenConn
This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. Such amount typically reflects adjustments similar to those made in preparing consolidated statements, including adjustments to eliminate intercompany gains and losses, and to amortize, if appropriate, any difference between cost and underlying equity in net assets of the investee at the date of investment.
Undistributed (earnings) losses in equity investments
Undistributed (earnings) losses in equity investments
Preferred Stock of Subsidiary [Abstract]
Preferred Stock of Subsidiary
Connecticut Yankee contract obligation
Contract obligation noncurrent
Connecticut Yankee contract obligation (Note J)
Sum of the carrying amounts of deferred costs that are expected to be recognized as a charge against earnings in periods after one year or beyond the normal operating cycle, if longer. Sum of the carrying amounts as of the balance sheet date of other assets that are expected to be realized in cash, sold or consumed after one year or beyond the normal operating cycle, if longer.
Total Deferred Charges and Other Assets
Total Deferred Charges and Other Assets
Deferred Charges and Other Assets [Abstract]
Deferred Charges and Other Assets
This item represents the carrying amount on the entity's balance sheet of its investment in GenConn. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.
Equity Method Investments Gen Conn
Equity investment in GenConn (Note A)
Carrying amount as of the balance sheet date of natural gas to meet future demands
Inventory Gas In Storage
Natural gas in storage, at average cost
Less: [Abstract]
Less:
Sum of operating profit and nonoperating income or expense, net of tax, before income or loss from equity method investments.
Income Before Equity Earnings
Income Before Equity Earnings