UIL (UIL) 10-Q 5 Aug 15 2015 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2015	Jul. 31, 2015
Document and Entity Information [Abstract]
Entity Registrant Name	UIL HOLDINGS CORP
Entity Central Index Key	1,082,510
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		56,629,082
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q2
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2015

CONSOLIDATED STATEMENT OF INCOM

CONSOLIDATED STATEMENT OF INCOME (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
CONSOLIDATED STATEMENT OF INCOME (Unaudited) [Abstract]
Operating Revenues	$ 312,007	$ 334,794	$ 896,060	$ 905,956
Operation
Purchased power	36,715	32,679	133,817	85,809
Natural gas purchased	40,101	76,557	214,621	291,482
Operation and maintenance	103,004	102,700	204,351	195,577
Transmission wholesale	17,988	19,064	37,697	39,975
Depreciation and amortization (Note F)	39,380	36,512	82,664	76,830
Taxes - other than income taxes (Note F)	31,834	30,541	73,149	70,077
Merger and acquisition-related expenses (Note A)	93	469	6,795	5,520
Total Operating Expenses	269,115	298,522	753,094	765,270
Operating Income	42,892	36,272	142,966	140,686
Other Income and (Deductions), net
Acquisition-related bridge facility fees (Note A)	0	(7,926)	0	(14,339)
Other income and (deductions) (Note F)	4,294	4,624	8,662	8,486
Total Other Income and (Deductions), net	4,294	(3,302)	8,662	(5,853)
Interest Charges, net
Interest on long-term debt	22,217	22,448	44,442	44,900
Other interest, net (Note F)	1,404	392	2,636	567
Interest charges, gross	23,621	22,840	47,078	45,467
Amortization of debt expense and redemption premiums	609	607	1,216	1,214
Total Interest Charges, net	24,230	23,447	48,294	46,681
Income from Equity Investments	3,940	3,520	6,876	6,906
Income Before Income Taxes	26,896	13,043	110,210	95,058
Income Taxes (Note E)	11,050	3,740	36,755	30,290
Net Income	15,846	9,303	73,455	64,768
Less: Preferred Stock Dividends of Subsidiary, Noncontrolling Interests	7	(40)	14	(27)
Net Income attributable to UIL Holdings	$ 15,839	$ 9,343	$ 73,441	$ 64,795
Average Number of Common Shares Outstanding - Basic (in shares)	56,950	56,842	56,918	56,814
Average Number of Common Shares Outstanding - Diluted (in shares)	57,241	57,102	57,229	57,079
Earnings Per Share of Common Stock - Basic (Note A) (in dollars per share)	$ 0.28	$ 0.16	$ 1.29	$ 1.14
Earnings Per Share of Common Stock - Diluted (Note A) (in dollars per share)	0.28	0.16	1.28	1.13
Cash Dividends Declared per share of Common Stock (in dollars per share)	$ 0.432	$ 0.432	$ 0.864	$ 0.864

CONSOLIDATED STATEMENT OF COMPR

CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME (Unaudited) [Abstract]
Net Income	$ 15,846	$ 9,303	$ 73,455	$ 64,768
Other Comprehensive Income (Loss), net of income taxes
Changes in unrealized gains (losses) related to pension and other post-retirement benefit plans	(57)	170	216	231
Other	(8)	(4)	(1)	8
Total Other Comprehensive Income (Loss), net of income taxes	(65)	166	215	239
Comprehensive Income	15,781	9,469	73,670	65,007
Less:
Preferred Stock Dividends of Subsidiary, Noncontrolling Interests	7	(40)	14	(27)
Comprehensive Income Attributable to UIL Holdings	$ 15,774	$ 9,509	$ 73,656	$ 65,034

CONSOLIDATED BALANCE SHEET (Una

CONSOLIDATED BALANCE SHEET (Unaudited) - USD ($) $ in Thousands		Jun. 30, 2015	Dec. 31, 2014
Current Assets
Unrestricted cash and temporary cash investments		$ 179,133	$ 115,579
Restricted cash		1,161	1,051
Accounts receivable less allowance of $9,257 and $8,881, respectively		217,740	232,887
Unbilled revenues		63,453	95,816
Current regulatory assets (Note A)		102,987	92,764
Natural gas in storage, at average cost		47,328	86,428
Refundable taxes		17,413	15,211
Current portion of derivative assets (Note A)		9,934	6,849
Prepayments		14,389	10,696
Other		12,567	12,815
Total Current Assets		666,105	670,096
Other investments
Equity investment in GenConn (Note A)		112,910	114,195
Other		27,348	25,777
Total Other investments		140,258	139,972
Net Property, Plant and Equipment (Note A)		3,407,309	3,292,690
Regulatory Assets (Note A)		681,091	687,198
Deferred Charges and Other Assets
Unamortized debt issuance expenses		12,953	13,571
Other long-term receivable		1,487	1,490
Derivative assets (Note A)		22,887	20,421
Goodwill		266,205	266,205
Other		2,867	20,292
Total Deferred Charges and Other Assets		306,399	321,979
Total Assets	[1]	5,201,162	5,111,935
Current Liabilities
Line of credit borrowings		80,000	89,000
Current portion of long-term debt		6,528	6,526
Accounts payable		145,543	217,700
Dividends payable		24,464	24,428
Accrued liabilities		63,318	71,182
Current regulatory liabilities (Note A)		44,242	17,026
Taxes accrued		18,323	20,184
Interest accrued		21,656	22,437
Deferred income taxes		16,691	3,767
Current portion of derivative liabilities (Note A)		27,513	23,308
Total Current Liabilities		448,278	495,558
Deferred Income Taxes		608,290	585,335
Regulatory Liabilities (Note A)		509,758	491,896
Other Noncurrent Liabilities
Pension accrued		264,540	265,009
Other post-retirement benefits accrued		86,940	85,777
Derivative liabilities (Note A)		79,643	61,766
Other		47,649	46,924
Total Other Noncurrent Liabilities		$ 478,772	$ 459,476
Commitments and Contingencies (Note J)
Capitalization (Note B)
Long-term debt, net of unamortized discount and premium		$ 1,758,987	$ 1,711,349
Preferred Stock, not subject to mandatory redemption		119	119
Common Stock Equity
Common stock		1,153,569	1,149,985
Paid-in capital		22,023	21,587
Retained earnings		221,428	196,907
Accumulated other comprehensive income (loss)		(62)	(277)
Net Common Stock Equity		1,396,958	1,368,202
Total Capitalization		3,156,064	3,079,670
Total Liabilities and Capitalization		$ 5,201,162	$ 5,111,935
[1]	Includes $266.2 million of goodwill in the Gas Distribution segment as of June 30, 2015 and December 31, 2014.

CONSOLIDATED BALANCE SHEET (Un5

CONSOLIDATED BALANCE SHEET (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Current Assets
Allowance for doubtful accounts receivable	$ 9,257	$ 8,881

CONSOLIDATED STATEMENT OF CASH

CONSOLIDATED STATEMENT OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014
Cash Flows From Operating Activities
Net income		$ 73,455	$ 64,768
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization		83,880	78,044
Deferred income taxes		35,515	28,053
Allowance for funds used during construction (AFUDC) - equity		(4,109)	(4,920)
Stock-based compensation expense (Note A)		5,377	3,564
Pension expense		18,516	15,672
Undistributed (earnings) losses in equity investments		(6,877)	(6,907)
Regulatory activity, net		31,944	75,925
Other non-cash items, net		(2,032)	2,637
Changes in:
Accounts receivable, net		15,826	9,230
Unbilled revenues		32,363	37,676
Natural gas in storage		39,100	21,522
Prepayments		(3,693)	3,759
Cash distributions from GenConn		5,578	6,662
Accounts payable		(62,663)	(32,892)
Interest accrued		(781)	262
Taxes accrued/refundable, net		(4,063)	(7,056)
Accrued liabilities		(9,931)	(8,510)
Accrued pension		(16,129)	(21,476)
Accrued other post-employment benefits		(1,693)	4,727
Other assets		(1,253)	3,104
Other liabilities		1,082	6,915
Total Adjustments		155,957	215,991
Net Cash provided by Operating Activities		229,412	280,759
Cash Flows from Investing Activities
Plant expenditures including AFUDC debt	[1]	(159,169)	(125,541)
Cash distributions from GenConn		2,581	2,134
Changes in restricted cash		(110)	(8)
Deposits in New England East West Solution (NEEWS) (Note C)		(1,451)	(1,749)
Net Cash used in Investing Activities		(158,149)	(125,164)
Cash Flows from Financing Activities
Issuance of long-term debt		50,000	0
Line of credit borrowings (repayments), net		(9,000)	0
Payment of common stock dividend		(48,884)	(48,853)
Other		175	(282)
Net Cash used in Financing Activities		(7,709)	(49,135)
Unrestricted Cash and Temporary Cash Investments:
Net change for the period		63,554	106,460
Balance at beginning of period		115,579	69,153
Balance at end of period		179,133	175,613
Non-cash investing activity:
Plant expenditures included in ending accounts payable		26,853	17,188
Plant expenditures funded by deposits in NEEWS		(20,012)	0
Deposits in New England East West Solution (NEEWS)		$ 20,012	$ 0
[1]	Information for segmenting total capital expenditures between Distribution and Transmission is not available. Total Electric Distribution and Transmission capital expenditures are disclosed in the Total Electric Distribution and Transmission column.

BUSINESS ORGANIZATION AND STATE

BUSINESS ORGANIZATION AND STATEMENT OF ACCOUNTING POLICIES	6 Months Ended
	Jun. 30, 2015
BUSINESS ORGANIZATION AND STATEMENT OF ACCOUNTING POLICIES [Abstract]
BUSINESS ORGANIZATION AND STATEMENT OF ACCOUNTING POLICIES	(A) BUSINESS ORGANIZATION AND STATEMENT OF ACCOUNTING POLICIES UIL Holdings is headquartered in New Haven, Connecticut, where its senior management maintains offices and is responsible for overall planning, operating and financial functions. The primary business of UIL Holdings is ownership of its operating regulated utility businesses. The utility businesses consist of the electric distribution and transmission operations of The United Illuminating Company (UI) and the natural gas transportation, distribution and sales operations and The Berkshire Gas Company (Berkshire, and together with SCG and CNG, the Gas Companies). UI is also a party to a joint venture with certain affiliates of NRG Energy, Inc. (NRG affiliates) pursuant to which UI holds 50% of the membership interests in GCE Holding LLC, whose wholly owned subsidiary, GenConn Energy LLC (collectively with GCE Holding LLC, GenConn) operates peaking generation plants in Devon, Connecticut (GenConn Devon) and Middletown, Connecticut (GenConn Middletown). Basis of Presentation The financial statements of UIL Holdings are prepared on a consolidated basis and therefore include the accounts of UIL Holdings’ majority-owned subsidiaries noted above. Intercompany accounts and transactions have been eliminated in consolidation. The year‑end balance sheet data was derived from audited financial statements, but does not include all disclosures required by accounting principles generally accepted in the United States of America (GAAP). Certain information and footnote disclosures, which are normally included in financial statements prepared in accordance with GAAP, have been condensed or omitted in accordance with Securities and Exchange Commission (SEC) rules and regulations. We believe that the disclosures made are adequate to make the information presented not misleading. The information presented in the Consolidated Financial Statements reflects all adjustments which, in our opinion, are necessary for a fair statement of the financial position and results of operations for the interim periods described herein. All such adjustments are of a normal and recurring nature. The results for the three- and six-month periods ended June 30, 2015 are not necessarily indicative of the results for the entire fiscal year ending December 31, 2015. Proposed Merger with Iberdrola USA On February 25, 2015, we announced that UIL Holdings had entered into a definitive merger agreement (the Agreement) with Iberdrola USA and its wholly-owned subsidiary, Green Merger Sub, Inc. (merger sub) under which Iberdrola USA will acquire UIL Holdings through a merger of UIL Holdings with and into merger sub and merger sub being the surviving corporation (the merger). Merger sub will change its name to UIL Holdings Corporation and remain a direct or indirect wholly-owned subsidiary of Iberdrola USA. Iberdrola USA will then become a newly listed U.S. publicly-traded company. In connection with the merger, each issued and outstanding share of the common stock of UIL Holdings will be converted into the right to receive one validly issued share of common stock of the newly listed company plus $10.50 in cash. Immediately following the consummation of the merger, former holders of UIL Holdings’ common stock will own approximately 18.5% of the newly listed company. The merger remains subject to certain closing conditions, including the approval of the shareowners of UIL Holdings and regulatory approvals from the Connecticut Public Utilities Regulatory Authority (PURA) and the Massachusetts Department of Public Utilities (DPU). Iberdrola USA and UIL Holdings made the required filings at the PURA and the DPU seeking approval of the change in control on March 25, 2015. On July 7, 2015, in response to the issuance of a draft decision issued by PURA, UIL Holdings and Iberdrola USA filed a letter with PURA withdrawing their pending application and on July 31, 2015, filed a new application for approval of the change in control. The new application includes commitments and identifies public interest benefits to meet the statutory requirements in Connecticut for approval of a change in control. The commitments include rate credits to customers (approximately $20 million), a distribution rate freeze to 2018 for SCG and CNG, and to 2017 for UI, commitments to contribute to a clean energy fund and disaster relief (together, approximately $7 million), accelerated capital investment in electric distribution system resiliency and gas distribution system replacement of cast iron and bare steel (delayed recovery in rates resulting in nearly $7 million), agreement to negotiate a consent order with DEEP to remediate the English Station site in New Haven, Connecticut, formerly owned by UI (DEEP informed UIL Holdings that it estimated the cost of the remediation to be approximately $30 million). In addition, in the new application the companies commit to no change in the day-to-day management and operation of UIL Holdings’ three Connecticut utilities, to hiring 150 employees or contractors within the State of Connecticut over the next three years, to maintain UI’s high service reliability and CNG and SCG’s high levels of gas leak response, and to improve The new application also proposes comprehensive “ring fencing” provisions to protect the Connecticut utilities from involuntary bankruptcy associated with potential future adverse changes in financial circumstances of Iberdrola affiliates. These provisions include the creation of a special purpose entity with at least one independent director, dividend limitations on the Connecticut utilities where the investment grade credit rating is in jeopardy or if a minimum common equity ratio is not maintained, commitments to maintain separate books and records and a prohibition on commingling of funds. The proceedings at the DPU remain pending. All other regulatory approvals have been received. We received approval from the Federal Communications Commission (FCC) on May 22, 2015 and from the Federal Energy Regulatory Commission (FERC) on June 2, 2015. In addition we received clearance from the Committee on Foreign Investments in the United States (CFIUS) on June 16, 2015 and the applicable waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976 (the HSR Act) We currently expect that the merger will close promptly after satisfaction or waiver of all closing conditions, including receipt of shareowner approval and all regulatory approvals, and not later than December 31, 2015. There are no assurances that the merger will be consummated on the currently expected timetable or at all. Unless stated otherwise, all forward-looking information contained in this report does not take into account or give any effect to the impact of the proposed merger. For the three and six months ended June 30, 2015, UIL Holdings incurred pre-tax merger-related expenses of approximately $0.1 Further information concerning the proposed merger is included in a proxy statement/prospectus contained in a registration statement on Form S-4 filed by Iberdrola USA with the SEC on July 17, 2015 in connection with the proposed merger. Philadelphia Gas Works In March 2014, UIL Holdings entered into an Asset Purchase Agreement (the Asset Purchase Agreement) with the City of Philadelphia pursuant to which UIL Holdings, through a wholly-owned subsidiary, was to acquire the operating assets and assume certain liabilities of Philadelphia Gas Works. The proposed acquisition was subject to the satisfaction or waiver of certain customary and other closing conditions for transactions of this type, including approval from the Philadelphia City Council. In light of the City Council’s October 2014 announcement to not endorse the proposed acquisition, we exercised our contractual right to terminate the Asset Purchase Agreement in December 2014. For the three and six month periods ended June 30, 2014, UIL Holdings incurred pre-tax acquisition-related expenses of approximately $8.4 Derivatives UIL Holdings’ regulated subsidiaries are parties to contracts, and involved in transactions, that are derivatives. Contracts for Differences (CfDs) Pursuant to Connecticut’s 2005 Energy Independence Act, PURA solicited bids to create new or incremental capacity resources in order to reduce federally mandated congestion charges, and selected four new capacity resources. To facilitate the transactions between the selected capacity resources and Connecticut electric customers, and provide the commitment necessary for owners of these resources to obtain necessary financing, PURA required that UI and The Connecticut Light and Power Company (CL&P) execute long-term contracts with the selected resources. In August 2007, PURA approved four CfDs, each of which specifies a capacity quantity and a monthly settlement that reflects the difference between a forward market price and the contract price. UI executed two of the contracts and CL&P executed the other two contracts. The costs or benefits of each contract will be paid by or allocated to customers and will be subject to a cost-sharing agreement between UI and CL&P pursuant to which approximately 20% of the cost or benefit is borne by or allocated to UI customers and approximately 80% is borne by or allocated to CL&P customers. PURA has determined that costs associated with these CfDs will be fully recoverable by UI and CL&P through electric rates, and in accordance with ASC 980 “Regulated Operations,” UI has deferred recognition of costs (a regulatory asset) or obligations (a regulatory liability). The CfDs are marked-to-market in accordance with ASC 815 “Derivatives and Hedging.” For those CfDs signed by CL&P, UI records its approximate 20% portion pursuant to the cost-sharing agreement noted above. As of June 30, 2015, UI has recorded a gross derivative asset of $32.8 million ($1.5 million of which is related to UI’s portion of the CfD signed by CL&P), a regulatory asset of $75.2 million, a gross derivative liability of $107.2 million ($68.0 million of which is related to UI’s portion of the CfD signed by CL&P) and a regulatory liability of $0.9 million. See Note (K) “Fair Value of Financial Instruments” for additional CfD information. The gross derivative assets and liabilities as of June 30, 2015 and December 31, 2014 were as follows: June 30, 2015 December 31, 2014 (In Thousands) Gross derivative assets: Current Assets $ 9,934 $ 6,849 Deferred Charges and Other Assets $ 22,887 $ 20,421 Gross derivative liabilities: Current Liabilities $ 27,513 $ 23,308 Noncurrent Liabilities $ 79,643 $ 61,766 The unrealized gains and losses from fair value adjustments to these derivatives, which are recorded in regulatory assets or regulatory liabilities, for the three- and six-month periods ended June 30, 2015 and 2014 were as follows: Three Months Ended June 30, Six Months Ended June 30, 2015 2014 2015 2014 (In Thousands) (In Thousands) Regulatory Assets - Derivative liabilities $ (2,812 ) $ (10,397 ) $ 10,957 $ (82,017 ) Regulatory Liabilities - Derivative assets $ 6,173 $ (8,751 ) $ 7,371 $ (11,693 ) The fluctuations in the balances of the derivatives as well as the related unrealized gains in the three- and six-month periods ended June 30, 2015 compared to the three- and six-month periods ended June 30, 2014 are primarily due to fluctuations in forward prices for capacity and reserves. Earnings per Share The following table presents a reconciliation of the basic and diluted earnings per share calculations for the three-month periods ended June 30, 2015 and 2014: Three Months Ended June 30, Six Months Ended June 30, 2015 2014 2015 2014 (In Thousands, except per share amounts) Numerator: Net income attributable to UIL Holdings $ 15,839 $ 9,343 $ 73,441 $ 64,795 Less: Net income allocated to unvested units 8 6 39 38 Net income attributable to common shareholders $ 15,831 $ 9,337 $ 73,402 $ 64,757 Denominator: Basic average number of shares outstanding 56,950 56,842 56,918 56,814 Effect of dilutive securities (1) 291 260 311 265 Diluted average number of shares outstanding 57,241 57,102 57,229 57,079 Earnings per share: Basic $ 0.28 $ 0.16 $ 1.29 $ 1.14 Diluted $ 0.28 $ 0.16 $ 1.28 $ 1.13 (1) Includes unvested restricted stock and performance shares. Equity Investments UI is party to a 50-50 joint venture with the NRG affiliates in GenConn, which operates two peaking generation plants in Connecticut. UI’s investment in GenConn is being accounted for as an equity investment, the carrying value of which was $112.9 million and $114.2 million as of June 30, 2015 and December 31, 2014, respectively. As of June 30, 2015, there was $1.3 million of undistributed earnings from UI’s equity investment in GenConn. UI’s pre-tax income from its equity investment in GenConn was $3.9 million and $3.5 million for the June 30, 2015 and 2014, respectively. UI’s pre-tax income from its equity investment in GenConn for each of the six-month periods ending June 30, 2015 and 2014 was $6.9 million. Cash distributions from GenConn are reflected as either distributions of earnings or as returns of capital in the operating and investing sections of the Consolidated Statement of Cash Flows, respectively. UI received cash distributions from GenConn of $2.7 million and $3.4 million in the June 30, 2015 and 2014, respectively. UI received cash distributions from GenConn of $8.1 million and $8.8 million in the June 30, 2015, respectively and 2014. On July 24, 2015, UIL Holdings announced its participation in Tennessee Gas Pipeline Company LLC’s (TGP) proposed Northeast Energy Direct project (NED pipeline), a new, “market path” natural gas pipeline segment of approximately 188 miles from Wright, New York, to Dracut, Massachusetts, through its acquisition of a 2.5% equity interest in Northeast Expansion LLC, a joint venture between Kinder Morgan, Inc., through its affiliate Kinder Morgan Operating Limited Partnership “A” (Kinder Morgan “A”), and Liberty Utilities (Pipeline & Transmission) Corp, which will construct and own the NED pipeline. This 2.5% equity interest, which UIL Holdings acquired for approximately $1.2 million, commits UIL Holdings to an initial capital investment opportunity that is expected to total up to approximately $80 million, depending on the final pipeline configuration and design capacity. Pursuant to an option agreement with Kinder Morgan “A”, UIL Holdings also has the option to acquire up to an additional 12.5% of equity interests in Northeast Expansion LLC under certain limited circumstances, including if certain additional firm transportation agreements for service on the NED pipeline are entered into or if TGP does not sell additional volume on the NED pipeline. Any increase in equity ownership would increase UIL Holdings’ investment commitment proportionately. In addition, as a condition to making this investment, UIL Holdings entered into a 20-year Precedent Agreement with TGP for pipeline capacity of 70,000 Dekatherms/day on the NED pipeline, which capacity commitment, under the terms of the Precedent Agreement, would be reduced in the event that TGP enters into additional precedent agreements with third parties for capacity on the NED pipeline. Regulatory Accounting Unless otherwise stated below, all of our regulatory assets earn a return. Our regulatory assets and liabilities as of June 30, 2015 Remaining June 30, December 31, (In Thousands) Regulatory Assets: Unamortized redemption costs 7 to 19 years $ 10,098 $ 10,499 Pension and other post-retirement benefit plans (a) 398,732 402,700 Environmental remediation costs 7 years 14,364 13,197 Hardship programs (b) 19,055 24,744 Debt premium 2 to 23 years 24,962 27,498 Income taxes due principally to book-tax differences (c) 165,726 164,466 Unfunded future income taxes (d) 16,734 14,859 Contracts for differences (e) 75,233 64,276 Deferred transmission expense (f) 23,914 17,387 Other (g) 35,260 40,336 Total regulatory assets 784,078 779,962 Less current portion of regulatory assets 102,987 92,764 Regulatory Assets, Net $ 681,091 $ 687,198 Regulatory Liabilities: Accumulated deferred investment tax credits 29 years $ 7,282 $ 4,319 Excess generation service charge (h) 39,350 28,692 Middletown/Norwalk local transmission network service collections 35 years 20,542 20,828 Pension and other post-retirement benefit plans (a) 10,851 9,536 Asset retirement obligation (i) 7,155 7,248 Low income programs (j) 29,064 19,065 Asset removal costs (i) 342,346 336,028 Unfunded future income taxes (d) 26,812 26,318 Contracts for differences (e) 899 6,472 Deferred purchased gas (k) 16,757 4,736 Non-firm margin sharing credits 9 years 15,181 8,933 Other (g) 37,761 36,747 Total regulatory liabilities 554,000 508,922 Less current portion of regulatory liabilities 44,242 17,026 Regulatory Liabilities, Net $ 509,758 $ 491,896 (a) Life is dependent upon timing of final pension plan distribution; balance, which is fully offset by a corresponding asset/liability, is recalculated each year in accordance with ASC 715 "Compensation-Retirement Benefits." See Note (G) “Pension and Other Benefits” for additional information. (b) Hardship customer accounts deferred for future recovery to the extent they exceed the amount in rates. (c) Amortization period and/or balance vary depending on the nature and/or remaining life of the underlying assets/liabilities. (d) The balance will be extinguished when the asset, which is fully offset by a corresponding liability, or liability has been realized or settled, respectively. (e) Asset life is equal to delivery term of related contracts (which vary from approximately 5 - 12 years); balance fluctuates based upon quarterly market analysis performed on the related derivatives (Note K); amount, which does not earn a return, is fully offset by corresponding derivative asset/liability. See “-Contracts for Differences” discussion above for additional information. (f) Regulatory asset or liability which defers transmission income or expense and fluctuates based upon actual revenues and revenue requirements. (g) Amortization period and/or balance vary depending on the nature, cost of removal and/or remaining life of the underlying assets/liabilities; asset amount includes certain amounts that are not currently earning a return; asset amount includes decoupling of $2.6 million; liability amount includes decoupling of $16.5 million. (h) Regulatory asset or liability which defers generation-related and nonbypassable federally mandated congestion costs or revenues for future recovery from or return to customers. Amount fluctuates based upon timing differences between revenues collected from rates and actual costs incurred. (i) The liability will be extinguished simultaneous with the retirement of the assets and settlement of the corresponding asset retirement obligation. (j) Various hardship and payment plan programs approved for recovery. (k) Deferred purchased gas costs balances at the end of the rate year are normally recorded/returned in the next year. Stock-Based Compensation Pursuant to the UIL Holdings 2008 Stock and Incentive Compensation Plan (2008 Stock Plan), 94,410 restricted stock units were granted to certain members of management in March 2015; the average of the high and low market prices on the grant date, which approximate fair value, was $49.72 per share. Also in March 2015, we granted a total of 1,584 shares of restricted stock to our President and Chief Executive Officer under the 2008 Stock Plan and in accordance with his employment agreement; the average of the high and low market price on the date of grant, which approximates fair value, was $49.72 per share. Such shares vest in equal annual installments over a five-year period. In May 2015, UIL Holdings granted a total of 18,801 shares of restricted stock to non-employee directors under the 2008 Stock Plan; the average of the high and low market price on the date of grant, which approximates fair value, was $48.37 per share. Such shares vest in May 2016. Total stock-based compensation expense for the three-month periods ended June 30, 2015 and 2014 June 30, 2015 and 2014 Variable Interest Entities We have identified GenConn as a variable interest entity (VIE), which is accounted for under the equity method. UIL Holdings is not the primary beneficiary of GenConn, as defined in ASC 810 “Consolidation,” because it shares control of all significant activities of GenConn with its joint venturer, NRG affiliates. As such, GenConn is not subject to consolidation. GenConn recovers its costs through CfDs, which are cost of service-based and have been approved by PURA. As a result, with the achievement of commercial operation by GenConn Devon and GenConn Middletown, our exposure to loss is primarily related to the potential for unrecovered GenConn operating or capital costs in a regulatory proceeding, the effect of which would be reflected in the carrying value of our 50% ownership position in GenConn and through “Income from Equity Investments” in UIL Holdings’ Consolidated Financial Statements. We have identified the selected capacity resources with which UI has CfDs as VIEs and have concluded that UI is not the primary beneficiary as UI does not have the power to direct any of the significant activities of these capacity resources. As such, we have not consolidated the selected capacity resources. UI’s maximum exposure to loss through these agreements is limited to the settlement amount under the CfDs as described in “–Derivatives – Contracts for Differences (CfDs)” above; however any such losses are fully recoverable through electric rates. UI has no requirement to absorb additional losses nor has UI provided any financial or other support during the periods presented that were not previously contractually required. We have identified the entities for which UI is required to enter into long-term contracts to purchase Renewable Energy Credits (RECs) as VIEs. In assessing these contracts for VIE identification and reporting purposes, we have aggregated the contracts based on similar risk characteristics and significance to UI. UI is not the primary beneficiary as UI does not have the power to direct any of the significant activities of these entities. UI’s exposure to loss is primarily related to the purchase and resale of the RECs, but, any losses incurred are recoverable through electric rates. For further discussion of RECs, see Note (C) “Regulatory Proceedings – Electric Distribution and Transmission – New Renewable Source Generation.” New Accounting Pronouncements In July 2015, the FASB issued Accounting Standards Update (ASU) 2015-11, “Inventory – Simplifying the Measurement of Inventory” which requires inventory that is measured using first-in, first-out or average cost methods to be measured using the lower of cost and net realizable value. ASU 2015-11 is effective for interim and annual reporting periods beginning after December 15, 2016 and is to be applied prospectively with earlier application permitted as of the beginning of an interim or annual reporting period. This is not expected to be material to UIL Holdings’ consolidated financial statements. In July 2015, the FASB voted to defer by one year the effective date of ASU 2014-09 which requires entities to recognize revenue in a way that depicts the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled to in exchange for those goods or services. A final Accounting Standards Update will be issued that reflects the revised effective date. We are currently evaluating the effect that adopting this new accounting guidance will have on our consolidated financial statements. In April 2015, the FASB issued Accounting Standards Update (ASU) 2015-03, “Interest-Imputation of Interest: Simplifying the Presentation of Debt Issuance Costs” which requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability. ASU 2015-03 is effective for interim and annual reporting periods beginning after December 15, 2015 and is to be applied retrospectively. The effect that adopting this new accounting guidance will have on our consolidated financial statements will be reductions in both Deferred Charges and Other Assets and Long-term debt on the consolidated balance sheet. This effect is not expected to be material to UIL Holdings’ consolidated financial statements.

CAPITALIZATION

CAPITALIZATION	6 Months Ended
	Jun. 30, 2015
CAPITALIZATION [Abstract]
CAPITALIZATION	(B) CAPITALIZATION Common Stock UIL Holdings had 56,629,082 shares of its common stock, no par value, outstanding at June 30, 2015 Long-term Debt On June 29, 2015 (the “execution date”), UI entered into a Note Purchase Agreement with a group of institutional accredited investors providing for the sale to such investors of UI’s 4.61% Senior Notes, Series G, due June 29, 2045, in the principal amount of $50 million which was issued on the execution date. UI used the net proceeds from this long-term debt issuance to re-pay $27.5 million of pollution control refunding revenue bonds which were subject to mandatory purchase on July 1, 2015 and plans on using the remaining funds for general corporate purposes or other purposes described in its application to PURA for approval of the issuance of debt and as approved by PURA.

REGULATORY PROCEEDINGS

REGULATORY PROCEEDINGS	6 Months Ended
	Jun. 30, 2015
REGULATORY PROCEEDINGS [Abstract]
REGULATORY PROCEEDINGS	(C) REGULATORY PROCEEDINGS Proposed Merger with Iberdrola USA As discussed in Note A “Organization and Statement of Accounting Policies”, on February 25, 2015 we announced that UIL Holdings had entered into a the Agreement with Iberdrola USA and merger sub under which Iberdrola USA will acquire UIL Holdings through a merger of UIL Holdings with and into merger sub and merger sub being the surviving corporation. The merger remains subject to certain closing conditions, including the approval of the shareowners of UIL Holdings and regulatory approval from PURA and the DPU. Iberdrola USA and UIL Holdings made the required filings at the PURA and the DPU seeking approval of the change in control on March 25, 2015. On July 7, 2015, in response to the issuance of a draft decision issued by PURA, UIL Holdings and Iberdrola USA filed a letter with PURA withdrawing their pending application and on July 31, 2015 filed a new application for approval of the change in control. The proceedings at the DPU remain pending. All other regulatory approvals have been received. We received approval from the FCC on May 22, 2015 and from the FERC on June 2, 2015, we received clearance from CFIUS on June 16, 2015 and the applicable waiting period under the HSR Act expired on April 7, 2015. Electric Distribution and Transmission Rates Utilities are entitled by Connecticut statutes to charge rates that are sufficient to allow them an opportunity to cover their reasonable operating and capital costs, to attract needed capital and to maintain their financial integrity, while also protecting relevant public interests. UI’s allowed distribution return on equity established by PURA is 9.15%. UI is required to return to customers 50% of any distribution earnings over the allowed ROE in a calendar year by means of an earnings sharing mechanism. Power Supply Arrangements UI has wholesale power supply agreements in place for its entire standard service load for all of 2015 and for 50% of its standard service load for the first half of 2016. Supplier of last resort service is procured on a quarterly basis, however, from time to time there are no bidders in the procurement process for supplier of last resort service and in such cases UI manages the load directly. UI determined that its contracts for standard service and supplier of last resort service are derivatives under ASC 815 “Derivatives and Hedging” and elected the “normal purchase, normal sale” exception under ASC 815 “Derivatives and Hedging.” UI regularly assesses the accounting treatment for its power supply contracts. These wholesale power supply agreements contain default provisions that include required performance assurance, including certain collateral obligations, in the event that UI’s credit rating on senior debt were to fall below investment grade. If UI’s credit rating were to decline one rating at Standard & Poor’s or two ratings at Moody’s and UI were to be placed on negative credit watch, monthly amounts due and payable to the power suppliers would be accelerated to semi-monthly payments. UI’s credit rating would have to decline two ratings at Standard & Poor’s and three ratings at Moody’s to fall below investment grade. If this were to occur, UI would have to deliver collateral security in an amount equal to the receivables due to the sellers for the thirty-day period immediately preceding the default notice. If such an event had occurred as of June 30, 2015 New Renewable Source Generation Pursuant to Connecticut law (PA 13-303), on September 19, 2013, at the direction of the Connecticut Department of Energy and Environmental Protection, (DEEP), UI entered into two contracts for energy and/or RECs from Class I renewable resources, totaling approximately 3.5% of UI’s distribution load, which were subsequently approved by PURA. Costs of each of these agreements will be fully recoverable through electric rates. On December 18, 2013, Allco Finance Limited, an unsuccessful bidder for such contracts, filed a complaint against DEEP in the United States District Court in Connecticut alleging that DEEP’s direction to UI and CL&P to enter into the contracts violated the Supremacy Clause of the U.S. Constitution and the Federal Power Act by setting wholesale electricity rates. This complaint was dismissed in December 2014. On January 2, 2015 Allco filed an appeal with the United States Court of Appeals for the Second Circuit. Transmission PURA decisions do not affect the revenue requirements determination for UI’s transmission business, including the applicable return on equity (ROE), which is within the jurisdiction of the FERC. For 2015, UI is estimating an overall allowed weighted-average ROE for its transmission business in the range of 11.3% to 11.4%. This includes the impact of the FERC orders issued in 2014 and 2015, and excludes any impacts of the reserve adjustment, both of which are discussed below. Beginning in 2011, several New England governmental entities, including PURA, the Connecticut Attorney General and the Connecticut Office of Consumer Council (OCC), jointly filed three separate complaints with the FERC against ISO-NE and several New England transmission owners, including UI. In the first complaint, filed in September 2011, the complainants claimed that the then current approved base ROE of 11.14% used in calculating formula rates for transmission service under the ISO-NE Open Access Transmission Tariff by the New England transmission owners was not just and reasonable and sought a reduction of the base ROE and a refund to customers for a refund period of October 1, 2011 through December 31, 2012. In 2012 and 2014, respectively, the complainants filed claims with the FERC similarly challenging the base ROE and seeking refunds for the 15-month periods beginning December 27, 2012 and July 31, 2014, respectively. The complainants in the third complaint also asked for a determination that the top of the zone of reasonableness caps the ROE for each individual project. The FERC issued an order consolidating the second and third complaints and establishing hearing procedures. The New England transmission owners petitioned FERC for a rehearing, which was denied in May 2015. Hearings were held in June 2015 on the second and third complaints before a FERC Administrative Law Judge, relating to the refund periods and going forward. On July 29, 2015, post-hearing briefs were filed by parties. An initial decision by the Administrative Law Judge is expected by December 31, 2015. On July 13, 2015, the New England transmission owners filed a petition for review of FERC’s orders establishing hearing and consolidation procedures for the second and third complaints with the U.S. Court of Appeals. In 2014, the FERC determined that the base ROE should be set at 10.57% for the first complaint refund period and that a utility's total or maximum ROE should not exceed 11.74%. The FERC ordered the New England transmission owners to provide refunds to customers for the first complaint refund period and set the new base ROE of 10.57% prospectively from October 16, 2014. On March 3, 2015, the FERC issued an Order on Rehearing in the first complaint (the March Order) denying all rehearing requests from the complainants and the New England transmission owners. On April 30, 2015, the New England transmission owners filed a petition for review of the FERC’s decisions on the first complaint with the U.S. Court of Appeals for the D.C. Circuit. On May 1, 2015, two additional petitions for review of those FERC decisions were also filed at the D.C. Circuit by the complainants and by several customers. The appeals of the FERC’s decisions on the first complaint have been consolidated and are currently pending before the D.C. Circuit. UI recorded additional pre-tax reserves of $3.2 million in the first six months of 2015 relating to the third complaint and the March Order. As of June 30, 2015, net pre-tax reserves relating to refunds and potential refunds to customers under all three claims were approximately $7 million and cumulative pre-tax reserves were approximately $11.4 million, of which $4.4 million has already been refunded to customers. New England East-West Solution Pursuant to which was fully energized in November 2013, t (IRP), which is expected to be placed in service in the fourth quarter 2015 the Central Connecticut Reliability Project, which was reassessed as part of Study (GHCC). Under the terms of the Agreement, UI has the option to make quarterly deposits to CL&P in exchange for ownership of specific NEEWS transmission assets as they are placed in service. UI has the right to invest up to the greater of $60 million or an amount equal to 8.4% of CL&P’s costs for the originally proposed Connecticut portions of the NEEWS projects. Based upon the current projected costs, UI’s investment rights in GSRP and IRP is approximately $45 million. In February 2015, ISO-NE issued its final GHCC transmission solutions report and, in March 2015, approved the proposed plan applications. UI and Eversource continue to evaluate the approved projects to determine the impact on UI’s aggregate investment in NEEWS. Deposits associated with NEEWS are recorded as assets at the time the deposit is made and they are reported in the ‘Other’ line item within the Deferred Charges and Other Assets section of the consolidated balance sheet. When title to the assets is transferred to UI, the amount of the corresponding deposit is reclassified from other assets to plant-in-service on the balance sheet and shown as a non-cash investing activity in the consolidated statement of cash flows. As of June 30, 2015 associated with the GSRP June 30, 2015 and 2014 June 30, 2015 and 2014 Other Proceedings On November 12, 2014, PURA issued a decision in a docket addressing UI’s semi-annual Generation Services Charge (GSC), bypassable federally mandated congestion charge and the non-bypassable federally mandated congestion charge (NBFMCC) reconciliations. PURA’s decision allowed for recovery of $7.7 million of the $11.3 million request included in UI’s filing for the reconciliation of certain revenues and expenses relating to the period from 2004 through 2013. This resulted in UI recording a pre-tax write-off of approximately $3.8 million during the fourth quarter of 2014, which amount included the disallowed portion of UI’s request as well as additional 2014 carrying charges. Also on November 12, 2014, PURA issued a final decision in UI’s final Competitive Transition Assessment (CTA) reconciliation proceeding which extinguished all remaining CTA balances. In addition, the final decision allowed for the application of an approximate $8.2 million remaining CTA regulatory liability, as well as an approximate $12.0 million regulatory liability related to the Connecticut Yankee Atomic Power Company litigation against the U.S. Department of Energy (DOE), against UI’s storm regulatory asset balance. The final decision required that remaining regulatory liability balance be applied to the GSC “working capital allowance” and be returned to customers through the NBFMCC. Because the two decisions noted above, among other things, fail to apply rate making principles on a consistent basis, UI filed appeals with the State of Connecticut Superior Court in December 2014 for both the GSC/NBFMCC and the CTA final decisions. On February 3, 2015, PURA filed a motion to dismiss UI’s appeal of the CTA final decision. On June 17, 2015, the Superior Court denied PURA’s motion to dismiss the CTA appeal. Gas Distribution Rates Utilities are entitled by Connecticut and Massachusetts statutes to charge rates that are sufficient to allow them an opportunity to cover their reasonable operating and capital costs, to attract needed capital and to maintain their financial integrity, while also protecting relevant public interests. The allowed returns on equity established by PURA are 9.18% and 9.36% for CNG and SCG, respectively. Berkshire’s rates are established by the DPU. Berkshire’s 10-year rate plan, which was approved by the DPU and included an approved ROE of 10.5%, expired on January 31, 2012. Berkshire continues to charge the rates that were in effect at the end of the rate plan and currently anticipates that a base rate case would likely be filed in 2016, based on a calendar year 2015 test year, for rates to be effective in 2017. Based on existing tracking mechanisms in place for gas and other costs, discussions with the DPU, and precedence set by other utility companies, Berkshire believes that regulatory assets are recoverable and regulatory liabilities are fairly stated. SCG and CNG each have purchased gas adjustment clauses and Berkshire has a cost of gas adjustment clause, approved by PURA and DPU, respectively, which enable them to pass their reasonably incurred cost of gas purchases through to customers. These clauses allow utilities to recover costs associated with changes in the market price of purchased natural gas, substantially eliminating exposure to natural gas price risk. Additionally, Berkshire’s mechanism allows for the recovery of the gas-cost portion of bad debt. On January 22, 2014, PURA approved new base delivery rates for CNG, with an effective date of January 10, 2014, which, among other things, approved an allowed ROE of 9.18%, a decoupling mechanism, and two separate ratemaking mechanisms that reconcile actual revenue requirements related to CNG’s cast iron and bare steel replacement program and system expansion. Additionally, the final decision requires the establishment of an earnings sharing mechanism by which CNG and customers share on a 50/50 basis all earnings above the allowed ROE in a calendar year. The decision also allows CNG, on a provisional basis, to reflect the increased rate base resulting from the accumulated deferred income tax (ADIT) impacts of the election of Section 338(h)(10) of the Internal Revenue Code upon its acquisition by UIL Holdings. The decision requires CNG to seek a private letter ruling from the Internal Revenue Service with regard to the specific question of whether, after extinguishment of an ADIT balance, a directive by a public utility commission to institute a ratemaking mechanism to reflect a credit to ratepayers of ADIT benefits lost through a Section 338(h)(10) election would result in a normalization violation. The decision states that in the event of a ruling from the Internal Revenue Service stating that imposing such a ratemaking mechanism would not create a normalization violation, PURA would adjust rates to offset the ratemaking impacts of the 338(h)(10) election on rate base. We estimate the impact to be an approximate $2.5 to $3.5 million decrease in annual revenue requirements. In March 2014, CNG filed a draft of its private letter ruling request with PURA for approval upon which PURA subsequently issued comments. During the first quarter of 2014, the OCC appealed PURA’s decision to the Connecticut Superior Court with regard to the establishment of an adjustment mechanism for incremental cast iron and bare steel replacement as well as PURA’s directive to seek a private letter ruling with respect to the extinguishment of ADITs rather than ordering a rate credit to hold customers harmless from the ratemaking effect of extinguishing the ADITs. At the request of PURA, the OCC and CNG engaged in settlement discussions regarding the appeal. Settlement discussions have now terminated. CNG has filed a motion with PURA to extend the due date for CNG’s response to PURA’s comments on the private letter ruling to September 24, 2015. Other Proceedings As discussed above, CNG’s 2013 rate proceeding provides for a decoupling mechanism as well as a rate making mechanism related to its cast iron and bare steel replacement program. Additionally, a comprehensive joint 10-year natural gas expansion plan (“Expansion Plan”) filed jointly by CNG, SCG and Yankee Gas Services Company in response to the gas expansion goals proposed in the Connecticut Governor’s Comprehensive Energy Strategy and Public Act 13-298 and approved by PURA includes a new business reconciliation mechanism that reconciles the actual new business revenue requirements each year with the revenues received from the new business customers. The initial filings for these mechanisms are discussed below. On March 2, 2015, CNG filed its initial decoupling adjustment which includes a $10.8 million credit to customers, which will be credited on customers’ bills during the period of April 1, 2015 through March 31, 2016. On March 20, 2015, SCG and CNG filed their initial System Expansion (SE) Rate reconciliation for 2014. The proposed SE rate was approved by PURA for implementation as of April 1, 2015, pending final PURA approval following a contested hearing. On April 1, 2015, CNG filed its initial Distribution Integrity Management Program (DIMP) reconciliation filing, which reconciles actual revenue requirements related to CNG’s cast iron and bare steel replacement program. The proposed DIMP rate was approved by PURA for implementation as of May 1, 2015.

SHORT-TERM CREDIT ARRANGEMENTS

SHORT-TERM CREDIT ARRANGEMENTS	6 Months Ended
	Jun. 30, 2015
SHORT-TERM CREDIT ARRANGEMENTS [Abstract]
SHORT-TERM CREDIT ARRANGEMENTS	(D) SHORT ‑ As of June 30, 2015, there was $80 million in borrowings outstanding under the existing revolving credit agreement among UIL Holdings, certain of its subsidiaries and a group of banks that expires on November 30, 2016 (the UIL Holdings Credit Facility) UIL Holdings UIL Holdings UIL Holdings UIL Holdings

INCOME TAXES

INCOME TAXES	6 Months Ended
	Jun. 30, 2015
INCOME TAXES [Abstract]
INCOME TAXES	(E) INCOME TAXES The significant portion of UIL Holdings’ income tax expense, including deferred taxes, is recovered through its regulated subsidiaries’ utility rates. UIL Holdings’ annual income tax expense and associated effective tax rate is impacted by differences in the treatment of certain transactions for book and tax purposes and by differences between the timing of deferred tax temporary difference activity and deferred tax recovery. In accordance with ASC 740, we use an estimated annual effective tax rate approach to calculate interim period income tax expense for ordinary income. We also record separate income tax effects for significant unusual or infrequent items. UIL Holdings’ income tax expense increased by $7.4 million, from $3.7 million in the second quarter of 2014 to $11.1 million in the second quarter of 2015. The increase was primarily attributable to the absence in 2015 of acquisition bridge facility fees and other increases in pre-tax earnings. UIL Holdings’ income tax expense increased $6.5 million, from $30.3 million in the first six months of 2014 to $36.8 million in the first six months of 2015. The increase was primarily attributable to higher pre-tax earnings due mainly to the absence in 2015 of acquisition bridge facility fees. The annualized effective income tax rates for the three-month periods ended June 30, 2015 and 2014 were 37.0% and 33.4%, respectively. The increase in the effective rate for the quarter was due primarily to changes in flow through impacts related to lower projected capital expenditures. The annualized effective income tax rates for the six-month periods ended June 30, 2015 and 2014 were 32.9% and 33.4%, respectively. The Internal Revenue Service completed its examination of UIL Holdings’ income tax years 2009 through 2012, resulting in the effective settlement of these tax years and the recording of an additional $1.1 million in tax expense during the second quarter of 2015.

SUPPLEMENTARY INFORMATION

SUPPLEMENTARY INFORMATION	6 Months Ended
	Jun. 30, 2015
SUPPLEMENTARY INFORMATION [Abstract]
SUPPLEMENTARY INFORMATION	(F) SUPPLEMENTARY INFORMATION Three Months Ended June 30, Six Months Ended June 30, 2015 2014 2015 2014 (In Thousands) (In Thousands) Depreciation and Amortization Property, plant, and equipment depreciation $ 34,363 $ 32,360 $ 69,104 $ 64,348 Amortization of regulatory assets 5,017 4,152 13,560 12,482 Total Depreciation and Amortization $ 39,380 $ 36,512 $ 82,664 $ 76,830 Taxes - Other than Income Taxes Operating: Connecticut gross earnings $ 15,207 $ 15,758 $ 38,173 $ 38,472 Local real estate and personal property 13,005 12,125 25,995 24,089 Payroll taxes 3,264 2,974 8,178 6,831 Other 358 (316 ) 803 685 Total Taxes - Other than Income Taxes $ 31,834 $ 30,541 $ 73,149 $ 70,077 Other Income and (Deductions) Interest income $ 672 $ 523 $ 1,381 $ 1,065 Allowance for funds used during construction - equity 1,952 2,370 4,109 4,920 Allowance for funds used during construction - debt 1,086 1,421 2,132 2,831 Weather insurance - (531 ) - (2,437 ) Other 584 841 1,040 2,107 Total Other Income and (Deductions) $ 4,294 $ 4,624 $ 8,662 $ 8,486

PENSION AND OTHER BENEFITS

PENSION AND OTHER BENEFITS	6 Months Ended
	Jun. 30, 2015
PENSION AND OTHER BENEFITS [Abstract]
PENSION AND OTHER BENEFITS	(G) PENSION AND OTHER BENEFITS During the six months ended June 30, 2015, we made pension contributions of $10 million. Additional contributions during the remainder of 2015 are expected to be approximately $5 million. The following tables represent the components of net periodic benefit cost for pension and other postretirement benefits as well as the actuarial weighted-average assumptions used in calculating net periodic benefit cost for the three-and six-month periods ended : Three Months Ended June 30, Pension Benefits Other Postretirement Benefits 2015 2014 2015 2014 (In Thousands) Components of net periodic benefit cost: Service cost $ 3,605 $ 2,896 $ 393 $ 404 Interest cost 10,505 11,019 1,327 1,487 Expected return on plan assets (14,120 ) (13,560 ) (690 ) (700 ) Amortization of prior service costs 48 73 75 71 Amortization of actuarial (gain) loss 4,845 3,097 176 (172 ) Net periodic benefit cost $ 4,883 $ 3,525 $ 1,281 $ 1,090 Six Months Ended June 30, Pension Benefits Other Postretirement Benefits 2015 2014 2015 2014 (In Thousands) Components of net periodic benefit cost: Service cost $ 7,210 $ 5,792 $ 786 $ 808 Interest cost 21,010 22,038 2,654 2,974 Expected return on plan assets (28,240 ) (27,120 ) (1,380 ) (1,400 ) Amortization of prior service costs 96 146 150 142 Amortization of actuarial (gain) loss 9,690 6,194 352 (344 ) Net periodic benefit cost $ 9,766 $ 7,050 $ 2,562 $ 2,180 Three and Six Months Ended June 30, Pension Benefits Other Postretirement Benefits 2015 2014 2015 2014 Discount rate 4.20%-4.30 % 4.90%-5.20 % 4.20%-4.30 % 4.85%-5.20 % Average wage increase 3.50%-3.80 % 3.50%-3.80 % N/ A N/ A Return on plan assets 7.75%-8.00 % 7.75%-8.00 % 5.56%-8.00 % 5.56%-8.00 % Composite health care trend rate (current year) N/ A N/ A 7.00 % 7.00 % Composite health care trend rate (2019 forward) N/ A N/ A 5.00 % 5.00 % N/A – not applicable

RELATED PARTY TRANSACTIONS

RELATED PARTY TRANSACTIONS	6 Months Ended
	Jun. 30, 2015
RELATED PARTY TRANSACTIONS [Abstract]
RELATED PARTY TRANSACTIONS	(H) RELATED PARTY TRANSACTIONS A Director of UIL Holdings holds a beneficial interest in the building located at 157 Church Street, New Haven, Connecticut, where UIL Holdings leases office space.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	6 Months Ended
	Jun. 30, 2015
COMMITMENTS AND CONTINGENCIES [Abstract]
COMMITMENTS AND CONTINGENCIES	(J) COMMITMENTS AND CONTINGENCIES In the ordinary course of business, we are involved in various proceedings, including legal, tax, regulatory and environmental matters, which require management’s assessment to determine the probability of whether a loss will occur and, if probable, an estimate of probable loss. When assessments indicate that it is probable that a liability has been incurred and an amount can be reasonably estimated, we accrue a reserve and disclose the reserve and related matter. We disclose material matters when losses are probable but for which an estimate cannot be reasonably estimated or when losses are not probable but are reasonably possible. Subsequent analysis is performed on a periodic basis to assess the impact of any changes in events or circumstances and any resulting need to adjust existing reserves or record additional reserves. However, given the inherent unpredictability of these legal and regulatory proceedings, we cannot assure you that our assessment of such proceedings will reflect the ultimate outcome, and an adverse outcome in certain matters could have a material adverse effect on our results of operations or cash flows. Connecticut Yankee Atomic Power Company UI has a 9.5% stock ownership share in the Connecticut Yankee Atomic Power Company, an inactive nuclear generating company (Connecticut Yankee), the carrying value of which was $0.2 million as of June 30, 2015. Connecticut Yankee has completed the physical decommissioning of its generation facilities and is now engaged primarily in the long-term storage of its spent nuclear fuel. Connecticut Yankee collects its costs through wholesale FERC-approved rates from UI and several other New England utilities. UI recovers these costs from its customers through electric rates. DOE Spent Fuel Litigation In 1998, Connecticut Yankee filed claims in the United States Court of Federal Claims seeking damages resulting from the breach of the 1983 spent fuel and high level waste disposal contract between Connecticut Yankee and the DOE. In September 2010, the court issued its decision and awarded Connecticut Yankee damages of $39.7 million for its spent fuel-related costs through 2001, which was affirmed in In December 2007, Connecticut Yankee filed a second set of complaints with the United States Court of Federal Claims against the DOE seeking damages incurred since January 1, 2002 for the DOE’s failure to remove Connecticut Yankee’s spent fuel. In November 2013, the court issued a final judgment, which was not appealed, awarding Connecticut Yankee damages of $126.3 million. In light of its ownership share, in June 2014, UI received approximately $12.0 million of such award which was applied, in part, against the remaining storm regulatory asset balance. The remaining regulatory liability balance was applied to the GSC “working capital allowance” and will be returned to customers through the nonbypassable federally mandated congestion charge. See Note (C) “Regulatory Proceedings – Electric Distribution and Transmission – Other Proceedings” for additional information. In August 2013, Connecticut Yankee filed a third set of complaints with the United States Court of Federal Claims against the DOE seeking an unspecified amount of damages incurred since January 1, 2009 for the DOE’s failure to remove Connecticut Yankee’s spent fuel. In April 2015, Connecticut Yankee provided the DOE with a third set of damage claims totaling approximately $32.9 million for damages incurred from January 1, 2009 through December 31, 2012. UI’s 9.5% ownership share would result in a receipt of approximately $3.1 million which, if awarded, would be refunded to customers. Environmental Matters In complying with existing environmental statutes and regulations and further developments in areas of environmental concern, including legislation and studies in the fields of water quality, hazardous waste handling and disposal, toxic substances, climate change and electric and magnetic fields, we may incur substantial capital expenditures for equipment modifications and additions, monitoring equipment and recording devices, as well as additional operating expenses. The total amount of these expenditures is not now determinable. Environmental damage claims may also arise from the operations of our subsidiaries. Significant environmental issues known to us at this time are described below. Site Decontamination, Demolition and Remediation Costs In January 2012, Evergreen Power, LLC (Evergreen Power) and Asnat Realty LLC (Asnat), then and current owners of a former generation site on the Mill River in New Haven (the “English Station site”) that UI sold to Quinnipiac Energy in 2000, filed a lawsuit in federal district court in Connecticut against UI seeking, among other things: (i) an order directing UI to reimburse the plaintiffs for costs they have incurred and will incur for the testing, investigation and remediation of hazardous substances at the English Station site and (ii) an order directing UI to investigate and remediate the site. In December 2013, Evergreen and Asnat filed a subsequent lawsuit in Connecticut state court seeking among other things: (i) remediation of the property; (ii) reimbursement of remediation costs; (iii) termination of UI’s easement rights; (iv) reimbursement for costs associated with securing the property; and (v) punitive damages. UI believes the claims are without merit. Management cannot presently assess the potential financial impact, if any, of the pending lawsuits. UI has not recorded a liability related to it. On April 8, 2013, DEEP issued an administrative order addressed to UI, Evergreen Power, Asnat and others, ordering the parties to take certain actions related to investigating and remediating the English Station site. Mediation of the matter began in the fourth quarter of 2013 and concluded unsuccessfully in April of 2015. Hearings on the administrative order are expected to take place in late February and early March 2016. UI has requested access to the English Station site from Evergreen Power and Asnat, the current property owners, for purposes of performing additional investigation; this access has not yet been granted. As discussed in our application with PURA for approval of the change in control of UIL Holdings to Iberdrola USA, we are negotiating a consent order with DEEP that would, upon closing of the merger, provide for UI to begin to investigate and remediate the English Station site. DEEP has informed us that it has estimated the approximate cost of the remediation of the English Station site to be $30 million. We have not assessed the accuracy of or any support for this the DEEP estimate. Until we have successfully negotiated and agreed to a consent order and have sufficient access to the English Station site to permit us to undertake a reliable investigation, we will not know the expected cost of the remediation or the extent of any potential liability. UI’s knowledge of the current conditions at the English Station site is insufficient for it to make a reliable investigation and remediation estimate at this time. Therefore, management cannot predict the financial impact on UI of DEEP’s administrative order, the agreements regarding the consent order or other matters relating to the English Station site, and no range of loss can be reasonably estimated at this time. UI has not recorded a liability related to it. With respect to transmission-related property adjacent to the New Haven Harbor Generating Station, UI performed an environmental analysis that indicated remediation expenses would be approximately $3.2 million. UI has accrued these estimated expenses, which were recovered in transmission rates. The Gas Companies own or have previously owned properties where Manufactured Gas Plants (MGPs) had historically operated and are contaminated as a result of MGP-related activities. Under existing regulations, the cleanup of such sites requires state and at times, federal, regulators’ involvement and approval before cleanup can commence. In certain cases, such contamination has been evaluated, characterized and remediated. In other cases, the sites have been evaluated and characterized, but not yet remediated. Finally, at some of these sites, the scope of the contamination has not yet been fully characterized; no liability was recorded in respect of these sites as of June 30, 2015 and no amount of loss, if any, can be reasonably estimated at this time SCG owns properties on Housatonic Avenue in Bridgeport, and on Chapel Street in New Haven, and CNG owns a property located on Columbus Boulevard in Hartford, all of which are former MGP sites. Costs associated with the remediation of the sites could be significant and will be subject to a review by PURA as to whether these costs are recoverable in rates. We cannot presently reasonably estimate the costs or range of costs of remediation or the likelihood of recoverability. As a result, as of , we have not recorded any liabilities related to these properties. Berkshire owns property on Mill Street in Greenfield, Massachusetts, a former MGP site. We estimate that expenses will likely amount to approximately $0.9 million and have recorded a liability and offsetting regulatory asset for such expenses as of . Historically, Berkshire formerly owned a site on East Street (the East Street Site) in Pittsfield, Massachusetts, a former MGP site which was sold to the General Electric Company (GE) in the 1970s. We reached a settlement with GE which provides, among other things, a framework for Berkshire and GE to allocate various monitoring and remediation costs at the East Street Site. As of , we had accrued approximately $3.2 million and established a regulatory asset for these and future . Historically, Middletown/Norwalk Transmission Project The general contractor 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 a lawsuit in Connecticut state court on September 22, 2009. On September 3, 2013, the court found for UI on all claims but one related to certain change orders, and ordered UI to pay the general contractor approximately $1.3 million, which has since been paid. expects to recover any amounts paid to resolve the contractor and subcontractor claims through UI’s transmission revenue requirements. In April 2013, an affiliate of the general contractor for the Middletown/Norwalk Transmission Project, purporting to act as a shareholder on behalf of UIL Holdings, filed a complaint against the UIL Holdings Board of Directors alleging that the directors breached a fiduciary duty by failing to undertake an independent investigation in response to a letter from the affiliate asking for an investigation regarding alleged improper practices by UI in connection with the Middletown/Norwalk Transmission Project. In October 2013, the court granted the defendants’ motion to dismiss the complaint, which dismissal was affirmed by the Connecticut Appellate Court in March 2015. The period to file a petition for review by the Connecticut Supreme Court has passed and the case is now concluded.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	6 Months Ended
	Jun. 30, 2015
FAIR VALUE MEASUREMENTS [Abstract]
FAIR VALUE MEASUREMENTS	(K) FAIR VALUE MEASUREMENTS As required by ASC 820 “Fair Value Measurements and Disclosures,” financial assets and liabilities are classified in their entirety, based on the lowest level of input that is significant to the fair value measurement. Our assessment of the significance of a particular input to the fair value measurement requires judgment, and may affect the valuation of the fair value of assets and liabilities and their placement within the fair value hierarchy levels. The following tables set forth the fair value of our financial assets and liabilities, other than pension benefits and other postretirement benefits, as of June 30, 2015 and December 31, 2014. Fair Value Measurements Using Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total June 30, 2015 (In Thousands) Assets: Derivative assets $ - $ - 32,822 $ 32,822 Noncurrent investments 13,820 - - 13,820 Deferred Compensation Plan 3,639 - - 3,639 Supplemental retirement benefit trust life insurance policies - 7,938 - 7,938 $ 17,459 $ 7,938 $ 32,822 $ 58,219 Liabilities: Derivative liabilities $ - $ - $ 107,156 $ 107,156 Long-term debt - 1,976,832 - 1,976,832 $ - $ 1,976,832 $ 107,156 $ 2,083,988 Net fair value assets/(liabilities), June 30, 2015 $ 17,459 $ (1,968,894 ) $ (74,334 ) $ (2,025,769 ) December 31, 2014 Assets: Derivative assets $ - $ - $ 27,270 $ 27,270 Noncurrent investments 11,387 - - 11,387 Deferred Compensation Plan 3,624 - - 3,624 Supplemental retirement benefit trust life insurance policies - 8,498 - 8,498 $ 15,011 $ 8,498 $ 27,270 $ 50,779 Liabilities: Derivative liabilities $ - $ - $ 85,074 $ 85,074 Long-term debt - 1,941,711 - 1,941,711 $ - $ 1,941,711 $ 85,074 $ 2,026,785 Net fair value assets/(liabilities), December 31, 2014 $ 15,011 $ (1,933,213 ) $ (57,804 ) $ (1,976,006 ) Fair value measurements categorized in Level 3 of the fair value hierarchy are prepared by individuals with expertise in valuation techniques, pricing of energy and energy-related products, and accounting requirements. The derivative assets consist primarily of CfDs. The determination of fair value of the CfDs was based on a probability-based expected cash flow analysis that was discounted at the June 30, 2015 or December 31, 2014 risk-free interest rates, as applicable, and an adjustment for non-performance risk using credit default swap rates. Certain management assumptions were required, including development of pricing that extended over the term of the contracts. We believe this methodology provides the most reasonable estimates of the amount of future discounted cash flows associated with the CfDs. Additionally, on a quarterly basis, we perform analytics to ensure that the fair value of the derivatives is consistent with changes, if any, in the various fair value model inputs. Additional quantitative information about Level 3 fair value measurements is as follows: Unobservable Input Range at June 30, 2015 Range at December 31, 2014 Contracts for differences Risk of non-performance 0.00% - 0.70% 0.00% - 0.66% Discount rate 1.63% - 2.35% 1.65% - 2.25% Forward pricing ($ per MW) $3.15 - $11.19 $3.15 - $14.59 Significant isolated changes in the risk of non-performance, the discount rate or the contract term pricing would result in an inverse change in the fair value of the CfDs. The fair value of the noncurrent investments is determined using quoted market prices in active markets for identical assets. The investments primarily consist of money market funds. 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 mutual funds and UIL Holdings common stock equivalents, with the exception of long-term incentive plan deferrals which are required to be invested in UIL Holdings common stock equivalents. These investments, which are actively traded in sufficient frequency and volume to provide pricing information on an ongoing basis, are marked-to-market based upon such pricing information. The determination of the fair value of the supplemental retirement benefit trust life insurance policies was based on quoted prices as of June 30, 2015 and December 31, 2014 in the active markets for the various funds within which the assets are held. Long-term debt is carried at cost on the consolidated balance sheet. The fair value of long-term debt as displayed in the table above is based on evaluated prices that reflect significant observable market information such as reported trades, actual trade information of similar securities, benchmark yields, broker/dealer quotes of new issue prices and relevant credit information. The following tables set forth a reconciliation of changes in the fair value of the assets and liabilities above that are classified as Level 3 in the fair value hierarchy for the six-month period ended June 30, 2015. Six Months Ended June 30, 2015 (In Thousands) Net derivative assets/(liabilities), December 31, 2014 $ (57,804 ) Unrealized gains and (losses), net (16,530 ) Net derivative assets/(liabilities), June 30, 2015 $ (74,334 ) Change in unrealized gains (losses), net relating to net derivative assets/(liabilities), still held as of June 30, 2015 $ (16,530 ) The following table sets forth a reconciliation of changes in the net regulatory asset/(liability) balances that were established to recover any unrealized gains/(losses) associated with the CfDs for the six-month period ended June 30, 2015. The amounts offset the net CfDs liabilities included in the derivative liabilities detailed above. Six Months Ended June 30, 2015 (In Thousands) Net regulatory assets/(liabilities), December 31, 2014 $ 57,804 Unrealized (gains) and losses, net 16,530 Net regulatory assets/(liabilities), June 30, 2015 $ 74,334

SEGMENT INFORMATION

SEGMENT INFORMATION	6 Months Ended
	Jun. 30, 2015
SEGMENT INFORMATION [Abstract]
SEGMENT INFORMATION	(M) SEGMENT INFORMATION UIL Holdings is organized into Electric Distribution, Electric Transmission and Gas Distribution reporting segments based on several factors including, but not limited to, the nature of each segment’s products and services, the sources of operating revenues and expenses and the regulatory environment in which each segment operates. The following measures of segment profit and loss are utilized by management to make decisions about allocating resources to the segments and assessing performance. The following table reconciles certain segment information with that provided in our Consolidated Financial Statements. In the table, distribution includes all electric utility revenue and expenses except for transmission, which is provided in a separate column. “Other” includes the information for the remainder of our non-utility activities and unallocated corporate costs, including minority interest investments and administrative costs. Revenues from inter-segment transactions are not material. All of our revenues are derived in the United States. (In Thousands) Three months ended June 30, 2015 Electric Distribution and Transmission Distribution Transmission Total Gas Distribution Other Total Operating Revenues $ 130,803 $ 59,632 $ 190,435 $ 121,572 $ - $ 312,007 Purchased power and gas 36,715 - 36,715 41,280 (1,179 ) 76,816 Operation and maintenance 50,049 14,089 64,138 43,938 (5,072 ) 103,004 Transmission wholesale - 17,988 17,988 - - 17,988 Depreciation and amortization 12,991 4,365 17,356 18,483 3,541 39,380 Taxes - other than income taxes 13,200 8,155 21,355 10,200 279 31,834 Merger and acquisition-related expenses - - - - 93 93 Operating Income 17,848 15,035 32,883 7,671 2,338 42,892 Other Income and (Deductions), net 1,968 1,065 3,033 564 697 4,294 Interest Charges, net 8,151 3,295 11,446 6,975 5,809 24,230 Income from Equity Investments 3,940 - 3,940 - - 3,940 Income (Loss) Before Income Taxes 15,605 12,805 28,410 1,260 (2,774 ) 26,896 Income Taxes 5,095 4,993 10,088 (151 ) 1,113 11,050 Net Income (Loss) 10,510 7,812 18,322 1,411 (3,887 ) 15,846 Less: Preferred Stock Dividends of Subsidiary, Noncontrolling Interests - - - 7 - 7 Net Income (Loss) attributable to UIL Holdings $ 10,510 $ 7,812 $ 18,322 $ 1,404 $ (3,887 ) $ 15,839 Total Capital Expenditures (1) $ - $ - $ 40,129 $ 30,146 $ 18,246 $ 88,521 Three months ended June 30, 2014 Electric Distribution and Transmission Distribution Transmission Total Gas Distribution Other Total Operating Revenues $ 117,906 $ 62,001 $ 179,907 $ 154,887 $ - $ 334,794 Purchased power and gas 32,679 - 32,679 76,557 - 109,236 Operation and maintenance 46,646 14,012 60,658 46,155 (4,113 ) 102,700 Transmission wholesale - 19,064 19,064 - - 19,064 Depreciation and amortization 11,896 4,202 16,098 17,769 2,645 36,512 Taxes - other than income taxes 11,492 8,039 19,531 10,358 652 30,541 Merger and Acquisition-related expenses - - - - 469 469 Operating Income 15,193 16,684 31,877 4,048 347 36,272 Other Income and (Deductions), net 3,440 929 4,369 (308 ) (7,363 ) (3,302 ) Interest Charges, net 7,239 3,253 10,492 7,441 5,514 23,447 Income from Equity Investments 3,520 - 3,520 - - 3,520 Income (Loss) Before Income Taxes 14,914 14,360 29,274 (3,701 ) (12,530 ) 13,043 Income Taxes 3,740 5,362 9,102 (1,439 ) (3,923 ) 3,740 Net Income (Loss) 11,174 8,998 20,172 (2,262 ) (8,607 ) 9,303 Less: Preferred Stock Dividends of Subsidiary, Noncontrolling Interests - - - (40 ) - (40 ) Net Income (Loss) attributable to UIL Holdings $ 11,174 $ 8,998 $ 20,172 $ (2,222 ) $ (8,607 ) $ 9,343 Total Capital Expenditures (1) $ - $ - $ 26,290 $ 25,493 $ 9,066 $ 60,849 (In Thousands) Six months ended June 30, 2015 Electric Distribution and Transmission Distribution Transmission Total Gas Distribution Other Total Operating Revenues $ 322,691 $ 117,714 $ 440,405 $ 455,655 $ - $ 896,060 Purchased power and gas 133,817 - 133,817 217,017 (2,396 ) 348,438 Operation and maintenance 97,353 27,577 124,930 89,785 (10,364 ) 204,351 Transmission wholesale - 37,697 37,697 - - 37,697 Depreciation and amortization 27,124 8,561 35,685 40,260 6,719 82,664 Taxes - other than income taxes 28,242 16,536 44,778 27,762 609 73,149 Merger and acquisition-related expenses - - - - 6,795 6,795 Operating Income 36,155 27,343 63,498 80,831 (1,363 ) 142,966 Other Income and (Deductions), net 3,909 2,550 6,459 1,023 1,180 8,662 Interest Charges, net 16,190 6,766 22,956 13,682 11,656 48,294 Income from Equity Investments 6,876 - 6,876 - - 6,876 Income (Loss) Before Income Taxes 30,750 23,127 53,877 68,172 (11,839 ) 110,210 Income Taxes 8,948 8,854 17,802 25,513 (6,560 ) 36,755 Net Income (Loss) 21,802 14,273 36,075 42,659 (5,279 ) 73,455 Less: Preferred Stock Dividends of Subsidiary, Noncontrolling Interests - - - 14 - 14 Net Income (Loss) attributable to UIL Holdings $ 21,802 $ 14,273 $ 36,075 $ 42,645 $ (5,279 ) $ 73,441 Total Capital Expenditures (1) $ - $ - $ 78,211 $ 53,350 $ 27,608 $ 159,169 Six months ended June 30, 2014 Electric Distribution and Transmission Distribution Transmission Total Gas Distribution Other Total Operating Revenues $ 263,095 $ 120,789 $ 383,884 $ 522,072 $ - $ 905,956 Purchased power and gas 85,809 - 85,809 291,482 - 377,291 Operation and maintenance 92,463 24,593 117,056 85,811 (7,290 ) 195,577 Transmission wholesale - 39,975 39,975 - - 39,975 Depreciation and amortization 23,959 8,427 32,386 39,517 4,927 76,830 Taxes - other than income taxes 24,353 16,391 40,744 27,998 1,335 70,077 Merger and acquisition-related expenses - - - - 5,520 5,520 Operating Income 36,511 31,403 67,914 77,264 (4,492 ) 140,686 Other Income and (Deductions), net 6,626 1,912 8,538 (1,289 ) (13,102 ) (5,853 ) Interest Charges, net 15,071 6,457 21,528 14,204 10,949 46,681 Income from Equity Investments 6,906 - 6,906 - - 6,906 Income (Loss) Before Income Taxes 34,972 26,858 61,830 61,771 (28,543 ) 95,058 Income Taxes 9,842 9,214 19,056 24,978 (13,744 ) 30,290 Net Income (Loss) 25,130 17,644 42,774 36,793 (14,799 ) 64,768 Less: Preferred Stock Dividends of Subsidiary, Noncontrolling Interests - - - (27 ) - (27 ) Net Income (Loss) attributable to UIL Holdings $ 25,130 $ 17,644 $ 42,774 $ 36,820 $ (14,799 ) $ 64,795 Total Capital Expenditures (1) $ - $ - $ 60,077 $ 45,352 $ 20,112 $ 125,541 Electric Distribution and Transmission (2) Distribution Transmission Total Gas Distribution (3) Other Total (3) Total Assets at June 30, 2015 $ - $ - $ 2,939,714 $ 2,072,868 $ 188,580 $ 5,201,162 Total Assets at December 31, 2014 $ - $ - $ 2,876,792 $ 2,087,284 $ 147,859 $ 5,111,935 (1) Information for segmenting total capital expenditures between Distribution and Transmission is not available. Total Electric Distribution and Transmission capital expenditures are disclosed in the Total Electric Distribution and Transmission column. (2) Information for segmenting total assets between Distribution and Transmission is not available. Total Electric Distribution and Transmission assets are disclosed in the Total Electric and Distribution and Transmission column. Net plant in service is segregated by segment and, as of June 30, 2015, was $1,304.9 million and $697.3 million for Distribution and Transmission, respectively. As of December 31, 2014, net plant in service was $1,283.6 million and $659.4 million for Distribution and Transmission, respectively. (3) Includes $266.2 million of goodwill in the Gas Distribution segment as of June 30, 2015 and December 31, 2014.

BUSINESS ORGANIZATION AND STA18

BUSINESS ORGANIZATION AND STATEMENT OF ACCOUNTING POLICIES (Policies)	6 Months Ended
	Jun. 30, 2015
BUSINESS ORGANIZATION AND STATEMENT OF ACCOUNTING POLICIES [Abstract]
Basis of Presentation	Basis of Presentation The financial statements of UIL Holdings are prepared on a consolidated basis and therefore include the accounts of UIL Holdings’ majority-owned subsidiaries noted above. Intercompany accounts and transactions have been eliminated in consolidation. The year‑end balance sheet data was derived from audited financial statements, but does not include all disclosures required by accounting principles generally accepted in the United States of America (GAAP). Certain information and footnote disclosures, which are normally included in financial statements prepared in accordance with GAAP, have been condensed or omitted in accordance with Securities and Exchange Commission (SEC) rules and regulations. We believe that the disclosures made are adequate to make the information presented not misleading. The information presented in the Consolidated Financial Statements reflects all adjustments which, in our opinion, are necessary for a fair statement of the financial position and results of operations for the interim periods described herein. All such adjustments are of a normal and recurring nature. The results for the three- and six-month periods ended June 30, 2015 are not necessarily indicative of the results for the entire fiscal year ending December 31, 2015.
Business Combinations	Proposed Merger with Iberdrola USA On February 25, 2015, we announced that UIL Holdings had entered into a definitive merger agreement (the Agreement) with Iberdrola USA and its wholly-owned subsidiary, Green Merger Sub, Inc. (merger sub) under which Iberdrola USA will acquire UIL Holdings through a merger of UIL Holdings with and into merger sub and merger sub being the surviving corporation (the merger). Merger sub will change its name to UIL Holdings Corporation and remain a direct or indirect wholly-owned subsidiary of Iberdrola USA. Iberdrola USA will then become a newly listed U.S. publicly-traded company. In connection with the merger, each issued and outstanding share of the common stock of UIL Holdings will be converted into the right to receive one validly issued share of common stock of the newly listed company plus $10.50 in cash. Immediately following the consummation of the merger, former holders of UIL Holdings’ common stock will own approximately 18.5% of the newly listed company. The merger remains subject to certain closing conditions, including the approval of the shareowners of UIL Holdings and regulatory approvals from the Connecticut Public Utilities Regulatory Authority (PURA) and the Massachusetts Department of Public Utilities (DPU). Iberdrola USA and UIL Holdings made the required filings at the PURA and the DPU seeking approval of the change in control on March 25, 2015. On July 7, 2015, in response to the issuance of a draft decision issued by PURA, UIL Holdings and Iberdrola USA filed a letter with PURA withdrawing their pending application and on July 31, 2015, filed a new application for approval of the change in control. The new application includes commitments and identifies public interest benefits to meet the statutory requirements in Connecticut for approval of a change in control. The commitments include rate credits to customers (approximately $20 million), a distribution rate freeze to 2018 for SCG and CNG, and to 2017 for UI, commitments to contribute to a clean energy fund and disaster relief (together, approximately $7 million), accelerated capital investment in electric distribution system resiliency and gas distribution system replacement of cast iron and bare steel (delayed recovery in rates resulting in nearly $7 million), agreement to negotiate a consent order with DEEP to remediate the English Station site in New Haven, Connecticut, formerly owned by UI (DEEP informed UIL Holdings that it estimated the cost of the remediation to be approximately $30 million). In addition, in the new application the companies commit to no change in the day-to-day management and operation of UIL Holdings’ three Connecticut utilities, to hiring 150 employees or contractors within the State of Connecticut over the next three years, to maintain UI’s high service reliability and CNG and SCG’s high levels of gas leak response, and to improve The new application also proposes comprehensive “ring fencing” provisions to protect the Connecticut utilities from involuntary bankruptcy associated with potential future adverse changes in financial circumstances of Iberdrola affiliates. These provisions include the creation of a special purpose entity with at least one independent director, dividend limitations on the Connecticut utilities where the investment grade credit rating is in jeopardy or if a minimum common equity ratio is not maintained, commitments to maintain separate books and records and a prohibition on commingling of funds. The proceedings at the DPU remain pending. All other regulatory approvals have been received. We received approval from the Federal Communications Commission (FCC) on May 22, 2015 and from the Federal Energy Regulatory Commission (FERC) on June 2, 2015. In addition we received clearance from the Committee on Foreign Investments in the United States (CFIUS) on June 16, 2015 and the applicable waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976 (the HSR Act) We currently expect that the merger will close promptly after satisfaction or waiver of all closing conditions, including receipt of shareowner approval and all regulatory approvals, and not later than December 31, 2015. There are no assurances that the merger will be consummated on the currently expected timetable or at all. Unless stated otherwise, all forward-looking information contained in this report does not take into account or give any effect to the impact of the proposed merger. For the three and six months ended June 30, 2015, UIL Holdings incurred pre-tax merger-related expenses of approximately $0.1 Further information concerning the proposed merger is included in a proxy statement/prospectus contained in a registration statement on Form S-4 filed by Iberdrola USA with the SEC on July 17, 2015 in connection with the proposed merger. Philadelphia Gas Works In March 2014, UIL Holdings entered into an Asset Purchase Agreement (the Asset Purchase Agreement) with the City of Philadelphia pursuant to which UIL Holdings, through a wholly-owned subsidiary, was to acquire the operating assets and assume certain liabilities of Philadelphia Gas Works. The proposed acquisition was subject to the satisfaction or waiver of certain customary and other closing conditions for transactions of this type, including approval from the Philadelphia City Council. In light of the City Council’s October 2014 announcement to not endorse the proposed acquisition, we exercised our contractual right to terminate the Asset Purchase Agreement in December 2014. For the three and six month periods ended June 30, 2014, UIL Holdings incurred pre-tax acquisition-related expenses of approximately $8.4
Derivatives	Derivatives UIL Holdings’ regulated subsidiaries are parties to contracts, and involved in transactions, that are derivatives. Contracts for Differences (CfDs) Pursuant to Connecticut’s 2005 Energy Independence Act, PURA solicited bids to create new or incremental capacity resources in order to reduce federally mandated congestion charges, and selected four new capacity resources. To facilitate the transactions between the selected capacity resources and Connecticut electric customers, and provide the commitment necessary for owners of these resources to obtain necessary financing, PURA required that UI and The Connecticut Light and Power Company (CL&P) execute long-term contracts with the selected resources. In August 2007, PURA approved four CfDs, each of which specifies a capacity quantity and a monthly settlement that reflects the difference between a forward market price and the contract price. UI executed two of the contracts and CL&P executed the other two contracts. The costs or benefits of each contract will be paid by or allocated to customers and will be subject to a cost-sharing agreement between UI and CL&P pursuant to which approximately 20% of the cost or benefit is borne by or allocated to UI customers and approximately 80% is borne by or allocated to CL&P customers. PURA has determined that costs associated with these CfDs will be fully recoverable by UI and CL&P through electric rates, and in accordance with ASC 980 “Regulated Operations,” UI has deferred recognition of costs (a regulatory asset) or obligations (a regulatory liability). The CfDs are marked-to-market in accordance with ASC 815 “Derivatives and Hedging.” For those CfDs signed by CL&P, UI records its approximate 20% portion pursuant to the cost-sharing agreement noted above. As of June 30, 2015, UI has recorded a gross derivative asset of $32.8 million ($1.5 million of which is related to UI’s portion of the CfD signed by CL&P), a regulatory asset of $75.2 million, a gross derivative liability of $107.2 million ($68.0 million of which is related to UI’s portion of the CfD signed by CL&P) and a regulatory liability of $0.9 million. See Note (K) “Fair Value of Financial Instruments” for additional CfD information. The gross derivative assets and liabilities as of June 30, 2015 and December 31, 2014 were as follows: June 30, 2015 December 31, 2014 (In Thousands) Gross derivative assets: Current Assets $ 9,934 $ 6,849 Deferred Charges and Other Assets $ 22,887 $ 20,421 Gross derivative liabilities: Current Liabilities $ 27,513 $ 23,308 Noncurrent Liabilities $ 79,643 $ 61,766 The unrealized gains and losses from fair value adjustments to these derivatives, which are recorded in regulatory assets or regulatory liabilities, for the three- and six-month periods ended June 30, 2015 and 2014 were as follows: Three Months Ended June 30, Six Months Ended June 30, 2015 2014 2015 2014 (In Thousands) (In Thousands) Regulatory Assets - Derivative liabilities $ (2,812 ) $ (10,397 ) $ 10,957 $ (82,017 ) Regulatory Liabilities - Derivative assets $ 6,173 $ (8,751 ) $ 7,371 $ (11,693 ) The fluctuations in the balances of the derivatives as well as the related unrealized gains in the three- and six-month periods ended June 30, 2015 compared to the three- and six-month periods ended June 30, 2014 are primarily due to fluctuations in forward prices for capacity and reserves.
Earnings per Share	Earnings per Share The following table presents a reconciliation of the basic and diluted earnings per share calculations for the three-month periods ended June 30, 2015 and 2014: Three Months Ended June 30, Six Months Ended June 30, 2015 2014 2015 2014 (In Thousands, except per share amounts) Numerator: Net income attributable to UIL Holdings $ 15,839 $ 9,343 $ 73,441 $ 64,795 Less: Net income allocated to unvested units 8 6 39 38 Net income attributable to common shareholders $ 15,831 $ 9,337 $ 73,402 $ 64,757 Denominator: Basic average number of shares outstanding 56,950 56,842 56,918 56,814 Effect of dilutive securities (1) 291 260 311 265 Diluted average number of shares outstanding 57,241 57,102 57,229 57,079 Earnings per share: Basic $ 0.28 $ 0.16 $ 1.29 $ 1.14 Diluted $ 0.28 $ 0.16 $ 1.28 $ 1.13 (1) Includes unvested restricted stock and performance shares.
Equity Investments	Equity Investments UI is party to a 50-50 joint venture with the NRG affiliates in GenConn, which operates two peaking generation plants in Connecticut. UI’s investment in GenConn is being accounted for as an equity investment, the carrying value of which was $112.9 million and $114.2 million as of June 30, 2015 and December 31, 2014, respectively. As of June 30, 2015, there was $1.3 million of undistributed earnings from UI’s equity investment in GenConn. UI’s pre-tax income from its equity investment in GenConn was $3.9 million and $3.5 million for the June 30, 2015 and 2014, respectively. UI’s pre-tax income from its equity investment in GenConn for each of the six-month periods ending June 30, 2015 and 2014 was $6.9 million. Cash distributions from GenConn are reflected as either distributions of earnings or as returns of capital in the operating and investing sections of the Consolidated Statement of Cash Flows, respectively. UI received cash distributions from GenConn of $2.7 million and $3.4 million in the June 30, 2015 and 2014, respectively. UI received cash distributions from GenConn of $8.1 million and $8.8 million in the June 30, 2015, respectively and 2014. On July 24, 2015, UIL Holdings announced its participation in Tennessee Gas Pipeline Company LLC’s (TGP) proposed Northeast Energy Direct project (NED pipeline), a new, “market path” natural gas pipeline segment of approximately 188 miles from Wright, New York, to Dracut, Massachusetts, through its acquisition of a 2.5% equity interest in Northeast Expansion LLC, a joint venture between Kinder Morgan, Inc., through its affiliate Kinder Morgan Operating Limited Partnership “A” (Kinder Morgan “A”), and Liberty Utilities (Pipeline & Transmission) Corp, which will construct and own the NED pipeline. This 2.5% equity interest, which UIL Holdings acquired for approximately $1.2 million, commits UIL Holdings to an initial capital investment opportunity that is expected to total up to approximately $80 million, depending on the final pipeline configuration and design capacity. Pursuant to an option agreement with Kinder Morgan “A”, UIL Holdings also has the option to acquire up to an additional 12.5% of equity interests in Northeast Expansion LLC under certain limited circumstances, including if certain additional firm transportation agreements for service on the NED pipeline are entered into or if TGP does not sell additional volume on the NED pipeline. Any increase in equity ownership would increase UIL Holdings’ investment commitment proportionately. In addition, as a condition to making this investment, UIL Holdings entered into a 20-year Precedent Agreement with TGP for pipeline capacity of 70,000 Dekatherms/day on the NED pipeline, which capacity commitment, under the terms of the Precedent Agreement, would be reduced in the event that TGP enters into additional precedent agreements with third parties for capacity on the NED pipeline.
Regulatory Accounting	Regulatory Accounting Unless otherwise stated below, all of our regulatory assets earn a return. Our regulatory assets and liabilities as of June 30, 2015 Remaining June 30, December 31, (In Thousands) Regulatory Assets: Unamortized redemption costs 7 to 19 years $ 10,098 $ 10,499 Pension and other post-retirement benefit plans (a) 398,732 402,700 Environmental remediation costs 7 years 14,364 13,197 Hardship programs (b) 19,055 24,744 Debt premium 2 to 23 years 24,962 27,498 Income taxes due principally to book-tax differences (c) 165,726 164,466 Unfunded future income taxes (d) 16,734 14,859 Contracts for differences (e) 75,233 64,276 Deferred transmission expense (f) 23,914 17,387 Other (g) 35,260 40,336 Total regulatory assets 784,078 779,962 Less current portion of regulatory assets 102,987 92,764 Regulatory Assets, Net $ 681,091 $ 687,198 Regulatory Liabilities: Accumulated deferred investment tax credits 29 years $ 7,282 $ 4,319 Excess generation service charge (h) 39,350 28,692 Middletown/Norwalk local transmission network service collections 35 years 20,542 20,828 Pension and other post-retirement benefit plans (a) 10,851 9,536 Asset retirement obligation (i) 7,155 7,248 Low income programs (j) 29,064 19,065 Asset removal costs (i) 342,346 336,028 Unfunded future income taxes (d) 26,812 26,318 Contracts for differences (e) 899 6,472 Deferred purchased gas (k) 16,757 4,736 Non-firm margin sharing credits 9 years 15,181 8,933 Other (g) 37,761 36,747 Total regulatory liabilities 554,000 508,922 Less current portion of regulatory liabilities 44,242 17,026 Regulatory Liabilities, Net $ 509,758 $ 491,896 (a) Life is dependent upon timing of final pension plan distribution; balance, which is fully offset by a corresponding asset/liability, is recalculated each year in accordance with ASC 715 "Compensation-Retirement Benefits." See Note (G) “Pension and Other Benefits” for additional information. (b) Hardship customer accounts deferred for future recovery to the extent they exceed the amount in rates. (c) Amortization period and/or balance vary depending on the nature and/or remaining life of the underlying assets/liabilities. (d) The balance will be extinguished when the asset, which is fully offset by a corresponding liability, or liability has been realized or settled, respectively. (e) Asset life is equal to delivery term of related contracts (which vary from approximately 5 - 12 years); balance fluctuates based upon quarterly market analysis performed on the related derivatives (Note K); amount, which does not earn a return, is fully offset by corresponding derivative asset/liability. See “-Contracts for Differences” discussion above for additional information. (f) Regulatory asset or liability which defers transmission income or expense and fluctuates based upon actual revenues and revenue requirements. (g) Amortization period and/or balance vary depending on the nature, cost of removal and/or remaining life of the underlying assets/liabilities; asset amount includes certain amounts that are not currently earning a return; asset amount includes decoupling of $2.6 million; liability amount includes decoupling of $16.5 million. (h) Regulatory asset or liability which defers generation-related and nonbypassable federally mandated congestion costs or revenues for future recovery from or return to customers. Amount fluctuates based upon timing differences between revenues collected from rates and actual costs incurred. (i) The liability will be extinguished simultaneous with the retirement of the assets and settlement of the corresponding asset retirement obligation. (j) Various hardship and payment plan programs approved for recovery. (k) Deferred purchased gas costs balances at the end of the rate year are normally recorded/returned in the next year.
Stock-Based Compensation	Stock-Based Compensation Pursuant to the UIL Holdings 2008 Stock and Incentive Compensation Plan (2008 Stock Plan), 94,410 restricted stock units were granted to certain members of management in March 2015; the average of the high and low market prices on the grant date, which approximate fair value, was $49.72 per share. Also in March 2015, we granted a total of 1,584 shares of restricted stock to our President and Chief Executive Officer under the 2008 Stock Plan and in accordance with his employment agreement; the average of the high and low market price on the date of grant, which approximates fair value, was $49.72 per share. Such shares vest in equal annual installments over a five-year period. In May 2015, UIL Holdings granted a total of 18,801 shares of restricted stock to non-employee directors under the 2008 Stock Plan; the average of the high and low market price on the date of grant, which approximates fair value, was $48.37 per share. Such shares vest in May 2016. Total stock-based compensation expense for the three-month periods ended June 30, 2015 and 2014 June 30, 2015 and 2014
Variable Interest Entities	Variable Interest Entities We have identified GenConn as a variable interest entity (VIE), which is accounted for under the equity method. UIL Holdings is not the primary beneficiary of GenConn, as defined in ASC 810 “Consolidation,” because it shares control of all significant activities of GenConn with its joint venturer, NRG affiliates. As such, GenConn is not subject to consolidation. GenConn recovers its costs through CfDs, which are cost of service-based and have been approved by PURA. As a result, with the achievement of commercial operation by GenConn Devon and GenConn Middletown, our exposure to loss is primarily related to the potential for unrecovered GenConn operating or capital costs in a regulatory proceeding, the effect of which would be reflected in the carrying value of our 50% ownership position in GenConn and through “Income from Equity Investments” in UIL Holdings’ Consolidated Financial Statements. We have identified the selected capacity resources with which UI has CfDs as VIEs and have concluded that UI is not the primary beneficiary as UI does not have the power to direct any of the significant activities of these capacity resources. As such, we have not consolidated the selected capacity resources. UI’s maximum exposure to loss through these agreements is limited to the settlement amount under the CfDs as described in “–Derivatives – Contracts for Differences (CfDs)” above; however any such losses are fully recoverable through electric rates. UI has no requirement to absorb additional losses nor has UI provided any financial or other support during the periods presented that were not previously contractually required. We have identified the entities for which UI is required to enter into long-term contracts to purchase Renewable Energy Credits (RECs) as VIEs. In assessing these contracts for VIE identification and reporting purposes, we have aggregated the contracts based on similar risk characteristics and significance to UI. UI is not the primary beneficiary as UI does not have the power to direct any of the significant activities of these entities. UI’s exposure to loss is primarily related to the purchase and resale of the RECs, but, any losses incurred are recoverable through electric rates. For further discussion of RECs, see Note (C) “Regulatory Proceedings – Electric Distribution and Transmission – New Renewable Source Generation.”
New Accounting Pronouncements	New Accounting Pronouncements In July 2015, the FASB issued Accounting Standards Update (ASU) 2015-11, “Inventory – Simplifying the Measurement of Inventory” which requires inventory that is measured using first-in, first-out or average cost methods to be measured using the lower of cost and net realizable value. ASU 2015-11 is effective for interim and annual reporting periods beginning after December 15, 2016 and is to be applied prospectively with earlier application permitted as of the beginning of an interim or annual reporting period. This is not expected to be material to UIL Holdings’ consolidated financial statements. In July 2015, the FASB voted to defer by one year the effective date of ASU 2014-09 which requires entities to recognize revenue in a way that depicts the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled to in exchange for those goods or services. A final Accounting Standards Update will be issued that reflects the revised effective date. We are currently evaluating the effect that adopting this new accounting guidance will have on our consolidated financial statements. In April 2015, the FASB issued Accounting Standards Update (ASU) 2015-03, “Interest-Imputation of Interest: Simplifying the Presentation of Debt Issuance Costs” which requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability. ASU 2015-03 is effective for interim and annual reporting periods beginning after December 15, 2015 and is to be applied retrospectively. The effect that adopting this new accounting guidance will have on our consolidated financial statements will be reductions in both Deferred Charges and Other Assets and Long-term debt on the consolidated balance sheet. This effect is not expected to be material to UIL Holdings’ consolidated financial statements.

BUSINESS ORGANIZATION AND STA19

BUSINESS ORGANIZATION AND STATEMENT OF ACCOUNTING POLICIES (Tables)	6 Months Ended
	Jun. 30, 2015
BUSINESS ORGANIZATION AND STATEMENT OF ACCOUNTING POLICIES [Abstract]
Value of Gross Derivative Assets and Liabilities	The gross derivative assets and liabilities as of June 30, 2015 and December 31, 2014 were as follows: June 30, 2015 December 31, 2014 (In Thousands) Gross derivative assets: Current Assets $ 9,934 $ 6,849 Deferred Charges and Other Assets $ 22,887 $ 20,421 Gross derivative liabilities: Current Liabilities $ 27,513 $ 23,308 Noncurrent Liabilities $ 79,643 $ 61,766
Unrealized Gains and Losses From Mark-To-Market Adjustments	The unrealized gains and losses from fair value adjustments to these derivatives, which are recorded in regulatory assets or regulatory liabilities, for the three- and six-month periods ended June 30, 2015 and 2014 were as follows: Three Months Ended June 30, Six Months Ended June 30, 2015 2014 2015 2014 (In Thousands) (In Thousands) Regulatory Assets - Derivative liabilities $ (2,812 ) $ (10,397 ) $ 10,957 $ (82,017 ) Regulatory Liabilities - Derivative assets $ 6,173 $ (8,751 ) $ 7,371 $ (11,693 )
Reconciliation of Basic and Diluted Earnings Per Share	The following table presents a reconciliation of the basic and diluted earnings per share calculations for the three-month periods ended June 30, 2015 and 2014: Three Months Ended June 30, Six Months Ended June 30, 2015 2014 2015 2014 (In Thousands, except per share amounts) Numerator: Net income attributable to UIL Holdings $ 15,839 $ 9,343 $ 73,441 $ 64,795 Less: Net income allocated to unvested units 8 6 39 38 Net income attributable to common shareholders $ 15,831 $ 9,337 $ 73,402 $ 64,757 Denominator: Basic average number of shares outstanding 56,950 56,842 56,918 56,814 Effect of dilutive securities (1) 291 260 311 265 Diluted average number of shares outstanding 57,241 57,102 57,229 57,079 Earnings per share: Basic $ 0.28 $ 0.16 $ 1.29 $ 1.14 Diluted $ 0.28 $ 0.16 $ 1.28 $ 1.13 (1) Includes unvested restricted stock and performance shares.
Regulatory Assets and Liabilities	Our regulatory assets and liabilities as of June 30, 2015 Remaining June 30, December 31, (In Thousands) Regulatory Assets: Unamortized redemption costs 7 to 19 years $ 10,098 $ 10,499 Pension and other post-retirement benefit plans (a) 398,732 402,700 Environmental remediation costs 7 years 14,364 13,197 Hardship programs (b) 19,055 24,744 Debt premium 2 to 23 years 24,962 27,498 Income taxes due principally to book-tax differences (c) 165,726 164,466 Unfunded future income taxes (d) 16,734 14,859 Contracts for differences (e) 75,233 64,276 Deferred transmission expense (f) 23,914 17,387 Other (g) 35,260 40,336 Total regulatory assets 784,078 779,962 Less current portion of regulatory assets 102,987 92,764 Regulatory Assets, Net $ 681,091 $ 687,198 Regulatory Liabilities: Accumulated deferred investment tax credits 29 years $ 7,282 $ 4,319 Excess generation service charge (h) 39,350 28,692 Middletown/Norwalk local transmission network service collections 35 years 20,542 20,828 Pension and other post-retirement benefit plans (a) 10,851 9,536 Asset retirement obligation (i) 7,155 7,248 Low income programs (j) 29,064 19,065 Asset removal costs (i) 342,346 336,028 Unfunded future income taxes (d) 26,812 26,318 Contracts for differences (e) 899 6,472 Deferred purchased gas (k) 16,757 4,736 Non-firm margin sharing credits 9 years 15,181 8,933 Other (g) 37,761 36,747 Total regulatory liabilities 554,000 508,922 Less current portion of regulatory liabilities 44,242 17,026 Regulatory Liabilities, Net $ 509,758 $ 491,896 (a) Life is dependent upon timing of final pension plan distribution; balance, which is fully offset by a corresponding asset/liability, is recalculated each year in accordance with ASC 715 "Compensation-Retirement Benefits." See Note (G) “Pension and Other Benefits” for additional information. (b) Hardship customer accounts deferred for future recovery to the extent they exceed the amount in rates. (c) Amortization period and/or balance vary depending on the nature and/or remaining life of the underlying assets/liabilities. (d) The balance will be extinguished when the asset, which is fully offset by a corresponding liability, or liability has been realized or settled, respectively. (e) Asset life is equal to delivery term of related contracts (which vary from approximately 5 - 12 years); balance fluctuates based upon quarterly market analysis performed on the related derivatives (Note K); amount, which does not earn a return, is fully offset by corresponding derivative asset/liability. See “-Contracts for Differences” discussion above for additional information. (f) Regulatory asset or liability which defers transmission income or expense and fluctuates based upon actual revenues and revenue requirements. (g) Amortization period and/or balance vary depending on the nature, cost of removal and/or remaining life of the underlying assets/liabilities; asset amount includes certain amounts that are not currently earning a return; asset amount includes decoupling of $2.6 million; liability amount includes decoupling of $16.5 million. (h) Regulatory asset or liability which defers generation-related and nonbypassable federally mandated congestion costs or revenues for future recovery from or return to customers. Amount fluctuates based upon timing differences between revenues collected from rates and actual costs incurred. (i) The liability will be extinguished simultaneous with the retirement of the assets and settlement of the corresponding asset retirement obligation. (j) Various hardship and payment plan programs approved for recovery. (k) Deferred purchased gas costs balances at the end of the rate year are normally recorded/returned in the next year.

SUPPLEMENTARY INFORMATION (Tabl

SUPPLEMENTARY INFORMATION (Tables)	6 Months Ended
	Jun. 30, 2015
SUPPLEMENTARY INFORMATION [Abstract]
Supplementary Information	Three Months Ended June 30, Six Months Ended June 30, 2015 2014 2015 2014 (In Thousands) (In Thousands) Depreciation and Amortization Property, plant, and equipment depreciation $ 34,363 $ 32,360 $ 69,104 $ 64,348 Amortization of regulatory assets 5,017 4,152 13,560 12,482 Total Depreciation and Amortization $ 39,380 $ 36,512 $ 82,664 $ 76,830 Taxes - Other than Income Taxes Operating: Connecticut gross earnings $ 15,207 $ 15,758 $ 38,173 $ 38,472 Local real estate and personal property 13,005 12,125 25,995 24,089 Payroll taxes 3,264 2,974 8,178 6,831 Other 358 (316 ) 803 685 Total Taxes - Other than Income Taxes $ 31,834 $ 30,541 $ 73,149 $ 70,077 Other Income and (Deductions) Interest income $ 672 $ 523 $ 1,381 $ 1,065 Allowance for funds used during construction - equity 1,952 2,370 4,109 4,920 Allowance for funds used during construction - debt 1,086 1,421 2,132 2,831 Weather insurance - (531 ) - (2,437 ) Other 584 841 1,040 2,107 Total Other Income and (Deductions) $ 4,294 $ 4,624 $ 8,662 $ 8,486

PENSION AND OTHER BENEFITS (Tab

PENSION AND OTHER BENEFITS (Tables)	6 Months Ended
	Jun. 30, 2015
PENSION AND OTHER BENEFITS [Abstract]
Components of Net Periodic Benefit Cost for Pension and Other Postretirement Benefits	The following tables represent the components of net periodic benefit cost for pension and other postretirement benefits as well as the actuarial weighted-average assumptions used in calculating net periodic benefit cost for the three-and six-month periods ended : Three Months Ended June 30, Pension Benefits Other Postretirement Benefits 2015 2014 2015 2014 (In Thousands) Components of net periodic benefit cost: Service cost $ 3,605 $ 2,896 $ 393 $ 404 Interest cost 10,505 11,019 1,327 1,487 Expected return on plan assets (14,120 ) (13,560 ) (690 ) (700 ) Amortization of prior service costs 48 73 75 71 Amortization of actuarial (gain) loss 4,845 3,097 176 (172 ) Net periodic benefit cost $ 4,883 $ 3,525 $ 1,281 $ 1,090 Six Months Ended June 30, Pension Benefits Other Postretirement Benefits 2015 2014 2015 2014 (In Thousands) Components of net periodic benefit cost: Service cost $ 7,210 $ 5,792 $ 786 $ 808 Interest cost 21,010 22,038 2,654 2,974 Expected return on plan assets (28,240 ) (27,120 ) (1,380 ) (1,400 ) Amortization of prior service costs 96 146 150 142 Amortization of actuarial (gain) loss 9,690 6,194 352 (344 ) Net periodic benefit cost $ 9,766 $ 7,050 $ 2,562 $ 2,180
Weighted Average Actuarial Assumption used in Calculating Net Periodic Benefit Cost	The following tables represent the components of net periodic benefit cost for pension and other postretirement benefits as well as the actuarial weighted-average assumptions used in calculating net periodic benefit cost for the three-and six-month periods ended : Three and Six Months Ended June 30, Pension Benefits Other Postretirement Benefits 2015 2014 2015 2014 Discount rate 4.20%-4.30 % 4.90%-5.20 % 4.20%-4.30 % 4.85%-5.20 % Average wage increase 3.50%-3.80 % 3.50%-3.80 % N/ A N/ A Return on plan assets 7.75%-8.00 % 7.75%-8.00 % 5.56%-8.00 % 5.56%-8.00 % Composite health care trend rate (current year) N/ A N/ A 7.00 % 7.00 % Composite health care trend rate (2019 forward) N/ A N/ A 5.00 % 5.00 % N/A – not applicable

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	6 Months Ended
	Jun. 30, 2015
FAIR VALUE MEASUREMENTS [Abstract]
Fair Value of Financial Assets and Liabilities	The following tables set forth the fair value of our financial assets and liabilities, other than pension benefits and other postretirement benefits, as of June 30, 2015 and December 31, 2014. Fair Value Measurements Using Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total June 30, 2015 (In Thousands) Assets: Derivative assets $ - $ - 32,822 $ 32,822 Noncurrent investments 13,820 - - 13,820 Deferred Compensation Plan 3,639 - - 3,639 Supplemental retirement benefit trust life insurance policies - 7,938 - 7,938 $ 17,459 $ 7,938 $ 32,822 $ 58,219 Liabilities: Derivative liabilities $ - $ - $ 107,156 $ 107,156 Long-term debt - 1,976,832 - 1,976,832 $ - $ 1,976,832 $ 107,156 $ 2,083,988 Net fair value assets/(liabilities), June 30, 2015 $ 17,459 $ (1,968,894 ) $ (74,334 ) $ (2,025,769 ) December 31, 2014 Assets: Derivative assets $ - $ - $ 27,270 $ 27,270 Noncurrent investments 11,387 - - 11,387 Deferred Compensation Plan 3,624 - - 3,624 Supplemental retirement benefit trust life insurance policies - 8,498 - 8,498 $ 15,011 $ 8,498 $ 27,270 $ 50,779 Liabilities: Derivative liabilities $ - $ - $ 85,074 $ 85,074 Long-term debt - 1,941,711 - 1,941,711 $ - $ 1,941,711 $ 85,074 $ 2,026,785 Net fair value assets/(liabilities), December 31, 2014 $ 15,011 $ (1,933,213 ) $ (57,804 ) $ (1,976,006 )
Additional Quantitative Information about Level 3 Fair Value Measurements	Fair value measurements categorized in Level 3 of the fair value hierarchy are prepared by individuals with expertise in valuation techniques, pricing of energy and energy-related products, and accounting requirements. The derivative assets consist primarily of CfDs. The determination of fair value of the CfDs was based on a probability-based expected cash flow analysis that was discounted at the June 30, 2015 or December 31, 2014 risk-free interest rates, as applicable, and an adjustment for non-performance risk using credit default swap rates. Certain management assumptions were required, including development of pricing that extended over the term of the contracts. We believe this methodology provides the most reasonable estimates of the amount of future discounted cash flows associated with the CfDs. Additionally, on a quarterly basis, we perform analytics to ensure that the fair value of the derivatives is consistent with changes, if any, in the various fair value model inputs. Additional quantitative information about Level 3 fair value measurements is as follows: Unobservable Input Range at June 30, 2015 Range at December 31, 2014 Contracts for differences Risk of non-performance 0.00% - 0.70% 0.00% - 0.66% Discount rate 1.63% - 2.35% 1.65% - 2.25% Forward pricing ($ per MW) $3.15 - $11.19 $3.15 - $14.59
Changes in Fair Value of Assets and Liabilities Classified as level 3	The following tables set forth a reconciliation of changes in the fair value of the assets and liabilities above that are classified as Level 3 in the fair value hierarchy for the six-month period ended June 30, 2015. Six Months Ended June 30, 2015 (In Thousands) Net derivative assets/(liabilities), December 31, 2014 $ (57,804 ) Unrealized gains and (losses), net (16,530 ) Net derivative assets/(liabilities), June 30, 2015 $ (74,334 ) Change in unrealized gains (losses), net relating to net derivative assets/(liabilities), still held as of June 30, 2015 $ (16,530 )
Change in Regulatory Asset/(Liability) Balance	The following table sets forth a reconciliation of changes in the net regulatory asset/(liability) balances that were established to recover any unrealized gains/(losses) associated with the CfDs for the six-month period ended June 30, 2015. The amounts offset the net CfDs liabilities included in the derivative liabilities detailed above. Six Months Ended June 30, 2015 (In Thousands) Net regulatory assets/(liabilities), December 31, 2014 $ 57,804 Unrealized (gains) and losses, net 16,530 Net regulatory assets/(liabilities), June 30, 2015 $ 74,334

SEGMENT INFORMATION (Tables)

SEGMENT INFORMATION (Tables)	6 Months Ended
	Jun. 30, 2015
SEGMENT INFORMATION [Abstract]
Reconciliation of Operating Profit (Loss) from Segments to Consolidated Financial Statements	UIL Holdings is organized into Electric Distribution, Electric Transmission and Gas Distribution reporting segments based on several factors including, but not limited to, the nature of each segment’s products and services, the sources of operating revenues and expenses and the regulatory environment in which each segment operates. The following measures of segment profit and loss are utilized by management to make decisions about allocating resources to the segments and assessing performance. The following table reconciles certain segment information with that provided in our Consolidated Financial Statements. In the table, distribution includes all electric utility revenue and expenses except for transmission, which is provided in a separate column. “Other” includes the information for the remainder of our non-utility activities and unallocated corporate costs, including minority interest investments and administrative costs. Revenues from inter-segment transactions are not material. All of our revenues are derived in the United States. (In Thousands) Three months ended June 30, 2015 Electric Distribution and Transmission Distribution Transmission Total Gas Distribution Other Total Operating Revenues $ 130,803 $ 59,632 $ 190,435 $ 121,572 $ - $ 312,007 Purchased power and gas 36,715 - 36,715 41,280 (1,179 ) 76,816 Operation and maintenance 50,049 14,089 64,138 43,938 (5,072 ) 103,004 Transmission wholesale - 17,988 17,988 - - 17,988 Depreciation and amortization 12,991 4,365 17,356 18,483 3,541 39,380 Taxes - other than income taxes 13,200 8,155 21,355 10,200 279 31,834 Merger and acquisition-related expenses - - - - 93 93 Operating Income 17,848 15,035 32,883 7,671 2,338 42,892 Other Income and (Deductions), net 1,968 1,065 3,033 564 697 4,294 Interest Charges, net 8,151 3,295 11,446 6,975 5,809 24,230 Income from Equity Investments 3,940 - 3,940 - - 3,940 Income (Loss) Before Income Taxes 15,605 12,805 28,410 1,260 (2,774 ) 26,896 Income Taxes 5,095 4,993 10,088 (151 ) 1,113 11,050 Net Income (Loss) 10,510 7,812 18,322 1,411 (3,887 ) 15,846 Less: Preferred Stock Dividends of Subsidiary, Noncontrolling Interests - - - 7 - 7 Net Income (Loss) attributable to UIL Holdings $ 10,510 $ 7,812 $ 18,322 $ 1,404 $ (3,887 ) $ 15,839 Total Capital Expenditures (1) $ - $ - $ 40,129 $ 30,146 $ 18,246 $ 88,521 Three months ended June 30, 2014 Electric Distribution and Transmission Distribution Transmission Total Gas Distribution Other Total Operating Revenues $ 117,906 $ 62,001 $ 179,907 $ 154,887 $ - $ 334,794 Purchased power and gas 32,679 - 32,679 76,557 - 109,236 Operation and maintenance 46,646 14,012 60,658 46,155 (4,113 ) 102,700 Transmission wholesale - 19,064 19,064 - - 19,064 Depreciation and amortization 11,896 4,202 16,098 17,769 2,645 36,512 Taxes - other than income taxes 11,492 8,039 19,531 10,358 652 30,541 Merger and Acquisition-related expenses - - - - 469 469 Operating Income 15,193 16,684 31,877 4,048 347 36,272 Other Income and (Deductions), net 3,440 929 4,369 (308 ) (7,363 ) (3,302 ) Interest Charges, net 7,239 3,253 10,492 7,441 5,514 23,447 Income from Equity Investments 3,520 - 3,520 - - 3,520 Income (Loss) Before Income Taxes 14,914 14,360 29,274 (3,701 ) (12,530 ) 13,043 Income Taxes 3,740 5,362 9,102 (1,439 ) (3,923 ) 3,740 Net Income (Loss) 11,174 8,998 20,172 (2,262 ) (8,607 ) 9,303 Less: Preferred Stock Dividends of Subsidiary, Noncontrolling Interests - - - (40 ) - (40 ) Net Income (Loss) attributable to UIL Holdings $ 11,174 $ 8,998 $ 20,172 $ (2,222 ) $ (8,607 ) $ 9,343 Total Capital Expenditures (1) $ - $ - $ 26,290 $ 25,493 $ 9,066 $ 60,849 (In Thousands) Six months ended June 30, 2015 Electric Distribution and Transmission Distribution Transmission Total Gas Distribution Other Total Operating Revenues $ 322,691 $ 117,714 $ 440,405 $ 455,655 $ - $ 896,060 Purchased power and gas 133,817 - 133,817 217,017 (2,396 ) 348,438 Operation and maintenance 97,353 27,577 124,930 89,785 (10,364 ) 204,351 Transmission wholesale - 37,697 37,697 - - 37,697 Depreciation and amortization 27,124 8,561 35,685 40,260 6,719 82,664 Taxes - other than income taxes 28,242 16,536 44,778 27,762 609 73,149 Merger and acquisition-related expenses - - - - 6,795 6,795 Operating Income 36,155 27,343 63,498 80,831 (1,363 ) 142,966 Other Income and (Deductions), net 3,909 2,550 6,459 1,023 1,180 8,662 Interest Charges, net 16,190 6,766 22,956 13,682 11,656 48,294 Income from Equity Investments 6,876 - 6,876 - - 6,876 Income (Loss) Before Income Taxes 30,750 23,127 53,877 68,172 (11,839 ) 110,210 Income Taxes 8,948 8,854 17,802 25,513 (6,560 ) 36,755 Net Income (Loss) 21,802 14,273 36,075 42,659 (5,279 ) 73,455 Less: Preferred Stock Dividends of Subsidiary, Noncontrolling Interests - - - 14 - 14 Net Income (Loss) attributable to UIL Holdings $ 21,802 $ 14,273 $ 36,075 $ 42,645 $ (5,279 ) $ 73,441 Total Capital Expenditures (1) $ - $ - $ 78,211 $ 53,350 $ 27,608 $ 159,169 Six months ended June 30, 2014 Electric Distribution and Transmission Distribution Transmission Total Gas Distribution Other Total Operating Revenues $ 263,095 $ 120,789 $ 383,884 $ 522,072 $ - $ 905,956 Purchased power and gas 85,809 - 85,809 291,482 - 377,291 Operation and maintenance 92,463 24,593 117,056 85,811 (7,290 ) 195,577 Transmission wholesale - 39,975 39,975 - - 39,975 Depreciation and amortization 23,959 8,427 32,386 39,517 4,927 76,830 Taxes - other than income taxes 24,353 16,391 40,744 27,998 1,335 70,077 Merger and acquisition-related expenses - - - - 5,520 5,520 Operating Income 36,511 31,403 67,914 77,264 (4,492 ) 140,686 Other Income and (Deductions), net 6,626 1,912 8,538 (1,289 ) (13,102 ) (5,853 ) Interest Charges, net 15,071 6,457 21,528 14,204 10,949 46,681 Income from Equity Investments 6,906 - 6,906 - - 6,906 Income (Loss) Before Income Taxes 34,972 26,858 61,830 61,771 (28,543 ) 95,058 Income Taxes 9,842 9,214 19,056 24,978 (13,744 ) 30,290 Net Income (Loss) 25,130 17,644 42,774 36,793 (14,799 ) 64,768 Less: Preferred Stock Dividends of Subsidiary, Noncontrolling Interests - - - (27 ) - (27 ) Net Income (Loss) attributable to UIL Holdings $ 25,130 $ 17,644 $ 42,774 $ 36,820 $ (14,799 ) $ 64,795 Total Capital Expenditures (1) $ - $ - $ 60,077 $ 45,352 $ 20,112 $ 125,541
Reconciliation of Total Assets from Segments to Consolidated Financial Statements	Electric Distribution and Transmission (2) Distribution Transmission Total Gas Distribution (3) Other Total (3) Total Assets at June 30, 2015 $ - $ - $ 2,939,714 $ 2,072,868 $ 188,580 $ 5,201,162 Total Assets at December 31, 2014 $ - $ - $ 2,876,792 $ 2,087,284 $ 147,859 $ 5,111,935 (1) Information for segmenting total capital expenditures between Distribution and Transmission is not available. Total Electric Distribution and Transmission capital expenditures are disclosed in the Total Electric Distribution and Transmission column. (2) Information for segmenting total assets between Distribution and Transmission is not available. Total Electric Distribution and Transmission assets are disclosed in the Total Electric and Distribution and Transmission column. Net plant in service is segregated by segment and, as of June 30, 2015, was $1,304.9 million and $697.3 million for Distribution and Transmission, respectively. As of December 31, 2014, net plant in service was $1,283.6 million and $659.4 million for Distribution and Transmission, respectively. (3) Includes $266.2 million of goodwill in the Gas Distribution segment as of June 30, 2015 and December 31, 2014.

BUSINESS ORGANIZATION AND STA24

BUSINESS ORGANIZATION AND STATEMENT OF ACCOUNTING POLICIES (Details)	Jun. 30, 2015
Ownership percentage in GenConn [Abstract]
Ownership percentage in joint venture (in hundredths)	50.00%

BUSINESS ORGANIZATION AND STA25

BUSINESS ORGANIZATION AND STATEMENT OF ACCOUNTING POLICIES, Proposed Merger with Iberddrola USA and Philadelphia Gas Works (Details) $ / shares in Units, $ in Thousands	Jul. 31, 2015USD ($)UtilitiesContractor	Jun. 30, 2015USD ($)	Jun. 30, 2014USD ($)	Jun. 30, 2015USD ($)	Jun. 30, 2014USD ($)	Feb. 25, 2015$ / shares
Business Acquisition [Line Items]
Merger and acquisition-related expenses		$ 93	$ 469	$ 6,795	$ 5,520
Acquisition-related bridge facility fees		0	(7,926)	0	(14,339)
Philadelphia Gas Works [Member] | Bridge Facility [Member]
Business Acquisition [Line Items]
Merger and acquisition-related expenses			500		5,500
Pre-tax acquisition-related expenses			8,400		19,900
Acquisition-related bridge facility fees			$ 7,900		$ 14,300
Iberdrola USA [Member]
Business Acquisition [Line Items]
Cash consideration per share (in dollars per share) | $ / shares						$ 10.5
Percentage of ownership arise from merger (in hundredths)						18.50%
Rate credits to customers	$ 20,000
Clean energy fund and disaster relief contributions	7,000
Delayed capital recovery	7,000
Estimated remediation costs	$ 30,000
Number of Connecticut Utilities | Utilities	3
Employees or contractors | Contractor	150
Number of years over which to hire employees or contractors	3 years
Number of years over which to improve metrics	3 years
Merger and acquisition-related expenses		$ 100		$ 6,800

BUSINESS ORGANIZATION AND STA26

BUSINESS ORGANIZATION AND STATEMENT OF ACCOUNTING POLICIES, Derivatives (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015USD ($)CapacityResourceCapacityResources	Jun. 30, 2014USD ($)	Jun. 30, 2015USD ($)CapacityResourceCapacityResources	Jun. 30, 2014USD ($)	Dec. 31, 2014USD ($)
Derivatives [Abstract]
Number of new capacity resources selected | CapacityResource	4		4
Number of Contracts for Differences (CfDs) | CapacityResources	4		4
Gross derivative assets [Abstract]
Gross derivative asset	$ 32,800		$ 32,800
Regulatory asset	75,200		75,200
Current Assets	9,934		9,934		$ 6,849
Deferred Charges and Other Assets	22,887		22,887		20,421
Gross derivative liabilities [Abstract]
Gross derivative liability	107,200		107,200
Regulatory liabilities	900		900
Current Liabilities	27,513		27,513		23,308
Noncurrent Liabilities	79,643		79,643		$ 61,766
Unrealized gain and losses from mark-to-market adjustments [Abstract]
Regulatory Assets - Derivative liability	(2,812)	$ (10,397)	10,957	$ (82,017)
Regulatory Liabilities - Derivative assets	$ 6,173	$ (8,751)	$ 7,371	$ (11,693)
United Illuminating Company (UI) [Member]
Derivatives [Abstract]
Number of Contracts for Differences (CfDs) | CapacityResources	2		2
Percentage of contract costs or benefits assumed by customers (in hundredths)	20.00%
Gross derivative assets [Abstract]
Gross derivative asset	$ 1,500		$ 1,500
Gross derivative liabilities [Abstract]
Gross derivative liability	$ 68,000		$ 68,000
Connecticut Light and Power [Member]
Derivatives [Abstract]
Number of Contracts for Differences (CfDs) | CapacityResources	2		2
Percentage of contract costs or benefits assumed by customers (in hundredths)	80.00%

BUSINESS ORGANIZATION AND STA27

BUSINESS ORGANIZATION AND STATEMENT OF ACCOUNTING POLICIES, Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Numerator [Abstract]
Net income attributable to UIL Holdings		$ 15,839	$ 9,343	$ 73,441	$ 64,795
Less: Net income allocated to unvested units		8	6	39	38
Net income attributable to common shareholders		$ 15,831	$ 9,337	$ 73,402	$ 64,757
Denominator [Abstract]
Basic average number of shares outstanding (in shares)		56,950	56,842	56,918	56,814
Effect of dilutive securities (in shares)	[1]	291	260	311	265
Diluted average number of shares outstanding (in shares)		57,241	57,102	57,229	57,079
Earnings per share [Abstract]
Basic (in dollars per share)		$ 0.28	$ 0.16	$ 1.29	$ 1.14
Diluted (in dollars per share)		$ 0.28	$ 0.16	$ 1.28	$ 1.13
[1]	Includes unvested restricted stock and performance shares.

BUSINESS ORGANIZATION AND STA28

BUSINESS ORGANIZATION AND STATEMENT OF ACCOUNTING POLICIES, Equity Investments (Details) $ in Thousands	Jul. 24, 2015USD ($)Dekathermsdaymi	Jun. 30, 2015USD ($)Plant	Jun. 30, 2014USD ($)	Jun. 30, 2015USD ($)Plant	Jun. 30, 2014USD ($)	Dec. 31, 2014USD ($)
Equity Investments [Abstract]
Carrying value of joint venture		$ 112,910		$ 112,910		$ 114,195
Undistributed earnings in equity method investment		1,300		1,300
Income (loss) from equity investment		$ 3,940	$ 3,520	$ 6,876	$ 6,906
GenConn [Member]
Equity Investments [Abstract]
Number of peaking generation plants | Plant		2		2
Carrying value of joint venture		$ 112,900		$ 112,900		$ 114,200
Income (loss) from equity investment		3,900	3,500	6,900	6,900
Distributions received from joint venture		$ 2,700	$ 3,400	$ 8,100	$ 8,800
Northeast Expansion LLC [Member]
Equity Investments [Abstract]
Carrying value of joint venture	$ 1,200
Miles of natural gas pipeline segment | mi	188
Equity interest (in hundredths)	2.50%
Initial capital investment	$ 80,000
Additional optional equity interest (in hundredths)	12.50%
Agreement period	20 years
Pipeline capacity (dekatherms per day) | Dekathermsday	70,000

BUSINESS ORGANIZATION AND STA29

BUSINESS ORGANIZATION AND STATEMENT OF ACCOUNTING POLICIES, Regulatory Assets (Details) - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2015	Dec. 31, 2014
Regulatory Assets [Line Items]
Total Regulatory Assets		$ 784,078	$ 779,962
Less current portion of regulatory assets		102,987	92,764
Regulatory Assets, Net		681,091	687,198
Asset decoupling amount		2,600
Unamortized Redemption Costs [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets		$ 10,098	10,499
Unamortized Redemption Costs [Member] | Minimum [Member]
Regulatory Assets [Line Items]
Remaining period		7 years
Unamortized Redemption Costs [Member] | Maximum [Member]
Regulatory Assets [Line Items]
Remaining period		19 years
Pension and Other Post-Retirement Benefit Plans [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	[1]	$ 398,732	402,700
Environmental Remediation Costs [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets		$ 14,364	13,197
Remaining period		7 years
Hardship Programs [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	[2]	$ 19,055	24,744
Debt Premium [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets		$ 24,962	27,498
Debt Premium [Member] | Minimum [Member]
Regulatory Assets [Line Items]
Remaining period		2 years
Debt Premium [Member] | Maximum [Member]
Regulatory Assets [Line Items]
Remaining period		23 years
Income Taxes Due Principally to Book Tax Differences Assets [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	[3]	$ 167,526	164,466
Unfunded Future Income Taxes [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	[4]	16,734	14,859
Contracts For Differences [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	[5]	$ 75,233	64,276
Contracts For Differences [Member] | Minimum [Member]
Regulatory Assets [Line Items]
Term of contracts		5 years
Contracts For Differences [Member] | Maximum [Member]
Regulatory Assets [Line Items]
Term of contracts		12 years
Deferred Transmission Income/Expense [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	[6]	$ 23,914	17,387
Other [Member]
Regulatory Assets [Line Items]
Total Regulatory Assets	[7]	$ 35,260	$ 40,336
[1]	Life is dependent upon timing of final pension plan distribution; balance, which is fully offset by a corresponding asset/liability, is recalculated each year in accordance with ASC 715 "Compensation-Retirement Benefits." See Note (G) "Pension and Other Benefits" for additional information.
[2]	Hardship customer accounts deferred for future recovery to the extent they exceed the amount in rates.
[3]	Amortization period and/or balance vary depending on the nature and/or remaining life of the underlying assets/liabilities.
[4]	The balance will be extinguished when the asset, which is fully offset by a corresponding liability, or liability has been realized or settled, respectively.
[5]	Asset life is equal to delivery term of related contracts (which vary from approximately 5 - 12 years); balance fluctuates based upon quarterly market analysis performed on the related derivatives (Note K); amount, which does not earn a return, is fully offset by corresponding derivative asset/liability. See "-Contracts for Differences" discussion above for additional information.
[6]	Regulatory asset or liability which defers transmission income or expense and fluctuates based upon actual revenues and revenue requirements.
[7]	Amortization period and/or balance vary depending on the nature, cost of removal and/or remaining life of the underlying assets/liabilities; asset amount includes certain amounts that are not currently earning a return; asset amount includes decoupling of $2.6 million; liability amount includes decoupling of $16.5 million.

BUSINESS ORGANIZATION AND STA30

BUSINESS ORGANIZATION AND STATEMENT OF ACCOUNTING POLICIES, Regulatory Liabilities (Details) - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2015	Dec. 31, 2014
Regulatory Liabilities [Line Items]
Total regulatory liabilities		$ 554,000	$ 508,922
Less current portion of regulatory liabilities		44,242	17,026
Regulatory Liabilities, Net		509,758	491,896
Accumulated Deferred Investment Tax Credits [Member]
Regulatory Liabilities [Line Items]
Total regulatory liabilities		$ 7,282	4,319
Remaining period		29 years
Excess Generation Service Charge [Member]
Regulatory Liabilities [Line Items]
Total regulatory liabilities	[1]	$ 39,350	28,692
Middletown/Norwalk Local Transmission Network Service Collections [Member]
Regulatory Liabilities [Line Items]
Total regulatory liabilities		$ 20,542	20,828
Remaining period		35 years
Pension and Other Post-Retirement Benefit Plans [Member]
Regulatory Liabilities [Line Items]
Total regulatory liabilities	[2]	$ 10,851	9,536
Asset Retirement Obligation [Member]
Regulatory Liabilities [Line Items]
Total regulatory liabilities	[3]	7,155	7,248
Low Income Programs [Member]
Regulatory Liabilities [Line Items]
Total regulatory liabilities	[4]	29,064	19,065
Asset Removal Costs [Member]
Regulatory Liabilities [Line Items]
Total regulatory liabilities	[3]	342,346	336,028
Unfunded Future Income Taxes [Member]
Regulatory Liabilities [Line Items]
Total regulatory liabilities	[5]	26,812	26,318
Contracts For Differences [Member]
Regulatory Liabilities [Line Items]
Total regulatory liabilities	[6]	899	6,472
Deferred Purchased Gas [Member]
Regulatory Liabilities [Line Items]
Total regulatory liabilities	[7]	16,757	4,736
Non-Firm Margin Sharing Credits [Member]
Regulatory Liabilities [Line Items]
Total regulatory liabilities		$ 15,181	8,933
Remaining period		9 years
Other [Member]
Regulatory Liabilities [Line Items]
Total regulatory liabilities	[8]	$ 37,761	$ 36,747
Decoupling Liability [Member]
Regulatory Liabilities [Line Items]
Liability decoupling amount		$ 16,500
[1]	Regulatory asset or liability which defers generation-related and nonbypassable federally mandated congestion costs or revenues for future recovery from or return to customers. Amount fluctuates based upon timing differences between revenues collected from rates and actual costs incurred.
[2]	Life is dependent upon timing of final pension plan distribution; balance, which is fully offset by a corresponding asset/liability, is recalculated each year in accordance with ASC 715 "Compensation-Retirement Benefits." See Note (G) "Pension and Other Benefits" for additional information.
[3]	The liability will be extinguished simultaneous with the retirement of the assets and settlement of the corresponding asset retirement obligation.
[4]	Various hardship and payment plan programs approved for recovery.
[5]	The balance will be extinguished when the asset, which is fully offset by a corresponding liability, or liability has been realized or settled, respectively.
[6]	Asset life is equal to delivery term of related contracts (which vary from approximately 5 - 12 years); balance fluctuates based upon quarterly market analysis performed on the related derivatives (Note K); amount, which does not earn a return, is fully offset by corresponding derivative asset/liability. See "-Contracts for Differences" discussion above for additional information.
[7]	Deferred purchased gas costs balances at the end of the rate year are normally recorded/returned in the next year.
[8]	Amortization period and/or balance vary depending on the nature, cost of removal and/or remaining life of the underlying assets/liabilities; asset amount includes certain amounts that are not currently earning a return; asset amount includes decoupling of $2.6 million; liability amount includes decoupling of $16.5 million.

BUSINESS ORGANIZATION AND STA31

BUSINESS ORGANIZATION AND STATEMENT OF ACCOUNTING POLICIES, Stock-Based Compensation (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended		3 Months Ended		6 Months Ended
	May. 31, 2015	Mar. 31, 2015	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense			$ 1.7	$ 1.1	$ 5.4	$ 3.6
Management [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted (in shares)		94,410
Weighted average grant date fair value (in dollars per share)		$ 49.72
President and Chief Executive Officer [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted (in shares)		1,584
Weighted average grant date fair value (in dollars per share)		$ 49.72
Vesting period		5 years
Non-Employee Directors [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted (in shares)	18,801
Weighted average grant date fair value (in dollars per share)	$ 48.37

CAPITALIZATION (Details)

CAPITALIZATION (Details) - USD ($) $ / shares in Units, $ in Millions	Jun. 29, 2015	Jun. 30, 2015
Series G Senior Notes Due in 2045 [Member]
Capitalization [Abstract]
Long term debt interest percentage (in hundredths)	4.61%
Long-term debt payable	$ 50
Repayment of pollution control refunding revenue bonds	$ 27.5
Common Stock [Member]
Capitalization [Abstract]
Common stock outstanding (in shares)		56,629,082
Common stock par value (in dollars per share)		$ 0

REGULATORY PROCEEDINGS, Rates (

REGULATORY PROCEEDINGS, Rates (Details) - United Illuminating Company (UI) [Member]	6 Months Ended
	Jun. 30, 2015
Distribution Rates [Abstract]
Return on equity, approved (in hundredths)	9.15%
Profit sharing percentage (in hundredths)	50.00%

REGULATORY PROCEEDINGS, Power S

REGULATORY PROCEEDINGS, Power Supply Arrangements (Details) - Jun. 30, 2015 $ in Millions	USD ($)Rating
Power Supply Arrangements [Abstract]
Percentage of standard service customers with wholesale power supply agreements in place for the first half of 2016 (in hundredths)	50.00%
Collateral required to be posted if the entity's credit rating declined two ratings to fall below investment grade | $	$ 10.9
Standard & Poor's [Member]
Power Supply Arrangements [Abstract]
Number of changes in credit rating on senior debt to be placed on negative credit watch	1
Number of changes in credit rating on senior debt to fall below investment grade	2
Moody's [Member]
Power Supply Arrangements [Abstract]
Number of changes in credit rating on senior debt to be placed on negative credit watch	2
Number of changes in credit rating on senior debt to fall below investment grade	3

REGULATORY PROCEEDINGS, New Ren

REGULATORY PROCEEDINGS, New Renewable Source Generation (Details) - 6 months ended Jun. 30, 2015 - DEEP [Member] - Renewable Energy Contracts [Member] - Contract	Total
New Renewable Source Generation [Abstract]
Number of contracts for energy and/or RECs	2
Percentage of distribution load represented by quantity of energy and RECs to be purchased (in hundredths)	3.50%

REGULATORY PROCEEDINGS, Transmi

REGULATORY PROCEEDINGS, Transmission (Details) - United Illuminating Company (UI) [Member] $ in Millions	Oct. 16, 2014	Jun. 30, 2015USD ($)	Sep. 30, 2011	Jun. 30, 2014Complaint	Dec. 31, 2014
Minimum [Member]
Transmission [Abstract]
Weighted average return on equity		11.30%
Maximum [Member]
Transmission [Abstract]
Weighted average return on equity		11.40%
FERC [Member]
Transmission [Abstract]
Number of complaints | Complaint				3
Refund period		15 months
FERC [Member] | First Complaint [Member]
Transmission [Abstract]
Current approved base return on equity			11.14%
Reasonable Base Return on equity	10.57%
FERC [Member] | First Complaint [Member] | Minimum [Member]
Transmission [Abstract]
Reasonable Base Return on equity					10.57%
FERC [Member] | First Complaint [Member] | Maximum [Member]
Transmission [Abstract]
Reasonable Base Return on equity					11.74%
FERC [Member] | Third Complaint [Member]
Transmission [Abstract]
Refund amount held for reserve		$ 3.2
FERC [Member] | All Three Complaints [Member]
Transmission [Abstract]
Net pre-tax reserves relating to refunds and potential refunds		7
Cumulative reserves recorded for refund		11.4
Amount of reserve refunded		$ 4.4

REGULATORY PROCEEDINGS, New Eng

REGULATORY PROCEEDINGS, New England East-West Solution (Details) - CL&P Agreement [Member] $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015USD ($)Project	Jun. 30, 2014USD ($)	Jun. 30, 2015USD ($)Project	Jun. 30, 2014USD ($)
New England East-West Solution [Abstract]
Number of inter related transmission projects | Project	4		4
Number of inter-related transmission projects with portions sited in Connecticut | Project	3		3
Minimum amount of entity's investment for ownership of specific transmission assets	$ 60		$ 60
Threshold percentage of CL&P's costs for the Connecticut portions of projects (in hundredths)	8.40%		8.40%
Approximate investment rights	$ 45		$ 45
Aggregate deposits since inception of agreement	45		45
Pre-tax income earned on each deposit in NEEWS project	0.5	$ 0.4	1.1	$ 0.7
GSRP [Member]
New England East-West Solution [Abstract]
Value of transferred assets	24.6		24.6
IRP [Member]
New England East-West Solution [Abstract]
Value of transferred assets	$ 20		$ 20

REGULATORY PROCEEDINGS, Other P

REGULATORY PROCEEDINGS, Other Proceedings (Details) - Nov. 12, 2014 - United Illuminating Company (UI) [Member] - USD ($) $ in Millions	Total
GSC/NBFMCC Proceeding [Member]
Other Proceedings [Abstract]
Amount approved for recovery	$ 7.7
Total estimated loss	11.3
Pre-tax write-off	3.8
CTA Reconciliation Proceeding [Member]
Other Proceedings [Abstract]
Remaining CTA regulatory liability	8.2
CTA Reconciliation Proceeding [Member] | Connecticut Yankee Atomic Power Company Litigation [Member]
Other Proceedings [Abstract]
Regulatory liability related to CT Yankee DOE litigation	$ 12

REGULATORY PROCEEDINGS, Gas Dis

REGULATORY PROCEEDINGS, Gas Distribution (Details) $ in Millions	Jan. 22, 2014USD ($)Mechanism	Jun. 30, 2015USD ($)
Connecticut Natural Gas Corporation (CNG) [Member]
Gas Distribution Rates [Abstract]
Return on equity, approved (in hundredths)	9.18%	9.18%
Number of Decoupling mechanisms | Mechanism	1
Number of rate making mechanisms | Mechanism	2
Earnings share mechanism ratio	50/50
Connecticut Natural Gas Corporation (CNG) [Member] | Minimum [Member]
Gas Distribution Rates [Abstract]
Decrease in annual revenue requirements	$ 2.5
Connecticut Natural Gas Corporation (CNG) [Member] | Maximum [Member]
Gas Distribution Rates [Abstract]
Decrease in annual revenue requirements	$ 3.5
Connecticut Natural Gas Corporation (CNG) [Member] | Expansion Plan [Member]
Other Proceedings [Abstract]
Duration of expansion plan		10 years
Credit to customer		$ 10.8
The Southern Connecticut Gas Company (SCG) [Member]
Gas Distribution Rates [Abstract]
Return on equity, approved (in hundredths)		9.36%
DPU [Member] | The Berkshire Gas Company [Member]
Gas Distribution Rates [Abstract]
Return on equity, approved (in hundredths)		10.50%
Duration of approved rate plan		10 years

SHORT-TERM CREDIT ARRANGEMENTS

SHORT-TERM CREDIT ARRANGEMENTS (Details) $ in Millions	Jun. 30, 2015USD ($)
Revolving Credit Facility [Member]
Disclosure of short-term credit arrangements [Abstract]
Amounts outstanding under the Credit Facility	$ 80
Available credit under the Credit Facility	315.6
Standby Letters of Credit [Member]
Disclosure of short-term credit arrangements [Abstract]
Standby letters of credit outstanding	$ 4.4

INCOME TAXES (Details)

INCOME TAXES (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
INCOME TAXES [Abstract]
Increase in income tax expense	$ 7,400		$ 6,500
Income tax expense	$ 11,050	$ 3,740	$ 36,755	$ 30,290
Effective book income tax rates (in hundredths)	37.00%	33.40%	32.90%	33.40%
Income tax expense adjustment	$ 1,100		$ 1,100

SUPPLEMENTARY INFORMATION (Deta

SUPPLEMENTARY INFORMATION (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Depreciation and Amortization [Abstract]
Property, plant and equipment depreciation	$ 34,363	$ 32,360	$ 69,104	$ 64,348
Amortization of regulatory assets	5,017	4,152	13,560	12,482
Total Depreciation and Amortization	39,380	36,512	82,664	76,830
Taxes - Other than Income Taxes - Operating [Abstract]
Connecticut gross earnings	15,207	15,758	38,173	38,472
Local real estate and personal property	13,005	12,125	25,995	24,089
Payroll taxes	3,264	2,974	8,178	6,831
Other	358	(316)	803	685
Total Taxes - Other than Income Taxes	31,834	30,541	73,149	70,077
Other Income and (Deductions) [Abstract]
Interest income	672	523	1,381	1,065
Allowance for funds used during construction - equity	1,952	2,370	4,109	4,920
Allowance for funds used during construction - debt	1,086	1,421	2,132	2,831
Weather insurance	0	(531)	0	(2,437)
Other	584	841	1,040	2,107
Total Other Income and (Deductions)	$ 4,294	$ 4,624	$ 8,662	$ 8,486

PENSION AND OTHER BENEFITS (Det

PENSION AND OTHER BENEFITS (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Defined Benefit Plan Disclosure [Line Items]
Pension contributions			$ 10,000
Additional contribution during remainder of 2015			5,000
Pension Benefit [Member]
Components of net periodic benefit cost [Abstract]
Service cost	$ 3,605	$ 2,896	7,210	$ 5,792
Interest cost	10,505	11,019	21,010	22,038
Expected return on plan assets	(14,120)	(13,560)	(28,240)	(27,120)
Amortization of prior service costs	48	73	96	146
Amortization of actuarial (gain) loss	4,845	3,097	9,690	6,194
Net periodic benefit cost	$ 4,883	$ 3,525	$ 9,766	$ 7,050
Pension Benefit [Member] | Minimum [Member]
Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount rate (in hundredths)	4.20%	4.90%	4.20%	4.90%
Average wage increase (in hundredths)	3.50%	3.50%	3.50%	3.50%
Return on plan assets (in hundredths)	7.75%	7.75%	7.75%	7.75%
Pension Benefit [Member] | Maximum [Member]
Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount rate (in hundredths)	4.30%	5.20%	4.30%	5.20%
Average wage increase (in hundredths)	3.80%	3.80%	3.80%	3.80%
Return on plan assets (in hundredths)	8.00%	8.00%	8.00%	8.00%
Other Postretirement Benefits [Member]
Components of net periodic benefit cost [Abstract]
Service cost	$ 393	$ 404	$ 786	$ 808
Interest cost	1,327	1,487	2,654	2,974
Expected return on plan assets	(690)	(700)	(1,380)	(1,400)
Amortization of prior service costs	75	71	150	142
Amortization of actuarial (gain) loss	176	(172)	352	(344)
Net periodic benefit cost	$ 1,281	$ 1,090	$ 2,562	$ 2,180
Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Composite health care trend rate (current year) (in hundredths)	7.00%	7.00%	7.00%	7.50%
Composite health care trend rate (2019 forward) (in hundredths)	5.00%	5.00%	5.00%	5.00%
Other Postretirement Benefits [Member] | Minimum [Member]
Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount rate (in hundredths)	4.20%	4.85%	4.20%	4.85%
Return on plan assets (in hundredths)	5.56%	5.56%	5.56%	5.56%
Other Postretirement Benefits [Member] | Maximum [Member]
Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount rate (in hundredths)	4.30%	5.20%	4.30%	5.20%
Return on plan assets (in hundredths)	8.00%	8.00%	8.00%	8.00%

RELATED PARTY TRANSACTIONS (Det

RELATED PARTY TRANSACTIONS (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Director of UIL Holdings [Member] | Lease Payments for Office Space [Member]
Related Party Transaction [Line Items]
Lease payments for office space	$ 0.4	$ 0.5	$ 0.7	$ 0.9

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Details) - USD ($) $ in Millions	Jun. 30, 2014	Nov. 30, 2013	Sep. 03, 2013	Jul. 31, 2013	May. 31, 2012	Apr. 30, 2015	Jun. 30, 2015	Mar. 31, 2015
Connecticut Yankee Atomic Power Company [Member]
Litigation Settlement [Abstract]
Percentage of ownership in equity method investment (in hundredths)								9.50%
Carrying value of equity method investment								$ 0.2
United Illuminating Company (UI) [Member] | Middletown/Norwalk Transmission Projects [Member]
Litigation Settlement [Abstract]
Damages awarded and paid to plaintiff			$ 1.3
United Illuminating Company (UI) [Member] | New Haven Harbor Station Site [Member]
Site Decontamination, Demolition and Remediation Costs [Abstract]
Site contingency, liability accrued							$ 3.2
United Illuminating Company (UI) [Member] | English Station Site [Member]
Site Decontamination, Demolition and Remediation Costs [Abstract]
Estimated remediation costs							30
United Illuminating Company and Connecticut Yankee Atomic Power Company [Member] | DOE Spent Fuel Litigation [Member]
Litigation Settlement [Abstract]
Litigation, amount awarded	$ 12	$ 126.3		$ 3.8	$ 39.7
Loss contingency damage claims						$ 32.9
Contingent award amount						$ 3.1
Berkshire Gas Company [Member] | Mill Street Greenfield Massachusetts Site [Member]
Site Decontamination, Demolition and Remediation Costs [Abstract]
Site contingency, liability accrued							0.9
Berkshire Gas Company [Member] | East Street Site Pittsfield Massachusetts [Member]
Site Decontamination, Demolition and Remediation Costs [Abstract]
Site contingency, liability accrued							$ 3.2

FAIR VALUE MEASUREMENTS, Fair V

FAIR VALUE MEASUREMENTS, Fair Value of Financial Assets and Liabilities (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Assets [Abstract]
Derivative assets	$ 32,822	$ 27,270
Noncurrent investments	13,820	11,387
Deferred Compensation Plan	3,639	3,624
Supplemental retirement benefit trust life insurance policies	7,938	8,498
Total financial assets, fair value	58,219	50,779
Liabilities [Abstract]
Derivative liabilities	107,156	85,074
Long-term debt	1,976,832	1,941,711
Total financial liabilities, fair value	2,083,988	2,026,785
Net fair value assets/(liabilities)	(2,025,769)	(1,976,006)
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets [Abstract]
Derivative assets	0	0
Noncurrent investments	13,820	11,387
Deferred Compensation Plan	3,639	3,624
Supplemental retirement benefit trust life insurance policies	0	0
Total financial assets, fair value	17,459	15,011
Liabilities [Abstract]
Derivative liabilities	0	0
Long-term debt	0	0
Total financial liabilities, fair value	0	0
Net fair value assets/(liabilities)	17,459	15,011
Significant Other Observable Inputs (Level 2) [Member]
Assets [Abstract]
Derivative assets	0	0
Noncurrent investments	0	0
Deferred Compensation Plan	0	0
Supplemental retirement benefit trust life insurance policies	7,938	8,498
Total financial assets, fair value	7,938	8,498
Liabilities [Abstract]
Derivative liabilities	0	0
Long-term debt	1,976,832	1,941,711
Total financial liabilities, fair value	1,976,832	1,941,711
Net fair value assets/(liabilities)	(1,968,894)	(1,933,213)
Significant Unobservable Inputs (Level 3) [Member]
Assets [Abstract]
Derivative assets	32,822	27,270
Noncurrent investments	0	0
Deferred Compensation Plan	0	0
Supplemental retirement benefit trust life insurance policies	0	0
Total financial assets, fair value	32,822	27,270
Liabilities [Abstract]
Derivative liabilities	107,156	85,074
Long-term debt	0	0
Total financial liabilities, fair value	107,156	85,074
Net fair value assets/(liabilities)	$ (74,334)	$ (57,804)

FAIR VALUE MEASUREMENTS, Unobse

FAIR VALUE MEASUREMENTS, Unobservable Input Reconciliation (Details) - Contracts for Differences [Member] - USD ($)	Jun. 30, 2015	Dec. 31, 2014
Minimum [Member]
Unobservable Input [Abstract]
Risk of non-performance range (in hundredths)	0.00%	0.00%
Discount rate range (in hundredths)	1.63%	1.65%
Forward pricing range (in dollars per MW)	$ 3.15	$ 3.15
Maximum [Member]
Unobservable Input [Abstract]
Risk of non-performance range (in hundredths)	0.70%	0.66%
Discount rate range (in hundredths)	2.35%	2.25%
Forward pricing range (in dollars per MW)	$ 11.19	$ 14.59

FAIR VALUE MEASUREMENTS, Assets

FAIR VALUE MEASUREMENTS, Assets and Liabilities Classified as Level 3 (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2015USD ($)
Changes in fair value of assets and liabilities classified as level 3 [Roll Forward]
Net derivative assets/(liabilities), Beginning balance	$ (57,804)
Unrealized gains and (losses), net	(16,530)
Net derivative assets/(liabilities), Ending balance	(74,334)
Change in unrealized gains (losses), net relating to net derivative assets/(liabilities), still held as of June 30, 2015	$ (16,530)

FAIR VALUE MEASUREMENTS, Regula

FAIR VALUE MEASUREMENTS, Regulatory Assets and Liabilities (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2015USD ($)
Change in regulatory asset/liability balances [Roll Forward]
Net regulatory assets/(liabilities), Beginning balance	$ 57,804
Unrealized (gains) and losses, net	16,530
Net regulatory assets/(liabilities), Ending balance	$ 74,334

SEGMENT INFORMATION (Details)

SEGMENT INFORMATION (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Segment Reporting Information [Line Items]
Operating Revenues		$ 312,007	$ 334,794	$ 896,060	$ 905,956
Purchased power and gas		76,816	109,236	348,438	377,291
Operation and maintenance		103,004	102,700	204,351	195,577
Transmission wholesale		17,988	19,064	37,697	39,975
Depreciation and amortization		39,380	36,512	82,664	76,830
Taxes, other than income taxes		31,834	30,541	73,149	70,077
Merger and acquisition-related expenses		93	469	6,795	5,520
Operating Income		42,892	36,272	142,966	140,686
Other Income and (Deductions), net		4,294	(3,302)	8,662	(5,853)
Interest Charges, net		24,230	23,447	48,294	46,681
Income from Equity Investments		3,940	3,520	6,876	6,906
Income (Loss) Before Income Taxes		26,896	13,043	110,210	95,058
Income Taxes		11,050	3,740	36,755	30,290
Net Income (Loss)		15,846	9,303	73,455	64,768
Less: Preferred Stock Dividends of Subsidiary, Noncontrolling Interests		7	(40)	14	(27)
Net Income (Loss) attributable to UIL Holdings		15,839	9,343	73,441	64,795
Total Capital Expenditure	[1]	88,521	60,849	159,169	125,541
Total Assets	[2]	5,201,162		5,201,162		$ 5,111,935
Goodwill		266,205		266,205		266,205
Reporting Segments [Member] | Electric Distribution [Member]
Segment Reporting Information [Line Items]
Operating Revenues		130,803	117,906	322,691	263,095
Purchased power and gas		36,715	32,679	133,817	85,809
Operation and maintenance		50,049	46,646	97,353	92,463
Transmission wholesale		0	0	0	0
Depreciation and amortization		12,991	11,896	27,124	23,959
Taxes, other than income taxes		13,200	11,492	28,242	24,353
Merger and acquisition-related expenses		0	0	0	0
Operating Income		17,848	15,193	36,155	36,511
Other Income and (Deductions), net		1,968	3,440	3,909	6,626
Interest Charges, net		8,151	7,239	16,190	15,071
Income from Equity Investments		3,940	3,520	6,876	6,906
Income (Loss) Before Income Taxes		15,605	14,914	30,750	34,972
Income Taxes		5,095	3,740	8,948	9,842
Net Income (Loss)		10,510	11,174	21,802	25,130
Less: Preferred Stock Dividends of Subsidiary, Noncontrolling Interests		0	0	0	0
Net Income (Loss) attributable to UIL Holdings		10,510	11,174	21,802	25,130
Total Capital Expenditure	[1]	0	0	0	0
Total Assets	[3]	0		0		0
Net plant in service		1,304,900		1,304,900		1,283,600
Reporting Segments [Member] | Electric Transmission [Member]
Segment Reporting Information [Line Items]
Operating Revenues		59,632	62,001	117,714	120,789
Purchased power and gas		0	0	0	0
Operation and maintenance		14,089	14,012	27,577	24,593
Transmission wholesale		17,988	19,064	37,697	39,975
Depreciation and amortization		4,365	4,202	8,561	8,427
Taxes, other than income taxes		8,155	8,039	16,536	16,391
Merger and acquisition-related expenses		0	0	0	0
Operating Income		15,035	16,684	27,343	31,403
Other Income and (Deductions), net		1,065	929	2,550	1,912
Interest Charges, net		3,295	3,253	6,766	6,457
Income from Equity Investments		0	0	0	0
Income (Loss) Before Income Taxes		12,805	14,360	23,127	26,858
Income Taxes		4,993	5,362	8,854	9,214
Net Income (Loss)		7,812	8,998	14,273	17,644
Less: Preferred Stock Dividends of Subsidiary, Noncontrolling Interests		0	0	0	0
Net Income (Loss) attributable to UIL Holdings		7,812	8,998	14,273	17,644
Total Capital Expenditure	[1]	0	0	0	0
Total Assets	[3]	0		0		0
Net plant in service		697,300		697,300		659,400
Reporting Segments [Member] | Total Electric Distribution and Transmission [Member]
Segment Reporting Information [Line Items]
Operating Revenues		190,435	179,907	440,405	383,884
Purchased power and gas		36,715	32,679	133,817	85,809
Operation and maintenance		64,138	60,658	124,930	117,056
Transmission wholesale		17,988	19,064	37,697	39,975
Depreciation and amortization		17,356	16,098	35,685	32,386
Taxes, other than income taxes		21,355	19,531	44,778	40,744
Merger and acquisition-related expenses		0	0	0	0
Operating Income		32,883	31,877	63,498	67,914
Other Income and (Deductions), net		3,033	4,369	6,459	8,538
Interest Charges, net		11,446	10,492	22,956	21,528
Income from Equity Investments		3,940	3,520	6,876	6,906
Income (Loss) Before Income Taxes		28,410	29,274	53,877	61,830
Income Taxes		10,088	9,102	16,702	19,056
Net Income (Loss)		18,322	20,172	37,175	42,774
Less: Preferred Stock Dividends of Subsidiary, Noncontrolling Interests		0	0	0	0
Net Income (Loss) attributable to UIL Holdings		18,322	20,172	37,175	42,774
Total Capital Expenditure	[1]	40,129	26,290	78,211	60,077
Total Assets	[3]	2,939,714		2,939,714		2,876,792
Reporting Segments [Member] | Gas Distribution [Member]
Segment Reporting Information [Line Items]
Operating Revenues		121,572	154,887	455,655	522,072
Purchased power and gas		41,280	76,557	217,017	291,482
Operation and maintenance		43,938	46,155	89,785	85,811
Transmission wholesale		0	0	0	0
Depreciation and amortization		18,483	17,769	40,260	39,517
Taxes, other than income taxes		10,200	10,358	27,762	27,998
Merger and acquisition-related expenses		0	0	0	0
Operating Income		7,671	4,048	80,831	77,264
Other Income and (Deductions), net		564	(308)	1,023	(1,289)
Interest Charges, net		6,975	7,441	13,682	14,204
Income from Equity Investments		0	0	0	0
Income (Loss) Before Income Taxes		1,260	(3,701)	68,172	61,771
Income Taxes		(151)	(1,439)	25,513	24,978
Net Income (Loss)		1,411	(2,262)	42,659	36,793
Less: Preferred Stock Dividends of Subsidiary, Noncontrolling Interests		7	(40)	14	(27)
Net Income (Loss) attributable to UIL Holdings		1,404	(2,222)	42,645	36,820
Total Capital Expenditure	[1]	30,146	25,493	53,350	45,352
Total Assets	[2]	2,072,868		2,072,868		2,087,284
Goodwill		266,200		266,200		266,200
Reporting Segments [Member] | Other [Member]
Segment Reporting Information [Line Items]
Operating Revenues		0	0	0	0
Purchased power and gas		(1,179)	0	(2,396)	0
Operation and maintenance		(5,072)	(4,113)	(10,364)	(7,290)
Transmission wholesale		0	0	0	0
Depreciation and amortization		3,541	2,645	6,719	4,927
Taxes, other than income taxes		279	652	609	1,335
Merger and acquisition-related expenses		93	469	6,795	5,520
Operating Income		2,338	347	(1,363)	(4,492)
Other Income and (Deductions), net		697	(7,363)	1,180	(13,102)
Interest Charges, net		5,809	5,514	11,656	10,949
Income from Equity Investments		0	0	0	0
Income (Loss) Before Income Taxes		(2,774)	(12,530)	(11,839)	(28,543)
Income Taxes		1,113	(3,923)	(6,560)	(13,744)
Net Income (Loss)		(3,887)	(8,607)	(5,279)	(14,799)
Less: Preferred Stock Dividends of Subsidiary, Noncontrolling Interests		0	0	0	0
Net Income (Loss) attributable to UIL Holdings		(3,887)	(8,607)	(5,279)	(14,799)
Total Capital Expenditure	[1]	18,246	$ 9,066	27,608	$ 20,112
Total Assets		$ 188,580		$ 188,580		$ 147,859
[1]	Information for segmenting total capital expenditures between Distribution and Transmission is not available. Total Electric Distribution and Transmission capital expenditures are disclosed in the Total Electric Distribution and Transmission column.
[2]	Includes $266.2 million of goodwill in the Gas Distribution segment as of June 30, 2015 and December 31, 2014.
[3]	Information for segmenting total assets between Distribution and Transmission is not available. Total Electric Distribution and Transmission assets are disclosed in the Total Electric and Distribution and Transmission column. Net plant in service is segregated by segment and, as of June 30, 2015, was $1,304.9 million and $697.3 million for Distribution and Transmission, respectively. As of December 31, 2014, net plant in service was $1,283.6 million and $659.4 million for Distribution and Transmission, respectively.