Unitil (UTL) 10-Q 21 Apr 16 2016 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2016	Apr. 18, 2016
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q1
Trading Symbol	UTL
Entity Registrant Name	UNITIL CORP
Entity Central Index Key	755,001
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		14,043,758

CONSOLIDATED STATEMENTS OF EARN

CONSOLIDATED STATEMENTS OF EARNINGS - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Operating Revenues
Gas	$ 73.1	$ 100.3
Electric	51.1	70.3
Other	1.6	1.6
Total Operating Revenues	125.8	172.2
Operating Expenses
Cost of Gas Sales	37.2	61.5
Cost of Electric Sales	31	49.1
Operation and Maintenance	17.4	16.9
Depreciation and Amortization	11.8	11.4
Taxes Other than Income Taxes	5	4.9
Total Operating Expenses	102.4	143.8
Operating Income	23.4	28.4
Interest Expense, net	5.5	5.8
Other Expense, net		0.1
Income Before Income Taxes	17.9	22.5
Income Taxes	7	8.9
Net Income	$ 10.9	$ 13.6
Net Income Per Common Share (Basic and Diluted)	$ 0.78	$ 0.98
Weighted Average Common Shares Outstanding - (Basic and Diluted)	14	13.9
Dividends Declared Per Share of Common Stock	$ 0.355	$ 0.350

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Current Assets:
Cash and Cash Equivalents	$ 8.1	$ 8.7	$ 11.2
Accounts Receivable, net	58	49.8	85.9
Accrued Revenue	42.1	38.4	64.2
Exchange Gas Receivable	6.8	11.1	4
Gas Inventory	0.4	0.8	0.4
Prepayments and Other	12.7	11.7	11.8
Total Current Assets	128.1	120.5	177.5
Utility Plant:
Gas	586.8	576.8	529.7
Electric	409.9	408.4	393.7
Common	35.8	35.5	34.6
Construction Work in Progress	56.9	59.9	39.4
Total Utility Plant	1,089.4	1,080.6	997.4
Less: Accumulated Depreciation	276.3	271.7	259.2
Net Utility Plant	813.1	808.9	738.2
Other Noncurrent Assets:
Regulatory Assets	98.2	99.6	106.2
Other Assets	13.5	9.8	13.2
Total Other Noncurrent Assets	111.7	109.4	119.4
TOTAL ASSETS	1,052.9	1,038.8	1,035.1
Current Liabilities:
Accounts Payable	27	33.3	34.8
Short-Term Debt	47.9	42	32
Long-Term Debt, Current Portion	17.1	17.1	3.7
Regulatory Liabilities	18.8	15.6	39.4
Energy Supply Obligations	13.9	14.6	12.6
Environmental Obligations	0.7	1.3	3.4
Capital Lease Obligations	3.1	3.1	0.5
Interest Payable	6.1	3.4	6.3
Other Current Liabilities	11.4	13.9	7.4
Total Current Liabilities	146	144.3	140.1
Noncurrent Liabilities:
Retirement Benefit Obligations	126.8	124.4	121.4
Deferred Income Taxes	93.1	87.5	84.7
Cost of Removal Obligations	72.3	70.1	65.7
Regulatory Liabilities	3.3	8.1
Capital Lease Obligations	10.4	11	8.2
Environmental Obligations	2	1.5	2
Other Noncurrent Liabilities	3.5	3.6	3.8
Total Noncurrent Liabilities	311.4	306.2	285.8
Capitalization:
Long-Term Debt, Less Current Portion	305.4	305.5	325.9
Stockholders' Equity:
Common Equity (Authorized: 25,000,000 and Outstanding:14,043,280, 13,966,150 and 13,991,430 Shares)	238.9	237.5	236
Retained Earnings	51	45.1	47.1
Total Common Stock Equity	289.9	282.6	283.1
Preferred Stock	0.2	0.2	0.2
Total Stockholders' Equity	290.1	282.8	283.3
Total Capitalization	$ 595.5	$ 588.3	$ 609.2
Commitments and Contingencies (Notes 6 & 7)
TOTAL LIABILITIES AND CAPITALIZATION	$ 1,052.9	$ 1,038.8	$ 1,035.1

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - shares	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Common Stock Authorized	25,000,000	25,000,000	25,000,000
Common Equity Outstanding	14,043,280	13,991,430	13,966,150

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Operating Activities:
Net Income	$ 10.9	$ 13.6
Adjustments to Reconcile Net Income to Cash Provided by Operating Activities:
Depreciation and Amortization	11.8	11.4
Deferred Tax Provision	5.7	8.8
Changes in Working Capital Items:
Accounts Receivable	(8.2)	(25.2)
Accrued Revenue	(3.7)	6.3
Exchange Gas Receivable	4.3	11
Regulatory Liabilities	3.2	8.7
Accounts Payable	(6.3)	(9.4)
Other Changes in Working Capital Items	2.2	1
Deferred Regulatory and Other Charges	(8.4)	(3.1)
Other, net	2.7	4.6
Cash Provided by Operating Activities	14.2	27.7
Investing Activities:
Property, Plant and Equipment Additions	(11.3)	(13)
Cash (Used in) Investing Activities	(11.3)	(13)
Financing Activities:
Proceeds from Short-Term Debt, net	5.9	2.7
Repayment of Long-Term Debt	(0.2)	(0.2)
(Decrease) / Increase in Capital Lease Obligations	(0.6)	0.7
Net Decrease in Exchange Gas Financing	(3.9)	(10.5)
Dividends Paid	(5)	(4.9)
Proceeds from Issuance of Common Stock	0.3	0.3
Cash (Used in) Financing Activities	(3.5)	(11.9)
Net (Decrease) / Increase in Cash and Cash Equivalents	(0.6)	2.8
Cash and Cash Equivalents at Beginning of Period	8.7	8.4
Cash and Cash Equivalents at End of Period	8.1	11.2
Supplemental Cash Flow Information:
Interest Paid	2.9	3.1
Income Taxes Paid	1	1.4
Payments on Capital Leases	0.9	0.2
Non-cash Investing Activity:
Capital Expenditures Included in Accounts Payable	$ 0.5	$ 0.4

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN COMMON STOCK EQUITY - USD ($) $ in Millions	Total	Common Equity	Retained Earnings
Beginning Balance at Dec. 31, 2014	$ 273.1	$ 234.7	$ 38.4
Net Income	13.6		13.6
Dividends on Common Shares	(4.9)		(4.9)
Stock Compensation Plans	1	1
Issuance of 10,114 Common Shares	0.3	0.3
Ending Balance at Mar. 31, 2015	283.1	236	47.1
Beginning Balance at Dec. 31, 2015	282.6	237.5	45.1
Net Income	10.9		10.9
Dividends on Common Shares	(5)		(5)
Stock Compensation Plans	1.1	1.1
Issuance of 10,114 Common Shares	0.3	0.3
Ending Balance at Mar. 31, 2016	$ 289.9	$ 238.9	$ 51

CONSOLIDATED STATEMENTS OF CHA7

CONSOLIDATED STATEMENTS OF CHANGES IN COMMON STOCK EQUITY (Parenthetical) - shares	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Common stock, shares issued	8,630	10,114

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	3 Months Ended
	Mar. 31, 2016
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	NOTE 1 – SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Nature of Operations The Company’s earnings are seasonal and are typically higher in the first and fourth quarters when customers use natural gas for heating purposes. Unitil’s principal business is the local distribution of electricity in the southeastern seacoast and state capital regions of New Hampshire and the greater Fitchburg area of north central Massachusetts, and the local distribution of natural gas in southeastern New Hampshire, portions of southern and central Maine and in the greater Fitchburg area of north central Massachusetts. Unitil has three distribution utility subsidiaries, Unitil Energy, which operates in New Hampshire, Fitchburg, which operates in Massachusetts and Northern Utilities, which operates in New Hampshire and Maine (collectively referred to as the distribution utilities). Granite State is a natural gas transportation pipeline, operating 86 miles of underground gas transmission pipeline primarily located in Maine and New Hampshire. Granite State provides Northern Utilities with interconnection to three major natural gas pipelines and access to domestic natural gas supplies in the south and Canadian natural gas supplies in the north. Granite State derives its revenues principally from the transportation services provided to Northern Utilities and, to a lesser extent, third-party marketers. A fifth utility subsidiary, Unitil Power, formerly functioned as the full requirements wholesale power supply provider for Unitil Energy. In connection with the implementation of electric industry restructuring in New Hampshire, Unitil Power ceased being the wholesale supplier of Unitil Energy on May 1, 2003 and divested of its long-term power supply contracts through the sale of the entitlements to the electricity associated with various electric power supply contracts it had acquired to serve Unitil Energy’s customers. Unitil also has three other wholly-owned subsidiaries: Unitil Service; Unitil Realty; and Unitil Resources. Unitil Service provides, at cost, a variety of administrative and professional services, including regulatory, financial, accounting, human resources, engineering, operations, technology, energy management and management services on a centralized basis to its affiliated Unitil companies. Unitil Realty owns and manages the Company’s corporate office in Hampton, New Hampshire and leases this facility to Unitil Service under a long-term lease arrangement. Unitil Resources is the Company’s wholly-owned non-regulated subsidiary. Usource, Inc. and Usource L.L.C. (collectively, Usource) are wholly-owned subsidiaries of Unitil Resources. Usource provides brokering and advisory services to large commercial and industrial customers in the northeastern United States. Basis of Presentation – Income Taxes – Provisions for income taxes are calculated in each of the jurisdictions in which the Company operates for each period for which a statement of earnings is presented. The Company accounts for income taxes in accordance with the FASB Codification guidance on Income Taxes, which requires an asset and liability approach for the financial accounting and reporting of income taxes. Significant judgments and estimates are required in determining the current and deferred tax assets and liabilities. The Company’s current and deferred tax assets and liabilities reflect its best assessment of estimated future taxes to be paid. In accordance with the FASB Codification, the Company periodically assesses the realization of its deferred tax assets and liabilities and adjusts the income tax provision, the current tax liability and deferred taxes in the period in which the facts and circumstances which gave rise to the revision become known. In the first quarter of 2016, the Company adopted ASU 2015-17 which simplifies the presentation of deferred income taxes in a classified statement of financial position. Current generally accepted accounting principles (GAAP) require an entity to separate deferred income tax liabilities and assets into current and noncurrent amounts in a classified statement of financial position. ASU 2015-17 amends current GAAP to require that deferred tax liabilities and assets be classified as noncurrent in a classified statement of financial position. For all periods presented in this Form 10-Q for the quarter ended March 31, 2016, deferred income taxes are reported as “Deferred Income Taxes” in the “Noncurrent Liabilities section on the Consolidated Balance Sheets. Prior to adoption, the Company reported deferred income taxes in either the “Current Assets” or “Current Liabilities” and “Other Noncurrent Assets” or “Noncurrent Liabilities” sections on the Consolidated Balance Sheets, depending on whether the net current deferred income taxes and net noncurrent deferred income taxes were in an asset or liability position, respectively. The change in presentation for the quarter ended March 31, 2016 resulted in a reduction of both “Current Assets” and “Noncurrent Liabilities” for all prior periods presented. Cash and Cash Equivalents – Allowance for Doubtful Accounts – The Allowance for Doubtful Accounts as of March 31, 2016, March 31, 2015 and December 31, 2015, which are included in Accounts Receivable, net on the accompanying unaudited consolidated balance sheets, was as follows: ($ millions) March 31, December 31, 2016 2015 2015 Allowance for Doubtful Accounts $ 1.5 $ 1.9 $ 1.2 Accrued Revenue – March 31, December 31, Accrued Revenue ($ millions) 2016 2015 2015 Regulatory Assets – Current $ 33.7 $ 33.7 $ 26.8 Gas Pipeline Refund (Note 6) — 22.0 — Unbilled Revenues 8.4 8.5 11.6 Total Accrued Revenue $ 42.1 $ 64.2 $ 38.4 Exchange Gas Receivable – March 31, December 31, Exchange Gas Receivable ($ millions) 2016 2015 2015 Northern Utilities $ 6.3 $ 3.6 $ 10.3 Fitchburg 0.5 0.4 0.8 Total Exchange Gas Receivable $ 6.8 $ 4.0 $ 11.1 Gas Inventory March 31, December 31, Gas Inventory ($ millions) 2016 2015 2015 Natural Gas $ 0.1 $ 0.1 $ 0.3 Propane 0.2 0.2 0.3 Liquefied Natural Gas & Other 0.1 0.1 0.2 Total Gas Inventory $ 0.4 $ 0.4 $ 0.8 Utility Plant – Regulatory Accounting – March 31, December 31, Regulatory Assets consist of the following ($ millions) 2016 2015 2015 Retirement Benefits $ 64.4 $ 65.0 $ 64.7 Energy Supply & Other Regulatory Tracker Mechanisms 28.2 28.5 21.3 Deferred Storm Charges 13.8 20.1 15.4 Environmental 11.9 11.0 11.2 Income Taxes 8.3 9.5 8.5 Other 5.3 5.8 5.3 Total Regulatory Assets 131.9 139.9 126.4 Less: Current Portion of Regulatory Assets (1) 33.7 33.7 26.8 Regulatory Assets – noncurrent $ 98.2 $ 106.2 $ 99.6 (1) Reflects amounts included in Accrued Revenue, discussed above, on the Company’s Consolidated Balance Sheets. March 31, December 31, Regulatory Liabilities consist of the following ($ millions) 2016 2015 2015 Regulatory Tracker Mechanisms $ 12.0 $ 17.4 $ 8.0 Gas Pipeline Refund (Note 6) 10.1 22.0 15.7 Total Regulatory Liabilities 22.1 39.4 23.7 Less: Current Portion of Regulatory Liabilities 18.8 39.4 15.6 Regulatory Liabilities – noncurrent $ 3.3 $ — $ 8.1 Generally, the Company receives a return on investment on its regulated assets for which a cash outflow has been made. Included in Regulatory Assets as of March 31, 2016 are $5.8 million of deferred storm charges to be recovered over the next two and a half years and $8.3 million of environmental costs, rate case costs and other expenditures to be recovered over varying periods in the next seven and a half years. Regulators have authorized recovery of these expenditures, but without a return. Regulatory commissions can reach different conclusions about the recovery of costs, which can have a material impact on the Company’s Consolidated Financial Statements. The Company believes it is probable that its regulated distribution and transmission utilities will recover their investments in long-lived assets, including regulatory assets. If the Company, or a portion of its assets or operations, were to cease meeting the criteria for application of these accounting rules, accounting standards for businesses in general would become applicable and immediate recognition of any previously deferred costs, or a portion of deferred costs, would be required in the year in which the criteria are no longer met, if such deferred costs were not recoverable in the portion of the business that continues to meet the criteria for application of the FASB Codification topic on Regulated Operations. If unable to continue to apply the FASB Codification provisions for Regulated Operations, the Company would be required to apply the provisions for the Discontinuation of Rate-Regulated Accounting included in the FASB Codification. In the Company’s opinion, its regulated operations will be subject to the FASB Codification provisions for Regulated Operations for the foreseeable future. Derivatives – The Company has a regulatory approved hedging program for Northern Utilities designed to fix or cap a portion of its gas supply costs for the coming years of service. The Company purchases call option contracts on NYMEX natural gas futures contracts for future winter period months. Any gains or losses resulting from the change in the fair value of these derivatives are passed through to ratepayers directly through Northern Utilities’ Cost of Gas Clause. The fair value of these derivatives is determined using Level 2 inputs (valuations based on quoted prices in markets that are not active or for which all significant inputs are observable, either directly or indirectly), specifically based on the NYMEX closing prices for outstanding contracts as of the balance sheet date. As a result of the ratemaking process, the Company records gains and losses resulting from the change in fair value of the derivatives as regulatory liabilities or assets, then reclassifies these gains or losses into Cost of Gas Sales when the gains and losses are passed through to customers through the Cost of Gas Clause. As of March 31, 2016, March 31, 2015 and December 31, 2015 the Company had 1.8 billion, 2.0 billion and 2.5 billion cubic feet (BCF), respectively, outstanding in natural gas futures and options contracts under its hedging program. As of March 31, 2016 and 2015, the Company’s derivatives that are not designated as hedging instruments under FASB ASC 815-20 have a fair value of less than $0.1 million and $0.1 million, respectively. Investments in Marketable Securities At March 31, 2016, March 31, 2015 and December 31, 2015, the fair value of the Company’s investments in these trading securities, which are recorded on the Consolidated Balance Sheets in Other Assets, were $0.7 million, $0 and $0.7 million, respectively, as shown in the table below. These investments are valued based on quoted prices from active markets and are categorized in Level 1 as they are actively traded and no valuation adjustments have been applied. Changes in the fair value of these investments are recorded in Other Expense, net. March 31, December 31, Fair Value of Marketable Securities ($ millions) 2016 2015 2015 Equity Funds $ 0.4 $ — $ 0.4 Fixed Income Funds 0.3 — 0.3 Total Marketable Securities $ 0.7 $ — $ 0.7 Energy Supply Obligations – March 31, December 31, Energy Supply Obligations ($ millions) 2016 2015 2015 Current: Exchange Gas Obligation $ 6.3 $ 3.6 $ 10.3 Renewable Energy Portfolio Standards 7.3 8.5 4.0 Power Supply Contract Divestitures 0.3 0.5 0.3 Total Energy Supply Obligations – Current 13.9 12.6 14.6 Long-Term: Power Supply Contract Divestitures 1.5 1.9 1.6 Total Energy Supply Obligations $ 15.4 $ 14.5 $ 16.2 Exchange Gas Obligation – Northern Utilities enters into gas exchange agreements under which Northern Utilities releases certain natural gas pipeline and storage assets, resells the natural gas storage inventory to an asset manager and subsequently repurchases the inventory over the course of the natural gas heating season at the same price at which it sold the natural gas inventory to the asset manager. The gas inventory related to these agreements is recorded in Exchange Gas Receivable on the Company’s Consolidated Balance Sheets while the corresponding obligations are recorded in Energy Supply Obligations. Renewable Energy Portfolio Standards – Renewable Energy Portfolio Standards (RPS) require retail electricity suppliers, including public utilities, to demonstrate that required percentages of their sales are met with power generated from certain types of resources or technologies. Compliance is demonstrated by purchasing and retiring Renewable Energy Certificates (REC) generated by facilities approved by the state as qualifying for REC treatment. Unitil Energy and Fitchburg purchase RECs in compliance with RPS legislation in New Hampshire and Massachusetts for supply provided to default service customers. RPS compliance costs are a supply cost that is recovered in customer default service rates. Unitil Energy and Fitchburg collect RPS compliance costs from customers throughout the year and demonstrate compliance for each calendar year on the following July 1. Due to timing differences between collection of revenue from customers and payment of REC costs to suppliers, Unitil Energy and Fitchburg typically maintain accrued revenue for RPS compliance which is recorded in Accrued Revenue with a corresponding liability in Energy Supply Obligations on the Company’s Consolidated Balance Sheets. Fitchburg has entered into long-term renewable contracts for electric energy and/or renewable energy credits. The generating facilities associated with two of these contracts have been constructed and are operating. Another contract has been approved by the MDPU and is pending facility construction and operation, which is anticipated to begin by the end of 2016. Fitchburg will recover its costs under this contract through a regulatory approved cost tracker rate mechanism. Power Supply Contract Divestitures – As a result of the restructuring of the utility industry in New Hampshire and Massachusetts, Unitil Energy’s and Fitchburg’s customers have the opportunity to purchase their electric or natural gas supplies from third-party suppliers. In connection with the implementation of retail choice, Unitil Power, which formerly functioned as the wholesale power supply provider for Unitil Energy, and Fitchburg divested their long-term power supply contracts through the sale of the entitlements to the electricity sold under those contracts. Unitil Energy and Fitchburg recover in their rates all the costs associated with the divestiture of their power supply portfolios and have secured regulatory approval from the NHPUC and MDPU, respectively, for the recovery of power supply-related stranded costs. The obligations related to these divestitures are recorded in Energy Supply Obligations on the Company’s Consolidated Balance Sheets with corresponding regulatory assets recorded in Accrued Revenue (current portion) and Regulatory Assets (long-term portion). Massachusetts Green Communities Act – In compliance with the Massachusetts Green Communities Act, discussed below in Note 6, Regulatory Matters, Fitchburg has entered into long-term renewable contracts for electric energy and/or renewable energy credits. The facility associated with two of these contracts has been constructed and is operating. The other contracts are pending approval by the MDPU as well as subsequent facility construction and operation. These facilities are anticipated to begin operation by the end of 2016. Fitchburg will recover its costs associated with long-term renewable contracts on a fully reconciling basis through a MDPU-approved cost recovery mechanism. Debt Issuance Costs – For all periods presented in this Form 10-Q for the quarter ended March 31, 2016, unamortized debt issuance costs related to the Company’s long-term debt are reported on the Consolidated Balance Sheets as a reduction of the carrying value of the related debt. Prior to adoption, the Company reported the unamortized debt issuance costs in “Other Assets” on the Consolidated Balance Sheets. The change in presentation resulted in a reduction of “Other Assets” and “Long-Term Debt” of $3.1 million and $2.9 million as of March 31, 2015 and December 31, 2015, respectively. Recently Issued Pronouncements – In March 2016, the FASB issued ASU 2016-09, which provides for improvements to employee share-based payment accounting. ASU 2016-09 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2016. ASU 2016-09 simplifies several aspects of the accounting for employee share-based payment transactions, including the accounting for income taxes, forfeitures, and statutory tax withholding requirements, as well as classification in the statement of cash flows. The Company is evaluating the impact that this new guidance will have on the Company’s Consolidated Financial Statements. In February 2016, the FASB issued ASU 2016-02, which replaces the existing guidance in Accounting Standard Codification 840, Leases. ASU 2016-02 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2018. ASU 2016-02 requires a dual approach for lessee accounting under which a lessee would account for leases as finance (also referred to as capital) leases or operating leases. Both finance leases and operating leases will result in the lessee recognizing a right-of-use asset and corresponding lease liability. For finance leases the lessee would recognize interest expense and amortization of the right-of-use asset and for operating leases the lessee would recognize straight-line total lease expense. The Company is evaluating the impact that this new guidance will have on the Company’s Consolidated Financial Statements. Other than the pronouncements discussed above, there are no recently issued pronouncements that the Company has not already adopted or that have a material impact on the Company. Subsequent Events –

DIVIDENDS DECLARED PER SHARE

DIVIDENDS DECLARED PER SHARE	3 Months Ended
	Mar. 31, 2016
DIVIDENDS DECLARED PER SHARE	NOTE 2 – DIVIDENDS DECLARED PER SHARE Declaration Date Date Paid (Payable) Shareholder of Record Date Dividend Amount 04/20/16 05/27/16 05/13/16 $ 0.355 01/27/16 02/26/16 02/12/16 $ 0.355 10/21/15 11/27/15 11/13/15 $ 0.350 07/22/15 08/28/15 08/14/15 $ 0.350 04/22/15 05/28/15 05/14/15 $ 0.350 01/26/15 02/27/15 02/13/15 $ 0.350

SEGMENT INFORMATION

SEGMENT INFORMATION	3 Months Ended
	Mar. 31, 2016
SEGMENT INFORMATION	NOTE 3 – SEGMENT INFORMATION The following table provides significant segment financial data for the three months ended March 31, 2016 and March 31, 2015: Three Months Ended March 31, 2016 ($ millions) Gas Electric Non- Regulated Other Total Revenues $ 73.1 $ 51.1 $ 1.6 $ — $ 125.8 Segment Profit (Loss) 9.4 1.3 0.3 (0.1 ) 10.9 Identifiable Segment Assets 596.9 420.8 6.8 28.4 1,052.9 Capital Expenditures 3.1 5.7 — 2.5 11.3 Three Months Ended March 31, 2015 ($ millions) Revenues $ 100.3 $ 70.3 $ 1.6 $ — $ 172.2 Segment Profit 11.6 1.8 0.3 (0.1 ) 13.6 Identifiable Segment Assets 590.4 418.6 5.6 20.5 1,035.1 Capital Expenditures 7.2 4.4 — 1.4 13.0 As of December 31, 2015 ($ millions) Identifiable Segment Assets $ 590.9 $ 415.1 $ 6.5 $ 26.3 $ 1,038.8

DEBT AND FINANCING ARRANGEMENTS

DEBT AND FINANCING ARRANGEMENTS	3 Months Ended
	Mar. 31, 2016
DEBT AND FINANCING ARRANGEMENTS	NOTE 4 – DEBT AND FINANCING ARRANGEMENTS Details on long-term debt at March 31, 2016, March 31, 2015 and December 31, 2015 are shown below: ($ millions) March 31, December 31, 2016 2015 2015 Unitil Corporation Senior Notes: 6.33% Notes, Due May 1, 2022 $ 20.0 $ 20.0 $ 20.0 Unitil Energy Systems, Inc.: First Mortgage Bonds: 5.24% Series, Due March 2, 2020 15.0 15.0 15.0 8.49% Series, Due October 14, 2024 12.0 15.0 12.0 6.96% Series, Due September 1, 2028 20.0 20.0 20.0 8.00% Series, Due May 1, 2031 15.0 15.0 15.0 6.32% Series, Due September 15, 2036 15.0 15.0 15.0 Fitchburg Gas and Electric Light Company: Long-Term Notes: 6.75% Notes, Due November 30, 2023 11.4 15.2 11.4 7.37% Notes, Due January 15, 2029 12.0 12.0 12.0 7.98% Notes, Due June 1, 2031 14.0 14.0 14.0 6.79% Notes, Due October 15, 2025 10.0 10.0 10.0 5.90% Notes, Due December 15, 2030 15.0 15.0 15.0 Northern Utilities Senior Notes: 6.95% Senior Notes, Series A, Due December 3, 2018 30.0 30.0 30.0 5.29% Senior Notes, Due March 2, 2020 25.0 25.0 25.0 7.72% Senior Notes, Series B, Due December 3, 2038 50.0 50.0 50.0 4.42% Senior Notes, Due October 15, 2044 50.0 50.0 50.0 Granite State Senior Notes: 7.15% Senior Notes, Due December 15, 2018 10.0 10.0 10.0 Unitil Realty Corp.: Senior Secured Notes: 8.00% Notes, Due Through August 1, 2017 0.9 1.5 1.1 Total Long-Term Debt 325.3 332.7 325.5 Less: Unamortized Debt Issuance Costs 2.8 3.1 2.9 Total Long-Term Debt, net of Unamortized Debt Issuance Costs 322.5 329.6 322.6 Less: Current Portion 17.1 3.7 17.1 Total Long-term Debt, Less Current Portion $ 305.4 $ 325.9 $ 305.5 Fair Value of Long-Term Debt term debt would be estimated based on the quoted market prices for the same or similar issues, or on the current rates offered to the Company for debt of the same remaining maturities. The fair value of the Company’s long-term debt is estimated using Level 2 inputs (valuations based on quoted prices available in active markets for similar assets or liabilities, quoted prices for identical or similar assets or liabilities in inactive markets, inputs other than quoted prices that are directly observable, and inputs derived principally from market data.) In estimating the fair value of the Company’s long-term debt, the assumed market yield reflects the Moody’s Baa Utility Bond Average Yield. Costs, including prepayment costs, associated with the early settlement of long-term debt are not taken into consideration in determining fair value. ($ millions) March 31, December 31, 2016 2015 2015 Estimated Fair Value of Long-Term Debt $ 355.7 $ 385.3 $ 345.2 Credit Arrangements On October 4, 2013, the Company entered into an Amended and Restated Credit Agreement (the “Credit Facility”) with a syndicate of lenders which amended and restated in its entirety the Company’s prior credit agreement, dated as of November 26, 2008, as amended. The Credit Facility extends to October 4, 2018 and provides for a new borrowing limit of $120 million which includes a $25 million sublimit for the issuance of standby letters of credit. The Credit Facility provides Unitil with the ability to elect that borrowings under the Credit Facility bear interest under several options, including at a daily fluctuating rate of interest per annum equal to one-month London Interbank Offered Rate (LIBOR) plus 1.375%. Provided there is no event of default under the Credit Facility, the Company may on a one-time basis request an increase in the aggregate commitments under the Credit Facility by an aggregate additional amount of up to $30 million. On July 24, 2015, the Company entered into the First Amendment to the Credit Facility. The First Amendment provides for an extension of the scheduled termination date to October 4, 2020, reduces the daily fluctuating rate of interest per annum equal to one-month LIBOR plus 1.25%, and reduces other customary credit facility fees. All other terms and conditions of the Credit Facility, including affirmative and negative covenants, remain substantially unchanged. The Company utilizes the credit facility for cash management purposes related to its short-term operating activities. Total gross borrowings were $55.9 million and $70.8 million for the quarters ended March 31, 2016 and March 31, 2015, respectively. Total gross repayments were $50.0 million and $68.1 million for the quarters ended March 31, 2016 and March 31, 2015, respectively. The following table details the borrowing limits, amounts outstanding and amounts available under the revolving Credit Facility as of March 31, 2016, March 31, 2015 and December 31, 2015: Revolving Credit Facility ($ millions) March 31, December 31, 2016 2015 2015 Limit $ 120.0 $ 120.0 $ 120.0 Outstanding $ 47.9 $ 32.0 $ 42.0 Available $ 72.1 $ 88.0 $ 78.0 The Credit Facility contains customary terms and conditions for credit facilities of this type, including affirmative and negative covenants. There are restrictions on, among other things, Unitil’s and its subsidiaries’ ability to permit liens or incur indebtedness, and restrictions on Unitil’s ability to merge or consolidate with another entity or change its line of business. The affirmative and negative covenants under the Credit Facility shall apply to Unitil until the Credit Facility terminates and all amounts borrowed under the Credit Facility are paid in full (or with respect to letters of credit, they are cash collateralized). The only financial covenant in the Credit Facility provides that Unitil’s Funded Debt to Capitalization (as each term is defined in the Credit Facility) cannot exceed 65%, tested on a quarterly basis. At March 31, 2016, March 31, 2015 and December 31, 2015, the Company was in compliance with the covenants contained in the Credit Facility in effect on that date. The weighted average interest rates on all short-term borrowings were 1.7% and 1.6% for the three months ended March 31, 2016 and March 31, 2015, respectively. The weighted average interest rate on all short-term borrowings for the twelve months ended December 31, 2015 was 1.5%. Unitil Corporation and its utility subsidiaries, Fitchburg, Unitil Energy, and Northern Utilities are currently rated “BBB+” by Standard & Poor’s Ratings Services. In April 2014, Unitil Service Corp. entered into a financing arrangement, structured as a capital lease obligation, for various information systems and technology equipment. Final funding under this capital lease occurred on October 30, 2015, resulting in total funding of $13.4 million. The capital lease matures on September 30, 2020. As of March 31, 2016, there are $2.6 million of current and $9.8 million of noncurrent obligations under this capital lease on the Company’s Consolidated Balance Sheets. Northern Utilities enters into asset management agreements under which Northern Utilities releases certain natural gas pipeline and storage assets, resells the natural gas storage inventory to an asset manager and subsequently repurchases the inventory over the course of the natural gas heating season at the same price at which it sold the natural gas inventory to the asset manager. There was $6.7 million, $5.6 million and $10.8 million of natural gas storage inventory at March 31, 2016, March 31, 2015 and December 31, 2015, respectively, related to these asset management agreements. The amount of natural gas inventory released in March 2016 and payable in April 2016 is $0.4 million and is recorded in Accounts Payable at March 31, 2016. The amount of natural gas inventory released in March 2015 and payable in April 2015 was $2.0 million and is recorded in Accounts Payable at March 31, 2015. The amount of natural gas inventory released in December 2015 and payable in January 2016 was $0.6 million and was recorded in Accounts Payable at December 31, 2015. Guarantees The Company provides limited guarantees on certain energy and natural gas storage management contracts entered into by the distribution utilities. The Company’s policy is to limit the duration of these guarantees. As of March 31, 2016, there were approximately $18.6 million of guarantees outstanding and the longest term guarantee extends through August 2016. The Company also guarantees the payment of principal, interest and other amounts payable on the notes issued by Unitil Realty and Granite State. As of March 31, 2016, the principal amount outstanding for the 8% Unitil Realty notes was $0.9 million, and the principal amount outstanding for the 7.15% Granite State notes was $10.0 million.

COMMON STOCK AND PREFERRED STOC

COMMON STOCK AND PREFERRED STOCK	3 Months Ended
	Mar. 31, 2016
COMMON STOCK AND PREFERRED STOCK	NOTE 5 – COMMON STOCK AND PREFERRED STOCK Common Stock The Company’s common stock trades on the New York Stock Exchange under the symbol, “UTL.” The Company had 13,966,150, 13,991,430 and 14,043,280 shares of common stock outstanding at March 31, 2015, December 31, 2015 and March 31, 2016, respectively. Dividend Reinvestment and Stock Purchase Plan – Stock Plan – The maximum number of shares available for awards to participants under the Stock Plan is 677,500. The maximum number of shares that may be awarded in any one calendar year to any one participant is 20,000. In the event of any change in capitalization of the Company, the Compensation Committee is authorized to make an equitable adjustment to the number and kind of shares of common stock that may be delivered under the Stock Plan and, in addition, may authorize and make an equitable adjustment to the Stock Plan’s annual individual award limit. Restricted Shares Outstanding awards of Restricted Shares fully vest over a period of four years at a rate of 25% each year. During the vesting period, dividends on Restricted Shares underlying the award may be credited to a participant’s account. The Company may deduct or withhold, or require a participant to remit to the Company, an amount sufficient to satisfy any taxes required by federal, state, or local law or regulation to be withheld with respect to any taxable event arising in connection with an Award. For purposes of compensation expense, Restricted Shares vest immediately upon a participant becoming eligible for retirement, as defined in the Stock Plan. Prior to the end of the vesting period, the restricted shares are subject to forfeiture if the participant ceases to be employed by the Company other than due to the participant’s death. On January 26, 2016, 43,220 Restricted Shares were issued in conjunction with the Stock Plan with an aggregate market value at the date of issuance of approximately $1.6 million. There were 94,706 and 81,251 non-vested shares under the Stock Plan as of March 31, 2016 and 2015, respectively. The weighted average grant date fair value of these shares was $35.24 and $33.15, respectively. The compensation expense associated with the issuance of shares under the Stock Plan is being recognized over the vesting period and was $1.6 million and $1.3 million for the three months ended March 31, 2016 and 2015, respectively. At March 31, 2016, there was approximately $1.7 million of total unrecognized compensation cost under the Stock Plan which is expected to be recognized over approximately 2.9 years. There were no forfeitures or cancellations under the Stock Plan during the three months ended March 31, 2016. Restricted Stock Units Restricted Stock Units earn dividend equivalents and will generally be settled by payment to each Director as soon as practicable following the Director’s separation from service to the Company. The Restricted Stock Units will be paid such that the Director will receive (i) 70% of the shares of the Company’s common stock underlying the restricted stock units and (ii) cash in an amount equal to the fair market value of 30% of the shares of the Company’s common stock underlying the Restricted Stock Units. The equity portion of Restricted Stock Units activity during the three months ended March 31, 2016 in conjunction with the Stock Plan are presented in the following table: Restricted Stock Units (Equity Portion) Units Weighted Average Stock Price Restricted Stock Units as of December 31, 2015 33,588 $ 31.83 Restricted Stock Units Granted — — Dividend Equivalents Earned 304 $ 39.18 Restricted Stock Units Settled — — Restricted Stock Units as of March 31, 2016 33,892 $ 31.89 There were 23,819 Restricted Stock Units outstanding as of March 31, 2015 with a weighted average stock price of $29.94. Included in Other Noncurrent Liabilities on the Company’s Consolidated Balance Sheets as of March 31, 2016, March 31, 2015 and December 31, 2015 is $0.6 million, $0.4 million and $0.5 million, respectively, representing the fair value of liabilities associated with the portion of fully vested RSUs that will be settled in cash. Preferred Stock There was $0.2 million, or 1,898 shares, of Unitil Energy’s 6.00% Series Preferred Stock outstanding as of March 31, 2016 and December 31, 2015. There was $0.2 million, or 2,250 shares, of Unitil Energy’s 6.00% Series Preferred Stock outstanding as of March 31, 2015. There were less than $0.1 million of total dividends declared on Preferred Stock in each of the three month periods ended March 31, 2016 and March 31, 2015, respectively.

REGULATORY MATTERS

REGULATORY MATTERS	3 Months Ended
	Mar. 31, 2016
REGULATORY MATTERS	NOTE 6 – REGULATORY MATTERS UNITIL’S REGULATORY MATTERS ARE DESCRIBED IN NOTE 8 TO THE FINANCIAL STATEMENTS IN ITEM 8 OF PART II OF UNITIL CORPORATION’S FORM 10-K FOR DECEMBER 31, 2015 AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON JANUARY 28, 2016. Regulatory Matters Unitil Energy – Base Rates – Fitchburg – Base Rates – Electric – Fitchburg – Base Rates – Gas – Northern Utilities – Base Rates – Maine – Northern Utilities – Base Rates – New Hampshire – Northern Utilities – Pipeline Refund – Granite State – Base Rates – Major Storms – Fitchburg and Unitil Energy Fitchburg – 2011 Storm Cost Deferral and 2012 Storm Costs – As part of its May 30, 2014 order approving a base rate increase for Fitchburg, the MDPU approved the recovery over three years, without carrying charges, of $5.0 million of costs of repair for damage due to severe storms, including previously deferred costs incurred in 2011, as well as costs incurred in 2012 as a result of Superstorm Sandy. Unitil Energy – 2012 Storm Costs – On April 25, 2013, the NHPUC approved the recovery of $2.3 million of costs to repair damage to Unitil Energy’s electrical system resulting from Superstorm Sandy over a five-year period, with carrying charges at the Company’s long-term cost of debt, net of deferred taxes, or 4.52%, applied to the uncollected balance through the recovery period. Thanksgiving 2014 Snow Storm – Unitil Energy has requested recovery of $1.7 million for the repair of damage due to this storm through its approved storm reserve fund. The request remains pending. The Company does not believe that its storm restoration expenditures and the timing of cost recovery will have a material adverse impact on the Company’s financial condition or results of operations. NHPUC Energy Efficiency Resource Standard Proceeding – Unitil Energy – Other – Fitchburg – Electric Operations – Fitchburg – Gas Operations – Fitchburg – Service Quality – MDPU Service Quality Guidelines – Fitchburg – Other – On January 28, 2016 the MDPU approved Fitchburg’s Three-Year Energy Efficiency Plan for 2016-2018, subject to limited modifications and directives in the Order. The Department found that the savings goals included in each Three-Year Plan are reasonable and are consistent with the achievement of all available cost-effective energy efficiency; approved each Program Administrator’s program implementation cost budget for the Three-Year Plans; approved the performance incentive pool, mechanism, and payout rates; found that all proposed energy efficiency programs are cost-effective; found that funding sources are reasonable and that each Program Administrator may recover the funds to implement its energy efficiency plan through its EES; and found that each Program Administrator’s Three-Year Plan is consistent with the Green Communities Act, the Guidelines, and Department precedent. FERC Transmission Formula Rate Proceeding – Legal Proceedings The Company is involved in legal and administrative proceedings and claims of various types, which arise in the ordinary course of business. The Company believes, based upon information furnished by counsel and others, that the ultimate resolution of these claims will not have a material impact on its financial position, operating results or cash flows. In early 2009, a putative class action complaint was filed against Unitil’s Massachusetts based utility, Fitchburg, in Massachusetts’ Worcester Superior Court (the “Court”), (captioned Bellermann et al v. Fitchburg Gas and Electric Light Company). The Complaint seeks an unspecified amount of damages, including the cost of temporary housing and alternative fuel sources, emotional and physical pain and suffering and property damages allegedly incurred by customers in connection with the loss of electric service during the ice storm in Fitchburg’s service territory in December 2008. The Town of Lunenburg has filed a separate action in the Court arising out of the December 2008 ice storm. The Company continues to believe that both of these suits are without merit and will continue to defend itself vigorously. The Company believes, based upon information furnished by counsel and others, that the ultimate resolution of these suits will not have a material impact on its financial position, operating results or cash flows.

ENVIRONMENTAL MATTERS

ENVIRONMENTAL MATTERS	3 Months Ended
	Mar. 31, 2016
ENVIRONMENTAL MATTERS	NOTE 7 – ENVIRONMENTAL MATTERS UNITIL’S ENVIRONMENTAL MATTERS ARE DESCRIBED IN NOTE 8 TO THE FINANCIAL STATEMENTS IN ITEM 8 OF PART II OF UNITIL CORPORATION’S FORM 10-K FOR DECEMBER 31, 2015 AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON JANUARY 28, 2016. The Company’s past and present operations include activities that are generally subject to extensive and complex federal and state environmental laws and regulations. The Company believes it is in material compliance with applicable environmental and safety laws and regulations, and the Company believes that as of March 31, 2016, there were no material losses reasonably likely to be incurred in excess of recorded amounts. However, we cannot assure you that significant costs and liabilities will not be incurred in the future. It is possible that other developments, such as increasingly stringent federal, state or local environmental laws and regulations could result in increased environmental compliance costs. Northern Utilities Manufactured Gas Plant Sites – Although remediation at the site in Exeter has been substantially completed, sediment contamination attributed to the former MGP was identified off-site. This off-site location has been investigated and associated remediation activities were completed in January 2016. The closure report, submitted by Northern Utilities in 2016, is currently under review by the regulatory agency. At the site in Somersworth, the regulatory agency in February 2016 requested that Northern Utilities prepare a work plan to investigate an on-site, groundwater impact. Northern Utilities submitted the work plan in April 2016 and is awaiting regulatory approval to proceed. The site in Portland has been investigated and remedial activities have largely been completed. Final remediation activities were completed in the fourth quarter of 2015, and closure documentation is expected to be submitted to the regulatory agency in the second quarter of 2016. The State of Maine completed its taking of the site via eminent domain for the expansion of the adjacent marine terminal in the second quarter of 2014. As a result of this taking, and pursuant to an agreement between the State of Maine and Northern Utilities, future remedial activities necessitated as a result of development of the site will be primarily the responsibility of the State of Maine. The NHPUC and MPUC have approved regulatory mechanisms for the recovery of MGP environmental costs. For Northern Utilities’ New Hampshire division, the NHPUC has approved the recovery of MGP environmental costs over succeeding seven-year periods, without carrying costs. For Northern Utilities’ Maine division, the MPUC has authorized the recovery of environmental remediation costs over succeeding five-year periods, without carrying costs. The Environmental Obligations table below shows the amounts accrued for Northern Utilities related to estimated future cleanup costs associated with Northern Utilities’ environmental remediation obligations for former MGP sites. Corresponding Regulatory Assets were recorded to reflect that the future recovery of these environmental remediation costs is expected based on regulatory precedent and established practices. Fitchburg’s Manufactured Gas Plant Site – The Environmental Obligations table below shows the amounts accrued for Fitchburg related to estimated future cleanup costs for permanent remediation of the Sawyer Passway site with a corresponding Regulatory Asset recorded to reflect that the recovery of these environmental remediation costs are probable through the regulatory process. The amounts recorded do not assume any amounts are recoverable from insurance companies or other third parties. Fitchburg recovers the environmental response costs incurred at this former MGP site in gas rates pursuant to the terms of a cost recovery agreement approved by the MDPU. Pursuant to this agreement, Fitchburg is authorized to amortize and recover environmental response costs from gas customers over succeeding seven-year periods, without carrying costs. The Company’s ultimate liability for future environmental remediation costs, including MGP site costs, may vary from estimates, which may be adjusted as new information or future developments become available. Based on the Company’s current assessment of its environmental responsibilities, existing legal requirements and regulatory policies, the Company does not believe that these environmental costs will have a material adverse effect on the Company’s consolidated financial position or results of operations. The following table sets forth a summary of changes in the Company’s liability for Environmental Obligations for the three months ended March 31, 2016 and 2015. Environmental Obligations ($ millions) Fitchburg Northern Total Three months ended March 31, 2016 2015 2016 2015 2016 2015 Total Balance at Beginning of Period $ 1.2 $ 1.9 $ 1.6 $ 3.6 $ 2.8 $ 5.5 Additions — — 1.0 0.1 1.0 0.1 Less: Payments / Reductions — 0.1 1.1 0.1 1.1 0.2 Total Balance at End of Period 1.2 1.8 1.5 3.6 2.7 5.4 Less: Current Portion 0.2 1.8 0.5 1.6 0.7 3.4 Noncurrent Balance at End of Period $ 1.0 $ — $ 1.0 $ 2.0 $ 2.0 $ 2.0

INCOME TAXES

INCOME TAXES	3 Months Ended
	Mar. 31, 2016
INCOME TAXES	NOTE 8: INCOME TAXES The Company filed its tax returns for the year ended December 31, 2014 with the Internal Revenue Service (IRS) in September 2015. As of December 31, 2015, the Company had recorded cumulative federal NOL carryforward assets and Research and Development (R&D) credit carryforwards of $11.3 million to offset against taxes payable in future periods. If unused, the Company’s federal NOL carryforward assets will begin to expire in 2029, and the federal R&D credits will begin to expire in 2035. In addition, at December 31, 2015, the Company had $2.1 million of cumulative Alternative Minimum Tax (AMT) credit carryforwards to offset future AMT taxes payable indefinitely. In 2015, the Company recognized research and development tax credits under the rules of Section 41 of the Internal Revenue Code. The Company will continue to recognize a tax benefit on its incremental qualified research expenses. The Company evaluated its tax positions at March 31, 2016 in accordance with the FASB Codification, and has concluded that no adjustment for recognition, derecognition, settlement and foreseeable future events to any tax liabilities or assets as defined by the FASB Codification is required. The Company remains subject to examination by Federal, Maine, Massachusetts, and New Hampshire tax authorities for the tax periods ended December 31, 2012; December 31, 2013; and December 31, 2014. The Company bills its customers for sales tax in Massachusetts and Maine and consumption tax in New Hampshire. These taxes are remitted to the appropriate departments of revenue in each state and are excluded from revenues on the Company’s unaudited Consolidated Statements of Earnings.

RETIREMENT BENEFIT OBLIGATIONS

RETIREMENT BENEFIT OBLIGATIONS	3 Months Ended
	Mar. 31, 2016
RETIREMENT BENEFIT OBLIGATIONS	NOTE 9: RETIREMENT BENEFIT OBLIGATIONS The Company co-sponsors the Unitil Corporation Retirement Plan (Pension Plan), the Unitil Retiree Health and Welfare Benefits Plan (PBOP Plan), and the Unitil Corporation Supplemental Executive Retirement Plan (SERP) to provide certain pension and postretirement benefits for its retirees and current employees. Please see Note 10 to the Consolidated Financial Statements in the Company’s Form 10-K for the year ended December 31, 2015 as filed with the SEC on January 28, 2016 for additional information regarding these plans. The following table includes the key weighted average assumptions used in determining the Company’s benefit plan costs and obligations: 2016 2015 Used to Determine Plan Costs Discount Rate 4.30 % 4.00 % Rate of Compensation Increase 3.00 % 3.00 % Expected Long-term rate of return on plan assets 8.00 % 8.00 % Health Care Cost Trend Rate Assumed for Next Year 7.00 % 6.00 % Ultimate Health Care Cost Trend Rate 4.00 % 4.00 % Year that Ultimate Health Care Cost Trend Rate is reached 2022 2018 The following table provides the components of the Company’s Retirement plan costs ($000’s): Pension Plan PBOP Plan SERP Three Months Ended March 31, 2016 2015 2016 2015 2016 2015 Service Cost $ 851 $ 916 $ 652 $ 656 $ 41 $ 28 Interest Cost 1,486 1,343 808 729 96 78 Expected Return on Plan Assets (1,814 ) (1,694 ) (301 ) (273 ) — — Prior Service Cost Amortization 66 54 372 420 47 3 Actuarial Loss Amortization 1,099 1,180 262 288 94 84 Sub-total 1,688 1,799 1,793 1,820 278 193 Amounts Capitalized and Deferred (610 ) (708 ) (737 ) (760 ) — — Net Periodic Benefit Cost Recognized $ 1,078 $ 1,091 $ 1,056 $ 1,060 $ 278 $ 193 Employer Contributions As of March 31, 2016, the Company had made $1.0 million and $0.4 million of contributions to its Pension Plan and PBOP Plan, respectively, in 2016. The Company, along with its subsidiaries, expects to continue to make contributions to its Pension and PBOP Plans in 2016 and future years at minimum required and discretionary funding levels consistent with the amounts recovered in the distribution utilities’ rates for these Pension and PBOP Plan costs. As of March 31, 2016, the Company had made $8,500 of benefit payments under the SERP Plan in 2016. The Company presently anticipates making an additional $25,600 of benefit payments under the SERP Plan in 2016.

SUMMARY OF SIGNIFICANT ACCOUN17

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	3 Months Ended
	Mar. 31, 2016
Nature of Operations	Nature of Operations The Company’s earnings are seasonal and are typically higher in the first and fourth quarters when customers use natural gas for heating purposes. Unitil’s principal business is the local distribution of electricity in the southeastern seacoast and state capital regions of New Hampshire and the greater Fitchburg area of north central Massachusetts, and the local distribution of natural gas in southeastern New Hampshire, portions of southern and central Maine and in the greater Fitchburg area of north central Massachusetts. Unitil has three distribution utility subsidiaries, Unitil Energy, which operates in New Hampshire, Fitchburg, which operates in Massachusetts and Northern Utilities, which operates in New Hampshire and Maine (collectively referred to as the distribution utilities). Granite State is a natural gas transportation pipeline, operating 86 miles of underground gas transmission pipeline primarily located in Maine and New Hampshire. Granite State provides Northern Utilities with interconnection to three major natural gas pipelines and access to domestic natural gas supplies in the south and Canadian natural gas supplies in the north. Granite State derives its revenues principally from the transportation services provided to Northern Utilities and, to a lesser extent, third-party marketers. A fifth utility subsidiary, Unitil Power, formerly functioned as the full requirements wholesale power supply provider for Unitil Energy. In connection with the implementation of electric industry restructuring in New Hampshire, Unitil Power ceased being the wholesale supplier of Unitil Energy on May 1, 2003 and divested of its long-term power supply contracts through the sale of the entitlements to the electricity associated with various electric power supply contracts it had acquired to serve Unitil Energy’s customers. Unitil also has three other wholly-owned subsidiaries: Unitil Service; Unitil Realty; and Unitil Resources. Unitil Service provides, at cost, a variety of administrative and professional services, including regulatory, financial, accounting, human resources, engineering, operations, technology, energy management and management services on a centralized basis to its affiliated Unitil companies. Unitil Realty owns and manages the Company’s corporate office in Hampton, New Hampshire and leases this facility to Unitil Service under a long-term lease arrangement. Unitil Resources is the Company’s wholly-owned non-regulated subsidiary. Usource, Inc. and Usource L.L.C. (collectively, Usource) are wholly-owned subsidiaries of Unitil Resources. Usource provides brokering and advisory services to large commercial and industrial customers in the northeastern United States.
Basis of Presentation	Basis of Presentation –
Income Taxes	Income Taxes – Provisions for income taxes are calculated in each of the jurisdictions in which the Company operates for each period for which a statement of earnings is presented. The Company accounts for income taxes in accordance with the FASB Codification guidance on Income Taxes, which requires an asset and liability approach for the financial accounting and reporting of income taxes. Significant judgments and estimates are required in determining the current and deferred tax assets and liabilities. The Company’s current and deferred tax assets and liabilities reflect its best assessment of estimated future taxes to be paid. In accordance with the FASB Codification, the Company periodically assesses the realization of its deferred tax assets and liabilities and adjusts the income tax provision, the current tax liability and deferred taxes in the period in which the facts and circumstances which gave rise to the revision become known. In the first quarter of 2016, the Company adopted ASU 2015-17 which simplifies the presentation of deferred income taxes in a classified statement of financial position. Current generally accepted accounting principles (GAAP) require an entity to separate deferred income tax liabilities and assets into current and noncurrent amounts in a classified statement of financial position. ASU 2015-17 amends current GAAP to require that deferred tax liabilities and assets be classified as noncurrent in a classified statement of financial position. For all periods presented in this Form 10-Q for the quarter ended March 31, 2016, deferred income taxes are reported as “Deferred Income Taxes” in the “Noncurrent Liabilities section on the Consolidated Balance Sheets. Prior to adoption, the Company reported deferred income taxes in either the “Current Assets” or “Current Liabilities” and “Other Noncurrent Assets” or “Noncurrent Liabilities” sections on the Consolidated Balance Sheets, depending on whether the net current deferred income taxes and net noncurrent deferred income taxes were in an asset or liability position, respectively. The change in presentation for the quarter ended March 31, 2016 resulted in a reduction of both “Current Assets” and “Noncurrent Liabilities” for all prior periods presented.
Cash and Cash Equivalents	Cash and Cash Equivalents –
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts – The Allowance for Doubtful Accounts as of March 31, 2016, March 31, 2015 and December 31, 2015, which are included in Accounts Receivable, net on the accompanying unaudited consolidated balance sheets, was as follows: ($ millions) March 31, December 31, 2016 2015 2015 Allowance for Doubtful Accounts $ 1.5 $ 1.9 $ 1.2
Accrued Revenue	Accrued Revenue – March 31, December 31, Accrued Revenue ($ millions) 2016 2015 2015 Regulatory Assets – Current $ 33.7 $ 33.7 $ 26.8 Gas Pipeline Refund (Note 6) — 22.0 — Unbilled Revenues 8.4 8.5 11.6 Total Accrued Revenue $ 42.1 $ 64.2 $ 38.4
Exchange Gas Receivable	Exchange Gas Receivable – March 31, December 31, Exchange Gas Receivable ($ millions) 2016 2015 2015 Northern Utilities $ 6.3 $ 3.6 $ 10.3 Fitchburg 0.5 0.4 0.8 Total Exchange Gas Receivable $ 6.8 $ 4.0 $ 11.1
Gas Inventory	Gas Inventory March 31, December 31, Gas Inventory ($ millions) 2016 2015 2015 Natural Gas $ 0.1 $ 0.1 $ 0.3 Propane 0.2 0.2 0.3 Liquefied Natural Gas & Other 0.1 0.1 0.2 Total Gas Inventory $ 0.4 $ 0.4 $ 0.8
Utility Plant	Utility Plant –
Regulatory Accounting	Regulatory Accounting – March 31, December 31, Regulatory Assets consist of the following ($ millions) 2016 2015 2015 Retirement Benefits $ 64.4 $ 65.0 $ 64.7 Energy Supply & Other Regulatory Tracker Mechanisms 28.2 28.5 21.3 Deferred Storm Charges 13.8 20.1 15.4 Environmental 11.9 11.0 11.2 Income Taxes 8.3 9.5 8.5 Other 5.3 5.8 5.3 Total Regulatory Assets 131.9 139.9 126.4 Less: Current Portion of Regulatory Assets (1) 33.7 33.7 26.8 Regulatory Assets – noncurrent $ 98.2 $ 106.2 $ 99.6 (1) Reflects amounts included in Accrued Revenue, discussed above, on the Company’s Consolidated Balance Sheets. March 31, December 31, Regulatory Liabilities consist of the following ($ millions) 2016 2015 2015 Regulatory Tracker Mechanisms $ 12.0 $ 17.4 $ 8.0 Gas Pipeline Refund (Note 6) 10.1 22.0 15.7 Total Regulatory Liabilities 22.1 39.4 23.7 Less: Current Portion of Regulatory Liabilities 18.8 39.4 15.6 Regulatory Liabilities – noncurrent $ 3.3 $ — $ 8.1 Generally, the Company receives a return on investment on its regulated assets for which a cash outflow has been made. Included in Regulatory Assets as of March 31, 2016 are $5.8 million of deferred storm charges to be recovered over the next two and a half years and $8.3 million of environmental costs, rate case costs and other expenditures to be recovered over varying periods in the next seven and a half years. Regulators have authorized recovery of these expenditures, but without a return. Regulatory commissions can reach different conclusions about the recovery of costs, which can have a material impact on the Company’s Consolidated Financial Statements. The Company believes it is probable that its regulated distribution and transmission utilities will recover their investments in long-lived assets, including regulatory assets. If the Company, or a portion of its assets or operations, were to cease meeting the criteria for application of these accounting rules, accounting standards for businesses in general would become applicable and immediate recognition of any previously deferred costs, or a portion of deferred costs, would be required in the year in which the criteria are no longer met, if such deferred costs were not recoverable in the portion of the business that continues to meet the criteria for application of the FASB Codification topic on Regulated Operations. If unable to continue to apply the FASB Codification provisions for Regulated Operations, the Company would be required to apply the provisions for the Discontinuation of Rate-Regulated Accounting included in the FASB Codification. In the Company’s opinion, its regulated operations will be subject to the FASB Codification provisions for Regulated Operations for the foreseeable future.
Derivatives	Derivatives – The Company has a regulatory approved hedging program for Northern Utilities designed to fix or cap a portion of its gas supply costs for the coming years of service. The Company purchases call option contracts on NYMEX natural gas futures contracts for future winter period months. Any gains or losses resulting from the change in the fair value of these derivatives are passed through to ratepayers directly through Northern Utilities’ Cost of Gas Clause. The fair value of these derivatives is determined using Level 2 inputs (valuations based on quoted prices in markets that are not active or for which all significant inputs are observable, either directly or indirectly), specifically based on the NYMEX closing prices for outstanding contracts as of the balance sheet date. As a result of the ratemaking process, the Company records gains and losses resulting from the change in fair value of the derivatives as regulatory liabilities or assets, then reclassifies these gains or losses into Cost of Gas Sales when the gains and losses are passed through to customers through the Cost of Gas Clause. As of March 31, 2016, March 31, 2015 and December 31, 2015 the Company had 1.8 billion, 2.0 billion and 2.5 billion cubic feet (BCF), respectively, outstanding in natural gas futures and options contracts under its hedging program. As of March 31, 2016 and 2015, the Company’s derivatives that are not designated as hedging instruments under FASB ASC 815-20 have a fair value of less than $0.1 million and $0.1 million, respectively.
Investments in Marketable Securities	Investments in Marketable Securities At March 31, 2016, March 31, 2015 and December 31, 2015, the fair value of the Company’s investments in these trading securities, which are recorded on the Consolidated Balance Sheets in Other Assets, were $0.7 million, $0 and $0.7 million, respectively, as shown in the table below. These investments are valued based on quoted prices from active markets and are categorized in Level 1 as they are actively traded and no valuation adjustments have been applied. Changes in the fair value of these investments are recorded in Other Expense, net. March 31, December 31, Fair Value of Marketable Securities ($ millions) 2016 2015 2015 Equity Funds $ 0.4 $ — $ 0.4 Fixed Income Funds 0.3 — 0.3 Total Marketable Securities $ 0.7 $ — $ 0.7
Energy Supply Obligations	Energy Supply Obligations – March 31, December 31, Energy Supply Obligations ($ millions) 2016 2015 2015 Current: Exchange Gas Obligation $ 6.3 $ 3.6 $ 10.3 Renewable Energy Portfolio Standards 7.3 8.5 4.0 Power Supply Contract Divestitures 0.3 0.5 0.3 Total Energy Supply Obligations – Current 13.9 12.6 14.6 Long-Term: Power Supply Contract Divestitures 1.5 1.9 1.6 Total Energy Supply Obligations $ 15.4 $ 14.5 $ 16.2 Exchange Gas Obligation – Northern Utilities enters into gas exchange agreements under which Northern Utilities releases certain natural gas pipeline and storage assets, resells the natural gas storage inventory to an asset manager and subsequently repurchases the inventory over the course of the natural gas heating season at the same price at which it sold the natural gas inventory to the asset manager. The gas inventory related to these agreements is recorded in Exchange Gas Receivable on the Company’s Consolidated Balance Sheets while the corresponding obligations are recorded in Energy Supply Obligations. Renewable Energy Portfolio Standards – Renewable Energy Portfolio Standards (RPS) require retail electricity suppliers, including public utilities, to demonstrate that required percentages of their sales are met with power generated from certain types of resources or technologies. Compliance is demonstrated by purchasing and retiring Renewable Energy Certificates (REC) generated by facilities approved by the state as qualifying for REC treatment. Unitil Energy and Fitchburg purchase RECs in compliance with RPS legislation in New Hampshire and Massachusetts for supply provided to default service customers. RPS compliance costs are a supply cost that is recovered in customer default service rates. Unitil Energy and Fitchburg collect RPS compliance costs from customers throughout the year and demonstrate compliance for each calendar year on the following July 1. Due to timing differences between collection of revenue from customers and payment of REC costs to suppliers, Unitil Energy and Fitchburg typically maintain accrued revenue for RPS compliance which is recorded in Accrued Revenue with a corresponding liability in Energy Supply Obligations on the Company’s Consolidated Balance Sheets. Fitchburg has entered into long-term renewable contracts for electric energy and/or renewable energy credits. The generating facilities associated with two of these contracts have been constructed and are operating. Another contract has been approved by the MDPU and is pending facility construction and operation, which is anticipated to begin by the end of 2016. Fitchburg will recover its costs under this contract through a regulatory approved cost tracker rate mechanism. Power Supply Contract Divestitures – As a result of the restructuring of the utility industry in New Hampshire and Massachusetts, Unitil Energy’s and Fitchburg’s customers have the opportunity to purchase their electric or natural gas supplies from third-party suppliers. In connection with the implementation of retail choice, Unitil Power, which formerly functioned as the wholesale power supply provider for Unitil Energy, and Fitchburg divested their long-term power supply contracts through the sale of the entitlements to the electricity sold under those contracts. Unitil Energy and Fitchburg recover in their rates all the costs associated with the divestiture of their power supply portfolios and have secured regulatory approval from the NHPUC and MDPU, respectively, for the recovery of power supply-related stranded costs. The obligations related to these divestitures are recorded in Energy Supply Obligations on the Company’s Consolidated Balance Sheets with corresponding regulatory assets recorded in Accrued Revenue (current portion) and Regulatory Assets (long-term portion). Massachusetts Green Communities Act – In compliance with the Massachusetts Green Communities Act, discussed below in Note 6, Regulatory Matters, Fitchburg has entered into long-term renewable contracts for electric energy and/or renewable energy credits. The facility associated with two of these contracts has been constructed and is operating. The other contracts are pending approval by the MDPU as well as subsequent facility construction and operation. These facilities are anticipated to begin operation by the end of 2016. Fitchburg will recover its costs associated with long-term renewable contracts on a fully reconciling basis through a MDPU-approved cost recovery mechanism.
Debt Issuance Costs	Debt Issuance Costs – For all periods presented in this Form 10-Q for the quarter ended March 31, 2016, unamortized debt issuance costs related to the Company’s long-term debt are reported on the Consolidated Balance Sheets as a reduction of the carrying value of the related debt. Prior to adoption, the Company reported the unamortized debt issuance costs in “Other Assets” on the Consolidated Balance Sheets. The change in presentation resulted in a reduction of “Other Assets” and “Long-Term Debt” of $3.1 million and $2.9 million as of March 31, 2015 and December 31, 2015, respectively.
Recently Issued Pronouncements	Recently Issued Pronouncements – In March 2016, the FASB issued ASU 2016-09, which provides for improvements to employee share-based payment accounting. ASU 2016-09 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2016. ASU 2016-09 simplifies several aspects of the accounting for employee share-based payment transactions, including the accounting for income taxes, forfeitures, and statutory tax withholding requirements, as well as classification in the statement of cash flows. The Company is evaluating the impact that this new guidance will have on the Company’s Consolidated Financial Statements. In February 2016, the FASB issued ASU 2016-02, which replaces the existing guidance in Accounting Standard Codification 840, Leases. ASU 2016-02 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2018. ASU 2016-02 requires a dual approach for lessee accounting under which a lessee would account for leases as finance (also referred to as capital) leases or operating leases. Both finance leases and operating leases will result in the lessee recognizing a right-of-use asset and corresponding lease liability. For finance leases the lessee would recognize interest expense and amortization of the right-of-use asset and for operating leases the lessee would recognize straight-line total lease expense. The Company is evaluating the impact that this new guidance will have on the Company’s Consolidated Financial Statements. Other than the pronouncements discussed above, there are no recently issued pronouncements that the Company has not already adopted or that have a material impact on the Company.
Subsequent Events	Subsequent Events –

SUMMARY OF SIGNIFICANT ACCOUN18

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	3 Months Ended
	Mar. 31, 2016
Allowance for Doubtful Accounts Included in Accounts Receivable Net	The Allowance for Doubtful Accounts as of March 31, 2016, March 31, 2015 and December 31, 2015, which are included in Accounts Receivable, net on the accompanying unaudited consolidated balance sheets, was as follows: ($ millions) March 31, December 31, 2016 2015 2015 Allowance for Doubtful Accounts $ 1.5 $ 1.9 $ 1.2
Components of Accrued Revenue	The following table shows the components of Accrued Revenue as of March 31, 2016, March 31, 2015 and December 31, 2015. March 31, December 31, Accrued Revenue ($ millions) 2016 2015 2015 Regulatory Assets – Current $ 33.7 $ 33.7 $ 26.8 Gas Pipeline Refund (Note 6) — 22.0 — Unbilled Revenues 8.4 8.5 11.6 Total Accrued Revenue $ 42.1 $ 64.2 $ 38.4
Components of Exchange Gas Receivable	The following table shows the components of Exchange Gas Receivable as of March 31, 2016, March 31, 2015 and December 31, 2015. March 31, December 31, Exchange Gas Receivable ($ millions) 2016 2015 2015 Northern Utilities $ 6.3 $ 3.6 $ 10.3 Fitchburg 0.5 0.4 0.8 Total Exchange Gas Receivable $ 6.8 $ 4.0 $ 11.1
Components of Gas Inventory	The following table shows the components of Gas Inventory as of March 31, 2016, March 31, 2015 and December 31, 2015. March 31, December 31, Gas Inventory ($ millions) 2016 2015 2015 Natural Gas $ 0.1 $ 0.1 $ 0.3 Propane 0.2 0.2 0.3 Liquefied Natural Gas & Other 0.1 0.1 0.2 Total Gas Inventory $ 0.4 $ 0.4 $ 0.8
Regulatory Assets	March 31, December 31, Regulatory Assets consist of the following ($ millions) 2016 2015 2015 Retirement Benefits $ 64.4 $ 65.0 $ 64.7 Energy Supply & Other Regulatory Tracker Mechanisms 28.2 28.5 21.3 Deferred Storm Charges 13.8 20.1 15.4 Environmental 11.9 11.0 11.2 Income Taxes 8.3 9.5 8.5 Other 5.3 5.8 5.3 Total Regulatory Assets 131.9 139.9 126.4 Less: Current Portion of Regulatory Assets (1) 33.7 33.7 26.8 Regulatory Assets – noncurrent $ 98.2 $ 106.2 $ 99.6 (1) Reflects amounts included in Accrued Revenue, discussed above, on the Company’s Consolidated Balance Sheets.
Regulatory Liabilities	March 31, December 31, Regulatory Liabilities consist of the following ($ millions) 2016 2015 2015 Regulatory Tracker Mechanisms $ 12.0 $ 17.4 $ 8.0 Gas Pipeline Refund (Note 6) 10.1 22.0 15.7 Total Regulatory Liabilities 22.1 39.4 23.7 Less: Current Portion of Regulatory Liabilities 18.8 39.4 15.6 Regulatory Liabilities – noncurrent $ 3.3 $ — $ 8.1
Fair Value of Marketable Securities	These investments are valued based on quoted prices from active markets and are categorized in Level 1 as they are actively traded and no valuation adjustments have been applied. Changes in the fair value of these investments are recorded in Other Expense, net. March 31, December 31, Fair Value of Marketable Securities ($ millions) 2016 2015 2015 Equity Funds $ 0.4 $ — $ 0.4 Fixed Income Funds 0.3 — 0.3 Total Marketable Securities $ 0.7 $ — $ 0.7
Components of Energy Supply Obligations (Current Portion) and Other Noncurrent Liabilities (Noncurrent Portion)	March 31, December 31, Energy Supply Obligations ($ millions) 2016 2015 2015 Current: Exchange Gas Obligation $ 6.3 $ 3.6 $ 10.3 Renewable Energy Portfolio Standards 7.3 8.5 4.0 Power Supply Contract Divestitures 0.3 0.5 0.3 Total Energy Supply Obligations – Current 13.9 12.6 14.6 Long-Term: Power Supply Contract Divestitures 1.5 1.9 1.6 Total Energy Supply Obligations $ 15.4 $ 14.5 $ 16.2

DIVIDENDS DECLARED PER SHARE (T

DIVIDENDS DECLARED PER SHARE (Tables)	3 Months Ended
	Mar. 31, 2016
Schedule of Dividends Declared	Declaration Date Date Paid (Payable) Shareholder of Record Date Dividend Amount 04/20/16 05/27/16 05/13/16 $ 0.355 01/27/16 02/26/16 02/12/16 $ 0.355 10/21/15 11/27/15 11/13/15 $ 0.350 07/22/15 08/28/15 08/14/15 $ 0.350 04/22/15 05/28/15 05/14/15 $ 0.350 01/26/15 02/27/15 02/13/15 $ 0.350

SEGMENT INFORMATION (Tables)

SEGMENT INFORMATION (Tables)	3 Months Ended
	Mar. 31, 2016
Significant Segment Financial Data	The following table provides significant segment financial data for the three months ended March 31, 2016 and March 31, 2015: Three Months Ended March 31, 2016 ($ millions) Gas Electric Non- Regulated Other Total Revenues $ 73.1 $ 51.1 $ 1.6 $ — $ 125.8 Segment Profit (Loss) 9.4 1.3 0.3 (0.1 ) 10.9 Identifiable Segment Assets 596.9 420.8 6.8 28.4 1,052.9 Capital Expenditures 3.1 5.7 — 2.5 11.3 Three Months Ended March 31, 2015 ($ millions) Revenues $ 100.3 $ 70.3 $ 1.6 $ — $ 172.2 Segment Profit 11.6 1.8 0.3 (0.1 ) 13.6 Identifiable Segment Assets 590.4 418.6 5.6 20.5 1,035.1 Capital Expenditures 7.2 4.4 — 1.4 13.0 As of December 31, 2015 ($ millions) Identifiable Segment Assets $ 590.9 $ 415.1 $ 6.5 $ 26.3 $ 1,038.8

DEBT AND FINANCING ARRANGEMEN21

DEBT AND FINANCING ARRANGEMENTS (Tables)	3 Months Ended
	Mar. 31, 2016
Details on Long Term Debt	Details on long-term debt at March 31, 2016, March 31, 2015 and December 31, 2015 are shown below: ($ millions) March 31, December 31, 2016 2015 2015 Unitil Corporation Senior Notes: 6.33% Notes, Due May 1, 2022 $ 20.0 $ 20.0 $ 20.0 Unitil Energy Systems, Inc.: First Mortgage Bonds: 5.24% Series, Due March 2, 2020 15.0 15.0 15.0 8.49% Series, Due October 14, 2024 12.0 15.0 12.0 6.96% Series, Due September 1, 2028 20.0 20.0 20.0 8.00% Series, Due May 1, 2031 15.0 15.0 15.0 6.32% Series, Due September 15, 2036 15.0 15.0 15.0 Fitchburg Gas and Electric Light Company: Long-Term Notes: 6.75% Notes, Due November 30, 2023 11.4 15.2 11.4 7.37% Notes, Due January 15, 2029 12.0 12.0 12.0 7.98% Notes, Due June 1, 2031 14.0 14.0 14.0 6.79% Notes, Due October 15, 2025 10.0 10.0 10.0 5.90% Notes, Due December 15, 2030 15.0 15.0 15.0 Northern Utilities Senior Notes: 6.95% Senior Notes, Series A, Due December 3, 2018 30.0 30.0 30.0 5.29% Senior Notes, Due March 2, 2020 25.0 25.0 25.0 7.72% Senior Notes, Series B, Due December 3, 2038 50.0 50.0 50.0 4.42% Senior Notes, Due October 15, 2044 50.0 50.0 50.0 Granite State Senior Notes: 7.15% Senior Notes, Due December 15, 2018 10.0 10.0 10.0 Unitil Realty Corp.: Senior Secured Notes: 8.00% Notes, Due Through August 1, 2017 0.9 1.5 1.1 Total Long-Term Debt 325.3 332.7 325.5 Less: Unamortized Debt Issuance Costs 2.8 3.1 2.9 Total Long-Term Debt, net of Unamortized Debt Issuance Costs 322.5 329.6 322.6 Less: Current Portion 17.1 3.7 17.1 Total Long-term Debt, Less Current Portion $ 305.4 $ 325.9 $ 305.5
Fair Value of Long Term Debt	($ millions) March 31, December 31, 2016 2015 2015 Estimated Fair Value of Long-Term Debt $ 355.7 $ 385.3 $ 345.2
Borrowing Limits Amounts Outstanding and Amounts Available under Revolving Credit Facility	The following table details the borrowing limits, amounts outstanding and amounts available under the revolving Credit Facility as of March 31, 2016, March 31, 2015 and December 31, 2015: Revolving Credit Facility ($ millions) March 31, December 31, 2016 2015 2015 Limit $ 120.0 $ 120.0 $ 120.0 Outstanding $ 47.9 $ 32.0 $ 42.0 Available $ 72.1 $ 88.0 $ 78.0

COMMON STOCK AND PREFERRED ST22

COMMON STOCK AND PREFERRED STOCK (Tables)	3 Months Ended
	Mar. 31, 2016
Restricted Stock Units Issued	The equity portion of Restricted Stock Units activity during the three months ended March 31, 2016 in conjunction with the Stock Plan are presented in the following table: Restricted Stock Units (Equity Portion) Units Weighted Average Stock Price Restricted Stock Units as of December 31, 2015 33,588 $ 31.83 Restricted Stock Units Granted — — Dividend Equivalents Earned 304 $ 39.18 Restricted Stock Units Settled — — Restricted Stock Units as of March 31, 2016 33,892 $ 31.89

ENVIRONMENTAL MATTERS (Tables)

ENVIRONMENTAL MATTERS (Tables)	3 Months Ended
	Mar. 31, 2016
Environmental Obligations Recognized by Company	The following table sets forth a summary of changes in the Company’s liability for Environmental Obligations for the three months ended March 31, 2016 and 2015. Environmental Obligations ($ millions) Fitchburg Northern Total Three months ended March 31, 2016 2015 2016 2015 2016 2015 Total Balance at Beginning of Period $ 1.2 $ 1.9 $ 1.6 $ 3.6 $ 2.8 $ 5.5 Additions — — 1.0 0.1 1.0 0.1 Less: Payments / Reductions — 0.1 1.1 0.1 1.1 0.2 Total Balance at End of Period 1.2 1.8 1.5 3.6 2.7 5.4 Less: Current Portion 0.2 1.8 0.5 1.6 0.7 3.4 Noncurrent Balance at End of Period $ 1.0 $ — $ 1.0 $ 2.0 $ 2.0 $ 2.0

RETIREMENT BENEFIT OBLIGATIONS

RETIREMENT BENEFIT OBLIGATIONS (Tables)	3 Months Ended
	Mar. 31, 2016
Key Weighted Average Assumptions used in Determining Benefit Plan Costs and Obligations	The following table includes the key weighted average assumptions used in determining the Company’s benefit plan costs and obligations: 2016 2015 Used to Determine Plan Costs Discount Rate 4.30 % 4.00 % Rate of Compensation Increase 3.00 % 3.00 % Expected Long-term rate of return on plan assets 8.00 % 8.00 % Health Care Cost Trend Rate Assumed for Next Year 7.00 % 6.00 % Ultimate Health Care Cost Trend Rate 4.00 % 4.00 % Year that Ultimate Health Care Cost Trend Rate is reached 2022 2018
Components of Retirement Plan Costs	The following table provides the components of the Company’s Retirement plan costs ($000’s): Pension Plan PBOP Plan SERP Three Months Ended March 31, 2016 2015 2016 2015 2016 2015 Service Cost $ 851 $ 916 $ 652 $ 656 $ 41 $ 28 Interest Cost 1,486 1,343 808 729 96 78 Expected Return on Plan Assets (1,814 ) (1,694 ) (301 ) (273 ) — — Prior Service Cost Amortization 66 54 372 420 47 3 Actuarial Loss Amortization 1,099 1,180 262 288 94 84 Sub-total 1,688 1,799 1,793 1,820 278 193 Amounts Capitalized and Deferred (610 ) (708 ) (737 ) (760 ) — — Net Periodic Benefit Cost Recognized $ 1,078 $ 1,091 $ 1,056 $ 1,060 $ 278 $ 193

Summary of Significant Accoun25

Summary of Significant Accounting Policies - Additional Information (Detail) Bcf in Billions	Dec. 31, 2015USD ($)Bcf	Mar. 31, 2015USD ($)Bcf	Mar. 31, 2016USD ($)SubsidiarymiBcf
Significant Accounting Policies [Line Items]
Length Of Pipeline | mi			86
Cost of Removal Obligations	$ 70,100,000	$ 65,700,000	$ 72,300,000
Regulatory Assets	$ 126,400,000	$ 139,900,000	$ 131,900,000
Number of Natural Gas Storage Outstanding | Bcf	2.5	2	1.8
Investments in trading securities	$ 700,000	$ 0	$ 700,000
Reduction of other assets	(2,900,000)	(3,100,000)
Reduction of long-term debt	(2,900,000)	(3,100,000)
Maximum
Significant Accounting Policies [Line Items]
Cash equivalents maturity period			3 months
ISO-NE Obligations
Significant Accounting Policies [Line Items]
Cash Deposits	2,300,000	1,500,000	$ 2,100,000
Natural Gas Hedging Program
Significant Accounting Policies [Line Items]
Cash Deposits	0	0	0
Not Designated as Hedging Instruments | Maximum
Significant Accounting Policies [Line Items]
Derivative Assets, not designated as hedging instruments		100,000	100,000
Deferred Storm Charges
Significant Accounting Policies [Line Items]
Regulatory Assets	$ 15,400,000	$ 20,100,000	13,800,000
Deferred Storm Charges | Recovered over the next two and a half years
Significant Accounting Policies [Line Items]
Regulatory Assets			5,800,000
Environmental Costs Rate Case Costs And Other Expenditures | Recovered over the next seven and a half years
Significant Accounting Policies [Line Items]
Regulatory Assets			$ 8,300,000
Unitil Service; Unitil Realty; and Unitil Resources
Significant Accounting Policies [Line Items]
Number of Subsidiaries | Subsidiary			3
Utilities
Significant Accounting Policies [Line Items]
Number of Subsidiaries | Subsidiary			3

Allowance for Doubtful Accounts

Allowance for Doubtful Accounts Included in Accounts Receivable Net (Detail) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Valuation Allowance [Line Items]
Allowance for Doubtful Accounts	$ 1.5	$ 1.2	$ 1.9

Components of Accrued Revenue (

Components of Accrued Revenue (Detail) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Deferred Revenue Arrangement [Line Items]
Accrued Revenue	$ 42.1	$ 38.4	$ 64.2
Unbilled Revenues
Deferred Revenue Arrangement [Line Items]
Accrued Revenue	8.4	11.6	8.5
Gas Pipeline Refund
Deferred Revenue Arrangement [Line Items]
Accrued Revenue			22
Regulatory Assets
Deferred Revenue Arrangement [Line Items]
Accrued Revenue	$ 33.7	$ 26.8	$ 33.7

Exchange Gas Receivable (Detail

Exchange Gas Receivable (Detail) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Receivables [Line Items]
Total Exchange Gas Receivable	$ 6.8	$ 11.1	$ 4
Northern Utilities Inc
Receivables [Line Items]
Total Exchange Gas Receivable	6.3	10.3	3.6
Fitchburg Gas and Electric Light Company
Receivables [Line Items]
Total Exchange Gas Receivable	$ 0.5	$ 0.8	$ 0.4

Components of Gas Inventory (De

Components of Gas Inventory (Detail) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Public Utilities, Inventory [Line Items]
Weighted average cost inventory amount	$ 0.4	$ 0.8	$ 0.4
Liquefied Natural Gas & Other
Public Utilities, Inventory [Line Items]
Weighted average cost inventory amount	0.1	0.2	0.1
Natural Gas
Public Utilities, Inventory [Line Items]
Weighted average cost inventory amount	0.1	0.3	0.1
Propane
Public Utilities, Inventory [Line Items]
Weighted average cost inventory amount	$ 0.2	$ 0.3	$ 0.2

Regulatory Assets (Detail)

Regulatory Assets (Detail) - USD ($) $ in Millions		Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Regulatory Assets [Line Items]
Regulatory Assets		$ 131.9	$ 126.4	$ 139.9
Less: Current Portion of Regulatory Assets	[1]	33.7	26.8	33.7
Regulatory Assets - noncurrent		98.2	99.6	106.2
Environmental Matters
Regulatory Assets [Line Items]
Regulatory Assets		11.9	11.2	11
Other Assets
Regulatory Assets [Line Items]
Regulatory Assets		5.3	5.3	5.8
Retirement Benefits
Regulatory Assets [Line Items]
Regulatory Assets		64.4	64.7	65
Deferred Storm Charges
Regulatory Assets [Line Items]
Regulatory Assets		13.8	15.4	20.1
Income Taxes
Regulatory Assets [Line Items]
Regulatory Assets		8.3	8.5	9.5
Energy Supply & Other Regulatory Tracker Mechanisms
Regulatory Assets [Line Items]
Regulatory Assets		$ 28.2	$ 21.3	$ 28.5
[1]	Reflects amounts included in Accrued Revenue, discussed above, on the Company's Consolidated Balance Sheets.

Regulatory Liabilities (Detail)

Regulatory Liabilities (Detail) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Regulatory Liabilities [Line Items]
Regulatory Liabilities	$ 22.1	$ 23.7	$ 39.4
Less: Current Portion of Regulatory Liabilities	18.8	15.6	39.4
Regulatory Liabilities-noncurrent	3.3	8.1
Regulatory Tracker Mechanisms
Regulatory Liabilities [Line Items]
Regulatory Liabilities	12	8	17.4
Gas Pipeline Refund
Regulatory Liabilities [Line Items]
Regulatory Liabilities	$ 10.1	$ 15.7	$ 22

Fair Value of Marketable Securi

Fair Value of Marketable Securities (Detail) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Trading Securities	$ 0.7	$ 0.7	$ 0
Fair Value, Inputs, Level 1
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Trading Securities	0.7	0.7
Fair Value, Inputs, Level 1 | Equity Funds
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Trading Securities	0.4	0.4
Fair Value, Inputs, Level 1 | Fixed Income Funds
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Trading Securities	$ 0.3	$ 0.3

Energy Supply Obligations (Curr

Energy Supply Obligations (Current Portion) and Other Noncurrent Liabilities (Noncurrent Portion) (Detail) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Contractual Obligation [Line Items]
Energy Supply Obligations - Current	$ 13.9	$ 14.6	$ 12.6
Power Supply Contract Divestitures, Noncurrent	1.5	1.6	1.9
Total Energy Supply Obligations	15.4	16.2	14.5
Exchange Gas Obligation
Contractual Obligation [Line Items]
Energy Supply Obligations - Current	6.3	10.3	3.6
Renewable Energy Portfolio Standards
Contractual Obligation [Line Items]
Energy Supply Obligations - Current	7.3	4	8.5
Power Supply Contract Divestitures
Contractual Obligation [Line Items]
Energy Supply Obligations - Current	$ 0.3	$ 0.3	$ 0.5

Dividends Declared Per Share (D

Dividends Declared Per Share (Detail) - $ / shares	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Dividends Payable [Line Items]
Dividend Amount	$ 0.355	$ 0.350
Group One
Dividends Payable [Line Items]
Declaration Date	Apr. 20, 2016
Date Paid (Payable)	May 27, 2016
Shareholder of Record Date	May 13, 2016
Dividend Amount	$ 0.355
Group Two
Dividends Payable [Line Items]
Declaration Date	Jan. 27, 2016
Date Paid (Payable)	Feb. 26, 2016
Shareholder of Record Date	Feb. 12, 2016
Dividend Amount	$ 0.355
Group Three
Dividends Payable [Line Items]
Declaration Date	Oct. 21, 2015
Date Paid (Payable)	Nov. 27, 2015
Shareholder of Record Date	Nov. 13, 2015
Dividend Amount	$ 0.350
Group Four
Dividends Payable [Line Items]
Declaration Date	Jul. 22, 2015
Date Paid (Payable)	Aug. 28, 2015
Shareholder of Record Date	Aug. 14, 2015
Dividend Amount	$ 0.350
Group Five
Dividends Payable [Line Items]
Declaration Date	Apr. 22, 2015
Date Paid (Payable)	May 28, 2015
Shareholder of Record Date	May 14, 2015
Dividend Amount	$ 0.350
Group Six
Dividends Payable [Line Items]
Declaration Date	Jan. 26, 2015
Date Paid (Payable)	Feb. 27, 2015
Shareholder of Record Date	Feb. 13, 2015
Dividend Amount	$ 0.350

Significant Segment Financial D

Significant Segment Financial Data (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenues	$ 125.8	$ 172.2
Segment Profit	10.9	13.6
Identifiable Segment Assets	1,052.9	1,035.1	$ 1,038.8
Capital Expenditures	11.3	13
Gas Segment
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenues	73.1	100.3
Segment Profit	9.4	11.6
Identifiable Segment Assets	596.9	590.4	590.9
Capital Expenditures	3.1	7.2
Electricity
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenues	51.1	70.3
Segment Profit	1.3	1.8
Identifiable Segment Assets	420.8	418.6	415.1
Capital Expenditures	5.7	4.4
All Other Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Segment Profit	(0.1)	(0.1)
Identifiable Segment Assets	28.4	20.5	26.3
Capital Expenditures	2.5	1.4
Unregulated Operation
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenues	1.6	1.6
Segment Profit	0.3	0.3
Identifiable Segment Assets	$ 6.8	$ 5.6	$ 6.5

Details on Long Term Debt (Deta

Details on Long Term Debt (Detail) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Debt Instrument [Line Items]
Total Long-Term Debt	$ 325.3	$ 325.5	$ 332.7
Less: Unamortized Debt Issuance Costs	2.8	2.9	3.1
Long-Term Debt	322.5	322.6	329.6
Less: Current Portion	17.1	17.1	3.7
Total Long-term Debt, Less Current Portion	305.4	305.5	325.9
6.33% Notes, Due May 1, 2022
Debt Instrument [Line Items]
Senior Notes	20	20	20
Unitil Energy Systems Inc | First Mortgage Bonds 5.24% Series, Due March 2, 2020
Debt Instrument [Line Items]
Long-Term Debt	15	15	15
Unitil Energy Systems Inc | First Mortgage Bonds 8.49% Series, Due October 14, 2024
Debt Instrument [Line Items]
Long-Term Debt	12	12	15
Unitil Energy Systems Inc | First Mortgage Bonds 6.96% Series, Due September 1, 2028
Debt Instrument [Line Items]
Long-Term Debt	20	20	20
Unitil Energy Systems Inc | First Mortgage Bonds 8.00% Series, Due May 1, 2031
Debt Instrument [Line Items]
Long-Term Debt	15	15	15
Unitil Energy Systems Inc | First Mortgage Bonds 6.32% Series, Due September 15, 2036
Debt Instrument [Line Items]
Long-Term Debt	15	15	15
Fitchburg Gas and Electric Light Company | 6.75% Notes, Due November 30, 2023
Debt Instrument [Line Items]
Long-Term Debt	11.4	11.4	15.2
Fitchburg Gas and Electric Light Company | 7.37% Notes, Due January 15, 2029
Debt Instrument [Line Items]
Long-Term Debt	12	12	12
Fitchburg Gas and Electric Light Company | 7.98% Notes, Due June 1, 2031
Debt Instrument [Line Items]
Long-Term Debt	14	14	14
Fitchburg Gas and Electric Light Company | 6.79% Notes, Due October 15, 2025
Debt Instrument [Line Items]
Long-Term Debt	10	10	10
Fitchburg Gas and Electric Light Company | 5.90% Notes, Due December 15, 2030
Debt Instrument [Line Items]
Long-Term Debt	15	15	15
Northern Utilities Inc | 6.95% Senior Notes, Series A, Due December 3, 2018
Debt Instrument [Line Items]
Senior Notes	30	30	30
Northern Utilities Inc | 5.29% Senior Notes, Due March 2, 2020
Debt Instrument [Line Items]
Senior Notes	25	25	25
Northern Utilities Inc | 7.72% Senior Notes, Series B, Due December 3, 2038
Debt Instrument [Line Items]
Senior Notes	50	50	50
Northern Utilities Inc | 4.42% Senior Notes, Due October 15, 2044
Debt Instrument [Line Items]
Senior Notes	50	50	50
Granite State Gas Transmission Inc | 7.15% Senior Notes, Due December 15, 2018
Debt Instrument [Line Items]
Senior Notes	10	10	10
Unitil Realty Corp | 8.00% Senior Secured Notes, Due August 1, 2017
Debt Instrument [Line Items]
Senior Secured Notes	$ 0.9	$ 1.1	$ 1.5

Details on Long Term Debt (Pare

Details on Long Term Debt (Parenthetical) (Detail)	3 Months Ended		12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
6.33% Notes, Due May 1, 2022
Debt Instrument [Line Items]
Stated interest rate	6.33%	6.33%	6.33%
Debt instrument due date	May 1, 2022	May 1, 2022	May 1, 2022
First Mortgage Bonds 5.24% Series, Due March 2, 2020 | Unitil Energy Systems Inc
Debt Instrument [Line Items]
Stated interest rate	5.24%	5.24%	5.24%
Debt instrument due date	Mar. 2, 2020	Mar. 2, 2020	Mar. 2, 2020
First Mortgage Bonds 8.49% Series, Due October 14, 2024 | Unitil Energy Systems Inc
Debt Instrument [Line Items]
Stated interest rate	8.49%	8.49%	8.49%
Debt instrument due date	Oct. 14, 2024	Oct. 14, 2024	Oct. 14, 2024
First Mortgage Bonds 6.96% Series, Due September 1, 2028 | Unitil Energy Systems Inc
Debt Instrument [Line Items]
Stated interest rate	6.96%	6.96%	6.96%
Debt instrument due date	Sep. 1, 2028	Sep. 1, 2028	Sep. 1, 2028
First Mortgage Bonds 8.00% Series, Due May 1, 2031 | Unitil Energy Systems Inc
Debt Instrument [Line Items]
Stated interest rate	8.00%	8.00%	8.00%
Debt instrument due date	May 1, 2031	May 1, 2031	May 1, 2031
First Mortgage Bonds 6.32% Series, Due September 15, 2036 | Unitil Energy Systems Inc
Debt Instrument [Line Items]
Stated interest rate	6.32%	6.32%	6.32%
Debt instrument due date	Sep. 15, 2036	Sep. 15, 2036	Sep. 15, 2036
6.75% Notes, Due November 30, 2023 | Fitchburg Gas and Electric Light Company
Debt Instrument [Line Items]
Stated interest rate	6.75%	6.75%	6.75%
Debt instrument due date	Nov. 30, 2023	Nov. 30, 2023	Nov. 30, 2023
7.37% Notes, Due January 15, 2029 | Fitchburg Gas and Electric Light Company
Debt Instrument [Line Items]
Stated interest rate	7.37%	7.37%	7.37%
Debt instrument due date	Jan. 15, 2029	Jan. 15, 2029	Jan. 15, 2029
7.98% Notes, Due June 1, 2031 | Fitchburg Gas and Electric Light Company
Debt Instrument [Line Items]
Stated interest rate	7.98%	7.98%	7.98%
Debt instrument due date	Jun. 1, 2031	Jun. 1, 2031	Jun. 1, 2031
6.79% Notes, Due October 15, 2025 | Fitchburg Gas and Electric Light Company
Debt Instrument [Line Items]
Stated interest rate	6.79%	6.79%	6.79%
Debt instrument due date	Oct. 15, 2025	Oct. 15, 2025	Oct. 15, 2025
5.90% Notes, Due December 15, 2030 | Fitchburg Gas and Electric Light Company
Debt Instrument [Line Items]
Stated interest rate	5.90%	5.90%	5.90%
Debt instrument due date	Dec. 15, 2030	Dec. 15, 2030	Dec. 15, 2030
6.95% Senior Notes, Series A, Due December 3, 2018 | Northern Utilities Inc
Debt Instrument [Line Items]
Stated interest rate	6.95%	6.95%	6.95%
Debt instrument due date	Dec. 3, 2018	Dec. 3, 2018	Dec. 3, 2018
5.29% Senior Notes, Due March 2, 2020 | Northern Utilities Inc
Debt Instrument [Line Items]
Stated interest rate	5.29%	5.29%	5.29%
Debt instrument due date	Mar. 2, 2020	Mar. 2, 2020	Mar. 2, 2020
7.72% Senior Notes, Series B, Due December 3, 2038 | Northern Utilities Inc
Debt Instrument [Line Items]
Stated interest rate	7.72%	7.72%	7.72%
Debt instrument due date	Dec. 3, 2038	Dec. 3, 2038	Dec. 3, 2038
4.42% Senior Notes, Due October 15, 2044 | Northern Utilities Inc
Debt Instrument [Line Items]
Stated interest rate	4.42%	4.42%	4.42%
Debt instrument due date	Oct. 15, 2044	Oct. 15, 2044	Oct. 15, 2044
7.15% Senior Notes, Due December 15, 2018 | Granite State Gas Transmission Inc
Debt Instrument [Line Items]
Stated interest rate	7.15%	7.15%	7.15%
Debt instrument due date	Dec. 15, 2018	Dec. 15, 2018	Dec. 15, 2018
8.00% Senior Secured Notes, Due August 1, 2017 | Unitil Realty Corp
Debt Instrument [Line Items]
Stated interest rate	8.00%	8.00%	8.00%
Debt instrument due date	Aug. 1, 2017	Aug. 1, 2017	Aug. 1, 2017

Estimated Fair Value of Long Te

Estimated Fair Value of Long Term Debt (Detail) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Fair Value, Inputs, Level 2
Debt Instrument [Line Items]
Estimated Fair Value of Long-Term Debt	$ 355.7	$ 345.2	$ 385.3

Debt and Financing Arrangemen39

Debt and Financing Arrangements - Additional Information (Detail) - USD ($)	Jul. 24, 2015	Oct. 04, 2013	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015	Oct. 30, 2015
Line of Credit Facility [Line Items]
Weighted average interest rate on short term borrowings			1.70%	1.60%	1.50%
Capital lease obligation, current fact already tagged			$ 3,100,000	$ 500,000	$ 3,100,000
Capital lease obligation, noncurrent fact already tagged			10,400,000	8,200,000	11,000,000
Accounts Payable			27,000,000	34,800,000	33,300,000
Guarantee outstanding			18,600,000
Northern Utilities Inc
Line of Credit Facility [Line Items]
Natural gas storage inventory			6,700,000	5,600,000	10,800,000
Accounts Payable			$ 400,000	2,000,000	600,000
Unitil Service Corp.
Line of Credit Facility [Line Items]
Capital lease obligation, total capitalized cost						$ 13,400,000
Capital lease obligation, maturity period			Sep. 30, 2020
Capital lease obligation, current fact already tagged			$ 2,600,000
Capital lease obligation, noncurrent fact already tagged			9,800,000
Revolving Credit Facility
Line of Credit Facility [Line Items]
Revolving credit facility			120,000,000	120,000,000	120,000,000
Proceeds from lines of credit			55,900,000	70,800,000
Repayments of lines of credit			$ 50,000,000	68,100,000
Credit Facility | Revolving Credit Facility
Line of Credit Facility [Line Items]
Revolving credit facility expiration date		Oct. 4, 2018
Revolving credit facility		$ 120,000,000
Sublimit for the issuance of standby letters of credit		25,000,000
Credit Facility by an aggregate additional amount		$ 30,000,000
Percentage of capitalization			The affirmative and negative covenants under the Credit Facility shall apply to Unitil until the Credit Facility terminates and all amounts borrowed under the Credit Facility are paid in full (or with respect to letters of credit, they are cash collateralized). The only financial covenant in the Credit Facility provides that Unitil’s Funded Debt to Capitalization (as each term is defined in the Credit Facility) cannot exceed 65%, tested on a quarterly basis. At March 31, 2016, March 31, 2015 and December 31, 2015, the Company was in compliance with the covenants contained in the Credit Facility in effect on that date. (See also “Credit Arrangements” in Note 5.)
Credit Facility | Revolving Credit Facility | London Interbank Offered Rate (LIBOR)
Line of Credit Facility [Line Items]
Credit facility, daily fluctuating rate of interest		1.375%
Credit Facility | Amended Credit Facility
Line of Credit Facility [Line Items]
Revolving credit facility expiration date	Oct. 4, 2020
Credit Facility | Amended Credit Facility | London Interbank Offered Rate (LIBOR)
Line of Credit Facility [Line Items]
Credit facility, daily fluctuating rate of interest	1.25%
8.00% Senior Secured Notes, Due August 1, 2017 | Unitil Realty Corp
Line of Credit Facility [Line Items]
Senior Secured Notes			$ 900,000	1,500,000	1,100,000
7.15% Senior Notes, Due December 15, 2018 | Granite State Gas Transmission Inc
Line of Credit Facility [Line Items]
Senior Notes			$ 10,000,000	$ 10,000,000	$ 10,000,000

Borrowing Limits Amounts Outsta

Borrowing Limits Amounts Outstanding and Amounts Available under Revolving Credit Facility (Detail) - Revolving Credit Facility - USD ($)	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Debt Instrument [Line Items]
Revolving credit facility	$ 120,000,000	$ 120,000,000	$ 120,000,000
Outstanding revolving credit facility	47,900,000	42,000,000	32,000,000
Available revolving credit facility	$ 72,100,000	$ 78,000,000	$ 88,000,000

Common Stock and Preferred St41

Common Stock and Preferred Stock - Additional Information (Detail) - USD ($)	Jan. 26, 2016	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Class of Stock [Line Items]
Common stock, shares outstanding		14,043,280	13,966,150	13,991,430
Common stock, shares issued		8,630	10,114
Proceeds from Issuance of Common Stock		$ 300,000	$ 300,000
Share based compensation expense		$ 1,600,000	1,300,000
Percentage of fully-vested restricted stock units that directors will receive in common shares when settled		70.00%
Percentage of fully-vested restricted stock units that directors will receive in cash when settled		30.00%
Fair value of liabilities associated with fully vested RSUs that will be settled in cash		$ 600,000	400,000	$ 500,000
Preferred Stock		200,000	200,000	$ 200,000
Maximum
Class of Stock [Line Items]
Dividend declared		100,000	$ 100,000
Dividend and Distribution Reinvestment and Share Purchase Plan
Class of Stock [Line Items]
Proceeds from Issuance of Common Stock		$ 338,000
Dividend and Distribution Reinvestment and Share Purchase Plan | Average
Class of Stock [Line Items]
Common stock price per share		$ 39.19
Dividend and Distribution Reinvestment and Share Purchase Plan | Common Stock
Class of Stock [Line Items]
Common stock, shares issued		8,630
Unitil Energy Systems Inc | Series 6
Class of Stock [Line Items]
Preferred stock, outstanding		1,898	2,250	1,898
Preferred Stock		$ 200,000	$ 200,000	$ 200,000
Dividend rate		6.00%	6.00%	6.00%
Restricted Stock
Class of Stock [Line Items]
Restricted stock vesting period		4 years
Restricted stock non-vested		94,706	81,251
Restricted stock weighted average grant date fair value		$ 35.24	$ 33.15
Unrecognized share based compensation		$ 1,700,000
Share compensation recognition period		2 years 10 months 24 days
Forfeitures or cancellations under the stock plan		0
Restricted Shares issued	43,220
Aggregate Market Value	$ 1,600,000
Restricted Stock | Maximum
Class of Stock [Line Items]
Restricted stock available for awards		677,500
Restricted stock that may be awarded in any one calendar year to any one participant		20,000
Restricted Stock | Vesting Annually
Class of Stock [Line Items]
Restricted stock vesting percentage annually		25.00%
Restricted Stock Units (RSUs)
Class of Stock [Line Items]
Restricted Shares issued		0
Restricted stock units outstanding			23,819
Weighted-Average Stock Price			$ 29.94

Restricted Stock Units Issued (

Restricted Stock Units Issued (Detail) - Restricted Stock Units (RSUs)	3 Months Ended
	Mar. 31, 2016$ / sharesshares
Restricted Stock Units
Beginning Restricted Stock Units | shares	33,588
Restricted Stock Units Granted | shares	0
Dividend Equivalents Earned | shares	304
Restricted Stock Units Settled | shares	0
Ending Restricted Stock Units | shares	33,892
Weighted-Average Stock Price
Beginning Restricted Stock Units | $ / shares	$ 31.83
Restricted Stock Units Granted | $ / shares	0
Dividend Equivalents Earned | $ / shares	39.18
Restricted Stock Units Settled | $ / shares	0
Ending Restricted Stock Units | $ / shares	$ 31.89

Regulatory Matters - Additional

Regulatory Matters - Additional Information (Detail) - USD ($) $ in Millions	Mar. 30, 2016	Jun. 16, 2015	May. 01, 2015	Apr. 15, 2015	May. 30, 2014	Apr. 25, 2013	Mar. 31, 2016	Jun. 30, 2015	Dec. 31, 2014	Dec. 31, 2015	Mar. 31, 2015
Regulatory Assets [Line Items]
Current Portion of Regulatory Liabilities							$ 18.8			$ 15.6	$ 39.4
Regulatory Liabilities - non current							$ 3.3			$ 8.1
Fitchburg Gas and Electric Light Company
Regulatory Assets [Line Items]
Amendment effective date							May 1, 2016
Fitchburg Gas and Electric Light Company | Cumulative capital investments for 2015 and 2016
Regulatory Assets [Line Items]
Recovery amount							$ 0.9
Fitchburg Gas and Electric Light Company | Electric base
Regulatory Assets [Line Items]
Increase in annual revenue		$ 3.8
Percentage of approved return on equity		5.60%
Fitchburg Gas and Electric Light Company | Gas base
Regulatory Assets [Line Items]
Increase in annual revenue		$ 3
Percentage of approved return on equity		8.30%
Fitchburg Gas and Electric Light Company | Storm Costs
Regulatory Assets [Line Items]
Storm expenditures					$ 5
Cost recovery period, years					3 years
Unitil Energy Systems Inc
Regulatory Assets [Line Items]
Interest rate allowed by regulators on the unrecovered amount of storm costs which have been approved for recovery through rate adjustments						4.52%
Recovery of damage of electrical system						$ 1.7
Unitil Energy Systems Inc | New Hampshire
Regulatory Assets [Line Items]
Increase in base rates, amount	$ 6
Percent of increase in total revenue	4.00%
Unitil Energy Systems Inc | Storm Costs
Regulatory Assets [Line Items]
Cost recovery period, years						5 years
Recovery amount						$ 2.3
Northern Utilities Inc
Regulatory Assets [Line Items]
TIRA initial term							Four years
Pipeline refund received				$ 22
Current Portion of Regulatory Liabilities							$ 6.8
Regulatory Liabilities - non current							$ 3.3
Northern Utilities Inc | First Annual Adjustment
Regulatory Assets [Line Items]
Annual TIRA Adjustment									$ 1.5
Annual TIRA Adjustment, effective date							May 1, 2016
Northern Utilities Inc | 2014 Step Adjustments
Regulatory Assets [Line Items]
Increase in annual revenue							$ 1.4
Amendment effective date							May 1, 2014
Northern Utilities Inc | New Hampshire
Regulatory Assets [Line Items]
Increase in annual revenue			$ 1.8
Amendment effective date							May 1, 2015
Grace period to receive refund							3 years
Northern Utilities Inc | New Hampshire | Natural Gas Distribution
Regulatory Assets [Line Items]
Increase in annual revenue							$ 4.6
Northern Utilities Inc | Maine
Regulatory Assets [Line Items]
Grace period to receive refund							3 years
Date to receive a refund as one-time lump sum payment							Oct. 5, 2015
Granite State Gas Transmission Inc | Gas Transportation and Storage
Regulatory Assets [Line Items]
Increase in annual revenue								$ 0.4
Amendment effective date								Aug. 1, 2015

Environmental Matters - Additio

Environmental Matters - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2016USD ($)
Maine | Environmental Restoration Costs
Site Contingency [Line Items]
Amortization period for environmental costs	5 years
New Hampshire | Environmental Restoration Costs
Site Contingency [Line Items]
Amortization period for environmental costs	7 years
Environmental Matters
Site Contingency [Line Items]
Income (loss) incurred in excess of recorded amount	$ 0
Fitchburg Gas and Electric Light Company | Environmental Restoration Costs
Site Contingency [Line Items]
Amortization period for environmental costs	7 years

Company's Liability for Environ

Company's Liability for Environmental Obligations (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Environmental Exit Cost [Line Items]
Total Balance at Beginning of period	$ 2.8	$ 5.5
Additions	1	0.1
Less: Payments / Reductions	1.1	0.2
Total Balance at End of period	2.7	5.4
Less: Current Portion			$ 0.7	$ 1.3	$ 3.4
Noncurrent Balance			2	1.5	2
Total Balance at End of period	2.7	5.4	2.7	2.8	5.4
Fitchburg Gas and Electric Light Company
Environmental Exit Cost [Line Items]
Total Balance at Beginning of period	1.2	1.9
Less: Payments / Reductions		0.1
Total Balance at End of period	1.2	1.8
Less: Current Portion			0.2		1.8
Noncurrent Balance			1
Total Balance at End of period	1.2	1.8	1.2	1.2	1.8
Northern Utilities Inc
Environmental Exit Cost [Line Items]
Total Balance at Beginning of period	1.6	3.6
Additions	1	0.1
Less: Payments / Reductions	1.1	0.1
Total Balance at End of period	1.5	3.6
Less: Current Portion			0.5		1.6
Noncurrent Balance			1		2
Total Balance at End of period	$ 1.5	$ 3.6	$ 1.5	$ 1.6	$ 3.6

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Operating Loss Carryforwards [Line Items]
Alternative Minimum tax credit carryforwards		$ 2.1
Internal Revenue Service (IRS)
Operating Loss Carryforwards [Line Items]
NOL carryforward assets and Research and Development (R&D) credit carryforwards		$ 11.3
NOL carryforward assets expiration date		2,029
R&D credits expiration year		2,035
Federal
Operating Loss Carryforwards [Line Items]
Tax examination description	The Company remains subject to examination by Federal, Maine, Massachusetts, and New Hampshire tax authorities for the tax periods ended December 31, 2012; December 31, 2013; and December 31, 2014.

Key Weighted Average Assumption

Key Weighted Average Assumptions Used in Determining Benefit Plan Costs and Obligations (Detail) - Benefit Plan Costs	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Discount Rate	4.30%	4.00%
Rate of Compensation Increase	3.00%	3.00%
Expected Long-term rate of return on plan assets	8.00%	8.00%
Health Care Cost Trend Rate Assumed for Next Year	7.00%	6.00%
Ultimate Health Care Cost Trend Rate	4.00%	4.00%
Year that Ultimate Health Care Cost Trend Rate is reached	2,022	2,018

Components of Retirement Plan C

Components of Retirement Plan Costs (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Pension Plans
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Service Cost	$ 851	$ 916
Interest Cost	1,486	1,343
Expected Return on Plan Assets	(1,814)	(1,694)
Prior Service Cost Amortization	66	54
Actuarial Loss Amortization	1,099	1,180
Sub-total	1,688	1,799
Amounts Capitalized and Deferred	(610)	(708)
Net Periodic Benefit Cost Recognized	1,078	1,091
Other Postretirement Benefit Plans, Defined Benefit
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Service Cost	652	656
Interest Cost	808	729
Expected Return on Plan Assets	(301)	(273)
Prior Service Cost Amortization	372	420
Actuarial Loss Amortization	262	288
Sub-total	1,793	1,820
Amounts Capitalized and Deferred	(737)	(760)
Net Periodic Benefit Cost Recognized	1,056	1,060
Supplemental Employee Retirement Plans, Defined Benefit
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Service Cost	41	28
Interest Cost	96	78
Prior Service Cost Amortization	47	3
Actuarial Loss Amortization	94	84
Sub-total	278	193
Net Periodic Benefit Cost Recognized	$ 278	$ 193

Retirement Benefit Obligation49

Retirement Benefit Obligations - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2016USD ($)
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Contributions to benefit plan	$ 1,000,000
Other Postretirement Benefit Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Contributions to benefit plan	400,000
Supplemental Employee Retirement Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Benefit payments under SERP Plan	8,500
Expected additional benefit payments under SERP Plan in 2016	$ 25,600