Unitil (UTL) 10-Q 30 Apr 20 2020 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 31, 2020	Apr. 27, 2020
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Entity Interactive Data Current	Yes
Document Transition Report	false
Amendment Flag	false
Document Period End Date	Mar. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Entity Registrant Name	UNITIL CORP
Entity Central Index Key	0000755001
Entity File Number	1-8858
Entity Tax Identification Number	02-0381573
Entity Incorporation, State or Country Code	NH
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Address, Address Line One	6 Liberty Lane West
Entity Address, City or Town	Hampton
Entity Address, Postal Zip Code	03842-1720
Entity Address, State or Province	NH
City Area Code	603
Local Phone Number	772-0775
Trading Symbol	UTL
Security Exchange Name	NYSE
Entity Common Stock, Shares Outstanding		14,959,262
Title of 12(b) Security	Common Stock , no par value

CONSOLIDATED STATEMENTS OF EARN

CONSOLIDATED STATEMENTS OF EARNINGS - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating Revenues
Total Operating Revenues	$ 130.4	$ 152.1
Operating Expenses
Operation and Maintenance	17.9	18.5
Depreciation and Amortization	13.5	13.8
Taxes Other than Income Taxes	6.5	6.4
Total Operating Expenses	102.8	123.3
Operating Income	27.6	28.8
Interest Expense, Net	6.2	6.2
Other Expense (Income), Net	1.5	(12.1)
Income Before Income Taxes	19.9	34.7
Provision For Income Taxes	4.7	8.2
Net Income	$ 15.2	$ 26.5
Net Income Per Common Share (Basic and Diluted)	$ 1.02	$ 1.78
Weighted Average Common Shares Outstanding – (Basic and Diluted)	14.9	14.9
Gas
Operating Revenues
Total Operating Revenues	$ 70.2	$ 86.4
Operating Expenses
Total Operating Expenses	27.8	42.9
Electric
Operating Revenues
Total Operating Revenues	60.2	64.8
Operating Expenses
Total Operating Expenses	$ 37.1	41.7
Other
Operating Revenues
Total Operating Revenues		$ 0.9

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Current Assets:
Cash and Cash Equivalents	$ 6.2	$ 5.2	$ 4.3
Accounts Receivable, Net	62.6	55.1	73.9
Accrued Revenue	38.6	50	40.2
Exchange Gas Receivable	2.2	6.1	0.4
Gas Inventory	0.4	0.8	0.5
Materials and Supplies	9.2	7.9	7.8
Prepayments and Other	6.6	5.8	6.8
Total Current Assets	125.8	130.9	133.9
Utility Plant:
Gas	869.7	837.7	778.6
Electric	538.4	529.7	511.3
Common	62.8	62.7	61.1
Construction Work in Progress	43.3	37.4	26.1
Total Utility Plant	1,514.2	1,467.5	1,377.1
Less: Accumulated Depreciation	389.1	356	339.3
Net Utility Plant	1,125.1	1,111.5	1,037.8
Other Noncurrent Assets:
Regulatory Assets	105.3	112	97.9
Operating Lease Right of Use Assets	4.9	4	3.9
Other Assets	17.3	12.4	16.7
Total Other Noncurrent Assets	127.5	128.4	118.5
TOTAL ASSETS	1,378.4	1,370.8	1,290.2
Current Liabilities:
Accounts Payable	26.5	37.6	33
Short-Term Debt	71.6	58.6	65.8
Long-Term Debt, Current Portion	6.3	19.5	19.5
Regulatory Liabilities	10.5	7.4	15
Energy Supply Obligations	7.9	10.5	4.6
Interest Payable	7.2	4.5	7
Environmental Obligations	0.3	0.6	0.6
Other Current Liabilities	16.8	21.1	19.3
Total Current Liabilities	147.1	159.8	164.8
Noncurrent Liabilities:
Retirement Benefit Obligations	145.4	141.9	122.9
Deferred Income Taxes, Net	108.7	103.6	103.8
Cost of Removal Obligations	98.8	96	93.7
Regulatory Liabilities	45.1	46.6	47.4
Environmental Obligations	1.9	2.1	1.4
Other Noncurrent Liabilities	7.2	6.5	9.3
Total Noncurrent Liabilities	407.1	396.7	378.5
Capitalization:
Long-Term Debt, Less Current Portion	436.3	437.5	373
Stockholders' Equity:
Common Equity (Authorized: 25,000,000 and Outstanding:14,963,444, 14,916,044 and 14,930,170 Shares)	284	282.5	280.7
Retained Earnings	103.7	94.1	93
Total Common Stock Equity	387.7	376.6	373.7
Preferred Stock	0.2	0.2	0.2
Total Stockholders' Equity	387.9	376.8	373.9
Total Capitalization	824.2	814.3	746.9
Commitments and Contingencies (Notes 6 & 7)
TOTAL LIABILITIES AND CAPITALIZATION	$ 1,378.4	$ 1,370.8	$ 1,290.2

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - shares	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Common Stock Authorized	25,000,000	25,000,000	25,000,000
Common Equity Outstanding	14,963,444	14,930,170	14,916,044

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating Activities:
Net Income	$ 15.2	$ 26.5
Adjustments to Reconcile Net Income to Cash Provided by Operating Activities:
Depreciation and Amortization	13.5	13.8
Deferred Tax Provision	4.7	8.2
Gain on Divestiture, Net (See Note 1)		(13.4)
Changes in Working Capital Items:
Accounts Receivable	(7.5)	(7.1)
Accrued Revenue	11.4	14.5
Exchange Gas Receivable	3.9	7.7
Regulatory Liabilities	3.1	3.5
Accounts Payable	(11.1)	(9.6)
Other Changes in Working Capital Items	(3)	0.3
Deferred Regulatory and Other Charges	(0.4)	(6.9)
Other, Net	(1.9)	0.3
Cash Provided by Operating Activities	27.9	37.8
Investing Activities:
Property, Plant and Equipment Additions	(16.8)	(10.9)
Proceeds from Divestiture, Net (See Note 1)		13.4
Cash Provided by (Used in) Investing Activities	(16.8)	2.5
Financing Activities:
Proceeds from (Repayment of) Short-Term Debt, Net	13	(17)
Repayment of Long-Term Debt	(14.4)	(13.4)
Increase (Decrease) in Capital Lease Obligations	0.2	(0.9)
Net Decrease in Exchange Gas Financing	(3.6)	(7.3)
Dividends Paid	(5.6)	(5.5)
Proceeds from Issuance of Common Stock	0.3	0.3
Cash (Used in) Financing Activities	(10.1)	(43.8)
Net Increase (Decrease) in Cash and Cash Equivalents	1	(3.5)
Cash and Cash Equivalents at Beginning of Period	5.2	7.8
Cash and Cash Equivalents at End of Period	6.2	4.3
Supplemental Cash Flow Information:
Interest Paid	3.6	3.6
Income Taxes Paid
Payments on Capital Leases	0.1	0.8
Non-cash Investing Activity:
Capital Expenditures Included in Accounts Payable	0.5	0.7
Right-of-Use Assets Obtained in Exchange for Lease Obligations	$ 0.9	$ 3.9

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, 2018	$ 351.1	$ 279.1	$ 72
Net Income	26.5		26.5
Dividends on Common Shares	(5.5)		(5.5)
Stock Compensation Plans	1.3	1.3
Issuance of Common Shares	0.3	0.3
Ending Balance at Mar. 31, 2019	373.7	280.7	93
Beginning Balance at Dec. 31, 2019	376.6	282.5	94.1
Net Income	15.2		15.2
Dividends on Common Shares	(5.6)		(5.6)
Stock Compensation Plans	1.2	1.2
Issuance of Common Shares	0.3	0.3
Ending Balance at Mar. 31, 2020	$ 387.7	$ 284	$ 103.7

CONSOLIDATED STATEMENTS OF CH_2

CONSOLIDATED STATEMENTS OF CHANGES IN COMMON STOCK EQUITY (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Dividends per Common Share	$ 0.375	$ 0.370
Common stock, shares issued	4,644	5,939

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Note 1 Summary of Significant Accounting Policies Nature of Operations non-regulated The Company’s earnings are seasonal and are typically higher in the first and fourth quarters when customers use gas for heating purposes. Unitil’s principal business is the local distribution of electricity in the southeastern seacoast and capital city areas of New Hampshire and the greater Fitchburg area of north central Massachusetts and the local distribution of gas in southeastern New Hampshire, portions of southern Maine to the Lewiston-Auburn area 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 an interstate gas transmission pipeline company, 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 gas pipelines and access to domestic gas supplies in the south and Canadian 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 See additional discussion in “Divestiture of Non-Regulated Basis of Presentation – 10-Q to the Consolidated Financial Statements – “Summary of Significant Accounting Policies” of the Company’s Form 10-K Divestiture of Non-Regulated Business Subsidiary – non-regulated after-tax pre-tax Utility Revenue Recognition – Billed and unbilled revenue is recorded when service is rendered or energy is delivered to customers. However, the determination of energy sales to individual customers is based on the reading of their meters, which occurs on a systematic basis throughout the month. At the end of each calendar month, amounts of energy delivered to customers since the date of the last meter reading are estimated and the corresponding unbilled revenues are calculated. These unbilled revenues are estimated each month based on estimated customer usage by class and applicable customer rates, taking into account current and historical weather data, assumptions pertaining to metering patterns, billing cycle statistics, and other estimates and assumptions, and are then reversed in the following month when billed to customers. A majority of the Company’s revenue from contracts with customers continues to be recognized on a monthly basis based on applicable tariffs and customer monthly consumption. Such revenue is recognized using the invoice practical expedient which allows an entity to recognize revenue in the amount that directly corresponds to the value transferred to the customer. The Company’s billed and unbilled revenue meets the definition of “revenues from contracts with customers” as defined in Accounting Standards Codification (ASC) 606. 980-605-25-3, 980-605-25-4. C 606 In the following tables, revenue is classified by the types of goods/services rendered and market/customer type. Three Months Ended March 31, 2020 Gas and Electric Operating Revenues ($ millions): Gas Electric Total Billed and Unbilled Revenue: Residential $ 31.1 $ 34.4 $ 65.5 C&I 42.3 24.1 66.4 Other 3.0 2.0 5.0 Total Billed and Unbilled Revenue 76.4 60.5 136.9 Rate Adjustment Mechanism Revenue (6.2 ) (0.3 ) (6.5 ) Total Gas and Electric Operating Revenues $ 70.2 $ 60.2 $ 130.4 Three Months Ended March 31, 2019 Gas and Electric Operating Revenues ($ millions): Gas Electric Total Billed and Unbilled Revenue: Residential $ 38.7 $ 35.7 $ 74.4 C&I 54.0 24.7 78.7 Other 6.5 2.3 8.8 Total Billed and Unbilled Revenue 99.2 62.7 161.9 Rate Adjustment Mechanism Revenue (12.8 ) 2.1 (10.7 ) Total Gas and Electric Operating Revenues $ 86.4 $ 64.8 $ 151.2 Fitchburg is subject to revenue decoupling. Revenue decoupling is the term given to the elimination of the dependency of a utility’s distribution revenue on the volume of electricity or gas sales. The difference between distribution revenue amounts billed to customers and the targeted revenue decoupling amounts is recorded as an increase or a decrease in Accrued Revenue, which forms the basis for resetting rates for future cash recoveries from, or credits to, customers. These revenue decoupling targets may be adjusted as a result of rate cases that the Company files with the MDPU. Other Operating Revenue – Non-regulated – non-regulated 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 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. Cash and Cash Equivalents – (ISO-NE) ISO-NE. 2-1/2 ISO-NE obligations. Financial Instruments – 2016-13, Allowance for Doubtful Accounts – The Company recognizes a provision for doubtful accounts that reflects the Company’s estimate of expected credit losses for electric and gas utility service accounts receivable. The allowance for doubtful accounts is calculated by applying a historical loss rate, which is adjusted for current conditions, customer trends, or other factors such as macroeconomic conditions, to customer account balances. The Company also calculates the amount of written-off The Allowance for Doubtful Accounts as of March 31, 2020, March 31, 2019 and December 31, 2019, was as follows: ($ millions) March 31, December 31, 2020 2019 2019 Allowance for Doubtful Accounts $ 1.8 $ 1.7 $ 1.0 Accounts Receivable, Net includes $1.7 million, $1.7 million, and $1.0 million of the Allowance for Doubtful Accounts at March 31, 2020, March 31, 2019 and December 31, 2019, respectively. Unbilled Revenues, net (a component of Accrued Revenue, shown in the table below) includes $0.1 million of the Allowance for Doubtful Accounts at March 31, 2020. Accrued Revenue – March 31, December 31, Accrued Revenue ($ millions) 2020 2019 2019 Regulatory Assets – Current $ 28.4 $ 29.4 $ 35.8 Unbilled Revenues , net 10.2 10.8 14.2 Total Accrued Revenue $ 38.6 $ 40.2 $ 50.0 Exchange Gas Receivable – shows March 31, December 31, Exchange Gas Receivable ($ millions) 2020 2019 2019 Northern Utilities $ 1.9 $ 0.2 $ 5.5 Fitchburg 0.3 0.2 0.6 Total Exchange Gas Receivable $ 2.2 $ 0.4 $ 6.1 Gas Inventory March 31, December 31, Gas Inventory ($ millions) 2020 2019 2019 Natural Gas $ — $ — $ 0.4 Propane 0.3 0.4 0.3 Liquefied Natural Gas & Other 0.1 0.1 0.1 Total Gas Inventory $ 0.4 $ 0.5 $ 0.8 Utility Plant – pitaliz Leases – Regulatory Accounting – The Company’s principal business is the distribution of electricity and gas by the three distribution utilities: Unitil Energy, Fitchburg and Northern Utilities. Unitil Energy and Fitchburg are subject to regulation by the FERC. Fitchburg is also regulated by the Massachusetts Department of Public Utilities (MDPU), Unitil Energy is regulated by the New Hampshire Public Utilities Commission (NHPUC) and Northern Utilities is regulated by the Maine Public Utilities Commission (MPUC) and NHPUC. Granite State, the Company’s gas transmission pipeline, is regulated by the FERC. Accordingly, the Company uses the Regulated Operations guidance as set forth in the FASB Codification. The Company has recorded Regulatory Assets and Regulatory Liabilities which will be recovered from customers, or applied for customer benefit, in accordance with rate provisions approved by the applicable public utility regulatory commission. March 31, December 31, Regulatory Assets consist of the following ($ millions) 2020 2019 2019 Retirement Benefits $ 80.8 $ 72.4 $ 88.9 Energy Supply & Other Rate Adjustment Mechanisms 25.7 25.1 31.0 Deferred Storm Charges 5.3 5.9 5.6 Environmental 6.4 7.6 7.2 Income Taxes 4.0 4.7 4.2 Other Deferred Charges 11.5 11.6 10.9 Total Regulatory Assets 133.7 127.3 147.8 Less: Current Portion of Regulatory Assets (1) 28.4 29.4 35.8 Regulatory Assets – noncurrent $ 105.3 $ 97.9 $ 112.0 (1) Reflects amounts included in the Accrued Revenue on the Company’s Consolidated Balance Sheets. March 31, December 31, Regulatory Liabilities consist of the following ($ millions) 2020 2019 2019 Income Taxes (Note 8) $ 46.1 $ 48.2 $ 47.6 Rate Adjustment Mechanisms 9.1 13.6 6.0 Other 0.4 0.6 0.4 Total Regulatory Liabilities 55.6 62.4 54.0 Less: Current Portion of Regulatory Liabilities 10.5 15.0 7.4 Regulatory Liabilities—noncurrent $ 45.1 $ 47.4 $ 46.6 Generally, the Company receives a return on investment on its regulat ory Derivatives – As discussed below in the “Fitchburg – Massachusetts RFP’s” section of Note 6 to the Consolidated Financial Statements , Fitchburg has entered into power purchase agreements for which contingencies exist. Until these contingencies are satisfied, these contracts will not qualify for derivative accounting. The Company believes that the power purchase obligations under these long-term contracts will have a material i ct on the contractual obligations and regulatory assets of Fitchburg, once they qualify for derivative accounting. Investments in Marketable Securities At March 31, 2020, March 31, 2019 and December 31, 2019, the fair value of the Company’s investments in these trading securities, which are recorded on the Consolidated Balance Sheets in Other Assets, were $5.5 million, $5.1 and $5.6 million, respectively, as shown in the table below. These investments are valued based on quoted prices from active markets and are categorized in Level 1 as they are actively traded and no valuation adjustments have been applied. Changes in the fair value of these investments are recorded in Other Expense, Net. March 31, December 31, Fair Value of Marketable Securities ($ millions) 2020 2019 2019 Money Market Funds $ 5.5 $ 5.1 $ 5.6 Total Marketable Securities $ 5.5 $ 5.1 $ 5.6 The Company also sponsors the Unitil Corporation Deferred Compensation Plan (the “DC Plan”). The DC Plan is a non-qualified tax-deferred At March 31, 2020, March 31, 2019 and December 31, 2019, the fair value of the Company’s investments in these trading securities related to the DC Plan, which are recorded on the Consolidated Balance Sheets in Other Assets, were $0.4 million, $0.1 million and $0.2 million, respectively, as shown in the table below. These investments are valued based on quoted prices from active markets and are categorized in Level 1 as they are actively traded and no valuation adjustments have been applied. Changes in the fair value of these investments are recorded in Other Expense, Net. 30 March 31, December 31, Fair Value of Marketable Securities ($ millions) 2020 2019 2019 Equity Funds $ 0.1 $ — $ 0.1 Money Market Funds 0.3 0.1 0.1 Total Marketable Securities $ 0.4 $ 0.1 $ 0.2 Energy Supply Obligations – March 31, December 31, Energy Supply Obligations ($ millions) 2020 2019 2019 Current: Exchange Gas Obligation $ 1.9 $ 0.2 $ 5.5 Renewable Energy Portfolio Standards 5.7 4.1 4.7 Power Supply Contract Divestitures 0.3 0.3 0.3 Total Energy Supply Obligations – Current 7.9 4.6 10.5 Long-Term: Power Supply Contract Divestitures 0.2 0.5 0.3 Total Energy Supply Obligations $ 8.1 $ 5.1 $ 10.8 Exchange Gas Obligation As discussed in “Exchange Gas Receivable” above, Northern Utilities enters into gas exchange agreements under which Northern Utilities releases certain gas pipeline and storage assets, resells the gas storage inventory to an asset manager and subsequently repurchases the inventory over the course of the gas heating season at the same price at which it sold the 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 Fitchburg has entered into long-term renewable contracts for the purchase of clean energy and/or RECs pursuant to Massachusetts legislation, specifically, An Act Relative to Green Communities (“Green Communities Act”, 2008), An Act Relative to Competitively Priced Electricity in the Commonwealth (2012) and An Act to Promote Energy Diversity (“Energy Diversity Act”, 2016). The generating facilities associated with four of these contracts have been constructed and are now operating. Since 2017, the Company has participated in two major statewide procurements which resulted in contracts for imported hydroelectric power and associated transmission and for offshore wind generation. The contracts were approved by the MDPU in the second quarter of 2019. Additional long-term clean energy contracts are expected in compliance with the Energy Diversity Act and An Act to Promote a Clean Energy Future (2018). Fitchburg recovers the costs associated with long-term renewable contracts on a fully reconciling basis through a MDPU-approved cost recovery mechanism. Power Supply Contract Divestitures – Subsequent Events –

DIVIDENDS DECLARED PER SHARE

DIVIDENDS DECLARED PER SHARE	3 Months Ended
	Mar. 31, 2020
DIVIDENDS DECLARED PER SHARE [Abstract]
DIVIDENDS DECLARED PER SHARE	Note 2 Dividends Declared Per Share Declaration Date Date Paid (Payable) Shareholder of Record Date Dividend Amount 04/29/20 05/29/20 05/15/20 $ 0.375 01/29/20 02/28/20 02/14/20 $ 0.375 10/23/19 11/27/19 11/13/19 $0.370 07/24/19 08/29/19 08/15/19 $0.370 04/24/19 05/29/19 05/15/19 $ 0.370 01/30/19 02/28/19 02/14/19 $ 0.370

SEGMENT INFORMATION

SEGMENT INFORMATION	3 Months Ended
	Mar. 31, 2020
SEGMENT INFORMATION	note 3 Segment Information The following table provides significant segment financial data for the three months ended March 31, 2020 and March 31, 2019: Gas Electric Non- Regulated Other Total Three Months Ended March 31, 2020 ($ millions) Revenues: Billed and Unbilled Revenue $ 76.4 $ 60.5 $ — $ — $ 136.9 Rate Adjustment Mechanism Revenue (6.2 ) (0.3 ) — — (6.5 ) Other Operating Revenue – Non-Regulated — — — — — Total Operating Revenues 70.2 60.2 — — 130.4 Segment Profit (Loss) 12.3 2.6 — 0.3 15.2 Identifiable Segment Assets 821.4 537.7 0.1 19.2 1,378.4 Capital Expenditures 5.8 9.9 — 1.1 16.8 Three Months Ended March 31, 2019 ($ millions) Revenues: Billed and Unbilled Revenue $ 99.2 $ 62.7 $ — $ — $ 161.9 Rate Adjustment Mechanism Revenue (12.8 ) 2.1 — — (10.7 ) Other Operating Revenue – Non-Regulated — — 0.9 — 0.9 Total Operating Revenues 86.4 64.8 0.9 — 152.1 Segment Profit (Loss) 13.7 1.9 10.1 0.8 26.5 Identifiable Segment Assets 771.6 502.3 0.1 16.2 1,290.2 Capital Expenditures 3.3 6.6 — 1.0 10.9

DEBT AND FINANCING ARRANGEMENTS

DEBT AND FINANCING ARRANGEMENTS	3 Months Ended
	Mar. 31, 2020
Debt Disclosure [Abstract]
DEBT AND FINANCING ARRANGEMENTS	Note 4 debt and financing arrangements Details on long-term debt at March 31, 2020, March 31, 2019 and December 31, 2019 are shown below: ($ millions) March 31, December 31, 2020 2019 2019 Unitil Corporation: 6.33% Senior Notes, Due May 1, 2022 $ 20.0 $ 20.0 $ 20.0 3.70% Senior Notes, Due August 1, 2026 30.0 30.0 30.0 3.43% Senior Notes, Due December 18, 2029 30.0 — 30.0 Unitil Energy First Mortgage Bonds: 5.24% Senior Secured Notes, Due March 2, 2020 — 5.0 5.0 8.49% Senior Secured Notes, Due October 14, 2024 4.5 6.0 4.5 6.96% Senior Secured Notes, Due September 1, 2028 18.0 20.0 18.0 8.00% Senior Secured Notes, Due May 1, 2031 15.0 15.0 15.0 6.32% Senior Secured Notes, Due September 15, 2036 15.0 15.0 15.0 4.18% Senior Secured Notes, Due November 30, 2048 30.0 30.0 30.0 Fitchburg: 6.75% Senior Notes, Due November 30, 2023 3.8 5.7 3.8 6.79% Senior Notes, Due October 15, 2025 10.0 10.0 10.0 3.52% Senior Notes, Due November 1, 2027 10.0 10.0 10.0 7.37% Senior Notes, Due January 15, 2029 10.8 12.0 12.0 5.90% Senior Notes, Due December 15, 2030 15.0 15.0 15.0 7.98% Senior Notes, Due June 1, 2031 14.0 14.0 14.0 4.32% Senior Notes, Due November 1, 2047 15.0 15.0 15.0 Northern Utilities: 5.29% Senior Notes, Due March 2, 2020 — 8.2 8.2 3.52% Senior Notes, Due November 1, 2027 20.0 20.0 20.0 7.72% Senior Notes, Due December 3, 2038 50.0 50.0 50.0 4.42% Senior Notes, Due October 15, 2044 50.0 50.0 50.0 4.32% Senior Notes, Due November 1, 2047 30.0 30.0 30.0 4.04% Senior Notes, Due September 12, 2049 40.0 — 40.0 Granite State: 3.72% Senior Notes, Due November 1, 2027 15.0 15.0 15.0 Total Long-Term Debt 446.1 395.9 460.5 Less: Unamortized Debt Issuance Costs 3.5 3.4 3.5 Total Long-Term Debt, net of Unamortized Debt Issuance Costs 442.6 392.5 457.0 Less: Current Portion 6.3 19.5 19.5 Total Long-term Debt, Less Current Portion $ 436.3 $ 373.0 $ 437.5 Fair Value of Long-Term Debt 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, 2020 2019 2019 Estimated Fair Value of Long-Term Debt $ 494.7 $ 418.0 $ 518.7 On July 25, 2018, the Company entered into a Second Amended and Restated Credit Agreement and related documents (collectively, the “Credit Facility”) with a syndicate of lenders, which amended and restated in its entirety the Company’s prior credit facility. The Credit Facility extends to July 25, 2023, subject to two one-year one-month The Company utilizes the Credit Facility for cash management purposes related to its short-term operating activities. Total gross borrowings were $74.3 million for the three months ended March 31, 2020. Total gross repayments were $61.3 million for the three months ended March 31, 2020. The following table details the borrowing limits, amounts outstanding and amounts available under the Credit Facility as of March 31 2020, March 30, 2019 and December 31, 2019: Revolving Credit Facility ($ millions) March 31, December 31, 2020 2019 2019 Limit $ 120.0 $ 120.0 $ 120.0 Short-Term Borrowings Outstanding 71.6 65.8 58.6 Letter of Credit Outstanding 0.1 — 0.1 Available $ 48.3 $ 54.2 $ 61.3 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, the Company’s and its subsidiaries’ ability to permit liens or incur indebtedness, and restrictions on the Company’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 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 Funded Debt to Capitalization (as each term is defined in the Credit Facility) cannot exceed 65%, tested on a quarterly basis. At March 31, 2020, March 31, 2019 and December 31, 2019, the Company was in compliance with the covenants contained in the Credit Facility in effect on that date. The average interest rates on all short-term borrowings and intercompany money pool transactions were 2.6% and 3.7% for the three months ended March 31, 2020 and March 31, 2019, respectively. The average interest rate on all short-term borrowings for the twelve months ended December 31, 2019 was 3.4%. As discussed previously, the Company divested of its non-regulated On December 18, 2019, Unitil Corporation issued $30 million of Notes due 2029 On September 12, 2019, Northern Utilities issued $40 million of Notes due 2049 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. This capital lease was paid off in the second quarter of 2019. Unitil Corporation and its utility subsidiaries, Fitchburg, Unitil Energy, Northern Utilities, and Granite State are currently rated “BBB+” by Standard & Poor’s Ratings Services. Unitil Corporation and Granite State are currently rated “Baa2”, and Fitchburg, Unitil Energy and Northern Utilities are currently rated “Baa1” by Moody’s Investors Services. Northern Utilities enters into asset management agreements under which Northern Utilities releases certain gas pipeline and storage assets, resells the gas storage inventory to an asset manager and subsequently repurchases the inventory over the course of the gas heating season at the same price at which it sold the gas inventory to the asset manager. There was $2.5 million, $2.2 million and $6.5 million of gas storage inventory at March 31, 2020, March 31, 2019 and December 31, 2019, respectively, related to these asset management agreements. The amount of gas inventory released in March 2020 and payable in April 2020 is $0.6 million and is recorded in Accounts Payable at March 31, 2020. The amount of gas inventory released in March 2019 and payable in April 2019 was $2.1 million and was recorded in Accounts Payable at March 31, 2019. The amount of gas inventory released in December 2019 and payable in January 2020 was $1.0 million and was recorded in Accounts Payable at December 31, 2019. Guarantees The Company provides limited guarantees on certain energy and 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, 2020, there were approximately $6.2 million of guarantees outstanding. Leases Unitil’s subsidiaries and also lease some of their vehicles, machinery and office equipment under both capital and operating lease arrangements. Total rental expense under operating leases charged to operations for the three months ended March 31, 2020 and 2019 amounted to $0.4 million and $0.4 million, respectively. The balance sheet classification of the Company’s lease obligations was as follows: March 31, December 31, Lease Obligations ($ millions) 2020 2019 2019 Operating Lease Obligations: Other Current Liabilities (current portion) $ 1.4 $ 1.1 $ 1.2 Other Noncurrent Liabilities (long-term portion) 3.5 2.8 2.8 Total Operating Lease Obligations $ 4.9 $ 3.9 $ 4.0 Capital Lease Obligations: Other Current Liabilities (current portion) $ 0.2 $ 3.0 $ 0.2 Other Noncurrent Liabilities (long-term portion) 0.4 1.9 0.3 Total Capital Lease Obligations $ 0.6 $ 4.9 $ 0.5 Total Lease Obligations $ 5.5 $ 8.8 $ 4.5 Cash paid for amounts included in the measurement of operating lease obligations for the three months ended March 31, 2020 was $0.4 million and was included in Cash Provided by Operating Activities on the Consolidated Statements of Cash Flows. Assets under capital leases amounted to approximately $1.2 million, $14.9 million and $1.2 million as of March 31, 2020, March 31, 2019 and December 31, 2019, respectively, less accumulated amortization of $0.7 million, $1.8 million and $0.6 million, respectively and are included in Net Utility Plant on the Company’s Consolidated Balance Sheets. The following table is a schedule of future operating lease payment obligations and future minimum lease payments under capital leases as of March 31, 2020. The payments for capital leases consist of $0.2 million of current capital lease obligations, which are included in Other Current Liabilities and $0.4 million of noncurrent capital lease obligations, which are included in Other Noncurrent Liabilities, on the Company’s Consolidated Balance Sheets as of March 31, 2020. The payments for operating leases consist of $1.4 million of current operating lease obligations, which are included in Other Current Liabilities and $3.5 million of noncurrent operating lease obligations, which are included in Other Noncurrent Liabilities, on the Company’s Consolidated Balance Sheets as of March 31, 2020. Lease Payments ($000’s) Year Ending December 31, Operating Capital Rest of 2020 $ 1,211 $ 215 2021 1,455 193 2022 1,174 130 2023 873 88 2024 544 33 2025-2029 140 — Total Payments 5,397 659 Less: Interest 497 35 Amount of Lease Obligations Recorded on Consolidated Balance Sheets $ 4,900 $ 624 Operating lease obligations are based on the net present value of the remaining lease payments over the remaining lease term. In determining the present value of lease payments, the Company used the interest rate stated in each lease agreement. As of March 31, 2020, the weighted average remaining lease term is 3.9 years and the weighted average operating discount rate used to determine the operating lease obligations was 4.9%.

COMMON STOCK AND PREFERRED STOC

COMMON STOCK AND PREFERRED STOCK	3 Months Ended
	Mar. 31, 2020
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 14,916,044, 14,930,170 and 14,963,444 shares of common stock outstanding at March 31, 2019, December 31, 2019 and March 31, 2020, 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 28, 2020, 28,630 Restricted Shares were issued in conjunction with the Stock Plan with an aggregate market value at the date of issuance of approximately $1.8 million. There were 56,813 and 60,496 non-vested 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, 2020 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, 2019 70,364 $ 41.20 Restricted Stock Units Granted — — Dividend Equivalents Earned 469 $ 56.34 Restricted Stock Units Settled — — Restricted Stock Units as of March 31, 2020 70,833 $ 41.30 There were 62,206 Restricted Stock Units outstanding as of March 31, 2019 with a weighted average stock price of $38.36. Included in Other Noncurrent Liabilities on the Company’s Consolidated Balance Sheets as of March 31, 2020, March 31, 2019 and December 31, 2019 is $1.6 million, $1.4 million and $1.9 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 1,887 shares, of Unitil Energy’s 6.00% Series Preferred Stock outstanding as of March 31, 2020. There was $0.2 million, or 1,893 shares, of Unitil Energy’s 6.00% Series Preferred Stock outstanding as of March 31, 2019. There were less than $0.1 million of total dividends declared on Preferred Stock in each of the three month periods ended March 31, 2020 and March 31, 2019, respectively.

REGULATORY MATTERS

REGULATORY MATTERS	3 Months Ended
	Mar. 31, 2020
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, 2019 as filed with the Securities and Exchange Commission on january 30, 2020. Tax Cuts and Jobs Act of 2017 On December 22, 2017, the Tax Cuts and Jobs Act of 2017 (TCJA) was signed into law. Among other things, the TCJA substantially reduced the corporate income tax rate to 21%, effective January 1, 2018. Each state public utility commission, with jurisdiction over the areas that are served by Unitil’s electric and gas subsidiary companies, issued orders directing how the tax law changes were to be reflected in rates. Unitil has complied with these orders and has made the required changes to its rates as directed by the commissions. The FERC issued a Notice of Proposed Rulemaking that would allow it to determine which pipelines under the Natural Gas Act may be collecting unjust and unreasonable rates in light of the corporate tax reduction. This matter has been resolved for Granite State in its May 2, 2018 uncontested rate settlement filing, which accounted for the effect of the TCJA. On November 21, 2019, the FERC issued Order No. 864, a final rule on Public Utility Transmission Rate Changes to Address Accumulated Deferred Income Taxes. The new rule requires public utilities with formula transmission rates to revise their formula rates to include a transparent methodology to address the impacts of the TCJA and future tax law changes on customer rates by accounting for “excess” or “deficient” Accumulated Deferred Income Taxes (ADIT). FERC also required transmission providers with stated rates to account for the ADIT impacts of the TCJA in their next rate case. The Company is complying with the new rule and there is no material impact on its financial position, operating results, or cash flows. Rate Case Activity Northern Utilities – Base Rates – Maine – % % % Northern Utilities – Targeted Infrastructure Replacement Adjustment (TIRA) – Maine – facilities was approved by the MPUC on April 29, 2020 Northern Utilities – Base Rates – New Hampshire – Unitil Energy – Base Rates – Fitchburg – Base Rates – Electric – million associated with the Company’s 2015-2018 capital expenditures. On December 16, 2019, the filing was approved, effective January 1, 2020, subject to further investigation and reconciliation. Final approval of the 2019 filing remains pending. On December 17, 2019, Fitchburg filed for a $2.7 million increase in its electric base revenue decoupling target, which represents a 4.1% increase over 2018 test year operating electric revenues. On April 17, 2020, MDPU approved a settlement agreement entered into by the Company and the Massachusetts Office of the Attorney General providing for a distribution increase of $1.1 million, effective November 1, 2020. The agreement provides for a return on equity of 9.7 % Fitchburg – Base Rates – Gas – On December 17, 2019, Fitchburg filed for a $7.3 million increase in its gas base revenue decoupling target, which represents a 20.8% increase over 2018 test year total gas operating revenues. On February 28, 2020, the MDPU approved a settlement agreement between the Company and the Massachusetts Office of the phased-in thousand % Fitchburg – Gas System Enhancement Program – In an Order issued on April 30, 2019, the MDPU approved Fitchburg’s 2018 GSEP Filing and increased the annual cap on recovery. Because the increase in the amount for recovery, $1.6 million, still exceeded the annual cap, the Order resulted in a revenue increase of $1.0 million that went into effect on May 1, 2019, subject to reconciliation. The amount that exceeded the cap, $0.6 million, has been deferred to be recovered in a later proceeding. On May 1, 2019, the Company made its 2019 GREC Filing, seeking a waiver of the annual cap and a revenue increase of $1.0 million. The MDPU approved the Company’s request in its Order issued October 31, 2019. On October 31, 2019, the Company made its annual filing for an increase in revenues associated with 2020 GSEP investment for rates effective May 1, 2020. On March 12, 2020, the Company made a revised GSEP filing to incorporate the inclusion of the 2015 through 2018 GSEP investments in base rates effective March 1, 2020. This matter remains pending before the MDPU. Granite State – Base Rates – Other Matters Fitchburg – Independent Statewide Examination of the Safety of the Commonwealth’s Gas Distribution System – Northern Utilities / Granite State – Firm Capacity Contract one-year 12-month Reconciliation Filings – Fitchburg – Massachusetts RFPs – The EDCs issued the RFP for Section 83D Long-Term Contracts for Qualified Clean Energy Projects in March 2017, and after selection of final projects and negotiation, final contracts for 9,554,940 MWh of Qualified Clean Energy and associated Environmental Attributes from hydroelectric generation were filed in July 2018 for approval by the MDPU. On June 25, 2019, the MDPU approved the power purchase agreements, including the EDCs’ proposal to sell the energy procured under the contract into the ISO-NE ISO-NE Also, the MDPU approved the EDCs’ proposal to amend their respective tariffs to include the recovery of costs associated with the contracts. The Company believes that the power purchase obligations under these long-term contracts will have a material impact on the contractual obligations and regulatory assets of Fitchburg, once certain conditions and contingencies are met. The EDCs issued the RFP pursuant to Section 83C for Long-Term Contracts for Offshore Wind Energy Generation in June 2017. Final selection of projects was made in May 2018, contracts were signed in July 2018 and on July 23, 2018, the EDCs, including Fitchburg, filed two long-term contracts, each for 400MW of offshore wind energy generation with the MDPU for approval. On April 12, 2019, the MDPU approved the Offshore Wind Energy Generation power purchase agreements, including the EDCs’ proposal to sell the energy procured under the contract into the ISO-NE ISO-NE The EDCs issued an RFP pursuant to Section 83C for Long-Term Contracts for Offshore Wind Energy Generation on May 23, 2019. This is the second solicitation pursuant to Section 83C and with the MDPU’s approval of the Vineyard Wind contracts for 800 MW of offshore wind energy generation as a result of the first solicitation, the remaining obligation under 83C is to procure an additional 800 MW of offshore wind energy generation. The EDCs selected an 800 MW project submitted by Mayflower Wind and contracts were executed on January 10, 2020. A filing with the MDPU for approval of two long-term contracts, each for 400 MW of offshore wind energy generation, was made on February 10, 2020. FERC Transmission Formula Rate Proceedings – ISO-New EL14-12, 14-12, Also pending at FERC is a Section 206 proceeding concerning the justness and reasonableness of ISO-New Legal Proceedings The Company is involved in legal and administrative proceedings and claims of various types, including those 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.

ENVIRONMENTAL MATTERS

ENVIRONMENTAL MATTERS	3 Months Ended
	Mar. 31, 2020
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, 2019 as filed with the Securities and Exchange Commission on january 30, 2020. 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 is in material compliance with applicable environmental and safety laws and regulations and, as of March 31, 2020 Northern Utilities Manufactured Gas Plant Sites – mid-1800s mid-1900s. Northern Utilities has worked with the Maine Department of Environmental Protection and New Hampshire Department of Environmental Services (NH DES) to address environmental concerns with these sites. Northern Utilities or others have completed remediation activities at all sites; however, on site monitoring continues at several sites which may result in future remedial actions as directed by the applicable regulatory agency. In July 2019, the NH DES requested that Northern Utilities review modeled expectations for groundwater contaminants against observed data at the Rochester site. Due to delays associated with the novel coronavirus ( COVID-19 ) . While any recommendation is subject to approval by the NH DES, the Company has accrued $ million for estimated costs to complete the remediation at the Rochester site, which is included in the Environmental Obligations table below. 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 five 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 – 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. The following table sets forth a summary of changes in the Company’s liability for Environmental Obligations for the three months ended March 31, 2020 and 2019. Environmental Obligations ($ millions) Fitchburg Northern Total Three months ended March 31, 2020 2019 2020 2019 2020 2019 Total Balance at Beginning of Period $ — $ — $ 2.7 $ 2.0 $ 2.7 $ 2.0 Additions — — — 0.1 — 0.1 Less: Payments / Reductions — — 0.5 0.1 0.5 0.1 Total Balance at End of Period — — 2.2 2.0 2.2 2.0 Less: Current Portion — — 0.3 0.6 0.3 0.6 Noncurrent Balance at End of Period $ — $ — $ 1.9 $ 1.4 $ 1.9 $ 1.4

INCOME TAXES

INCOME TAXES	3 Months Ended
	Mar. 31, 2020
INCOME TAXES	Note 8: INCOME TAXES In March 2020 the Coronavirus Aid, Relief and Economic Security (“CARES”) Act was signed into law. The CARES Act included several tax changes as part of its economic package. These changes principally related to expanded Net Operating Loss (NOL) carryback periods, increases to interest deductibility limitations, and accelerated Alternative Minimum Tax (AMT) refunds. The Company has evaluated these items and included them in its tax computation as of March 31, 2020. Income tax filings for the year ended December 31, 2018 have been filed with the IRS, Massachusetts Department of Revenue, the Maine Revenue Service, and the New Hampshire Department of Revenue Administration. The Company evaluated its tax positions at March 31, 2020 in accordance with the FASB Codification, and has concluded that no adjustment for recognition, de-recognition, In December 2017, the Tax Cuts and Jobs Act (TCJA), which included a reduction to the corporate federal income tax rate to 21% effective January 1, 2018, was signed into law. In accordance with GAAP Accounting Standard 740, the Company revalued its Accumulated Deferred Income Taxes (ADIT) at the new 21% tax rate at which the ADIT will be reversed in future periods. The Company recorded a net Regulatory Liability in the amount of $48.9 million at December 31, 2017 as a result of the ADIT revaluation. In March 2020 , The MDPU issued a multi-utility Order D.P.U. 18-15-E non-plant reconcile excess ADIT amounts previously collected from ratepayers through reconciliation mechanisms in the next filing of each of those individual reconciling mechanisms. Fitchburg was ordered to begin flowing back to customers excess D.P.U.18-15-E On November 15, 2018 the FERC issued two pronouncements regarding the accounting for income taxes due to the TCJA; 1) Notice of Proposed Rulemaking Docket No. RM 19-5-000 19-2-000 According to the FERC guidance; the amount of the reduction to ADIT that was previously collected from customers but is no longer payable to the IRS is excess ADIT and should be flowed back to ratepayers under general ratemaking principles. On November 21, 2019 the FERC issued a final order Docket No. RM19-5-000 Based on communications received by the Company from its state regulators in rate cases and other regulatory proceedings in the first quarter of 2018 and as prescribed in the TCJA, the recent FERC guidance noted above and IRS normalization rules; the benefit of these protected excess ADIT amounts will be subject to flow back to customers in future utility rates according to the Average Rate Assumption Method (ARAM). ARAM reconciles excess ADIT at the reversal rate of the underlying book/tax temporary timing differences. The Company estimates the ARAM flow back period for protected and unprotected excess ADIT to be between fifteen and twenty years, over the remaining life of the related utility plant. Subject to regulatory approval, the Company expects to flow back to customers a net $47.1 million of protected excess ADIT created as a result of the lowering of the statutory tax rate by the TCJA over periods estimated to be fifteen to twenty years. In addition to the protected excess $47.1 million ADIT amounts the Company expects to flow through to customers in utility rates, as noted above, there is approximately $1.8 million of excess ADIT created through reconciling mechanisms at December 31, 2017, related to the implementation of the new federal tax rate of the TCJA, which had not been previously collected from customers through utility rates. The Company will reconcile these excess ADIT amounts through the specific reconciliation mechanisms in the next filing of each of those individual reconciling mechanisms which will be subject to the review of state regulators. In addition to the $48.9 million of net excess ADIT noted above, as of December 31, 2018, there was $2.0 million of remaining excess ADIT created by the recognition of Net Operating Loss Carryforward assets (NOLC), discussed below, and related to the implementation of the new federal tax rate of the TCJA, which had not been previously included in utility rates. The Company is recognizing the benefit of this excess ADIT in accordance with the regulatory treatment of excess ADIT for each of jurisdiction. As of December 31, 2019 there was $0.3 million remaining; of which, $0.2 million was recognized as of March 31, 2020. The remaining $0.1 million will be recognized in 2020. The Company has received regulatory orders in its Massachusetts and Maine jurisdictions regarding the flow-back of excess deferred income taxes. The Company’s New Hampshire regulators are expected to issue additional ratemaking guidance in future periods that will determine the final disposition of the re-measurement Under the Company’s Tax Sharing Agreement (the “Agreement”) which was approved upon the formation of Unitil as a public utility holding company; the Company files consolidated Federal and State tax returns and Unitil Corporation and each of its utility operating subsidiaries recognize the results of their operations in its tax returns as if it were a stand-alone taxpayer. The Agreement provides that the Company will account for income taxes in compliance with U.S. GAAP and regulatory accounting principles. The Company filed its tax returns for the year ended December 31, 2018 with the IRS in September 2019 and utilized federal NOLC assets of $5.7 million principally due to pension cost deductions, tax repair deductions, tax depreciation and research and development deductions. For the tax year ended December 31, 2019, the Company used $3.5 million of the NOLC in calculating the 2019 federal tax provision. As of December 31, 2019, the Company had recorded cumulative federal NOLC assets of $1.6 million to offset against taxes payable in future periods. If unused, the Company’s NOLC carryforward assets will begin to expire in 2029. The Company received $0.9 million of the Alternative Minimum Tax (AMT) credits in 2019 and will receive $0.9 million of the AMT credits in 2020 In addition, at December 31, 2019, the Company had $1.9 million of cumulative alternative minimum tax credits, general business tax credit and other state tax credit carryforwards to offset future income taxes payable. In assessing the near-term use of NOLCs and tax credits, the Company evaluates the expected level of future taxable income, available tax planning strategies, reversals of existing taxable temporary differences and taxable income available in carryback years. Based on all available evidence, both positive and negative, and the weight of that evidence to the extent such evidence can be objectively verified, the Company expects to utilize all of its NOLCs by December 31, 2020 prior to their expiration in 2029. The Company bills its customers for sales tax in Massachusetts and Maine. 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, 2020
RETIREMENT BENEFIT OBLIGATIONS	Note 9: Retirement Benefit obligations The Company co-sponsors 10-K The following table includes the key weighted average assumptions used in determining the Company’s benefit plan costs and obligations: Used to Determine Plan Costs 2020 2019 Discount Rate 3.25 % 4.25 % Rate of Compensation Increase 3.00 % 3.00 % Expected Long-term rate of return on plan assets 7.40 % 7.75 % Health Care Cost Trend Rate Assumed for Next Year 7.00 % 7.00 % Ultimate Health Care Cost Trend Rate 4.50 % 4.50 % Year that Ultimate Health Care Cost Trend Rate is reached 2029 2024 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, 2020 2019 2020 2019 2020 2019 Service Cost $ 831 $ 776 $ 675 $ 576 $ 71 $ 60 Interest Cost 1,444 1,621 780 856 137 139 Expected Return on Plan Assets (2,255 ) (2,119 ) (516 ) (411 ) — — Prior Service Cost Amortization 80 80 303 303 14 3 Actuarial Loss Amortization 1,618 1,081 186 57 259 158 Sub-total 1,718 1,439 1,428 1,381 481 360 Amounts Capitalized and Deferred (630 ) (412 ) (532 ) (474 ) (138 ) (103 ) Net Periodic Benefit Cost Recognized $ 1,088 $ 1,027 $ 896 $ 907 $ 343 $ 257 Employer Contributions As of March 31, 2020, the Company had not made any contributions to its Pension Plan and PBOP Plan, respectively, in 2020. The Company, along with its subsidiaries, expects to continue to make contributions to its Pension and PBOP Plans in 2020 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, 2020, the Company had made $0.2 million of benefit payments under the SERP Plan in 2020. The Company presently anticipates making an additional $0.5 million of benefit payments under the SERP Plan in 2020.

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Nature of Operations	Nature of Operations non-regulated The Company’s earnings are seasonal and are typically higher in the first and fourth quarters when customers use gas for heating purposes. Unitil’s principal business is the local distribution of electricity in the southeastern seacoast and capital city areas of New Hampshire and the greater Fitchburg area of north central Massachusetts and the local distribution of gas in southeastern New Hampshire, portions of southern Maine to the Lewiston-Auburn area 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 an interstate gas transmission pipeline company, 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 gas pipelines and access to domestic gas supplies in the south and Canadian 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 See additional discussion in “Divestiture of Non-Regulated
Basis of Presentation	Basis of Presentation – 10-Q to the Consolidated Financial Statements – “Summary of Significant Accounting Policies” of the Company’s Form 10-K Divestiture of Non-Regulated Business Subsidiary – non-regulated after-tax pre-tax
Divestiture of Non-Regulated Business Subsidiary
Utility Revenue Recognition	Utility Revenue Recognition – Billed and unbilled revenue is recorded when service is rendered or energy is delivered to customers. However, the determination of energy sales to individual customers is based on the reading of their meters, which occurs on a systematic basis throughout the month. At the end of each calendar month, amounts of energy delivered to customers since the date of the last meter reading are estimated and the corresponding unbilled revenues are calculated. These unbilled revenues are estimated each month based on estimated customer usage by class and applicable customer rates, taking into account current and historical weather data, assumptions pertaining to metering patterns, billing cycle statistics, and other estimates and assumptions, and are then reversed in the following month when billed to customers. A majority of the Company’s revenue from contracts with customers continues to be recognized on a monthly basis based on applicable tariffs and customer monthly consumption. Such revenue is recognized using the invoice practical expedient which allows an entity to recognize revenue in the amount that directly corresponds to the value transferred to the customer. The Company’s billed and unbilled revenue meets the definition of “revenues from contracts with customers” as defined in Accounting Standards Codification (ASC) 606. 980-605-25-3, 980-605-25-4. C 606 In the following tables, revenue is classified by the types of goods/services rendered and market/customer type. Three Months Ended March 31, 2020 Gas and Electric Operating Revenues ($ millions): Gas Electric Total Billed and Unbilled Revenue: Residential $ 31.1 $ 34.4 $ 65.5 C&I 42.3 24.1 66.4 Other 3.0 2.0 5.0 Total Billed and Unbilled Revenue 76.4 60.5 136.9 Rate Adjustment Mechanism Revenue (6.2 ) (0.3 ) (6.5 ) Total Gas and Electric Operating Revenues $ 70.2 $ 60.2 $ 130.4 Three Months Ended March 31, 2019 Gas and Electric Operating Revenues ($ millions): Gas Electric Total Billed and Unbilled Revenue: Residential $ 38.7 $ 35.7 $ 74.4 C&I 54.0 24.7 78.7 Other 6.5 2.3 8.8 Total Billed and Unbilled Revenue 99.2 62.7 161.9 Rate Adjustment Mechanism Revenue (12.8 ) 2.1 (10.7 ) Total Gas and Electric Operating Revenues $ 86.4 $ 64.8 $ 151.2 Fitchburg is subject to revenue decoupling. Revenue decoupling is the term given to the elimination of the dependency of a utility’s distribution revenue on the volume of electricity or gas sales. The difference between distribution revenue amounts billed to customers and the targeted revenue decoupling amounts is recorded as an increase or a decrease in Accrued Revenue, which forms the basis for resetting rates for future cash recoveries from, or credits to, customers. These revenue decoupling targets may be adjusted as a result of rate cases that the Company files with the MDPU.
Other Operating Revenue - Non-regulated	Other Operating Revenue – Non-regulated – non-regulated
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 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.
Cash and Cash Equivalents	Cash and Cash Equivalents – (ISO-NE) ISO-NE. 2-1/2 ISO-NE obligations.
Financial Instruments	Financial Instruments – 2016-13,
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts – The Company recognizes a provision for doubtful accounts that reflects the Company’s estimate of expected credit losses for electric and gas utility service accounts receivable. The allowance for doubtful accounts is calculated by applying a historical loss rate, which is adjusted for current conditions, customer trends, or other factors such as macroeconomic conditions, to customer account balances. The Company also calculates the amount of written-off The Allowance for Doubtful Accounts as of March 31, 2020, March 31, 2019 and December 31, 2019, was as follows: ($ millions) March 31, December 31, 2020 2019 2019 Allowance for Doubtful Accounts $ 1.8 $ 1.7 $ 1.0
Accrued Revenue	Accounts Receivable, Net includes $1.7 million, $1.7 million, and $1.0 million of the Allowance for Doubtful Accounts at March 31, 2020, March 31, 2019 and December 31, 2019, respectively. Unbilled Revenues, net (a component of Accrued Revenue, shown in the table below) includes $0.1 million of the Allowance for Doubtful Accounts at March 31, 2020. Accrued Revenue –
Exchange Gas Receivable	Exchange Gas Receivable – shows March 31, December 31, Exchange Gas Receivable ($ millions) 2020 2019 2019 Northern Utilities $ 1.9 $ 0.2 $ 5.5 Fitchburg 0.3 0.2 0.6 Total Exchange Gas Receivable $ 2.2 $ 0.4 $ 6.1
Gas Inventory	Gas Inventory March 31, December 31, Gas Inventory ($ millions) 2020 2019 2019 Natural Gas $ — $ — $ 0.4 Propane 0.3 0.4 0.3 Liquefied Natural Gas & Other 0.1 0.1 0.1 Total Gas Inventory $ 0.4 $ 0.5 $ 0.8
Utility Plant	Utility Plant – pitaliz
Leases	Leases –
Regulatory Accounting	Regulatory Accounting – The Company’s principal business is the distribution of electricity and gas by the three distribution utilities: Unitil Energy, Fitchburg and Northern Utilities. Unitil Energy and Fitchburg are subject to regulation by the FERC. Fitchburg is also regulated by the Massachusetts Department of Public Utilities (MDPU), Unitil Energy is regulated by the New Hampshire Public Utilities Commission (NHPUC) and Northern Utilities is regulated by the Maine Public Utilities Commission (MPUC) and NHPUC. Granite State, the Company’s gas transmission pipeline, is regulated by the FERC. Accordingly, the Company uses the Regulated Operations guidance as set forth in the FASB Codification. The Company has recorded Regulatory Assets and Regulatory Liabilities which will be recovered from customers, or applied for customer benefit, in accordance with rate provisions approved by the applicable public utility regulatory commission. March 31, December 31, Regulatory Assets consist of the following ($ millions) 2020 2019 2019 Retirement Benefits $ 80.8 $ 72.4 $ 88.9 Energy Supply & Other Rate Adjustment Mechanisms 25.7 25.1 31.0 Deferred Storm Charges 5.3 5.9 5.6 Environmental 6.4 7.6 7.2 Income Taxes 4.0 4.7 4.2 Other Deferred Charges 11.5 11.6 10.9 Total Regulatory Assets 133.7 127.3 147.8 Less: Current Portion of Regulatory Assets (1) 28.4 29.4 35.8 Regulatory Assets – noncurrent $ 105.3 $ 97.9 $ 112.0 (1) Reflects amounts included in the Accrued Revenue on the Company’s Consolidated Balance Sheets. March 31, December 31, Regulatory Liabilities consist of the following ($ millions) 2020 2019 2019 Income Taxes (Note 8) $ 46.1 $ 48.2 $ 47.6 Rate Adjustment Mechanisms 9.1 13.6 6.0 Other 0.4 0.6 0.4 Total Regulatory Liabilities 55.6 62.4 54.0 Less: Current Portion of Regulatory Liabilities 10.5 15.0 7.4 Regulatory Liabilities—noncurrent $ 45.1 $ 47.4 $ 46.6 Generally, the Company receives a return on investment on its regulat ory
Derivatives	Derivatives – As discussed below in the “Fitchburg – Massachusetts RFP’s” section of Note 6 to the Consolidated Financial Statements , Fitchburg has entered into power purchase agreements for which contingencies exist. Until these contingencies are satisfied, these contracts will not qualify for derivative accounting. The Company believes that the power purchase obligations under these long-term contracts will have a material i ct on the contractual obligations and regulatory assets of Fitchburg, once they qualify for derivative accounting.
Investments in Marketable Securities	Investments in Marketable Securities At March 31, 2020, March 31, 2019 and December 31, 2019, the fair value of the Company’s investments in these trading securities, which are recorded on the Consolidated Balance Sheets in Other Assets, were $5.5 million, $5.1 and $5.6 million, respectively, as shown in the table below. These investments are valued based on quoted prices from active markets and are categorized in Level 1 as they are actively traded and no valuation adjustments have been applied. Changes in the fair value of these investments are recorded in Other Expense, Net. March 31, December 31, Fair Value of Marketable Securities ($ millions) 2020 2019 2019 Money Market Funds $ 5.5 $ 5.1 $ 5.6 Total Marketable Securities $ 5.5 $ 5.1 $ 5.6 The Company also sponsors the Unitil Corporation Deferred Compensation Plan (the “DC Plan”). The DC Plan is a non-qualified tax-deferred At March 31, 2020, March 31, 2019 and December 31, 2019, the fair value of the Company’s investments in these trading securities related to the DC Plan, which are recorded on the Consolidated Balance Sheets in Other Assets, were $0.4 million, $0.1 million and $0.2 million, respectively, as shown in the table below. These investments are valued based on quoted prices from active markets and are categorized in Level 1 as they are actively traded and no valuation adjustments have been applied. Changes in the fair value of these investments are recorded in Other Expense, Net. March 31, December 31, Fair Value of Marketable Securities ($ millions) 2020 2019 2019 Equity Funds $ 0.1 $ — $ 0.1 Money Market Funds 0.3 0.1 0.1 Total Marketable Securities $ 0.4 $ 0.1 $ 0.2
Energy Supply Obligations	Energy Supply Obligations – March 31, December 31, Energy Supply Obligations ($ millions) 2020 2019 2019 Current: Exchange Gas Obligation $ 1.9 $ 0.2 $ 5.5 Renewable Energy Portfolio Standards 5.7 4.1 4.7 Power Supply Contract Divestitures 0.3 0.3 0.3 Total Energy Supply Obligations – Current 7.9 4.6 10.5 Long-Term: Power Supply Contract Divestitures 0.2 0.5 0.3 Total Energy Supply Obligations $ 8.1 $ 5.1 $ 10.8 Exchange Gas Obligation As discussed in “Exchange Gas Receivable” above, Northern Utilities enters into gas exchange agreements under which Northern Utilities releases certain gas pipeline and storage assets, resells the gas storage inventory to an asset manager and subsequently repurchases the inventory over the course of the gas heating season at the same price at which it sold the 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 Fitchburg has entered into long-term renewable contracts for the purchase of clean energy and/or RECs pursuant to Massachusetts legislation, specifically, An Act Relative to Green Communities (“Green Communities Act”, 2008), An Act Relative to Competitively Priced Electricity in the Commonwealth (2012) and An Act to Promote Energy Diversity (“Energy Diversity Act”, 2016). The generating facilities associated with four of these contracts have been constructed and are now operating. Since 2017, the Company has participated in two major statewide procurements which resulted in contracts for imported hydroelectric power and associated transmission and for offshore wind generation. The contracts were approved by the MDPU in the second quarter of 2019. Additional long-term clean energy contracts are expected in compliance with the Energy Diversity Act and An Act to Promote a Clean Energy Future (2018). Fitchburg recovers the costs associated with long-term renewable contracts on a fully reconciling basis through a MDPU-approved cost recovery mechanism. Power Supply Contract Divestitures –
Subsequent Events	Subsequent Events –

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	3 Months Ended
	Mar. 31, 2020
Components of Gas and Electric Operating Revenue	Three Months Ended March 31, 2020 Gas and Electric Operating Revenues ($ millions): Gas Electric Total Billed and Unbilled Revenue: Residential $ 31.1 $ 34.4 $ 65.5 C&I 42.3 24.1 66.4 Other 3.0 2.0 5.0 Total Billed and Unbilled Revenue 76.4 60.5 136.9 Rate Adjustment Mechanism Revenue (6.2 ) (0.3 ) (6.5 ) Total Gas and Electric Operating Revenues $ 70.2 $ 60.2 $ 130.4 Three Months Ended March 31, 2019 Gas and Electric Operating Revenues ($ millions): Gas Electric Total Billed and Unbilled Revenue: Residential $ 38.7 $ 35.7 $ 74.4 C&I 54.0 24.7 78.7 Other 6.5 2.3 8.8 Total Billed and Unbilled Revenue 99.2 62.7 161.9 Rate Adjustment Mechanism Revenue (12.8 ) 2.1 (10.7 ) Total Gas and Electric Operating Revenues $ 86.4 $ 64.8 $ 151.2
Allowance for Doubtful Accounts Included in Accounts Receivable Net	was as follows: ($ millions) March 31, December 31, 2020 2019 2019 Allowance for Doubtful Accounts $ 1.8 $ 1.7 $ 1.0
Components of Accrued Revenue	March 31, December 31, Accrued Revenue ($ millions) 2020 2019 2019 Regulatory Assets – Current $ 28.4 $ 29.4 $ 35.8 Unbilled Revenues , net 10.2 10.8 14.2 Total Accrued Revenue $ 38.6 $ 40.2 $ 50.0
Components of Exchange Gas Receivable	March 31, December 31, Exchange Gas Receivable ($ millions) 2020 2019 2019 Northern Utilities $ 1.9 $ 0.2 $ 5.5 Fitchburg 0.3 0.2 0.6 Total Exchange Gas Receivable $ 2.2 $ 0.4 $ 6.1
Components of Gas Inventory	The following table shows the components of Gas Inventory as of March 31, 2020, March 31, 2019 and December 31, 2019. March 31, December 31, Gas Inventory ($ millions) 2020 2019 2019 Natural Gas $ — $ — $ 0.4 Propane 0.3 0.4 0.3 Liquefied Natural Gas & Other 0.1 0.1 0.1 Total Gas Inventory $ 0.4 $ 0.5 $ 0.8
Regulatory Assets	March 31, December 31, Regulatory Assets consist of the following ($ millions) 2020 2019 2019 Retirement Benefits $ 80.8 $ 72.4 $ 88.9 Energy Supply & Other Rate Adjustment Mechanisms 25.7 25.1 31.0 Deferred Storm Charges 5.3 5.9 5.6 Environmental 6.4 7.6 7.2 Income Taxes 4.0 4.7 4.2 Other Deferred Charges 11.5 11.6 10.9 Total Regulatory Assets 133.7 127.3 147.8 Less: Current Portion of Regulatory Assets (1) 28.4 29.4 35.8 Regulatory Assets – noncurrent $ 105.3 $ 97.9 $ 112.0 (1) Reflects amounts included in the Accrued Revenue on the Company’s Consolidated Balance Sheets.
Regulatory Liabilities	March 31, December 31, Regulatory Liabilities consist of the following ($ millions) 2020 2019 2019 Income Taxes (Note 8) $ 46.1 $ 48.2 $ 47.6 Rate Adjustment Mechanisms 9.1 13.6 6.0 Other 0.4 0.6 0.4 Total Regulatory Liabilities 55.6 62.4 54.0 Less: Current Portion of Regulatory Liabilities 10.5 15.0 7.4 Regulatory Liabilities—noncurrent $ 45.1 $ 47.4 $ 46.6
Fair Value of Marketable Securities	Changes in the fair value of these investments are recorded in Other Expense, Net. March 31, December 31, Fair Value of Marketable Securities ($ millions) 2020 2019 2019 Money Market Funds $ 5.5 $ 5.1 $ 5.6 Total Marketable Securities $ 5.5 $ 5.1 $ 5.6
Components of Energy Supply Obligations	The following discussion and table summarize the nature and amounts of the items recorded as Energy Supply Obligations (current portion) and Other Noncurrent Liabilities (noncurrent portion) on the Company’s Consolidated Balance Sheets. March 31, December 31, Energy Supply Obligations ($ millions) 2020 2019 2019 Current: Exchange Gas Obligation $ 1.9 $ 0.2 $ 5.5 Renewable Energy Portfolio Standards 5.7 4.1 4.7 Power Supply Contract Divestitures 0.3 0.3 0.3 Total Energy Supply Obligations – Current 7.9 4.6 10.5 Long-Term: Power Supply Contract Divestitures 0.2 0.5 0.3 Total Energy Supply Obligations $ 8.1 $ 5.1 $ 10.8
Deferred Compensation Plan [Member]
Fair Value of Marketable Securities	Changes in the fair value of these investments are recorded in Other Expense, Net. March 31, December 31, Fair Value of Marketable Securities ($ millions) 2020 2019 2019 Equity Funds $ 0.1 $ — $ 0.1 Money Market Funds 0.3 0.1 0.1 Total Marketable Securities $ 0.4 $ 0.1 $ 0.2

DIVIDENDS DECLARED PER SHARE (T

DIVIDENDS DECLARED PER SHARE (Tables)	3 Months Ended
	Mar. 31, 2020
DIVIDENDS DECLARED PER SHARE [Abstract]
Schedule of Dividends Declared	Declaration Date Date Paid (Payable) Shareholder of Record Date Dividend Amount 04/29/20 05/29/20 05/15/20 $ 0.375 01/29/20 02/28/20 02/14/20 $ 0.375 10/23/19 11/27/19 11/13/19 $0.370 07/24/19 08/29/19 08/15/19 $0.370 04/24/19 05/29/19 05/15/19 $ 0.370 01/30/19 02/28/19 02/14/19 $ 0.370

SEGMENT INFORMATION (Tables)

SEGMENT INFORMATION (Tables)	3 Months Ended
	Mar. 31, 2020
Significant Segment Financial Data	The following table provides significant segment financial data for the three months ended March 31, 2020 and March 31, 2019: Gas Electric Non- Regulated Other Total Three Months Ended March 31, 2020 ($ millions) Revenues: Billed and Unbilled Revenue $ 76.4 $ 60.5 $ — $ — $ 136.9 Rate Adjustment Mechanism Revenue (6.2 ) (0.3 ) — — (6.5 ) Other Operating Revenue – Non-Regulated — — — — — Total Operating Revenues 70.2 60.2 — — 130.4 Segment Profit (Loss) 12.3 2.6 — 0.3 15.2 Identifiable Segment Assets 821.4 537.7 0.1 19.2 1,378.4 Capital Expenditures 5.8 9.9 — 1.1 16.8 Three Months Ended March 31, 2019 ($ millions) Revenues: Billed and Unbilled Revenue $ 99.2 $ 62.7 $ — $ — $ 161.9 Rate Adjustment Mechanism Revenue (12.8 ) 2.1 — — (10.7 ) Other Operating Revenue – Non-Regulated — — 0.9 — 0.9 Total Operating Revenues 86.4 64.8 0.9 — 152.1 Segment Profit (Loss) 13.7 1.9 10.1 0.8 26.5 Identifiable Segment Assets 771.6 502.3 0.1 16.2 1,290.2 Capital Expenditures 3.3 6.6 — 1.0 10.9

DEBT AND FINANCING ARRANGEMEN_2

DEBT AND FINANCING ARRANGEMENTS (Tables)	3 Months Ended
	Mar. 31, 2020
Details on Long Term Debt	Details on long-term debt at March 31, 2020, March 31, 2019 and December 31, 2019 are shown below: ($ millions) March 31, December 31, 2020 2019 2019 Unitil Corporation: 6.33% Senior Notes, Due May 1, 2022 $ 20.0 $ 20.0 $ 20.0 3.70% Senior Notes, Due August 1, 2026 30.0 30.0 30.0 3.43% Senior Notes, Due December 18, 2029 30.0 — 30.0 Unitil Energy First Mortgage Bonds: 5.24% Senior Secured Notes, Due March 2, 2020 — 5.0 5.0 8.49% Senior Secured Notes, Due October 14, 2024 4.5 6.0 4.5 6.96% Senior Secured Notes, Due September 1, 2028 18.0 20.0 18.0 8.00% Senior Secured Notes, Due May 1, 2031 15.0 15.0 15.0 6.32% Senior Secured Notes, Due September 15, 2036 15.0 15.0 15.0 4.18% Senior Secured Notes, Due November 30, 2048 30.0 30.0 30.0 Fitchburg: 6.75% Senior Notes, Due November 30, 2023 3.8 5.7 3.8 6.79% Senior Notes, Due October 15, 2025 10.0 10.0 10.0 3.52% Senior Notes, Due November 1, 2027 10.0 10.0 10.0 7.37% Senior Notes, Due January 15, 2029 10.8 12.0 12.0 5.90% Senior Notes, Due December 15, 2030 15.0 15.0 15.0 7.98% Senior Notes, Due June 1, 2031 14.0 14.0 14.0 4.32% Senior Notes, Due November 1, 2047 15.0 15.0 15.0 Northern Utilities: 5.29% Senior Notes, Due March 2, 2020 — 8.2 8.2 3.52% Senior Notes, Due November 1, 2027 20.0 20.0 20.0 7.72% Senior Notes, Due December 3, 2038 50.0 50.0 50.0 4.42% Senior Notes, Due October 15, 2044 50.0 50.0 50.0 4.32% Senior Notes, Due November 1, 2047 30.0 30.0 30.0 4.04% Senior Notes, Due September 12, 2049 40.0 — 40.0 Granite State: 3.72% Senior Notes, Due November 1, 2027 15.0 15.0 15.0 Total Long-Term Debt 446.1 395.9 460.5 Less: Unamortized Debt Issuance Costs 3.5 3.4 3.5 Total Long-Term Debt, net of Unamortized Debt Issuance Costs 442.6 392.5 457.0 Less: Current Portion 6.3 19.5 19.5 Total Long-term Debt, Less Current Portion $ 436.3 $ 373.0 $ 437.5
Fair Value of Long Term Debt	($ millions) March 31, December 31, 2020 2019 2019 Estimated Fair Value of Long-Term Debt $ 494.7 $ 418.0 $ 518.7
Borrowing Limits Amounts Outstanding and Amounts Available under Credit Facility	The following table details the borrowing limits, amounts outstanding and amounts available under the Credit Facility as of March 31 2020, March 30, 2019 and December 31, 2019: Revolving Credit Facility ($ millions) March 31, December 31, 2020 2019 2019 Limit $ 120.0 $ 120.0 $ 120.0 Short-Term Borrowings Outstanding 71.6 65.8 58.6 Letter of Credit Outstanding 0.1 — 0.1 Available $ 48.3 $ 54.2 $ 61.3
Classification of the Company Lease Obligations	The balance sheet classification of the Company’s lease obligations was as follows: March 31, December 31, Lease Obligations ($ millions) 2020 2019 2019 Operating Lease Obligations: Other Current Liabilities (current portion) $ 1.4 $ 1.1 $ 1.2 Other Noncurrent Liabilities (long-term portion) 3.5 2.8 2.8 Total Operating Lease Obligations $ 4.9 $ 3.9 $ 4.0 Capital Lease Obligations: Other Current Liabilities (current portion) $ 0.2 $ 3.0 $ 0.2 Other Noncurrent Liabilities (long-term portion) 0.4 1.9 0.3 Total Capital Lease Obligations $ 0.6 $ 4.9 $ 0.5 Total Lease Obligations $ 5.5 $ 8.8 $ 4.5
Future Operating Lease Payment Obligations and Future Minimum Lease Payments under Capital Leases	The following table is a schedule of future operating lease payment obligations and future minimum lease payments under capital leases as of March 31, 2020. The payments for capital leases consist of $0.2 million of current capital lease obligations, which are included in Other Current Liabilities and $0.4 million of noncurrent capital lease obligations, which are included in Other Noncurrent Liabilities, on the Company’s Consolidated Balance Sheets as of March 31, 2020. The payments for operating leases consist of $1.4 million of current operating lease obligations, which are included in Other Current Liabilities and $3.5 million of noncurrent operating lease obligations, which are included in Other Noncurrent Liabilities, on the Company’s Consolidated Balance Sheets as of March 31, 2020. Lease Payments ($000’s) Year Ending December 31, Operating Capital Rest of 2020 $ 1,211 $ 215 2021 1,455 193 2022 1,174 130 2023 873 88 2024 544 33 2025-2029 140 — Total Payments 5,397 659 Less: Interest 497 35 Amount of Lease Obligations Recorded on Consolidated Balance Sheets $ 4,900 $ 624

COMMON STOCK AND PREFERRED ST_2

COMMON STOCK AND PREFERRED STOCK (Tables)	3 Months Ended
	Mar. 31, 2020
Table Text Block Supplement [Abstract]
Restricted Stock Units Issued	The equity portion of Restricted Stock Units activity during the three months ended March 31, 2020 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, 2019 70,364 $ 41.20 Restricted Stock Units Granted — — Dividend Equivalents Earned 469 $ 56.34 Restricted Stock Units Settled — — Restricted Stock Units as of March 31, 2020 70,833 $ 41.30

ENVIRONMENTAL MATTERS (Tables)

ENVIRONMENTAL MATTERS (Tables)	3 Months Ended
	Mar. 31, 2020
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, 2020 and 2019. Environmental Obligations ($ millions) Fitchburg Northern Total Three months ended March 31, 2020 2019 2020 2019 2020 2019 Total Balance at Beginning of Period $ — $ — $ 2.7 $ 2.0 $ 2.7 $ 2.0 Additions — — — 0.1 — 0.1 Less: Payments / Reductions — — 0.5 0.1 0.5 0.1 Total Balance at End of Period — — 2.2 2.0 2.2 2.0 Less: Current Portion — — 0.3 0.6 0.3 0.6 Noncurrent Balance at End of Period $ — $ — $ 1.9 $ 1.4 $ 1.9 $ 1.4

RETIREMENT BENEFIT OBLIGATIONS

RETIREMENT BENEFIT OBLIGATIONS (Tables)	3 Months Ended
	Mar. 31, 2020
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: Used to Determine Plan Costs 2020 2019 Discount Rate 3.25 % 4.25 % Rate of Compensation Increase 3.00 % 3.00 % Expected Long-term rate of return on plan assets 7.40 % 7.75 % Health Care Cost Trend Rate Assumed for Next Year 7.00 % 7.00 % Ultimate Health Care Cost Trend Rate 4.50 % 4.50 % Year that Ultimate Health Care Cost Trend Rate is reached 2029 2024
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, 2020 2019 2020 2019 2020 2019 Service Cost $ 831 $ 776 $ 675 $ 576 $ 71 $ 60 Interest Cost 1,444 1,621 780 856 137 139 Expected Return on Plan Assets (2,255 ) (2,119 ) (516 ) (411 ) — — Prior Service Cost Amortization 80 80 303 303 14 3 Actuarial Loss Amortization 1,618 1,081 186 57 259 158 Sub-total 1,718 1,439 1,428 1,381 481 360 Amounts Capitalized and Deferred (630 ) (412 ) (532 ) (474 ) (138 ) (103 ) Net Periodic Benefit Cost Recognized $ 1,088 $ 1,027 $ 896 $ 907 $ 343 $ 257

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)Subsidiarymi	Mar. 31, 2019USD ($)	Dec. 31, 2019USD ($)
Significant Accounting Policies [Line Items]
Length Of Pipeline | mi	86
Gain on divestiture of business, pretax		$ 13.4
Gain on divestiture of business, net	$ 9.8	9.8
Provision for income taxes		3.6
Cost of removal obligation	98.8	93.7	$ 96
Regulatory assets	133.7	127.3	147.8
Investments in trading securities	5.5	5.1	5.6
Allowance for doubtful accounts	1.8	1.7	1
Unbilled Revenues
Significant Accounting Policies [Line Items]
Allowance for doubtful accounts	0.1
Accounts Receivable
Significant Accounting Policies [Line Items]
Allowance for doubtful accounts	$ 1.7	1.7	1
Utilities
Significant Accounting Policies [Line Items]
Number of Subsidiaries | Subsidiary	3
Unitil Service; Unitil Realty; and Unitil Resources
Significant Accounting Policies [Line Items]
Number of Subsidiaries | Subsidiary	3
Environmental and Rate Case Costs and Other Expenditures | Recovered over the next seven years
Significant Accounting Policies [Line Items]
Regulatory assets	$ 7.5
ISO-NE Obligations
Significant Accounting Policies [Line Items]
Cash Deposits	$ 2.4	3	1.9
Lease term	12 months
Deferred Compensation Plan [Member]
Significant Accounting Policies [Line Items]
Investments in trading securities	$ 0.4	$ 0.1	$ 0.2

Components of Gas and Electric

Components of Gas and Electric Operating Revenue (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	$ 130.4	$ 151.2
Billed and Unbilled Revenue
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	136.9	161.9
Rate Adjustment Mechanism Revenue
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	(6.5)	(10.7)
Gas Segment
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	70.2	86.4
Gas Segment | Billed and Unbilled Revenue
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	76.4	99.2
Gas Segment | Rate Adjustment Mechanism Revenue
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	(6.2)	(12.8)
Electric
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	60.2	64.8
Electric | Billed and Unbilled Revenue
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	60.5	62.7
Electric | Rate Adjustment Mechanism Revenue
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	(0.3)	2.1
Residential | Billed and Unbilled Revenue
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	65.5	74.4
Residential | Gas Segment | Billed and Unbilled Revenue
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	31.1	38.7
Residential | Electric | Billed and Unbilled Revenue
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	34.4	35.7
C&I | Billed and Unbilled Revenue
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	66.4	78.7
C&I | Gas Segment | Billed and Unbilled Revenue
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	42.3	54
C&I | Electric | Billed and Unbilled Revenue
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	24.1	24.7
Other | Billed and Unbilled Revenue
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	5	8.8
Other | Gas Segment | Billed and Unbilled Revenue
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	3	6.5
Other | Electric | Billed and Unbilled Revenue
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	$ 2	$ 2.3

Allowance for Doubtful Accounts

Allowance for Doubtful Accounts Included in Accounts Receivable Net (Detail) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Valuation Allowance [Line Items]
Allowance for Doubtful Accounts	$ 1.8	$ 1	$ 1.7

Components of Accrued Revenue (

Components of Accrued Revenue (Detail) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Deferred Revenue Arrangement [Line Items]
Regulatory Assets – Current	$ 28.4	$ 35.8	$ 29.4
Total Accrued Revenue	38.6	50	40.2
Unbilled Revenues
Deferred Revenue Arrangement [Line Items]
Regulatory Assets – Current	10.2	14.2	10.8
Regulatory Assets
Deferred Revenue Arrangement [Line Items]
Regulatory Assets – Current	$ 28.4	$ 35.8	$ 29.4

Components of Exchange Gas Rece

Components of Exchange Gas Receivable (Detail) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Receivables [Line Items]
Total Exchange Gas Receivable	$ 2.2	$ 6.1	$ 0.4
Northern Utilities Inc
Receivables [Line Items]
Total Exchange Gas Receivable	1.9	5.5	0.2
Fitchburg
Receivables [Line Items]
Total Exchange Gas Receivable	$ 0.3	$ 0.6	$ 0.2

Components of Gas Inventory (De

Components of Gas Inventory (Detail) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Public Utilities, Inventory [Line Items]
Weighted average cost inventory amount	$ 0.4	$ 0.8	$ 0.5
Liquefied Natural Gas & Other
Public Utilities, Inventory [Line Items]
Weighted average cost inventory amount	0.1	0.1	0.1
Natural Gas
Public Utilities, Inventory [Line Items]
Weighted average cost inventory amount	0	0.4	0
Propane
Public Utilities, Inventory [Line Items]
Weighted average cost inventory amount	$ 0.3	$ 0.3	$ 0.4

Regulatory Assets (Detail)

Regulatory Assets (Detail) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Regulatory Assets [Line Items]
Regulatory assets	$ 133.7	$ 147.8	$ 127.3
Less: Current Portion of Regulatory Assets	28.4	35.8	29.4
Regulatory Assets - noncurrent	105.3	112	97.9
Environmental Matters
Regulatory Assets [Line Items]
Regulatory assets	6.4	7.2	7.6
Other Deferred Charges
Regulatory Assets [Line Items]
Regulatory assets	11.5	10.9	11.6
Retirement Benefits
Regulatory Assets [Line Items]
Regulatory assets	80.8	88.9	72.4
Deferred Storm Charges
Regulatory Assets [Line Items]
Regulatory assets	5.3	5.6	5.9
Income Taxes
Regulatory Assets [Line Items]
Regulatory assets	4	4.2	4.7
Energy Supply & Other Rate Adjustment Mechanisms
Regulatory Assets [Line Items]
Regulatory assets	$ 25.7	$ 31	$ 25.1

Regulatory Liabilities (Detail)

Regulatory Liabilities (Detail) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2017
Regulatory Liabilities [Line Items]
Regulatory Liabilities	$ 55.6	$ 54	$ 62.4
Less: Current Portion of Regulatory Liabilities	10.5	7.4	15
Regulatory Liabilities-noncurrent	45.1	46.6	47.4
Income Taxes
Regulatory Liabilities [Line Items]
Regulatory Liabilities	46.1	47.6	48.2	$ 48.9
Rate Adjustment Mechanisms
Regulatory Liabilities [Line Items]
Regulatory Liabilities	9.1	6	13.6
Other
Regulatory Liabilities [Line Items]
Regulatory Liabilities	$ 0.4	$ 0.4	$ 0.6

Fair Value of Marketable Securi

Fair Value of Marketable Securities (Detail) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading Securities	$ 5.5	$ 5.6	$ 5.1
Deferred Compensation Plan [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading Securities	0.4	0.2	0.1
Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading Securities	5.5	5.6	5.1
Fair Value, Inputs, Level 1 | Deferred Compensation Plan [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading Securities	0.4	0.2	0.1
Fair Value, Inputs, Level 1 | Equity Funds | Deferred Compensation Plan [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading Securities	0.1	0.1
Fair Value, Inputs, Level 1 | Money Market Funds
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading Securities	5.5	5.6	5.1
Fair Value, Inputs, Level 1 | Money Market Funds | Deferred Compensation Plan [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading Securities	$ 0.3	$ 0.1	$ 0.1

Components of Energy Supply Obl

Components of Energy Supply Obligations (Detail) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Contractual Obligation [Line Items]
Energy Supply Obligations-Current	$ 7.9	$ 10.5	$ 4.6
Power Supply Contract Divestitures, Noncurrent	0.2	0.3	0.5
Total Energy Supply Obligations	8.1	10.8	5.1
Renewable Energy Portfolio Standards
Contractual Obligation [Line Items]
Energy Supply Obligations-Current	5.7	4.7	4.1
Power Supply Contract Divestitures
Contractual Obligation [Line Items]
Energy Supply Obligations-Current	0.3	0.3	0.3
Exchange Gas Obligation
Contractual Obligation [Line Items]
Energy Supply Obligations-Current	$ 1.9	$ 5.5	$ 0.2

Dividends Declared Per Share (D

Dividends Declared Per Share (Detail) - $ / shares	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Dividends Payable [Line Items]
Dividend Amount	$ 0.375	$ 0.370
Group One
Dividends Payable [Line Items]
Declaration Date	Apr. 29, 2020
Date Paid (Payable)	May 29, 2020
Shareholder of Record Date	May 15, 2020
Dividend Amount	$ 0.375
Group Two
Dividends Payable [Line Items]
Declaration Date	Jan. 29, 2020
Date Paid (Payable)	Feb. 28, 2020
Shareholder of Record Date	Feb. 14, 2020
Dividend Amount	$ 0.375
Group Three
Dividends Payable [Line Items]
Declaration Date	Oct. 23, 2019
Date Paid (Payable)	Nov. 27, 2019
Shareholder of Record Date	Nov. 13, 2019
Dividend Amount	$ 0.370
Group Four
Dividends Payable [Line Items]
Declaration Date	Jul. 24, 2019
Date Paid (Payable)	Aug. 29, 2019
Shareholder of Record Date	Aug. 15, 2019
Dividend Amount	$ 0.370
Group Five
Dividends Payable [Line Items]
Declaration Date	Apr. 24, 2019
Date Paid (Payable)	May 29, 2019
Shareholder of Record Date	May 15, 2019
Dividend Amount	$ 0.370
Group Six
Dividends Payable [Line Items]
Declaration Date	Jan. 30, 2019
Date Paid (Payable)	Feb. 28, 2019
Shareholder of Record Date	Feb. 14, 2019
Dividend Amount	$ 0.370

Significant Segment Financial D

Significant Segment Financial Data (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Other Operating Revenue - Non-Regulated	$ 0	$ 0.9
Total Operating Revenues	130.4	152.1
Segment Profit (Loss)	15.2	26.5
Identifiable Segment Assets	1,378.4	1,290.2	$ 1,370.8
Capital Expenditures	16.8	10.9
Billed and Unbilled Revenue
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total Operating Revenues	136.9	161.9
Rate Adjustment Mechanism Revenue
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total Operating Revenues	(6.5)	(10.7)
Gas Segment
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total Operating Revenues	70.2	86.4
Segment Profit (Loss)	12.3	13.7
Identifiable Segment Assets	821.4	771.6
Capital Expenditures	5.8	3.3
Gas Segment | Billed and Unbilled Revenue
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total Operating Revenues	76.4	99.2
Gas Segment | Rate Adjustment Mechanism Revenue
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total Operating Revenues	(6.2)	(12.8)
Electric
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total Operating Revenues	60.2	64.8
Segment Profit (Loss)	2.6	1.9
Identifiable Segment Assets	537.7	502.3
Capital Expenditures	9.9	6.6
Electric | Billed and Unbilled Revenue
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total Operating Revenues	60.5	62.7
Electric | Rate Adjustment Mechanism Revenue
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total Operating Revenues	(0.3)	2.1
All Other Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Segment Profit (Loss)	0.3	0.8
Identifiable Segment Assets	19.2	16.2
Capital Expenditures	1.1	1
Unregulated Operation
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Other Operating Revenue - Non-Regulated	0	0.9
Total Operating Revenues	0	0.9
Segment Profit (Loss)	0	10.1
Identifiable Segment Assets	$ 0.1	$ 0.1

Details on Long Term Debt (Deta

Details on Long Term Debt (Detail) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Debt Instrument [Line Items]
Total Long-Term Debt	$ 446.1	$ 460.5	$ 395.9
Less: Unamortized Debt Issuance Costs	3.5	3.5	3.4
Long-Term Debt	442.6	457	392.5
Less: Current Portion	6.3	19.5	19.5
Total Long-Term Debt, Less Current Portion	436.3	437.5	373
Long-Term Debt	442.6	457	392.5
6.33% Senior Notes, Due May 1, 2022
Debt Instrument [Line Items]
Total Long-Term Debt	20	20	20
3.70% Senior Notes, Due August 1, 2026
Debt Instrument [Line Items]
Total Long-Term Debt	30	30	30
3.43% Senior Notes, Due December 18, 2029
Debt Instrument [Line Items]
Total Long-Term Debt	30	30
Unitil Energy Systems Inc | First Mortgage Bonds 5.24% Senior Secured Notes, Due March 2, 2020
Debt Instrument [Line Items]
Total Long-Term Debt	0	5	5
Unitil Energy Systems Inc | First Mortgage Bonds 8.49% Senior Secured Notes, Due October 14, 2024
Debt Instrument [Line Items]
Total Long-Term Debt	4.5	4.5	6
Unitil Energy Systems Inc | First Mortgage Bonds 6.96% Senior Secured Notes, Due September 1, 2028
Debt Instrument [Line Items]
Total Long-Term Debt	18	18	20
Unitil Energy Systems Inc | First Mortgage Bonds 8.00% Senior Secured Notes, Due May 1, 2031
Debt Instrument [Line Items]
Total Long-Term Debt	15	15	15
Unitil Energy Systems Inc | First Mortgage Bonds 6.32% Senior Secured Notes, Due September 15, 2036
Debt Instrument [Line Items]
Total Long-Term Debt	15	15	15
Unitil Energy Systems Inc | First Mortgage Bonds 4.18% Senior Secured Notes Due November 30, 2048
Debt Instrument [Line Items]
Total Long-Term Debt	30	30	30
Fitchburg Gas and Electric Light Company | 6.75% Senior Notes, Due November 30, 2023
Debt Instrument [Line Items]
Total Long-Term Debt	3.8	3.8	5.7
Fitchburg Gas and Electric Light Company | 6.79% Senior Notes, Due October 15, 2025
Debt Instrument [Line Items]
Total Long-Term Debt	10	10	10
Fitchburg Gas and Electric Light Company | 3.52% Senior Notes, Due November 1, 2027
Debt Instrument [Line Items]
Total Long-Term Debt	10	10	10
Fitchburg Gas and Electric Light Company | 7.37% Notes, Due January 15, 2029
Debt Instrument [Line Items]
Total Long-Term Debt	10.8	12	12
Fitchburg Gas and Electric Light Company | 5.90% Notes, Due December 15, 2030
Debt Instrument [Line Items]
Total Long-Term Debt	15	15	15
Fitchburg Gas and Electric Light Company | 7.98% Notes, Due June 1, 2031
Debt Instrument [Line Items]
Total Long-Term Debt	14	14	14
Fitchburg Gas and Electric Light Company | 4.32% Senior Notes, Due November 1, 2047
Debt Instrument [Line Items]
Total Long-Term Debt	15	15	15
Northern Utilities Inc | 3.52% Senior Notes, Due November 1, 2027
Debt Instrument [Line Items]
Total Long-Term Debt	20	20	20
Northern Utilities Inc | 4.32% Senior Notes, Due November 1, 2047
Debt Instrument [Line Items]
Total Long-Term Debt	30	30	30
Northern Utilities Inc | 5.29% Senior Notes, Due March 2, 2020
Debt Instrument [Line Items]
Total Long-Term Debt	0	8.2	8.2
Northern Utilities Inc | 7.72% Senior Notes, Due December 3, 2038
Debt Instrument [Line Items]
Total Long-Term Debt	50	50	50
Northern Utilities Inc | 4.42% Senior Notes, Due October 15, 2044
Debt Instrument [Line Items]
Total Long-Term Debt	50	50	50
Northern Utilities Inc | 4.04% Senior Notes, Due September 12, 2049
Debt Instrument [Line Items]
Total Long-Term Debt	40	40
Granite State Gas Transmission Inc | 3.72% Senior Notes, Due November 1, 2027
Debt Instrument [Line Items]
Total Long-Term Debt	$ 15	$ 15	$ 15

Details on Long Term Debt (Pare

Details on Long Term Debt (Parenthetical) (Detail)	Sep. 12, 2019	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
6.33% Senior 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
3.70% Senior Notes, Due August 1, 2026
Debt Instrument [Line Items]
Stated interest rate		3.70%	3.70%	3.70%
Debt instrument due date		Aug. 1, 2026	Aug. 1, 2026	Aug. 1, 2026
3.43% Senior Notes, Due December 18, 2029
Debt Instrument [Line Items]
Stated interest rate		3.43%	3.43%	3.43%
Debt instrument due date		Dec. 18, 2029	Dec. 18, 2029	Dec. 18, 2029
First Mortgage Bonds 5.24% Senior Secured Notes, Due March 2, 2020
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% Senior Secured Notes, Due October 14, 2024
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% Senior Secured Notes, Due September 1, 2028
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% Senior Secured Notes, Due May 1, 2031
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% Senior Secured Notes, Due September 15, 2036
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
First Mortgage Bonds 4.18% Senior Secured Notes Due November 30, 2048
Debt Instrument [Line Items]
Stated interest rate		4.18%	4.18%	4.18%
Debt instrument due date		Nov. 30, 2048	Nov. 30, 2048	Nov. 30, 2048
6.75% Senior Notes, Due November 30, 2023
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
6.79% Senior Notes, Due October 15, 2025
Debt Instrument [Line Items]
Stated interest rate		6.79%	6.79%	6.79%
Debt instrument due date		Oct. 15, 2025		Oct. 15, 2025
3.52% Senior Notes, Due November 1, 2027
Debt Instrument [Line Items]
Stated interest rate		3.52%	3.52%	3.52%
Debt instrument due date		Nov. 1, 2027	Nov. 1, 2027	Nov. 1, 2027
7.37% Notes, Due January 15, 2029
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
5.90% Notes, Due December 15, 2030
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
7.98% Notes, Due June 1, 2031
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
4.32% Senior Notes, Due November 1, 2047 | Fitchburg Gas and Electric Light Company
Debt Instrument [Line Items]
Stated interest rate		4.32%	4.32%	4.32%
Debt instrument due date		Nov. 1, 2047	Nov. 1, 2047	Nov. 1, 2047
4.32% Senior Notes, Due November 1, 2047 | Northern Utilities Inc
Debt Instrument [Line Items]
Stated interest rate		4.32%	4.32%	4.32%
Debt instrument due date		Nov. 1, 2047		Nov. 1, 2047
5.29% Senior Notes, Due March 2, 2020
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, Due December 3, 2038
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
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
4.04% Senior Notes, Due September 12, 2049
Debt Instrument [Line Items]
Stated interest rate		4.04%	4.04%	4.04%
Debt instrument due date		Sep. 12, 2049	Sep. 12, 2049	Sep. 12, 2049
4.04% Senior Notes, Due September 12, 2049 | Northern Utilities Inc
Debt Instrument [Line Items]
Stated interest rate	4.04%
Debt instrument due date	Sep. 12, 2049
3.72% Senior Notes, Due November 1, 2027
Debt Instrument [Line Items]
Stated interest rate		3.72%	3.72%	3.72%
Debt instrument due date		Nov. 1, 2027	Nov. 1, 2027	Nov. 1, 2027

Estimated Fair Value of Long Te

Estimated Fair Value of Long Term Debt (Detail) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Fair Value, Inputs, Level 2
Debt Instrument [Line Items]
Estimated Fair Value of Long-Term Debt	$ 494.7	$ 518.7	$ 418

Debt and Financing Arrangemen_3

Debt and Financing Arrangements - Additional Information (Detail) - USD ($)	Dec. 18, 2019	Sep. 12, 2019	Jul. 25, 2018	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Oct. 30, 2015
Line of Credit Facility [Line Items]
Weighted average interest rate on short term borrowings				2.60%	3.70%	3.40%
Gain on divestiture of business, net				$ 9,800,000	$ 9,800,000
Capital lease obligation, total capitalized cost				624,000	4,900,000	$ 500,000
Capital lease obligation, current				200,000	3,000,000	200,000
Capital lease obligation, noncurrent				400,000	1,900,000	300,000
Accounts Payable				26,500,000	33,000,000	37,600,000
Guarantee outstanding				6,200,000
Total rental expense under operating leases				400,000	400,000
Operating lease obligations				400,000
Net Utility Plant				1,125,100,000	1,037,800,000	1,111,500,000
Other current operating lease obligation				1,400,000	1,100,000	1,200,000
Other noncurrent operating lease obligation				$ 3,500,000	$ 2,800,000	$ 2,800,000
Issuance of long-term debt	$ 200,000	$ 200,000
Operating lease, weighted average remaining lease term				3 years 10 months 24 days
Operating lease, weighted average discount rate percentage				4.90%
Credit Facility [Member] | Second Amended Credit Facility
Line of Credit Facility [Line Items]
Revolving credit facility			$ 120,000,000
Sublimit for the issuance of standby letters of credit			$ 25,000,000
Revolving credit facility termination date			Jul. 25, 2023
Increase in borrowing limit			$ 50,000,000
Credit Facility [Member] | London Interbank Offered Rate | Second Amended Credit Facility
Line of Credit Facility [Line Items]
Credit facility, daily fluctuating rate of interest			1.125%
3.43% Senior Notes, Due December 18, 2029
Line of Credit Facility [Line Items]
Long-term debt, stated interest rate				3.43%	3.43%	3.43%
Long-term debt, maturity date				Dec. 18, 2029	Dec. 18, 2029	Dec. 18, 2029
4.04% Senior Notes, Due September 12, 2049
Line of Credit Facility [Line Items]
Long-term debt, stated interest rate				4.04%	4.04%	4.04%
Long-term debt, maturity date				Sep. 12, 2049	Sep. 12, 2049	Sep. 12, 2049
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Revolving credit facility				$ 120,000,000	$ 120,000,000	$ 120,000,000
Proceeds from lines of credit				74,300,000
Repayments of lines of credit				$ 61,300,000
Revolving Credit Facility [Member] | Credit Facility [Member]
Line of Credit Facility [Line Items]
Percentage of capitalization				The affirmative and negative covenants under the Credit Facility shall apply 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 Funded Debt to Capitalization (as each term is defined in the Credit Facility) cannot exceed 65%, tested on a quarterly basis. At March 31, 2020, March 31, 2019 and December 31, 2019, the Company was in compliance with the covenants contained in the Credit Facility in effect on that date.
Unitil Service Corp [Member]
Line of Credit Facility [Line Items]
Capital lease obligation, total capitalized cost							$ 13,400,000
Northern Utilities Inc
Line of Credit Facility [Line Items]
Accounts Payable				$ 600,000	2,100,000	1,000,000
Natural gas storage inventory				$ 2,500,000	2,200,000	6,500,000
Total funded indebtedness as percentage of capitalization				65.00%
Northern Utilities Inc | 4.04% Senior Notes, Due September 12, 2049
Line of Credit Facility [Line Items]
Long-term debt, aggregate principal amount		$ 40,000,000
Long-term debt, stated interest rate		4.04%
Long-term debt, maturity date		Sep. 12, 2049
Unitil Corporation | 3.43% Senior Notes, Due December 18, 2029
Line of Credit Facility [Line Items]
Long-term debt, aggregate principal amount	$ 30,000,000
Long-term debt, stated interest rate	3.43%
Long-term debt, maturity date	Dec. 18, 2029
Assets under Capital Leases [Member]
Line of Credit Facility [Line Items]
Net Utility Plant				$ 1,200,000	14,900,000	1,200,000
Net Utility Plant, accumulated amortization				$ 700,000	$ 1,800,000	$ 600,000

Borrowing Limits Amounts Outsta

Borrowing Limits Amounts Outstanding and Amounts Available under Revolving Credit Facility (Detail) - USD ($)	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Debt Instrument [Line Items]
Short-Term Borrowings Outstanding	$ 71,600,000	$ 58,600,000	$ 65,800,000
Revolving Credit Facility
Debt Instrument [Line Items]
Revolving credit facility, limit	120,000,000	120,000,000	120,000,000
Short-Term Borrowings Outstanding	71,600,000	58,600,000	65,800,000
Letters of Credit Outstanding	100,000	100,000
Available revolving credit facility	$ 48,300,000	$ 61,300,000	$ 54,200,000

Debt and Financing Arrangemen_4

Debt and Financing Arrangements - Classification of the Company Lease Obligations (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Operating Lease Obligations:
Other Current Liabilities (current portion)	$ 1,400	$ 1,200	$ 1,100
Other Noncurrent Liabilities (long-term portion)	3,500	2,800	2,800
Total Operating Lease Obligations	4,900	4,000	3,900
Capital Lease Obligations:
Other Current Liabilities (current portion)	200	200	3,000
Other Noncurrent Liabilities (long-term portion)	400	300	1,900
Total Capital Lease Obligations	624	500	4,900
Total Lease Obligations	$ 5,500	$ 4,500	$ 8,800

Future Operating Lease Payment

Future Operating Lease Payment Obligations and Future Minimum Lease Payments under Capital Leases (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Operating leases
Rest of 2020	$ 1,211
2021	1,455
2022	1,174
2023	873
2024	544
2024-2028	140
Total Payments	5,397
Less: Interest	497
Amount of Lease Obligations Recorded on Consolidated Balance Sheets	4,900	$ 4,000	$ 3,900
Capital lease
Rest of 2020	215
2021	193
2022	130
2023	88
2024	33
2024-2028	0
Total Payments	659
Less: Interest	35
Amount of Lease Obligations Recorded on Consolidated Balance Sheets	$ 624	$ 500	$ 4,900

Common Stock And Preferred St_3

Common Stock And Preferred Stock - Additional Information (Detail) - USD ($)	Jan. 28, 2020	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Class of Stock [Line Items]
Common stock, shares outstanding		14,963,444	14,916,044	14,930,170
Common stock, shares issued		4,644	5,939
Proceeds from Issuance of Common Stock		$ 300,000	$ 300,000
Restricted stock weighted average grant date fair value		$ 54.88	$ 46.23
Share based compensation expense		$ 1,800,000	$ 1,700,000
Percentage of fully-vested restricted stock units that directors will receive in common shares when settled		70.00%
Fair value of liabilities associated with fully vested RSUs that will be settled in cash		$ 1,600,000	1,400,000	$ 1,900,000
Percentage of fully-vested restricted stock units that directors will receive in cash when settled		30.00%
Preferred Stock		$ 200,000	$ 200,000	$ 200,000
Maximum
Class of Stock [Line Items]
Dividend declared		$ 100,000
Restricted Stock
Class of Stock [Line Items]
Restricted stock vesting period		4 years
Restricted stock non-vested		56,813	60,496
Unrecognized share based compensation		$ 1,100,000
Share compensation recognition period		3 years
Restricted Stock Units Granted	28,630
Aggregate Market Value		$ 1,800,000
Forfeitures under the stock plan		0
Cancellations under the stock plan		0
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 Stock Units Granted		0
Restricted stock units outstanding			62,206
Weighted-Average Stock Price			$ 38.36
Series 6 | Unitil Energy Systems Inc
Class of Stock [Line Items]
Preferred stock, outstanding		1,887	1,893
Preferred Stock		$ 200,000	$ 200,000
Dividend rate		6.00%	6.00%
Dividend and Distribution Reinvestment and Share Purchase Plan
Class of Stock [Line Items]
Proceeds from Issuance of Common Stock		$ 284,000
Dividend and Distribution Reinvestment and Share Purchase Plan | Average
Class of Stock [Line Items]
Common stock price per share		$ 61.16
Dividend and Distribution Reinvestment and Share Purchase Plan | Common Stock
Class of Stock [Line Items]
Common stock, shares issued		4,644

Restricted Stock Units Issued (

Restricted Stock Units Issued (Detail) - Restricted Stock Units (RSUs)	3 Months Ended
	Mar. 31, 2020$ / sharesshares
Restricted Stock Units
Beginning Restricted Stock Units | shares	70,364
Restricted Stock Units Granted | shares	0
Dividend Equivalents Earned | shares	469
Restricted Stock Units Settled | shares	0
Ending Restricted Stock Units | shares	70,833
Weighted-Average Stock Price
Beginning Restricted Stock Units | $ / shares	$ 41.20
Restricted Stock Units Granted | $ / shares	0
Dividend Equivalents Earned | $ / shares	56.34
Restricted Stock Units Settled | $ / shares	0
Ending Restricted Stock Units | $ / shares	$ 41.30

Regulatory Matters - Additional

Regulatory Matters - Additional Information (Detail)

Mar. 01, 2021USD ($)

May 01, 2020USD ($)

Mar. 26, 2020USD ($)

Feb. 28, 2020USD ($)

Jan. 31, 2020USD ($)

Dec. 17, 2019USD ($)

Oct. 29, 2019USD ($)

May 01, 2019USD ($)

Apr. 30, 2019USD ($)

Apr. 22, 2019USD ($)

Apr. 17, 2019USD ($)

Nov. 01, 2018USD ($)

Mar. 31, 2020USD ($)

Jun. 28, 2019USD ($)

May 01, 2019USD ($)

May 02, 2018USD ($)

Dec. 31, 2017

Apr. 20, 2017USD ($)

Mar. 31, 2020

Jun. 30, 2027MW

Dec. 31, 2022MWh

Jul. 31, 2018MWhMW

Jun. 30, 2017MW

Tax Year 2018

Regulatory Assets [Line Items]

Corporate income tax rate

21.00%

21.00%

Offshore Wind Energy

Regulatory Assets [Line Items]

Power generation facility | MW

1,600

Unitil Energy Systems Inc | New Hampshire

Regulatory Assets [Line Items]

Approved annual increase in rates

$ 340,000

$ 4,100,000

Fitchburg Gas and Electric Light Company

Regulatory Assets [Line Items]

Requested annual increase in rates

$ 2,700,000

$ 1,100,000

$ 900,000

Increase in annual base rate

4.10%

Percentage of approved return on equity

9.70%

Percentage of approved return on equity, reflecting on equity

52.45%

Percentage of approved return on equity, reflecting on debt

47.55%

Revenue impact threshold

$ 100,000

Fitchburg Gas and Electric Light Company | Offshore Wind Energy

Regulatory Assets [Line Items]

Power generation facility | MW

400

Remuneration Percentage

2.75

2.75

Fitchburg Gas and Electric Light Company | Offshore Wind Energy | First Solicitation [Member]

Regulatory Assets [Line Items]

Power generation facility | MW

800

Fitchburg Gas and Electric Light Company | Offshore Wind Energy | Second Solicitation [Member]

Regulatory Assets [Line Items]

Power generation facility | MW

800

Fitchburg Gas and Electric Light Company | Qualified Clean Energy

Regulatory Assets [Line Items]

Power Generation Capacity | MWh

9,554,940

Fitchburg Gas and Electric Light Company | Minimum [Member] | Offshore Wind Energy

Regulatory Assets [Line Items]

Power generation facility | MW

400

Fitchburg Gas and Electric Light Company | Scenario Forecast

Regulatory Assets [Line Items]

Power Generation Capacity | MWh

9,450,000

Northern Utilities Inc

Regulatory Assets [Line Items]

Approved annual increase in rates

$ 1,400,000

Northern Utilities Inc | Maine

Regulatory Assets [Line Items]

Requested annual increase in rates

$ 7,000,000

Increase in annual base rate

3.60%

2.10%

Approved annual increase in rates

$ 3,600,000

$ 1,000,000

Percentage of approved return on equity

9.48%

Percentage of approved return on equity, reflecting on equity

50.00%

Percentage of approved return on equity, reflecting on debt

50.00%

Northern Utilities Inc | New Hampshire

Regulatory Assets [Line Items]

Approved annual increase in rates

$ 3,200,000

Northern Utilities Inc | New Hampshire | Scenario Forecast

Regulatory Assets [Line Items]

Requested annual increase in rates

$ 1,400,000

Fitchburg Gas Company

Regulatory Assets [Line Items]

Requested annual increase in rates

$ 7,300,000

Percentage of change in revenue over previous year

20.80%

Approved annual increase in rates

$ 4,600,000

$ 1,100,000

$ 600,000

$ 1,600,000

$ 3,700,000

$ 1,000,000

Percentage of approved return on equity

9.70%

Percentage of approved return on equity, reflecting on equity

52.45%

Percentage of approved return on equity, reflecting on debt

47.55%

Revenue impact threshold

$ 400,000,000

Fitchburg Gas Company | Scenario Forecast

Regulatory Assets [Line Items]

Approved annual increase in rates

$ 900,000

Environmental Matters - Additio

Environmental Matters - Additional Information (Detail) - Environmental Restoration Costs $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)
Maine
Site Contingency [Line Items]
Amortization period for environmental costs	5 years
New Hampshire
Site Contingency [Line Items]
Amortization period for environmental costs	7 years
Northern Utilities Manufactured Gas Plant Sites
Site Contingency [Line Items]
Estimated Costs Accrued For Remediation	$ 0.8

Company's Liability for Environ

Company's Liability for Environmental Obligations (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Sep. 30, 2018
Environmental Exit Cost [Line Items]
Total Balance at Beginning of Period	$ 2.7	$ 2
Additions		0.1
Less: Payments / Reductions	0.5	0.1
Total Balance at End of Period	2.2	2
Less: Current Portion	0.3	0.6	$ 0.6	$ 0.6
Noncurrent Balance at End of Period	1.9	1.4	$ 2.1	1.4
Fitchburg Gas and Electric Light Company
Environmental Exit Cost [Line Items]
Total Balance at Beginning of Period
Additions
Less: Payments / Reductions
Total Balance at End of Period
Less: Current Portion
Noncurrent Balance at End of Period
Northern Utilities Inc
Environmental Exit Cost [Line Items]
Total Balance at Beginning of Period	2.7	2
Additions		0.1
Less: Payments / Reductions	0.5	0.1
Total Balance at End of Period	2.2	$ 2
Less: Current Portion	0.3			0.6
Noncurrent Balance at End of Period	$ 1.9			$ 1.4

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended		3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2017	Mar. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2020	Mar. 31, 2019
Income Taxes [Line Items]
Regulatory Liability	$ 55.6		$ 55.6	$ 54				$ 62.4
Regulatory liability, expected flow back to customers			47.1		$ 48.9
Regulatory liability, expected pass back to ratepayers			0.2	0.3
Net Operating Loss Carryforwards Utilized For Income Taxes					5.7
Deferred tax assets, operating loss carryforwards, federal				1.6
Alternative minimum tax credit carryforwards	0.9		0.9	0.9			$ 0.1
Additional Alternative minimum tax credit carryforwards				1.9
Reconciling Mechanisms
Income Taxes [Line Items]
Regulatory liability, expected pass back to ratepayers						$ 1.8
Net Operating Loss Carryforward Assets
Income Taxes [Line Items]
Regulatory liability, expected pass back to ratepayers					$ 2
Income Tax Related Liabilities
Income Taxes [Line Items]
Regulatory Liability	46.1	$ 48.9	46.1	47.6		$ 48.9		$ 48.2
Electric Ratepayers | Fitchburg Gas and Electric Light Company
Income Taxes [Line Items]
Regulatory liability, expected flow back to customers			10.1
Gas Ratepayers | Fitchburg Gas and Electric Light Company
Income Taxes [Line Items]
Regulatory liability, expected flow back to customers			$ 10.4
Gas Ratepayers | Northern Utilities Inc
Income Taxes [Line Items]
Regulatory liability, expected flow back to customers	$ 12.3
Average Rate Assumption Method estimated flow back period	20 years
Tax Year 2018
Income Taxes [Line Items]
Corporate federal income tax		21.00%	21.00%
Tax Year 2019
Income Taxes [Line Items]
Net Operating Loss Carryforwards Utilized For Income Taxes				$ 3.5

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, 2020	Mar. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Discount Rate	3.25%	4.25%
Rate of Compensation Increase	3.00%	3.00%
Expected Long-term rate of return on plan assets	7.40%	7.75%
Health Care Cost Trend Rate Assumed for Next Year	7.00%	7.00%
Ultimate Health Care Cost Trend Rate	4.50%	4.50%
Year that Ultimate Health Care Cost Trend Rate is reached	2029	2024

Components of Retirement Plan C

Components of Retirement Plan Costs (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service Cost	$ 831	$ 776
Interest Cost	1,444	1,621
Expected Return on Plan Assets	(2,255)	(2,119)
Prior Service Cost Amortization	80	80
Actuarial Loss Amortization	1,618	1,081
Sub-total	1,718	1,439
Amounts Capitalized and Deferred	(630)	(412)
Net Periodic Benefit Cost Recognized	1,088	1,027
Other Postretirement Benefit Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Service Cost	675	576
Interest Cost	780	856
Expected Return on Plan Assets	(516)	(411)
Prior Service Cost Amortization	303	303
Actuarial Loss Amortization	186	57
Sub-total	1,428	1,381
Amounts Capitalized and Deferred	(532)	(474)
Net Periodic Benefit Cost Recognized	896	907
Supplemental Employee Retirement Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Service Cost	71	60
Interest Cost	137	139
Prior Service Cost Amortization	14	3
Actuarial Loss Amortization	259	158
Sub-total	481	360
Amounts Capitalized and Deferred	(138)	(103)
Net Periodic Benefit Cost Recognized	$ 343	$ 257

Retirement Benefit Obligation_2

Retirement Benefit Obligations - Additional Information (Detail) - Supplemental Employee Retirement Plans, Defined Benefit $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)
Defined Benefit Plan Disclosure [Line Items]
Benefit payments under SERP Plan	$ 0.2
Expected additional benefit payments for the remainder of 2019	$ 0.5