Unitil (UTL) 10-Q 30 Jul 20 2020 Q2 Quarterly report Financial data

Cover Page

Cover Page - shares	6 Months Ended
	Jun. 30, 2020	Jul. 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	Jun. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
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		14,997,329
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		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Operating Revenues
Total Operating Revenues	$ 83.9	$ 84.4	$ 214.3	$ 236.5
Operating Expenses
Operation and Maintenance	14.6	15.9	32.5	34.4
Depreciation and Amortization	13.5	12.4	27	26.2
Taxes Other Than Income Taxes	6.1	5.1	12.6	11.5
Total Operating Expenses	72.8	72.1	175.6	195.4
Operating Income	11.1	12.3	38.7	41.1
Interest Expense, Net	5.9	5.9	12.1	12.1
Other Expense (Income), Net	1.4	1.3	2.9	(10.8)
Income Before Income Taxes	3.8	5.1	23.7	39.8
Provision for Income Taxes	0.7	1.1	5.4	9.3
Net Income	$ 3.1	$ 4	$ 18.3	$ 30.5
Net Income Per Common Share (Basic and Diluted)	$ 0.21	$ 0.27	$ 1.23	$ 2.05
Weighted Average Common Shares Outstanding – (Basic and Diluted)	14.9	14.9	14.9	14.9
Gas
Operating Revenues
Total Operating Revenues	$ 33.7	$ 32.6	$ 103.9	$ 119
Operating Expenses
Total Operating Expenses	10.8	9.3	38.6	52.2
Electric
Operating Revenues
Total Operating Revenues	50.2	51.8	110.4	116.6
Operating Expenses
Total Operating Expenses	$ 27.8	$ 29.4	$ 64.9	71.1
Other
Operating Revenues
Total Operating Revenues				$ 0.9

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Current Assets:
Cash and Cash Equivalents	$ 4.2	$ 5.2	$ 4.8
Accounts Receivable, Net	48.3	55.1	48.7
Accrued Revenue	34.9	50	32.1
Exchange Gas Receivable	4.2	6.1	5.3
Gas Inventory	0.5	0.8	0.7
Materials and Supplies	9.2	7.9	7.5
Prepayments and Other	8.3	5.8	8.3
Total Current Assets	109.6	130.9	107.4
Utility Plant:
Gas	870.5	837.7	779.4
Electric	541.7	529.7	511.6
Common	62.8	62.7	61.2
Construction Work in Progress	68.9	37.4	44.9
Utility Plant	1,543.9	1,467.5	1,397.1
Less: Accumulated Depreciation	396.3	356	343.6
Net Utility Plant	1,147.6	1,111.5	1,053.5
Other Noncurrent Assets:
Regulatory Assets	104.9	112	97.3
Operating Lease Right of Use Assets	4.5	4	3.6
Other Assets	17.9	12.4	17.5
Total Other Noncurrent Assets	127.3	128.4	118.4
TOTAL ASSETS	1,384.5	1,370.8	1,279.3
Current Liabilities:
Accounts Payable	24.7	37.6	21.9
Short-Term Debt	74.9	58.6	64.8
Long-Term Debt, Current Portion	6.3	19.5	19.5
Regulatory Liabilities	12.6	7.4	18.5
Energy Supply Obligations	8.4	10.5	9.2
Interest Payable	4.2	4.5	4
Environmental Obligations	0.3	0.6	0.6
Other Current Liabilities	17.9	21.1	17.5
Total Current Liabilities	149.3	159.8	156
Noncurrent Liabilities:
Retirement Benefit Obligations	147.5	141.9	123.3
Deferred Income Taxes, net	109	103.6	104.1
Cost of Removal Obligations	102.6	96	94
Regulatory Liabilities	44.8	46.6	46.9
Environmental Obligations	1.9	2.1	1.4
Other Noncurrent Liabilities	7.3	6.5	7.5
Total Noncurrent Liabilities	413.1	396.7	377.2
Capitalization:
Long-Term Debt, Less Current Portion	436.4	437.5	373.1
Stockholders' Equity:
Common Equity (Authorized: 25,000,000 and Outstanding: 14,996,231, 14,921,171 and 14,930,170 Shares)	284.4	282.5	281.3
Retained Earnings	101.1	94.1	91.5
Total Common Stock Equity	385.5	376.6	372.8
Preferred Stock	0.2	0.2	0.2
Total Stockholders' Equity	385.7	376.8	373
Total Capitalization	822.1	814.3	746.1
TOTAL LIABILITIES AND CAPITALIZATION	$ 1,384.5	$ 1,370.8	$ 1,279.3

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - shares	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Common Stock Authorized	25,000,000	25,000,000	25,000,000
Common Equity Outstanding	14,996,231	14,930,170	14,921,171

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Operating Activities:
Net Income	$ 18.3	$ 30.5
Adjustments to Reconcile Net Income to Cash Provided by Operating Activities:
Depreciation and Amortization	27	26.2
Deferred Tax Provision	4.8	8.4
Gain on Divestiture, Net (See Note 1)		(13.4)
Changes in Working Capital Items:
Accounts Receivable	6.8	18.1
Accrued Revenue	15.1	22.6
Exchange Gas Receivable	1.9	2.8
Regulatory Liabilities	5.2	7
Accounts Payable	(12.9)	(20.7)
Other Changes in Working Capital Items	(8)	(3.1)
Deferred Regulatory and Other Charges	(0.8)	(8)
Other, net	0.9	1.7
Cash Provided by Operating Activities	58.3	72.1
Investing Activities:
Property, Plant and Equipment Additions	(48.8)	(38.7)
Proceeds from Divestiture, Net (See Note 1)		13.4
Cash (Used in) Investing Activities	(48.8)	(25.3)
Financing Activities:
Proceeds from (Repayment of) Short-Term Debt, net	16.3	(18)
Repayment of Long-Term Debt	(14.4)	(13.4)
Increase (Decrease) in Capital Lease Obligations		(5.4)
Net Decrease in Exchange Gas Financing	(1.6)	(2.6)
Dividends Paid	(11.3)	(11)
Proceeds from Issuance of Common Stock	0.5	0.6
Cash (Used in) Financing Activities	(10.5)	(49.8)
Net Decrease in Cash and Cash Equivalents	(1)	(3)
Cash and Cash Equivalents at Beginning of Period	5.2	7.8
Cash and Cash Equivalents at End of Period	4.2	4.8
Supplemental Cash Flow Information:
Interest Paid	12.6	12.7
Income Taxes Paid	0.6	0.9
Payments on Capital Leases	0.2	5.3
Non-cash Investing Activity:
Capital Expenditures Included in Accounts Payable	0.9	0.7
Right-of-Use Assets Obtained in Exchange for Lease Obligations	$ 0.5	$ 3.6

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	30.5		30.5
Dividends on Common Shares	(11)		(11)
Stock Compensation Plans	1.6	1.6
Issuance of Common Shares	0.6	0.6
Ending Balance at Jun. 30, 2019	372.8	281.3	91.5
Beginning Balance at Mar. 31, 2019	373.7	280.7	93
Net Income	4		4
Dividends on Common Shares	(5.5)		(5.5)
Stock Compensation Plans	0.3	0.3
Issuance of Common Shares	0.3	0.3
Ending Balance at Jun. 30, 2019	372.8	281.3	91.5
Beginning Balance at Dec. 31, 2019	376.6	282.5	94.1
Net Income	18.3		18.3
Dividends on Common Shares	(11.3)		(11.3)
Stock Compensation Plans	1.4	1.4
Issuance of Common Shares	0.5	0.5
Ending Balance at Jun. 30, 2020	385.5	284.4	101.1
Beginning Balance at Mar. 31, 2020	387.7	284	103.7
Net Income	3.1		3.1
Dividends on Common Shares	(5.7)		(5.7)
Stock Compensation Plans	0.2	0.2
Issuance of Common Shares	0.2	0.2
Ending Balance at Jun. 30, 2020	$ 385.5	$ 284.4	$ 101.1

CONSOLIDATED STATEMENTS OF CH_2

CONSOLIDATED STATEMENTS OF CHANGES IN COMMON STOCK EQUITY (Parenthetical) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Dividends per Common Share	$ 0.375	$ 0.370	$ 0.750	$ 0.740
Common stock, shares issued	5,555	5,127	10,199	11,066

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	6 Months Ended
	Jun. 30, 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 Non-Regulated Basis of Presentation – 10-Q 10-K Divestiture of Non-Regulated 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. Revenue recognized in connection with rate adjustment mechanisms is consistent with the definition of alternative revenue programs in ASC 980-605-25-3, 980-605-25-4. In the following tables, revenue is classified by the types of goods/services rendered and market/customer type. Three Months Ended June 30, 2020 Gas and Electric Operating Revenues ($ millions): Gas Electric Total Billed and Unbilled Revenue: Residential $ 14.3 $ 30.2 $ 44.5 C&I 19.0 20.5 39.5 Other 1.2 1.5 2.7 Total Billed and Unbilled Revenue 34.5 52.2 86.7 Rate Adjustment Mechanism Revenue (0.8 ) (2.0 ) (2.8 ) Total Gas and Electric Operating Revenues $ 33.7 $ 50.2 $ 83.9 Three Months Ended June 30, 2019 Gas and Electric Operating Revenues ($ millions): Gas Electric Total Billed and Unbilled Revenue: Residential $ 15.7 $ 27.7 $ 43.4 C&I 23.1 23.0 46.1 Other 1.5 2.1 3.6 Total Billed and Unbilled Revenue 40.3 52.8 93.1 Rate Adjustment Mechanism Revenue (7.7 ) (1.0 ) (8.7 ) Total Gas and Electric Operating Revenues $ 32.6 $ 51.8 $ 84.4 Six Months Ended June 30, 2020 Gas and Electric Operating Revenues ($ millions): Gas Electric Total Billed and Unbilled Revenue: Residential $ 45.4 $ 64.6 $ 110.0 C&I 61.3 44.7 106.0 Other 4.2 3.5 7.7 Total Billed and Unbilled Revenue 110.9 112.8 223.7 Rate Adjustment Mechanism Revenue (7.0 ) (2.4 ) (9.4 ) Total Gas and Electric Operating Revenues $ 103.9 $ 110.4 $ 214.3 Six Months Ended June 30, 2019 Gas and Electric Operating Revenues ($ millions): Gas Electric Total Billed and Unbilled Revenue: Residential $ 54.4 $ 63.5 $ 117.9 C&I 77.1 47.7 124.8 Other 8.0 4.3 12.3 Total Billed and Unbilled Revenue 139.5 115.5 255.0 Rate Adjustment Mechanism Revenue (20.5 ) 1.1 (19.4 ) Total Gas and Electric Operating Revenues $ 119.0 $ 116.6 $ 235.6 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 natural 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. The Company estimates that revenue decoupling applies to approximately 27% and 11% of Unitil’s total annual electric and natural gas sales volumes, respectively. Other Operating Revenue – Non-regulated 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 Financial Instruments – 2016-13, – Allowance for Doubtful Accounts – written-off The Allowance for Doubtful Accounts as of June 30, 2020, June 30, 2019 and December 31, 2019, was as follows: June 30, December 31, ($ millions) 2020 2019 2019 Allowance for Doubtful Accounts $ 1.4 $ 1.6 $ 1.0 Accounts Receivable, Net includes $1.3 million, $1.6 million, and $1.0 million of the Allowance for Doubtful Accounts at June 30, 2020, June 30, 2019 and December 31, 2019, respectively. Unbilled Revenues, net (a component of Accrued Revenue, shown in the table below) includes $0.1 million of the Allowance for Doubtful Accounts at June 30, 2020. Accrued Revenue June 30, December 31, Accrued Revenue ($ millions) 2020 2019 2019 Regulatory Assets – Current $ 26.8 $ 23.1 $ 35.8 Unbilled Revenues 8.1 9.0 14.2 Total Accrued Revenue $ 34.9 $ 32.1 $ 50.0 Exchange Gas Receivable - June 30, December 31, Exchange Gas Receivable ($ millions) 2020 2019 Northern Utilities $ 3.9 $ 4.9 $ 5.5 Fitchburg 0.3 0.4 0.6 Total Exchange Gas Receivable $ 4.2 $ 5.3 $ 6.1 Gas Inventory June 30, December 31, Gas Inventory ($ millions) 2020 2019 2019 Natural Gas $ 0.1 $ 0.2 $ 0.4 Propane 0.3 0.4 0.3 Liquefied Natural Gas & Other 0.1 0.1 0.1 Total Gas Inventory $ 0.5 $ 0.7 $ 0.8 Utility Plant – Leases – Regulatory Accounting – June 30, December 31, Regulatory Assets consist of the following ($ millions) 2020 2019 2019 Retirement Benefits $ 80.8 $ 73.2 $ 88.9 Energy Supply & Other Rate Adjustment Mechanisms 23.8 18.5 31.0 Deferred Storm Charges 4.9 5.5 5.6 Environmental 6.2 7.4 7.2 Income Taxes 3.8 4.5 4.2 Other Deferred Charges 12.2 11.3 10.9 Total Regulatory Assets $ 131.7 $ 120.4 $ 147.8 Less: Current Portion of Regulatory Assets (1) 26.8 23.1 35.8 Regulatory Assets – noncurrent $ 104.9 $ 97.3 $ 112.0 (1) Reflects amounts included in Accrued Revenue, discussed above, on the Company’s Consolidated Balance Sheets. June 30, December 31, Regulatory Liabilities consist of the following ($ millions) 2020 2019 2019 Income Taxes (Note 8) $ 45.9 $ 47.8 $ 47.6 Rate Adjustment Mechanisms 11.2 17.0 6.0 Other 0.3 0.6 0.4 Total Regulatory Liabilities $ 57.4 $ 65.4 $ 54.0 Less: Current Portion of Regulatory Liabilities 12.6 18.5 7.4 Regulatory Liabilities – noncurrent $ 44.8 $ 46.9 $ 46.6 Generally, the Company receives a return on investment on its regulatory assets for which a cash outflow has been made. Regulatory Assets at June 30, 2020 include $7.9 million of environmental costs, rate case costs and other expenditures to be recovered over varying periods in the next seven years. Regulators have authorized recovery of these expenditures, but without a return. Regulatory commissions can reach different conclusions about the recovery of costs, which can have a material impact on the Company’s Consolidated Financial Statements. The Company believes it is probable that its regulated distribution and transmission utilities will recover their investments in long-lived assets, including regulatory assets. If the Company, or a portion of its assets or operations, were to cease meeting the criteria for application of accounting rules for regulated operations, accounting standards for businesses in general would become applicable and immediate recognition of any previously deferred costs, or a portion of deferred costs, would be required in the year in which the criteria are no longer met, if such deferred costs were not recoverable in the portion of the business that continues to meet the criteria for application of the FASB Codification topic on Regulated Operations. If unable to continue to apply the FASB Codification provisions for Regulated Operations, the Company would be required to apply the provisions for the Discontinuation of Rate-Regulated Accounting included in the FASB Codification. In the Company’s opinion, its regulated operations will be subject to the FASB Codification provisions for Regulated Operations for the foreseeable future. Derivatives – As discussed 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 impact on the contractual obligations and regulatory assets of Fitchburg, once these contracts qualify for derivative accounting. Investments in Marketable Securities The fair value of the Company’s investments in these trading securities, which are recorded on the Consolidated Balance Sheets in Other Assets, are shown in the following table. 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 (Income), Net. June 30, December 31, Fair Value of Marketable Securities ($ millions) 2020 2019 2019 Money Market Funds $ 5.6 $ 5.5 $ 5.6 Total Marketable Securities $ 5.6 $ 5.5 $ 5.6 The Company also sponsors the Unitil Corporation Deferred Compensation Plan (the “DC Plan”). The DC Plan is a non-qualified tax-deferred 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, are shown in the following table. 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 (Income), Net. June 30, 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 - June 30, December 31, Energy Supply Obligations ($ millions) 2020 2019 2019 Current: Exchange Gas Obligation $ 3.9 $ 4.9 $ 5.5 Renewable Energy Portfolio Standards 4.2 4.0 4.7 Power Supply Contract Divestitures 0.3 0.3 0.3 Total Energy Supply Obligations – Current 8.4 9.2 10.5 Noncurrent: Power Supply Contract Divestitures 0.1 0.4 0.3 Total Energy Supply Obligations $ 8.5 $ 9.6 $ 10.8 Exchange Gas Obligation - 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 three major statewide procurements which resulted in contracts for imported hydroelectric power and associated transmission and two for offshore wind generation. The contract for imported hydroelectric power and one of the offshore wind contracts were approved by the MDPU in the second quarter of 2019 and one offshore wind contract is scheduled for hearing the last week of July 2020. 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	6 Months Ended
	Jun. 30, 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 07/29/20 08/28/20 08/14/20 $ 0.375 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	6 Months Ended
	Jun. 30, 2020
SEGMENT INFORMATION	NOTE 3 – SEGMENT INFORMATION The following table provides significant segment financial data for the three and six months ended June 30, 2020 and June 30, 2019: Gas Electric Non- Regulated Other Total Three Months Ended June 30, 2020 ($ millions) Revenues: Billed and Unbilled Revenue $ 34.5 $ 52.2 $ — $ — $ 86.7 Rate Adjustment Mechanism Revenue (0.8 ) (2.0 ) — — (2.8 ) Other Operating Revenue – Non-Regulated — — — — — Total Operating Revenues $ 33.7 $ 50.2 $ — $ — $ 83.9 Segment Profit (0.1 ) 3.1 — 0.1 3.1 Capital Expenditures 16.8 14.0 — 1.2 32.0 Three Months Ended June 30, 2019 ($ millions) Revenues: Billed and Unbilled Revenue $ 40.3 $ 52.8 $ — $ — $ 93.1 Rate Adjustment Mechanism Revenue (7.7 ) (1.0 ) — — (8.7 ) Other Operating Revenue – Non-Regulated — — — — — Total Operating Revenues $ 32.6 $ 51.8 $ — $ — $ 84.4 Segment Profit (Loss) 0.3 3.4 0.1 0.2 4.0 Capital Expenditures 18.1 8.3 — 1.4 27.8 Six Months Ended June 30, 2020 ($ millions) Revenues: Billed and Unbilled Revenue $ 110.9 $ 112.8 $ — $ — $ 223.7 Rate Adjustment Mechanism Revenue (7.0 ) (2.4 ) — — (9.4 ) Other Operating Revenue – Non-Regulated — — — — — Total Operating Revenues $ 103.9 $ 110.4 $ — $ — $ 214.3 Segment Profit 12.2 5.7 — 0.4 18.3 Capital Expenditures 22.6 23.9 — 2.3 48.8 Segment Assets 821.1 543.8 — 19.6 1,384.5 Six Months Ended June 30, 2019 ($ millions) Revenues: Billed and Unbilled Revenue $ 139.5 $ 115.5 $ — $ — $ 255.0 Rate Adjustment Mechanism Revenue (20.5 ) 1.1 — — (19.4 ) Other Operating Revenue – Non-Regulated — — 0.9 — 0.9 Total Operating Revenues $ 119.0 $ 116.6 $ 0.9 $ — $ 236.5 Segment Profit 14.0 5.3 10.2 1.0 30.5 Capital Expenditures 21.4 14.9 — 2.4 38.7 Segment Assets 760.0 500.4 0.6 18.3 1,279.3

DEBT AND FINANCING ARRANGEMENTS

DEBT AND FINANCING ARRANGEMENTS	6 Months Ended
	Jun. 30, 2020
Debt Disclosure [Abstract]
DEBT AND FINANCING ARRANGEMENTS	NOTE 4 –DEBT AND FINANCING ARRANGEMENTS Details on long-term debt at June 30, 2020, June 30, 2019 and December 31, 2019 are shown below: ($ millions) June 30, 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 3.4 3.3 3.5 Total Long-Term Debt, net of Unamortized Debt Issuance Costs 442.7 392.6 457.0 Less: Current Portion 6.3 19.5 19.5 Total Long-term Debt, Less Current Portion $ 436.4 $ 373.1 $ 437.5 Fair Value of Long-Term Debt market for the Company’s debt securities, the fair value of the Company’s long-term debt would be estimated based on the quoted market prices for the same or similar issues, or on the current rates offered to the Company for debt of the same remaining maturities. The fair value of the Company’s long-term debt is estimated using Level 2 inputs (valuations based on quoted prices available in active markets for similar assets or liabilities, quoted prices for identical or similar assets or liabilities in inactive markets, inputs other than quoted prices that are directly observable, and inputs derived principally from market data.) In estimating the fair value of the Company’s long-term debt, the assumed market yield reflects the Moody’s Baa Utility Bond Average Yield. Costs, including prepayment costs, associated with the early settlement of long-term debt are not taken into consideration in determining fair value. ($ millions) June 30, December 31, 2020 2019 2019 Estimated Fair Value of Long-Term Debt $ 516.6 $ 430.6 $ 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 $ 121.6 million for the six months ended June 30, 2020. Total gross repayments were $105.3 million for the six months ended June 30, 2020. The following table details the borrowing limits, amounts outstanding and amounts available under the Credit Facility as of June 30 2020, June 30, 2019 and December 31, 2019: Revolving Credit Facility ($ millions) June 30, December 31, 2020 2019 2019 Limit $ 120.0 $ 120.0 $ 120.0 Short-Term Borrowings Outstanding 74.9 64.8 58.6 Letter of Credit Outstanding 0.1 — 0.1 Available $ 45.0 $ 55.2 $ 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 June 30, 2020, June 30, 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 1.5% and 3.6% for the three months ended June 30, 2020 and June 30, 2019, respectively. The average interest rates on all short-term borrowings and intercompany money pool transactions were 2.0% and 3.7% for the six months ended June 30, 2020 and June 30, 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 June 16, 2020, the distribution utilities priced $95 million collectively of long-term financings through a private placement marketing process to institutional investors as follows. Northern Utilities and Fitchburg priced $67.5 million collectively of Senior Unsecured Notes (Notes). Unitil Energy priced $27.5 million of First Mortgage Bonds (Bonds). Northern Utilities priced $40 million of Notes due 2040 at 3.78%. Fitchburg priced $27.5 million of Notes due 2040 at 3.78%. Unitil Energy priced $27.5 million of Bonds due 2040 at 3.58%. Northern Utilities, Fitchburg and Unitil Energy plan to use the net proceeds from the offering to repay short-term debt and for general corporate purposes. Northern Utilities, Fitchburg and Unitil Energy anticipate closing this long-term financing in the third quarter of 2020. However the issuance of the Notes and Bonds are subject to customary closing conditions for transactions of this type. The Northern Utilities Notes, the Fitchburg Notes, and the Unitil Energy Bonds have not been and will not be registered under the Securities Act of 1933 (Act) or any state securities laws, and may not be offered or sold in the United States absent registration or an applicable exemption from the registration requirements of the Act and applicable state securities laws. 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 $3.9 million, $5.0 million and $6.5 million of gas storage inventory at June 30, 2020, June 30, 2019 and December 31, 2019, respectively, related to these asset management agreements. The amount of gas inventory released in June 2020 and payable in July 2020 is less than $0.1 million and is recorded in Accounts Payable at June 30, 2020. The amount of gas inventory released in June 2019 and payable in July 2019 was $0.1 million and was recorded in Accounts Payable at June 30, 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 June 30, 2020, there were approximately $6.2 million of guarantees outstanding. Leases Unitil’s subsidiaries 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 June 30, 2020 and 2019 amounted to $0.4 million and $0.3 million, respectively. Total rental expense under operating leases charged to operations for the six months ended June 30, 2020 and 2019 amounted to $0.8 million and $0.7 million, respectively. The balance sheet classification of the Company’s lease obligations was as follows: June 30, December 31, Lease Obligations ($ millions) 2020 2019 2019 Operating Lease Obligations: Other Current Liabilities (current portion) $ 1.3 $ 1.0 $ 1.2 Other Noncurrent Liabilities (long-term portion) 3.2 2.6 2.8 Total Operating Lease Obligations $ 4.5 $ 3.6 $ 4.0 Capital Lease Obligations: Other Current Liabilities (current portion) $ 0.2 $ 0.2 $ 0.2 Other Noncurrent Liabilities (long-term portion) 0.3 0.2 0.3 Total Capital Lease Obligations $ 0.5 $ 0.4 $ 0.5 Total Lease Obligations $ 5.0 $ 4.0 $ 4.5 Cash paid for amounts included in the measurement of operating lease obligations for the six months ended June 30, 2020 was $0.8 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, $1.5 million and $1.2 million as of June 30, 2020, June 30, 2019 and December 31, 2019, respectively, less accumulated amortization of $0.6 million, $1.0 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 June 30, 2020. The payments for capital leases consist of $0.2 million of current capital lease obligations, which are included in Other Current Liabilities and $0.3 million of noncurrent capital lease obligations, which are included in Other Noncurrent Liabilities, on the Company’s Consolidated Balance Sheets as of June 30, 2020. The payments for operating leases consist of $1.3 million of current operating lease obligations, which are included in Other Current Liabilities and $3.2 million of noncurrent operating lease obligations, which are included in Other Noncurrent Liabilities, on the Company’s Consolidated Balance Sheets as of June 30, 2020. Lease Payments ($000’s) Operating Capital Year Ending December 31, Leases Leases Rest of 2020 $ 795 $ 138 2021 1,448 194 2022 1,169 130 2023 873 88 2024 544 33 2025-2029 140 — Total Payments 4,969 583 Less: Interest 436 34 Amount of Lease Obligations Recorded on Consolidated Balance Sheets $ 4,533 $ 549 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 June 30, 2020, the weighted average remaining lease term is 3.8 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	6 Months Ended
	Jun. 30, 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 14,921,171, 14,930,170 and 14,996,231 shares of common stock outstanding at June 30, 2019, December 31, 2019 and June 30, 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 59,651 non-vested Restricted Stock Units Non-management Restricted Stock Units (Equity Portion) Units Weighted Restricted Stock Units as of December 31, 2019 70,364 $ 41.20 Restricted Stock Units Granted — — Dividend Equivalents Earned 768 $ 53.16 Restricted Stock Units Settled (32,422 ) $ 41.09 Restricted Stock Units as of June 30, 2020 38,710 $ 41.54 There were 62,615 Restricted Stock Units outstanding as of June 30, 2019 with a weighted average stock price of $38.48. Included in Other Noncurrent Liabilities on the Company’s Consolidated Balance Sheets as of June 30, 2020, June 30, 2019 and December 31, 2019 is $0.7 million, $1.6 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 June 30, 2020 and December 31, 2019. There was $0.2 million, or 1,893 shares, of Unitil Energy’s 6.00% Series Preferred Stock outstanding as of June 30, 2019. There were less than $0.1 million of total dividends declared on Preferred Stock in each of the three and six month periods ended June 30, 2020 and June 30, 2019, respectively.

REGULATORY MATTERS

REGULATORY MATTERS	6 Months Ended
	Jun. 30, 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 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— Northern Utilities – Base Rates – New Hampshire TCJA, and an initial step increase to recover post-test year capital investments. The Company’s second step increase of approximately $1.4 million of annual revenue was approved by the NHPUC, effective May 1, 2019, to recover eligible capital investments in 2018. According to the terms of the settlement agreement, Northern Utilities’ next distribution base rate case shall be based on a historic test year of no earlier than the twelve months ending December 31, 2020. Unitil Energy – Base Rates – Fitchburg – Base Rates – Electric – On April 17, 2020, the 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 Company’s subsequent Compliance Filing reflected an adjusted distribution increase of $0.9 million, a decrease of $0.2 million from the original settlement amount. On May 21, 2020, the MDPU approved the Company’s Compliance Filing. The agreement provides for a return on equity of 9.7% and a capital structure reflecting 52.45% equity and 47.55% long-term debt. Under the agreement, the Company will not increase or redesign base distribution rates to become effective prior to November 1, 2023, though the Company may seek cost recovery for certain exogenous events that meet a revenue impact threshold of $0.1 million. The agreement also provides for the implementation of a major storm reserve fund, whereby the Company may recover the costs of restoration for qualifying storm events. In addition, the agreement provides for the extension of the annual capital cost recovery mechanism, modified to allow the recovery of property tax on the cumulative net capital expenditures. Fitchburg – Base Rates – Ga s – On February 28, 2020, the MDPU approved a settlement agreement between the Company and the Massachusetts Office of the Attorney General. The agreement provides for an annual distribution revenue increase of $4.6 million to be phased-in thousand Fitchburg – Gas System Enhancement Program the Company is required to make two annual filings with the MDPU: a forward-looking filing for the subsequent construction year, to be filed on or before October 31 (the “GSEP Filing”); and a filing, submitted on or before May 1, of final project documentation for projects completed during the prior year, demonstrating substantial compliance with its plan in effect for that year and showing that project costs were reasonably and prudently incurred (the “GREC Filing”). The Company considers these to be routine regulatory proceedings and there are no material issues outstanding. 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. On April 30, 2020, the MDPU approved the Company’s filing. On May 1, 2020, the Company made its 2020 GREC Filing. However, in accordance with the approved gas rate case settlement agreement, the Company decreased the Gas System Enhancement Reconciliation Adjustment Factors (“GSERAF”) and Gas System Enhancement Adjustment Factors to zero effective March 1, 2020 and will recover the February 29, 2020 GSEP deferral balance including interest over a 24 month period beginning March 1, 2021. This results in this year’s GSERAF changing on March 1, 2021 instead of November 1, 2020. The preliminary GSERAF recovery amount to be recovered over 24 months beginning March 1, 2021 is $2.1 million. 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 Utiliti es 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 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 400 MW 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. This filing remains pending before the MDPU. 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	6 Months Ended
	Jun. 30, 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 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 June 30, 2020, has not identified any material losses reasonably likely to be incurred in excess of recorded amounts. However, the Company cannot assure that significant costs and liabilities will not be incurred in the future. It is possible that other developments, such as increasingly stringent federal, state or local environmental laws and regulations could result in increased environmental compliance costs. Based on the Company’s current assessment of its environmental responsibilities, existing legal requirements and regulatory policies, the Company does not believe that these environmental costs will have a material adverse effect on the Company’s consolidated financial position or results of operations. Northern Utilities Manufactured Gas Plant Sites – Northern Utilities has an extensive program to identify, investigate and remediate former manufactured gas plant (MGP) sites, which were operated from the mid-1800s through the mid-1900s. In New Hampshire, MGP sites were identified in Dover, Exeter, Portsmouth, Rochester and Somersworth. In Maine, Northern Utilities has documented the presence of MGP sites in Lewiston and Portland, and a former MGP disposal site in Scarborough. 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. In June 2020, the NH DES coupled the submittal of the review to a proposed extension of the gas distribution system by Northern Utilities; Both the review and extension are expected to be completed by the end of the fourth quarter of 2020. While any recommendation is subject to approval by the NH DES, the Company has accrued $0.8 million for estimated costs to complete the remediation at the Rochester site, which is included in the Environmental Obligations table below. The NHPUC and MPUC have approved regulatory mechanisms for the recovery of MGP environmental costs. For Northern Utilities’ New Hampshire division, the NHPUC has approved the recovery of MGP environmental costs over succeeding seven-year periods. For Northern Utilities’ Maine division, the MPUC has authorized the recovery of environmental remediation costs over succeeding five-year The Environmental Obligations table below shows the amounts accrued for Northern Utilities related to estimated future cleanup costs associated with Northern Utilities’ environmental remediation obligations for former MGP sites. Corresponding Regulatory Assets were recorded to reflect that the future recovery of these environmental remediation costs is expected based on regulatory precedent and established practices. Fitchburg’s Manufactured Gas Plant Site – Fitchburg recovers the environmental response costs incurred at this former MGP site in gas rates pursuant to the terms of a cost recovery agreement approved by the MDPU. Pursuant to this agreement, Fitchburg is authorized to amortize and recover environmental response costs from gas customers over succeeding seven-year The following table sets forth a summary of changes in the Company’s liability for Environmental Obligations for the six months ended June 30, 2020 and 2019. Environmental Obligations ($ millions) Fitchburg Northern Total Six months ended June 30, 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	6 Months Ended
	Jun. 30, 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 June 30, 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 June 30, 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 FASB Codification section 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. Of the $48.9 million, $47.1 million represents the protected excess ADIT. 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 the protected excess ADIT amount 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. In March 2020, the MPUC approved Northern Utilities’ base rate increase effective April 1, 2020. Part of the base rate increase is the flow back of excess ADIT through base rates. Northern Utilities was ordered to begin flowing back to customer excess ADIT of $12.3 million to gas ratepayers under the ARAM over approximately years. The MDPU issued a multi-utility Order D.P.U. 18-15-E non-plant and 3) excess ADIT created through reconciling mechanisms. In the Order, all Massachusetts utilities were ordered to begin flow back of protected and unprotected excess ADIT on February 1, 2019 and to 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 ADIT of $10.1 million and $10.4 million to electric and gas ratepayers, respectively, under the ARAM over approximately fifteen years. Fitchburg filed its compliance filing under D.P.U.18-15-E on January , for rates effective February , . The MDPU approved this filing on January , . The filing will be updated and the balances of excess ADIT will be reconciled annually. 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 RM19-5-000 In addition to the protected excess ADIT of $47.1 million, 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 June 30, 2020. The remaining $0.1 million will be recognized in 2020. As described above, 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 of regulatory deferred income tax balances. At this time, the Company has applied a reasonable interpretation of the TCJA and a reasonable estimate of the regulatory resolution. Future clarification of TCJA matters with the Company’s regulators may change the amounts estimated. 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 as provided for in the CARES Act. 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	6 Months Ended
	Jun. 30, 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 tables provide the components of the Company’s Retirement plan costs ($000’s): Pension Plan PBOP Plan SERP Plan Three Months Ended June 30, 2020 2019 2020 2019 2020 2019 Service Cost $ 831 $ 776 $ 675 $ 576 $ 71 $ 63 Interest Cost 1,443 1,621 779 856 138 145 Expected Return on Plan Assets (2,255 ) (2,118 ) (516 ) (411 ) — — Prior Service Cost Amortization 80 80 303 303 14 25 Actuarial Loss Amortization 1,618 1,081 186 57 259 156 Sub-total 1,717 1,440 1,427 1,381 482 389 Amounts Capitalized and Deferred (807 ) (597 ) (695 ) (606 ) (152) (112 ) Net Periodic Benefit Cost Recognized $ 910 $ 843 $ 732 $ 775 $ 330 $ 277 Pension Plan PBOP Plan SERP Plan Six Months Ended June 30, 2020 2019 2020 2019 2020 2019 Service Cost $ 1,662 $ 1,552 $ 1,350 $ 1,152 $ 142 $ 123 Interest Cost 2,887 3,242 1,559 1,712 275 284 Expected Return on Plan Assets (4,510 ) (4,237 ) (1,032 ) (822 ) — — Prior Service Cost Amortization 160 160 606 606 28 28 Actuarial Loss Amortization 3,236 2,162 372 114 518 314 Sub-total 3,435 2,879 2,855 2,762 963 749 Amounts Capitalized and Deferred (1,437 ) (1,009 ) (1,227 ) (1,080 ) (290 ) (215 ) Net Periodic Benefit Cost Recognized $ 1,998 $ 1,870 $ 1,628 $ 1,682 $ 673 $ 534 Employer Contribution s As of June 30, 2020, the Company had not made any contributions to its Pension Plan and had made $1.4 million of contributions to its PBOP Plan 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 June 30, 2020, the Company had made $0.3 million of benefit payments

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	6 Months Ended
	Jun. 30, 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 Non-Regulated
Basis of Presentation	Basis of Presentation – 10-Q 10-K
Divestiture of Non-Regulated Business Subsidiary	Divestiture of Non-Regulated non-regulated after-tax pre-tax
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. Revenue recognized in connection with rate adjustment mechanisms is consistent with the definition of alternative revenue programs in ASC 980-605-25-3, 980-605-25-4. In the following tables, revenue is classified by the types of goods/services rendered and market/customer type. Three Months Ended June 30, 2020 Gas and Electric Operating Revenues ($ millions): Gas Electric Total Billed and Unbilled Revenue: Residential $ 14.3 $ 30.2 $ 44.5 C&I 19.0 20.5 39.5 Other 1.2 1.5 2.7 Total Billed and Unbilled Revenue 34.5 52.2 86.7 Rate Adjustment Mechanism Revenue (0.8 ) (2.0 ) (2.8 ) Total Gas and Electric Operating Revenues $ 33.7 $ 50.2 $ 83.9 Three Months Ended June 30, 2019 Gas and Electric Operating Revenues ($ millions): Gas Electric Total Billed and Unbilled Revenue: Residential $ 15.7 $ 27.7 $ 43.4 C&I 23.1 23.0 46.1 Other 1.5 2.1 3.6 Total Billed and Unbilled Revenue 40.3 52.8 93.1 Rate Adjustment Mechanism Revenue (7.7 ) (1.0 ) (8.7 ) Total Gas and Electric Operating Revenues $ 32.6 $ 51.8 $ 84.4 Six Months Ended June 30, 2020 Gas and Electric Operating Revenues ($ millions): Gas Electric Total Billed and Unbilled Revenue: Residential $ 45.4 $ 64.6 $ 110.0 C&I 61.3 44.7 106.0 Other 4.2 3.5 7.7 Total Billed and Unbilled Revenue 110.9 112.8 223.7 Rate Adjustment Mechanism Revenue (7.0 ) (2.4 ) (9.4 ) Total Gas and Electric Operating Revenues $ 103.9 $ 110.4 $ 214.3 Six Months Ended June 30, 2019 Gas and Electric Operating Revenues ($ millions): Gas Electric Total Billed and Unbilled Revenue: Residential $ 54.4 $ 63.5 $ 117.9 C&I 77.1 47.7 124.8 Other 8.0 4.3 12.3 Total Billed and Unbilled Revenue 139.5 115.5 255.0 Rate Adjustment Mechanism Revenue (20.5 ) 1.1 (19.4 ) Total Gas and Electric Operating Revenues $ 119.0 $ 116.6 $ 235.6 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 natural 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. The Company estimates that revenue decoupling applies to approximately 27% and 11% of Unitil’s total annual electric and natural gas sales volumes, respectively.
Other Operating Revenue - Non-regulated	Other Operating Revenue – Non-regulated 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
Financial Instruments	Financial Instruments – 2016-13, –
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts – written-off The Allowance for Doubtful Accounts as of June 30, 2020, June 30, 2019 and December 31, 2019, was as follows: June 30, December 31, ($ millions) 2020 2019 2019 Allowance for Doubtful Accounts $ 1.4 $ 1.6 $ 1.0 Accounts Receivable, Net includes $1.3 million, $1.6 million, and $1.0 million of the Allowance for Doubtful Accounts at June 30, 2020, June 30, 2019 and December 31, 2019, respectively. Unbilled Revenues, net (a component of Accrued Revenue, shown in the table below) includes $0.1 million of the Allowance for Doubtful Accounts at June 30, 2020.
Accrued Revenue	Accrued Revenue June 30, December 31, Accrued Revenue ($ millions) 2020 2019 2019 Regulatory Assets – Current $ 26.8 $ 23.1 $ 35.8 Unbilled Revenues 8.1 9.0 14.2 Total Accrued Revenue $ 34.9 $ 32.1 $ 50.0
Exchange Gas Receivable	Exchange Gas Receivable - June 30, December 31, Exchange Gas Receivable ($ millions) 2020 2019 Northern Utilities $ 3.9 $ 4.9 $ 5.5 Fitchburg 0.3 0.4 0.6 Total Exchange Gas Receivable $ 4.2 $ 5.3 $ 6.1
Gas Inventory	Gas Inventory June 30, December 31, Gas Inventory ($ millions) 2020 2019 2019 Natural Gas $ 0.1 $ 0.2 $ 0.4 Propane 0.3 0.4 0.3 Liquefied Natural Gas & Other 0.1 0.1 0.1 Total Gas Inventory $ 0.5 $ 0.7 $ 0.8
Utility Plant	Utility Plant –
Leases	Leases –
Regulatory Accounting	Regulatory Accounting – June 30, December 31, Regulatory Assets consist of the following ($ millions) 2020 2019 2019 Retirement Benefits $ 80.8 $ 73.2 $ 88.9 Energy Supply & Other Rate Adjustment Mechanisms 23.8 18.5 31.0 Deferred Storm Charges 4.9 5.5 5.6 Environmental 6.2 7.4 7.2 Income Taxes 3.8 4.5 4.2 Other Deferred Charges 12.2 11.3 10.9 Total Regulatory Assets $ 131.7 $ 120.4 $ 147.8 Less: Current Portion of Regulatory Assets (1) 26.8 23.1 35.8 Regulatory Assets – noncurrent $ 104.9 $ 97.3 $ 112.0 (1) Reflects amounts included in Accrued Revenue, discussed above, on the Company’s Consolidated Balance Sheets. June 30, December 31, Regulatory Liabilities consist of the following ($ millions) 2020 2019 2019 Income Taxes (Note 8) $ 45.9 $ 47.8 $ 47.6 Rate Adjustment Mechanisms 11.2 17.0 6.0 Other 0.3 0.6 0.4 Total Regulatory Liabilities $ 57.4 $ 65.4 $ 54.0 Less: Current Portion of Regulatory Liabilities 12.6 18.5 7.4 Regulatory Liabilities – noncurrent $ 44.8 $ 46.9 $ 46.6 Generally, the Company receives a return on investment on its regulatory assets for which a cash outflow has been made. Regulatory Assets at June 30, 2020 include $7.9 million of environmental costs, rate case costs and other expenditures to be recovered over varying periods in the next seven years. Regulators have authorized recovery of these expenditures, but without a return. Regulatory commissions can reach different conclusions about the recovery of costs, which can have a material impact on the Company’s Consolidated Financial Statements. The Company believes it is probable that its regulated distribution and transmission utilities will recover their investments in long-lived assets, including regulatory assets. If the Company, or a portion of its assets or operations, were to cease meeting the criteria for application of accounting rules for regulated operations, accounting standards for businesses in general would become applicable and immediate recognition of any previously deferred costs, or a portion of deferred costs, would be required in the year in which the criteria are no longer met, if such deferred costs were not recoverable in the portion of the business that continues to meet the criteria for application of the FASB Codification topic on Regulated Operations. If unable to continue to apply the FASB Codification provisions for Regulated Operations, the Company would be required to apply the provisions for the Discontinuation of Rate-Regulated Accounting included in the FASB Codification. In the Company’s opinion, its regulated operations will be subject to the FASB Codification provisions for Regulated Operations for the foreseeable future.
Derivatives	Derivatives – As discussed 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 impact on the contractual obligations and regulatory assets of Fitchburg, once these contracts qualify for derivative accounting.
Investments in Marketable Securities	Investments in Marketable Securities The fair value of the Company’s investments in these trading securities, which are recorded on the Consolidated Balance Sheets in Other Assets, are shown in the following table. 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 (Income), Net. June 30, December 31, Fair Value of Marketable Securities ($ millions) 2020 2019 2019 Money Market Funds $ 5.6 $ 5.5 $ 5.6 Total Marketable Securities $ 5.6 $ 5.5 $ 5.6 The Company also sponsors the Unitil Corporation Deferred Compensation Plan (the “DC Plan”). The DC Plan is a non-qualified tax-deferred 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, are shown in the following table. 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 (Income), Net. June 30, 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 - June 30, December 31, Energy Supply Obligations ($ millions) 2020 2019 2019 Current: Exchange Gas Obligation $ 3.9 $ 4.9 $ 5.5 Renewable Energy Portfolio Standards 4.2 4.0 4.7 Power Supply Contract Divestitures 0.3 0.3 0.3 Total Energy Supply Obligations – Current 8.4 9.2 10.5 Noncurrent: Power Supply Contract Divestitures 0.1 0.4 0.3 Total Energy Supply Obligations $ 8.5 $ 9.6 $ 10.8 Exchange Gas Obligation - 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 three major statewide procurements which resulted in contracts for imported hydroelectric power and associated transmission and two for offshore wind generation. The contract for imported hydroelectric power and one of the offshore wind contracts were approved by the MDPU in the second quarter of 2019 and one offshore wind contract is scheduled for hearing the last week of July 2020. 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)	6 Months Ended
	Jun. 30, 2020
Components of Gas and Electric Operating Revenue	Three Months Ended June 30, 2020 Gas and Electric Operating Revenues ($ millions): Gas Electric Total Billed and Unbilled Revenue: Residential $ 14.3 $ 30.2 $ 44.5 C&I 19.0 20.5 39.5 Other 1.2 1.5 2.7 Total Billed and Unbilled Revenue 34.5 52.2 86.7 Rate Adjustment Mechanism Revenue (0.8 ) (2.0 ) (2.8 ) Total Gas and Electric Operating Revenues $ 33.7 $ 50.2 $ 83.9 Three Months Ended June 30, 2019 Gas and Electric Operating Revenues ($ millions): Gas Electric Total Billed and Unbilled Revenue: Residential $ 15.7 $ 27.7 $ 43.4 C&I 23.1 23.0 46.1 Other 1.5 2.1 3.6 Total Billed and Unbilled Revenue 40.3 52.8 93.1 Rate Adjustment Mechanism Revenue (7.7 ) (1.0 ) (8.7 ) Total Gas and Electric Operating Revenues $ 32.6 $ 51.8 $ 84.4 Six Months Ended June 30, 2020 Gas and Electric Operating Revenues ($ millions): Gas Electric Total Billed and Unbilled Revenue: Residential $ 45.4 $ 64.6 $ 110.0 C&I 61.3 44.7 106.0 Other 4.2 3.5 7.7 Total Billed and Unbilled Revenue 110.9 112.8 223.7 Rate Adjustment Mechanism Revenue (7.0 ) (2.4 ) (9.4 ) Total Gas and Electric Operating Revenues $ 103.9 $ 110.4 $ 214.3 Six Months Ended June 30, 2019 Gas and Electric Operating Revenues ($ millions): Gas Electric Total Billed and Unbilled Revenue: Residential $ 54.4 $ 63.5 $ 117.9 C&I 77.1 47.7 124.8 Other 8.0 4.3 12.3 Total Billed and Unbilled Revenue 139.5 115.5 255.0 Rate Adjustment Mechanism Revenue (20.5 ) 1.1 (19.4 ) Total Gas and Electric Operating Revenues $ 119.0 $ 116.6 $ 235.6
Allowance for Doubtful Accounts Included in Accounts Receivable Net	The Allowance for Doubtful Accounts as of June 30, 2020, June 30, 2019 and December 31, 2019, was as follows: June 30, December 31, ($ millions) 2020 2019 2019 Allowance for Doubtful Accounts $ 1.4 $ 1.6 $ 1.0
Components of Accrued Revenue	June 30, December 31, Accrued Revenue ($ millions) 2020 2019 2019 Regulatory Assets – Current $ 26.8 $ 23.1 $ 35.8 Unbilled Revenues 8.1 9.0 14.2 Total Accrued Revenue $ 34.9 $ 32.1 $ 50.0
Components of Exchange Gas Receivable	June 30, December 31, Exchange Gas Receivable ($ millions) 2020 2019 Northern Utilities $ 3.9 $ 4.9 $ 5.5 Fitchburg 0.3 0.4 0.6 Total Exchange Gas Receivable $ 4.2 $ 5.3 $ 6.1
Components of Gas Inventory	The following table shows the components of Gas Inventory as of June 30, 2020, June 30, 2019 and December 31, 2019. June 30, December 31, Gas Inventory ($ millions) 2020 2019 2019 Natural Gas $ 0.1 $ 0.2 $ 0.4 Propane 0.3 0.4 0.3 Liquefied Natural Gas & Other 0.1 0.1 0.1 Total Gas Inventory $ 0.5 $ 0.7 $ 0.8
Regulatory Assets	June 30, December 31, Regulatory Assets consist of the following ($ millions) 2020 2019 2019 Retirement Benefits $ 80.8 $ 73.2 $ 88.9 Energy Supply & Other Rate Adjustment Mechanisms 23.8 18.5 31.0 Deferred Storm Charges 4.9 5.5 5.6 Environmental 6.2 7.4 7.2 Income Taxes 3.8 4.5 4.2 Other Deferred Charges 12.2 11.3 10.9 Total Regulatory Assets $ 131.7 $ 120.4 $ 147.8 Less: Current Portion of Regulatory Assets (1) 26.8 23.1 35.8 Regulatory Assets – noncurrent $ 104.9 $ 97.3 $ 112.0 (1) Reflects amounts included in Accrued Revenue, discussed above, on the Company’s Consolidated Balance Sheets.
Regulatory Liabilities	June 30, December 31, Regulatory Liabilities consist of the following ($ millions) 2020 2019 2019 Income Taxes (Note 8) $ 45.9 $ 47.8 $ 47.6 Rate Adjustment Mechanisms 11.2 17.0 6.0 Other 0.3 0.6 0.4 Total Regulatory Liabilities $ 57.4 $ 65.4 $ 54.0 Less: Current Portion of Regulatory Liabilities 12.6 18.5 7.4 Regulatory Liabilities – noncurrent $ 44.8 $ 46.9 $ 46.6
Fair Value of Marketable Securities	June 30, December 31, Fair Value of Marketable Securities ($ millions) 2020 2019 2019 Money Market Funds $ 5.6 $ 5.5 $ 5.6 Total Marketable Securities $ 5.6 $ 5.5 $ 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. June 30, December 31, Energy Supply Obligations ($ millions) 2020 2019 2019 Current: Exchange Gas Obligation $ 3.9 $ 4.9 $ 5.5 Renewable Energy Portfolio Standards 4.2 4.0 4.7 Power Supply Contract Divestitures 0.3 0.3 0.3 Total Energy Supply Obligations – Current 8.4 9.2 10.5 Noncurrent: Power Supply Contract Divestitures 0.1 0.4 0.3 Total Energy Supply Obligations $ 8.5 $ 9.6 $ 10.8
Deferred Compensation Plan [Member]
Fair Value of Marketable Securities	June 30, 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)	6 Months Ended
	Jun. 30, 2020
DIVIDENDS DECLARED PER SHARE [Abstract]
Schedule of Dividends Declared	Declaration Date Date Paid (Payable) Shareholder of Record Date Dividend Amount 07/29/20 08/28/20 08/14/20 $ 0.375 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)	6 Months Ended
	Jun. 30, 2020
Significant Segment Financial Data	The following table provides significant segment financial data for the three and six months ended June 30, 2020 and June 30, 2019: Gas Electric Non- Regulated Other Total Three Months Ended June 30, 2020 ($ millions) Revenues: Billed and Unbilled Revenue $ 34.5 $ 52.2 $ — $ — $ 86.7 Rate Adjustment Mechanism Revenue (0.8 ) (2.0 ) — — (2.8 ) Other Operating Revenue – Non-Regulated — — — — — Total Operating Revenues $ 33.7 $ 50.2 $ — $ — $ 83.9 Segment Profit (0.1 ) 3.1 — 0.1 3.1 Capital Expenditures 16.8 14.0 — 1.2 32.0 Three Months Ended June 30, 2019 ($ millions) Revenues: Billed and Unbilled Revenue $ 40.3 $ 52.8 $ — $ — $ 93.1 Rate Adjustment Mechanism Revenue (7.7 ) (1.0 ) — — (8.7 ) Other Operating Revenue – Non-Regulated — — — — — Total Operating Revenues $ 32.6 $ 51.8 $ — $ — $ 84.4 Segment Profit (Loss) 0.3 3.4 0.1 0.2 4.0 Capital Expenditures 18.1 8.3 — 1.4 27.8 Six Months Ended June 30, 2020 ($ millions) Revenues: Billed and Unbilled Revenue $ 110.9 $ 112.8 $ — $ — $ 223.7 Rate Adjustment Mechanism Revenue (7.0 ) (2.4 ) — — (9.4 ) Other Operating Revenue – Non-Regulated — — — — — Total Operating Revenues $ 103.9 $ 110.4 $ — $ — $ 214.3 Segment Profit 12.2 5.7 — 0.4 18.3 Capital Expenditures 22.6 23.9 — 2.3 48.8 Segment Assets 821.1 543.8 — 19.6 1,384.5 Six Months Ended June 30, 2019 ($ millions) Revenues: Billed and Unbilled Revenue $ 139.5 $ 115.5 $ — $ — $ 255.0 Rate Adjustment Mechanism Revenue (20.5 ) 1.1 — — (19.4 ) Other Operating Revenue – Non-Regulated — — 0.9 — 0.9 Total Operating Revenues $ 119.0 $ 116.6 $ 0.9 $ — $ 236.5 Segment Profit 14.0 5.3 10.2 1.0 30.5 Capital Expenditures 21.4 14.9 — 2.4 38.7 Segment Assets 760.0 500.4 0.6 18.3 1,279.3

DEBT AND FINANCING ARRANGEMEN_2

DEBT AND FINANCING ARRANGEMENTS (Tables)	6 Months Ended
	Jun. 30, 2020
Details on Long Term Debt	Details on long-term debt at June 30, 2020, June 30, 2019 and December 31, 2019 are shown below: ($ millions) June 30, 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 3.4 3.3 3.5 Total Long-Term Debt, net of Unamortized Debt Issuance Costs 442.7 392.6 457.0 Less: Current Portion 6.3 19.5 19.5 Total Long-term Debt, Less Current Portion $ 436.4 $ 373.1 $ 437.5
Fair Value of Long Term Debt	($ millions) June 30, December 31, 2020 2019 2019 Estimated Fair Value of Long-Term Debt $ 516.6 $ 430.6 $ 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 June 30 2020, June 30, 2019 and December 31, 2019: Revolving Credit Facility ($ millions) June 30, December 31, 2020 2019 2019 Limit $ 120.0 $ 120.0 $ 120.0 Short-Term Borrowings Outstanding 74.9 64.8 58.6 Letter of Credit Outstanding 0.1 — 0.1 Available $ 45.0 $ 55.2 $ 61.3
Classification of the Company Lease Obligations	The balance sheet classification of the Company’s lease obligations was as follows: June 30, December 31, Lease Obligations ($ millions) 2020 2019 2019 Operating Lease Obligations: Other Current Liabilities (current portion) $ 1.3 $ 1.0 $ 1.2 Other Noncurrent Liabilities (long-term portion) 3.2 2.6 2.8 Total Operating Lease Obligations $ 4.5 $ 3.6 $ 4.0 Capital Lease Obligations: Other Current Liabilities (current portion) $ 0.2 $ 0.2 $ 0.2 Other Noncurrent Liabilities (long-term portion) 0.3 0.2 0.3 Total Capital Lease Obligations $ 0.5 $ 0.4 $ 0.5 Total Lease Obligations $ 5.0 $ 4.0 $ 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 June 30, 2020. The payments for capital leases consist of $0.2 million of current capital lease obligations, which are included in Other Current Liabilities and $0.3 million of noncurrent capital lease obligations, which are included in Other Noncurrent Liabilities, on the Company’s Consolidated Balance Sheets as of June 30, 2020. The payments for operating leases consist of $1.3 million of current operating lease obligations, which are included in Other Current Liabilities and $3.2 million of noncurrent operating lease obligations, which are included in Other Noncurrent Liabilities, on the Company’s Consolidated Balance Sheets as of June 30, 2020. Lease Payments ($000’s) Operating Capital Year Ending December 31, Leases Leases Rest of 2020 $ 795 $ 138 2021 1,448 194 2022 1,169 130 2023 873 88 2024 544 33 2025-2029 140 — Total Payments 4,969 583 Less: Interest 436 34 Amount of Lease Obligations Recorded on Consolidated Balance Sheets $ 4,533 $ 549

COMMON STOCK AND PREFERRED ST_2

COMMON STOCK AND PREFERRED STOCK (Tables)	6 Months Ended
	Jun. 30, 2020
Table Text Block Supplement [Abstract]
Restricted Stock Units Issued	The equity portion of Restricted Stock Units activity during the six months ended June 30, 2020 in conjunction with the Stock Plan is presented in the following table: Restricted Stock Units (Equity Portion) Units Weighted Restricted Stock Units as of December 31, 2019 70,364 $ 41.20 Restricted Stock Units Granted — — Dividend Equivalents Earned 768 $ 53.16 Restricted Stock Units Settled (32,422 ) $ 41.09 Restricted Stock Units as of June 30, 2020 38,710 $ 41.54

ENVIRONMENTAL MATTERS (Tables)

ENVIRONMENTAL MATTERS (Tables)	6 Months Ended
	Jun. 30, 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 six months ended June 30, 2020 and 2019. Environmental Obligations ($ millions) Fitchburg Northern Total Six months ended June 30, 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)	6 Months Ended
	Jun. 30, 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 tables provide the components of the Company’s Retirement plan costs ($000’s): Pension Plan PBOP Plan SERP Plan Three Months Ended June 30, 2020 2019 2020 2019 2020 2019 Service Cost $ 831 $ 776 $ 675 $ 576 $ 71 $ 63 Interest Cost 1,443 1,621 779 856 138 145 Expected Return on Plan Assets (2,255 ) (2,118 ) (516 ) (411 ) — — Prior Service Cost Amortization 80 80 303 303 14 25 Actuarial Loss Amortization 1,618 1,081 186 57 259 156 Sub-total 1,717 1,440 1,427 1,381 482 389 Amounts Capitalized and Deferred (807 ) (597 ) (695 ) (606 ) (152) (112 ) Net Periodic Benefit Cost Recognized $ 910 $ 843 $ 732 $ 775 $ 330 $ 277 Pension Plan PBOP Plan SERP Plan Six Months Ended June 30, 2020 2019 2020 2019 2020 2019 Service Cost $ 1,662 $ 1,552 $ 1,350 $ 1,152 $ 142 $ 123 Interest Cost 2,887 3,242 1,559 1,712 275 284 Expected Return on Plan Assets (4,510 ) (4,237 ) (1,032 ) (822 ) — — Prior Service Cost Amortization 160 160 606 606 28 28 Actuarial Loss Amortization 3,236 2,162 372 114 518 314 Sub-total 3,435 2,879 2,855 2,762 963 749 Amounts Capitalized and Deferred (1,437 ) (1,009 ) (1,227 ) (1,080 ) (290 ) (215 ) Net Periodic Benefit Cost Recognized $ 1,998 $ 1,870 $ 1,628 $ 1,682 $ 673 $ 534

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Detail) $ in Millions	3 Months Ended	6 Months Ended
	Mar. 31, 2019USD ($)	Jun. 30, 2020USD ($)miSubsidiary	Jun. 30, 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
Provision for income taxes			3.6
Cost of removal obligation		$ 102.6	94	$ 96
Regulatory assets		131.7	120.4	147.8
Allowance for doubtful accounts		1.4	1.6	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		$ 1.3	1.6	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
Annual Electric Sales Volume
Significant Accounting Policies [Line Items]
Percentage of total sales volumes revenue subject to RDM		27.00%
Annual Natural Gas Sales Volume
Significant Accounting Policies [Line Items]
Percentage of total sales volumes revenue subject to RDM		11.00%
Environmental and Rate Case Costs and Other Expenditures | Recovered over the next seven years
Significant Accounting Policies [Line Items]
Regulatory assets		$ 7.9
ISO-NE Obligations
Significant Accounting Policies [Line Items]
Cash Deposits		$ 1.4	$ 1.4	$ 1.9
Lease term		12 months

Components of Gas and Electric

Components of Gas and Electric Operating Revenue (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	$ 83.9	$ 84.4	$ 214.3	$ 235.6
Billed and Unbilled Revenue
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	86.7	93.1	223.7	255
Rate Adjustment Mechanism Revenue
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	(2.8)	(8.7)	(9.4)	(19.4)
Gas Segment
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	33.7	32.6	103.9	119
Gas Segment | Billed and Unbilled Revenue
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	34.5	40.3	110.9	139.5
Gas Segment | Rate Adjustment Mechanism Revenue
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	(0.8)	(7.7)	(7)	(20.5)
Electric
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	50.2	51.8	110.4	116.6
Electric | Billed and Unbilled Revenue
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	52.2	52.8	112.8	115.5
Electric | Rate Adjustment Mechanism Revenue
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	(2)	(1)	(2.4)	1.1
Residential | Billed and Unbilled Revenue
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	44.5	43.4	110	117.9
Residential | Gas Segment | Billed and Unbilled Revenue
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	14.3	15.7	45.4	54.4
Residential | Electric | Billed and Unbilled Revenue
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	30.2	27.7	64.6	63.5
C&I | Billed and Unbilled Revenue
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	39.5	46.1	106	124.8
C&I | Gas Segment | Billed and Unbilled Revenue
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	19	23.1	61.3	77.1
C&I | Electric | Billed and Unbilled Revenue
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	20.5	23	44.7	47.7
Other | Billed and Unbilled Revenue
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	2.7	3.6	7.7	12.3
Other | Gas Segment | Billed and Unbilled Revenue
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	1.2	1.5	4.2	8
Other | Electric | Billed and Unbilled Revenue
Operating Revenues [Line Items]
Total Gas and Electric Operating Revenues	$ 1.5	$ 2.1	$ 3.5	$ 4.3

Allowance for Doubtful Accounts

Allowance for Doubtful Accounts Included in Accounts Receivable Net (Detail) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Allowance for Doubtful Accounts Included in Accounts Receivable Net Detail [Abstract]
Allowance for Doubtful Accounts	$ 1.4	$ 1	$ 1.6

Components of Accrued Revenue (

Components of Accrued Revenue (Detail) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Deferred Revenue Arrangement [Line Items]
Regulatory Assets – Current	$ 26.8	$ 35.8	$ 23.1
Total Accrued Revenue	34.9	50	32.1
Unbilled Revenues
Deferred Revenue Arrangement [Line Items]
Regulatory Assets – Current	8.1	14.2	9
Regulatory Assets
Deferred Revenue Arrangement [Line Items]
Regulatory Assets – Current	$ 26.8	$ 35.8	$ 23.1

Components of Exchange Gas Rece

Components of Exchange Gas Receivable (Detail) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Receivables [Line Items]
Total Exchange Gas Receivable	$ 4.2	$ 6.1	$ 5.3
Northern Utilities Inc
Receivables [Line Items]
Total Exchange Gas Receivable	3.9	5.5	4.9
Fitchburg
Receivables [Line Items]
Total Exchange Gas Receivable	$ 0.3	$ 0.6	$ 0.4

Components of Gas Inventory (De

Components of Gas Inventory (Detail) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Public Utilities, Inventory [Line Items]
Weighted average cost inventory amount	$ 0.5	$ 0.8	$ 0.7
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	0.1	0.4	0.2
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	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Regulatory Assets [Line Items]
Regulatory assets	$ 131.7	$ 147.8	$ 120.4
Less: Current Portion of Regulatory Assets	26.8	35.8	23.1
Regulatory Assets - noncurrent	104.9	112	97.3
Environmental Matters
Regulatory Assets [Line Items]
Regulatory assets	6.2	7.2	7.4
Other Deferred Charges
Regulatory Assets [Line Items]
Regulatory assets	12.2	10.9	11.3
Retirement Benefits
Regulatory Assets [Line Items]
Regulatory assets	80.8	88.9	73.2
Deferred Storm Charges
Regulatory Assets [Line Items]
Regulatory assets	4.9	5.6	5.5
Income Taxes
Regulatory Assets [Line Items]
Regulatory assets	3.8	4.2	4.5
Energy Supply & Other Rate Adjustment Mechanisms
Regulatory Assets [Line Items]
Regulatory assets	$ 23.8	$ 31	$ 18.5

Regulatory Liabilities (Detail)

Regulatory Liabilities (Detail) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2017
Regulatory Liabilities [Line Items]
Regulatory Liabilities	$ 57.4	$ 54	$ 65.4
Less: Current Portion of Regulatory Liabilities	12.6	7.4	18.5
Regulatory Liabilities-noncurrent	44.8	46.6	46.9
Income Taxes
Regulatory Liabilities [Line Items]
Regulatory Liabilities	45.9	47.6	47.8	$ 48.9
Rate Adjustment Mechanisms
Regulatory Liabilities [Line Items]
Regulatory Liabilities	11.2	6	17
Other
Regulatory Liabilities [Line Items]
Regulatory Liabilities	$ 0.3	$ 0.4	$ 0.6

Fair Value of Marketable Securi

Fair Value of Marketable Securities (Detail) - Fair Value, Inputs, Level 1 - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading Securities	$ 5.6	$ 5.6	$ 5.5
Deferred Compensation Plan [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading Securities	0.4	0.2	0.1
Equity Funds | Deferred Compensation Plan [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading Securities	0.1	0.1
Money Market Funds
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading Securities	5.6	5.6	5.5
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	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Contractual Obligation [Line Items]
Energy Supply Obligations-Current	$ 8.4	$ 10.5	$ 9.2
Power Supply Contract Divestitures, Noncurrent	0.1	0.3	0.4
Total Energy Supply Obligations	8.5	10.8	9.6
Renewable Energy Portfolio Standards
Contractual Obligation [Line Items]
Energy Supply Obligations-Current	4.2	4.7	4
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	$ 3.9	$ 5.5	$ 4.9

Dividends Declared Per Share (D

Dividends Declared Per Share (Detail) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Dividends Payable [Line Items]
Dividend Amount	$ 0.375	$ 0.370	$ 0.750	$ 0.740
Group One
Dividends Payable [Line Items]
Declaration Date			Jul. 29, 2020
Date Paid (Payable)			Aug. 28, 2020
Shareholder of Record Date			Aug. 14, 2020
Dividend Amount			$ 0.375
Group Two
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 Three
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 Four
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 Five
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 Six
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 Seven
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		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 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		$ 0.9
Total Operating Revenues	83.9	84.4	$ 214.3	236.5
Segment Profit (Loss)	3.1	4	18.3	30.5
Capital Expenditures	32	27.8	48.8	38.7
Segment Assets	1,384.5	1,279.3	1,384.5	1,279.3	$ 1,370.8
Billed and Unbilled Revenue
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total Operating Revenues	86.7	93.1	223.7	255
Rate Adjustment Mechanism Revenue
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total Operating Revenues	(2.8)	(8.7)	(9.4)	(19.4)
Gas Segment
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total Operating Revenues	33.7	32.6	103.9	119
Segment Profit (Loss)	(0.1)	0.3	12.2	14
Capital Expenditures	16.8	18.1	22.6	21.4
Segment Assets	821.1	760	821.1	760
Gas Segment | Billed and Unbilled Revenue
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total Operating Revenues	34.5	40.3	110.9	139.5
Gas Segment | Rate Adjustment Mechanism Revenue
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total Operating Revenues	(0.8)	(7.7)	(7)	(20.5)
Electric
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total Operating Revenues	50.2	51.8	110.4	116.6
Segment Profit (Loss)	3.1	3.4	5.7	5.3
Capital Expenditures	14	8.3	23.9	14.9
Segment Assets	543.8	500.4	543.8	500.4
Electric | Billed and Unbilled Revenue
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total Operating Revenues	52.2	52.8	112.8	115.5
Electric | Rate Adjustment Mechanism Revenue
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total Operating Revenues	(2)	(1)	(2.4)	1.1
All Other Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Segment Profit (Loss)	0.1	0.2	0.4	1
Capital Expenditures	1.2	1.4	2.3	2.4
Segment Assets	$ 19.6	18.3	$ 19.6	18.3
Unregulated Operation
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Other Operating Revenue - Non-Regulated				0.9
Total Operating Revenues				0.9
Segment Profit (Loss)		0.1		10.2
Segment Assets		$ 0.6		$ 0.6

Details on Long Term Debt (Deta

Details on Long Term Debt (Detail) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Debt Instrument [Line Items]
Total Long-Term Debt	$ 446.1	$ 460.5	$ 395.9
Less: Unamortized Debt Issuance Costs	3.4	3.5	3.3
Long-Term Debt	442.7	457	392.6
Less: Current Portion	6.3	19.5	19.5
Total Long-Term Debt, Less Current Portion	436.4	437.5	373.1
Long-Term Debt	442.7	457	392.6
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		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		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	Jun. 30, 2020	Jun. 30, 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	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	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%		4.04%
Debt instrument due date	Sep. 12, 2049		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	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Fair Value, Inputs, Level 2
Debt Instrument [Line Items]
Estimated Fair Value of Long-Term Debt	$ 516.6	$ 518.7	$ 430.6

Debt and Financing Arrangemen_3

Debt and Financing Arrangements - Additional Information (Detail) - USD ($)	Dec. 18, 2019	Sep. 12, 2019	Jun. 30, 2020	Jul. 25, 2018	Jun. 30, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Jun. 16, 2020	Oct. 30, 2015
Line of Credit Facility [Line Items]
Weighted average interest rate on short term borrowings			1.50%		1.50%	3.60%		1.50%	3.60%	3.40%
Gain on divestiture of business, net							$ 9,800,000
Capital lease obligation, total capitalized cost			$ 549,000		$ 549,000	$ 400,000		$ 549,000	$ 400,000	$ 500,000
Capital lease obligation, current			200,000		200,000	200,000		200,000	200,000	200,000
Capital lease obligation, noncurrent			300,000		300,000	200,000		300,000	200,000	300,000
Accounts Payable			24,700,000		24,700,000	21,900,000		24,700,000	21,900,000	37,600,000
Guarantee outstanding			6,200,000		6,200,000			6,200,000
Total rental expense under operating leases					400,000	300,000		800,000	700,000
Operating lease obligations								800,000
Net Utility Plant			1,147,600,000		1,147,600,000	1,053,500,000		1,147,600,000	1,053,500,000	1,111,500,000
Other current operating lease obligation			1,300,000		1,300,000	1,000,000		1,300,000	1,000,000	1,200,000
Other noncurrent operating lease obligation			$ 3,200,000		$ 3,200,000	2,600,000		$ 3,200,000	2,600,000	2,800,000
Issuance of long-term debt	$ 200,000	$ 200,000
Operating lease, weighted average remaining lease term			3 years 9 months 18 days		3 years 9 months 18 days			3 years 9 months 18 days
Operating lease, weighted average discount rate percentage			4.90%		4.90%			4.90%
Long-term Debt, Gross			$ 446,100,000		$ 446,100,000	$ 395,900,000		$ 446,100,000	$ 395,900,000	$ 460,500,000
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%		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%		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		$ 120,000,000	$ 120,000,000	$ 120,000,000
Proceeds from lines of credit								121,600,000
Repayments of lines of credit								$ 105,300,000
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 June 30, 2020, June 30, 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			100,000		100,000	100,000		$ 100,000	100,000	1,000,000
Natural gas storage inventory			3,900,000		3,900,000	$ 5,000,000		$ 3,900,000	$ 5,000,000	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%				4.04%			4.04%
Long-term debt, maturity date		Sep. 12, 2049							Sep. 12, 2049
Long-term Debt, Gross			$ 40,000,000		40,000,000			$ 40,000,000		40,000,000
Northern Utilities Inc | Senior Unsecured Notes Due 2040
Line of Credit Facility [Line Items]
Debt instrument year of maturity			2040
Northern Utilities Inc | Senior Unsecured Notes Due 2040 | Private Placement [Member]
Line of Credit Facility [Line Items]
Long-term debt, stated interest rate											3.78%
Long-term Debt, Gross											$ 40,000,000
Unitil Energy [Member] | First Mortgage Bonds Due 2040
Line of Credit Facility [Line Items]
Debt instrument year of maturity			2040
Fitchburg Gas and Electric Light Company | Senior Unsecured Notes Due 2040
Line of Credit Facility [Line Items]
Debt instrument year of maturity			2040
Fitchburg Gas and Electric Light Company | Senior Unsecured Notes Due 2040 | Private Placement [Member]
Line of Credit Facility [Line Items]
Long-term debt, stated interest rate											3.78%
Long-term Debt, Gross											$ 27,500,000
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
Northern Utilities And Fitchburg | Senior Unsecured Notes Due 2040 | Private Placement [Member]
Line of Credit Facility [Line Items]
Long-term Debt, Gross											67,500,000
Unitil Energy Systems Inc | Private Placement [Member]
Line of Credit Facility [Line Items]
Long-term Debt, Gross											$ 95,000,000
Unitil Energy Systems Inc | First Mortgage Bonds Due 2040 | Private Placement [Member]
Line of Credit Facility [Line Items]
Long-term debt, stated interest rate											3.58%
Long-term Debt, Gross											$ 27,500,000
Assets under Capital Leases [Member]
Line of Credit Facility [Line Items]
Net Utility Plant			$ 1,200,000		1,200,000	$ 1,500,000		1,200,000	$ 1,500,000	1,200,000
Net Utility Plant, accumulated amortization			$ 600,000		$ 600,000	$ 1,000,000		$ 600,000	$ 1,000,000	$ 600,000

Borrowing Limits Amounts Outsta

Borrowing Limits Amounts Outstanding and Amounts Available under Revolving Credit Facility (Detail) - USD ($)	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Debt Instrument [Line Items]
Short-Term Borrowings Outstanding	$ 74,900,000	$ 58,600,000	$ 64,800,000
Revolving Credit Facility
Debt Instrument [Line Items]
Revolving credit facility, limit	120,000,000	120,000,000	120,000,000
Short-Term Borrowings Outstanding	74,900,000	58,600,000	64,800,000
Letters of Credit Outstanding	100,000	100,000
Available revolving credit facility	$ 45,000,000	$ 61,300,000	$ 55,200,000

Debt and Financing Arrangemen_4

Debt and Financing Arrangements - Classification of the Company Lease Obligations (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Operating Lease Obligations:
Other Current Liabilities (current portion)	$ 1,300	$ 1,200	$ 1,000
Other Noncurrent Liabilities (long-term portion)	3,200	2,800	2,600
Total Operating Lease Obligations	4,533	4,000	3,600
Capital Lease Obligations:
Other Current Liabilities (current portion)	200	200	200
Other Noncurrent Liabilities (long-term portion)	300	300	200
Total Capital Lease Obligations	549	500	400
Total Lease Obligations	$ 5,000	$ 4,500	$ 4,000

Future Operating Lease Payment

Future Operating Lease Payment Obligations and Future Minimum Lease Payments under Capital Leases (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Operating leases
Rest of 2020	$ 795
2021	1,448
2022	1,169
2023	873
2024	544
2024-2028	140
Total Payments	4,969
Less: Interest	436
Amount of Lease Obligations Recorded on Consolidated Balance Sheets	4,533	$ 4,000	$ 3,600
Capital lease
Rest of 2020	138
2021	194
2022	130
2023	88
2024	33
2024-2028	0
Total Payments	583
Less: Interest	34
Amount of Lease Obligations Recorded on Consolidated Balance Sheets	$ 549	$ 500	$ 400

Common Stock And Preferred St_3

Common Stock And Preferred Stock - Additional Information (Detail) - USD ($)	Jan. 28, 2020	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Class of Stock [Line Items]
Common stock, shares outstanding		14,996,231	14,921,171	14,996,231	14,921,171	14,930,170
Common stock, shares issued		5,555	5,127	10,199	11,066
Proceeds from Issuance of Common Stock				$ 500,000	$ 600,000
Restricted stock weighted average grant date fair value				$ 54.88	$ 46.23
Share based compensation expense				$ 1,900,000	$ 2,100,000
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		$ 700,000	$ 1,600,000	$ 700,000	1,600,000	$ 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	200,000	$ 200,000
Maximum
Class of Stock [Line Items]
Dividend declared		$ 100,000	$ 100,000	$ 100,000	$ 100,000
Restricted Stock
Class of Stock [Line Items]
Restricted stock vesting period				4 years
Restricted stock non-vested		56,813	59,651	56,813	59,651
Unrecognized share based compensation		$ 900,000		$ 900,000
Share compensation recognition period				2 years 9 months 18 days
Restricted Stock Units Granted	28,630
Aggregate Market Value				$ 1,800,000
Forfeitures under the stock plan				5,190
Cancellations under the stock plan				0
Restricted Stock | Maximum
Class of Stock [Line Items]
Restricted stock available for awards		677,500		677,500
Restricted stock that may be awarded in any one calendar year to any one participant		20,000		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			62,615		62,615
Weighted-Average Stock Price			$ 38.48		$ 38.48
Series 6 | Unitil Energy Systems Inc
Class of Stock [Line Items]
Preferred stock, outstanding		1,887	1,893	1,887	1,893	1,887
Preferred Stock		$ 200,000	$ 200,000	$ 200,000	$ 200,000	$ 200,000
Dividend rate				6.00%	6.00%	6.00%
Dividend and Distribution Reinvestment and Share Purchase Plan
Class of Stock [Line Items]
Proceeds from Issuance of Common Stock				$ 549,200
Dividend and Distribution Reinvestment and Share Purchase Plan | Average
Class of Stock [Line Items]
Common stock price per share		$ 53.85		$ 53.85
Dividend and Distribution Reinvestment and Share Purchase Plan | Common Stock
Class of Stock [Line Items]
Common stock, shares issued				10,199

Restricted Stock Units Issued (

Restricted Stock Units Issued (Detail) - Restricted Stock Units (RSUs)	6 Months Ended
	Jun. 30, 2020$ / sharesshares
Restricted Stock Units
Beginning Restricted Stock Units | shares	70,364
Restricted Stock Units Granted | shares	0
Dividend Equivalents Earned | shares	768
Restricted Stock Units Settled | shares	(32,422)
Ending Restricted Stock Units | shares	38,710
Weighted-Average Stock Price
Beginning Restricted Stock Units | $ / shares	$ 41.20
Restricted Stock Units Granted | $ / shares	0
Dividend Equivalents Earned | $ / shares	53.16
Restricted Stock Units Settled | $ / shares	41.09
Ending Restricted Stock Units | $ / shares	$ 41.54

Regulatory Matters - Additional

Regulatory Matters - Additional Information (Detail)

Mar. 01, 2021USD ($)

May 01, 2020USD ($)

Mar. 26, 2020USD ($)

Feb. 28, 2020USD ($)

Jan. 31, 2020USD ($)

Oct. 29, 2019USD ($)

May 01, 2019USD ($)

Apr. 30, 2019USD ($)

Apr. 22, 2019USD ($)

Nov. 01, 2018USD ($)

Mar. 31, 2020USD ($)

May 01, 2019USD ($)

May 02, 2018USD ($)

Dec. 31, 2017

Apr. 20, 2017USD ($)

Jun. 30, 2020USD ($)

Jun. 30, 2027MW

Dec. 31, 2022MWh

Jul. 31, 2018MWMWh

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

$ 1,100,000

$ 900,000

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

$ 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]

Increase in annual base rate

3.60%

Approved annual increase in rates

$ 3,600,000

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]

Requested annual increase in rates

$ 1,400,000

Approved annual increase in rates

$ 3,200,000

Fitchburg Gas Company

Regulatory Assets [Line Items]

Approved annual increase in rates

$ 4,600,000

$ 1,100,000

$ 600,000

$ 1,600,000

$ 3,700,000

$ 1,000,000

Approved annual increase in rates

$ 900,000

Apporved annual decrease in rates

$ (200,000)

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

$ 40

Regulatory assets approved increase in revenue due to be recovered

$ 2,100,000

Regulatory assets approved revenue increase decrease regulatory period

24 months

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	6 Months Ended
	Jun. 30, 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	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Environmental Exit Cost [Line Items]
Total Balance at Beginning of Period	$ 2.7	$ 2
Additions	0	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
Noncurrent Balance at End of Period	1.9	1.4	$ 2.1
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	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	6 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2017	Mar. 31, 2018	Jun. 30, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2020	Jun. 30, 2019
Income Taxes [Line Items]
Regulatory Liability				$ 57.4	$ 54				$ 65.4
Regulatory liability, expected flow back to customers			$ 47.1	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			$ 0.1
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		$ 48.9		45.9	47.6		$ 48.9		$ 47.8
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	6 Months Ended
	Jun. 30, 2020	Jun. 30, 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		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service Cost	$ 831	$ 776	$ 1,662	$ 1,552
Interest Cost	1,443	1,621	2,887	3,242
Expected Return on Plan Assets	(2,255)	(2,118)	(4,510)	(4,237)
Prior Service Cost Amortization	80	80	160	160
Actuarial Loss Amortization	1,618	1,081	3,236	2,162
Sub-total	1,717	1,440	3,435	2,879
Amounts Capitalized and Deferred	(807)	(597)	(1,437)	(1,009)
Net Periodic Benefit Cost Recognized	910	843	1,998	1,870
Other Postretirement Benefit Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Service Cost	675	576	1,350	1,152
Interest Cost	779	856	1,559	1,712
Expected Return on Plan Assets	(516)	(411)	(1,032)	(822)
Prior Service Cost Amortization	303	303	606	606
Actuarial Loss Amortization	186	57	372	114
Sub-total	1,427	1,381	2,855	2,762
Amounts Capitalized and Deferred	(695)	(606)	(1,227)	(1,080)
Net Periodic Benefit Cost Recognized	732	775	1,628	1,682
Supplemental Employee Retirement Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Service Cost	71	63	142	123
Interest Cost	138	145	275	284
Prior Service Cost Amortization	14	25	28	28
Actuarial Loss Amortization	259	156	518	314
Sub-total	482	389	963	749
Amounts Capitalized and Deferred	(152)	(112)	(290)	(215)
Net Periodic Benefit Cost Recognized	$ 330	$ 277	$ 673	$ 534

Retirement Benefit Obligation_2

Retirement Benefit Obligations - Additional Information (Detail) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2020USD ($)	Jun. 30, 2020USD ($)
Defined Benefit Plan Disclosure [Line Items]
Contributions to benefit plan	$ 0
Other Postretirement Benefit Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Contributions to benefit plan	1.4
Supplemental Employee Retirement Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Benefit payments under SERP Plan		$ 0.3
Expected additional benefit payments for the remainder of 2019	$ 0.4	$ 0.4