Amount of contractual obligation, including, but not limited to, long-term debt, lease obligation, purchase obligation, and other commitments.

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-Topic 235
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Percentage of public utility's approved return on equity.

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Percentage of public utility's requested equity to capital, including debt and equity.

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Amount of public utility's requested rate increase (decrease) with regulatory agency.

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Amount of capital expenditure approved by regulatory authority

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Amount of replacement investments approved by regulatory authority

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Budget for Additional investment

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Budget For EV program

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Budget for replacement investments

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Cost of Damages due to Natural Calamaties

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Expenses associated with the program excluded from the revenue requirement as per order and adjusted increase amount will result in reasonable rates

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Facility Power Capacity

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Public utilities approved increase amount of annual revenue to recover eligible capital investments

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Public Utilities Approved Rate Increase Amount.

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Recovery of deferred costs

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Remuneration percentage.

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Threshold amount that will be allowed to adjust distribution rates upward or downward during the term of stay out period

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Transfer In Revenue Requirements Amount

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Weighted Average Cost Of Capital

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Regulatory Matters - Additional Information (Detail) $ in Millions	Nov. 02, 2023 USD ($)	Sep. 20, 2023 USD ($)	Aug. 17, 2023 USD ($)	Jul. 27, 2023 USD ($)	May 01, 2023 USD ($)	Apr. 15, 2023 USD ($)	Feb. 14, 2023 USD ($)	Dec. 30, 2022 USD ($)	Nov. 02, 2022 USD ($)	Aug. 19, 2022 USD ($)	Jul. 28, 2022 USD ($)	Jul. 20, 2022 USD ($)	Jul. 15, 2022 USD ($)	Jun. 08, 2022 USD ($)	May 12, 2022 USD ($)	May 03, 2022 USD ($)	Nov. 02, 2021 USD ($)	Aug. 24, 2021 USD ($)	Nov. 30, 2020 USD ($)	Jul. 31, 2018 MW MWh	Jun. 30, 2017	Jun. 30, 2027 MW MWh	Nov. 30, 2022 USD ($)	Oct. 31, 2022 USD ($)	Oct. 07, 2022 USD ($)	May 31, 2022 MW	May 27, 2022 USD ($)	May 07, 2021 MW
Regulatory Asset [Line Items]
Requested annual increase in rates					$ 2.1
Cost of Damages due to Natural Calamaties	$ 4.8
Budget For EV program								$ 1.0
Program Segment spendings description								The Company may shift spending between program segments and between years over the five-year term of its program, subject to a 15% cap. Any spending above the approved EV program budget or above the 15% cap for each program segment is not eligible for targeted cost recovery through the GMF
Offshore Wind Energy
Regulatory Asset [Line Items]
Power generation facility \| MW																						1,600
Northern Utilities Inc
Regulatory Asset [Line Items]
Percentage of approved return on equity																9.20%
Percentage of approved return on equity, reflecting on equity																52.00%
Percentage of approved return on equity, reflecting on debt																48.00%
Approved annual increase in rates		$ 7.6					$ 1.2							$ 1.6		$ 6.3
Public utilities approved increase amount of annual revenue to recover eligible capital investments											$ 1.3
Return on equity		9.35%
Equity ratio		52.01%
weighted average cost of capital		7.22%
Northern Utilities Inc \| Settlement Agreement [Member]
Regulatory Asset [Line Items]
Approved annual increase in rates												$ 6.1
Northern Utilities Inc \| Arrearage Management Program [Member]
Regulatory Asset [Line Items]
Expenses associated with the program excluded from the revenue requirement as per order and adjusted increase amount will result in reasonable rates															$ 5.9
Northern Utilities Inc \| New Hampshire
Regulatory Asset [Line Items]
Percentage of approved return on equity													9.30%
Percentage of approved return on equity, reflecting on equity													52.00%
Percentage of approved return on equity, reflecting on debt													48.00%
Threshold amount that will be allowed to adjust distribution rates upward or downward during the term of stay out period													$ 200,000.0
Fitchburg Gas and Electric Light Company
Regulatory Asset [Line Items]
Increase (decrease) in annual revenue	$ 3.6								$ 3.1								$ 1.6
Power generation capacity \| MWh																						9,450,000
Remuneration Percentage								2.25%
Requested annual increase in rates			$ 6.8
Approved annual increase in rates			4.1
Transfer in Revenue Requirements			2.7
Fitchburg Gas and Electric Light Company \| Offshore Wind Energy
Regulatory Asset [Line Items]
Power generation capacity \| MW																				400
Remuneration Percentage																				2.75%	2.75%
Fitchburg Gas and Electric Light Company \| Offshore Wind Energy \| Second Solicitation [Member]
Regulatory Asset [Line Items]
Power generation capacity \| MW																										1,600		1,600
Fitchburg Gas and Electric Light Company \| Qualified Clean Energy
Regulatory Asset [Line Items]
Power generation capacity \| MWh																				9,554,940
Fitchburg Gas Company
Regulatory Asset [Line Items]
Regulatory assets approved increase in revenue due to be recovered					$ 6.4																			$ 4.5			$ 0.4
Recovery of deferred costs						$ 1.0
Requested annual increase in rates			10.9
Approved annual increase in rates			6.7
Transfer in Revenue Requirements			$ 4.2
Fitchburg Gas Company \| Track One [Member]
Regulatory Asset [Line Items]
Amount of capital expenditure approved by regulatory authority																									$ 9.3
Fitchburg Gas Company \| Track Two [Member]
Regulatory Asset [Line Items]
Budget for Additional investment																							$ 1.5
Budget for replacement investments																							11.2
Amount of replacement investments approved by regulatory authority																							$ 2.3
Granite State
Regulatory Asset [Line Items]
Increase (decrease) in annual revenue				$ 1.0						$ 0.3								$ 0.1	$ 1.3
Spending cap																			$ 14.6
Public Infrastructure Offering [Member]
Regulatory Asset [Line Items]
Budget For EV program								$ 0.5
Electric Vehicle Supply Equipment [Member]
Regulatory Asset [Line Items]
Budget For EV program								$ 0.3