Summary of Significant Accounting Policies and Other Matters (Policies)	9 Months Ended
Sep. 30, 2024
Accounting Policies [Abstract]
Reclassification	Reclassification Certain prior period amounts have been reclassified to conform with the current period presentation.
Earnings Per Share	Earnings Per Share Con Edison presents basic and diluted earnings per share (EPS) on the face of its consolidated income statement. Basic EPS is calculated by dividing earnings available to common shareholders (“Net income for common stock” on Con Edison’s consolidated income statement) by the weighted average number of Con Edison common shares outstanding during the period. In the calculation of diluted EPS, weighted average shares outstanding are increased for additional shares that would be outstanding if potentially dilutive securities were converted to common stock. Potentially dilutive securities for Con Edison consist of restricted stock units and deferred stock units for which the average market price of the common shares for the period was greater than the estimated vesting price.
Fair Value Measurements	Fair Value Measurements The accounting rules for fair value measurements and disclosures define fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date in a principal or most advantageous market. Fair value is a market-based measurement that is determined based on inputs, that refer broadly to assumptions that market participants use in pricing assets or liabilities. These inputs can be readily observable, market corroborated, or generally unobservable firm inputs. The Companies often make certain assumptions that market participants would use in pricing the asset or liability, including assumptions about risk, and the risks inherent in the inputs to valuation techniques. The Companies use valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs. The accounting rules for fair value measurements and disclosures established a fair value hierarchy, that prioritizes the inputs to valuation techniques used to measure fair value in three broad levels. The rules require that assets and liabilities be classified in their entirety based on the level of input that is significant to the fair value measurement. Assessing the significance of a particular input may require judgment considering factors specific to the asset or liability and may affect the valuation of the asset or liability and their placement within the fair value hierarchy. The Companies classify fair value balances based on the fair value hierarchy defined by the accounting rules for fair value measurements and disclosures as follows: •Level 1 – Consists of assets or liabilities whose value is based on unadjusted quoted prices in active markets at the measurement date. An active market is one in which transactions for assets or liabilities occur with sufficient frequency and volume to provide pricing information on an ongoing basis. This category includes contracts traded on active exchange markets valued using unadjusted prices quoted directly from the exchange. •Level 2 – Consists of assets or liabilities valued using industry standard models and based on prices, other than quoted prices within Level 1, that are either directly or indirectly observable as of the measurement date. The industry standard models consider observable assumptions including time value, volatility factors and current market and contractual prices for the underlying commodities, in addition to other economic measures. This category includes contracts traded on active exchanges or in over-the-counter markets priced with industry standard models. •Level 3 – Consists of assets or liabilities whose fair value is estimated based on internally developed models or methodologies using inputs that are generally less readily observable and supported by little, if any, market activity at the measurement date. Unobservable inputs are developed based on the best available information and subject to cost benefit constraints. This category includes contracts priced using models that are internally developed and contracts placed in illiquid markets. It also includes contracts that expire after the period of time for which quoted prices are available and internal models are used to determine a significant portion of the value.
New Financial Accounting Standards	New Financial Accounting Standards In November 2023, the Financial Accounting Standards Board (FASB) issued amendments to the disclosure requirements for a public entity’s reportable segments through ASU 2023-07, “Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures." The amendments improve the disclosures about a public entity’s reportable segments and address requests from investors for additional, more detailed information about a reportable segment’s expenses. The amendments are effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. A public entity should apply these amendments retrospectively to all prior periods presented in the financial statements. The Companies do not expect the new guidance to have a material impact on their financial position, results of operations and liquidity. In December 2023, the FASB issued amendments to the guidance on accounting for Income Taxes (Topic 740) through ASU 2023-09 to improve disclosures related to income taxes. The amendments focus on three key areas: rate reconciliation, income taxes paid, and income (or loss)/income tax expense (or benefit) from disaggregated continuing operations. For public entities, the amendments are effective for annual reporting periods beginning after December 15, 2024. Early adoption is permitted for annual financial statements. The Companies do not expect the new guidance to have a material impact on their financial position, results of operations and liquidity. In November 2024, the FASB issued ASU 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40) to improve disclosures about a public business entity's expenses. The ASU addresses requests from investors for more detailed information about the types of expenses (including purchases of inventory, employee compensation, depreciation, amortization, and depletion) in commonly presented expense captions. The amendments require a public business entity to disclose, in the notes to the financial statements, specified information about certain costs and expenses at each interim and annual reporting period. The amendments are effective for annual reporting periods beginning after December 15, 2026, and interim reporting periods beginning after December 15, 2027. Early adoption is permitted. The Companies are in the process of evaluating the potential impact of the ASU on their financial position, results of operations and liquidity.

Summary of Significant Accounting Policies and Other Matters (Policies)

9 Months Ended

Sep. 30, 2024

Certain prior period amounts have been reclassified to conform with the current period presentation.

Con Edison presents basic and diluted earnings per share (EPS) on the face of its consolidated income statement. Basic EPS is calculated by dividing earnings available to common shareholders (“Net income for common stock” on Con Edison’s consolidated income statement) by the weighted average number of Con Edison common shares outstanding during the period. In the calculation of diluted EPS, weighted average shares outstanding are increased for additional shares that would be outstanding if potentially dilutive securities were converted to common stock.

Potentially dilutive securities for Con Edison consist of restricted stock units and deferred stock units for which the average market price of the common shares for the period was greater than the estimated vesting price.

Fair Value Measurements

The accounting rules for fair value measurements and disclosures define fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date in a principal or most advantageous market. Fair value is a market-based measurement that is determined based on inputs, that refer broadly to assumptions that market participants use in pricing assets or liabilities. These inputs can be readily observable, market corroborated, or generally unobservable firm inputs. The Companies often make certain assumptions that market participants would use in pricing the asset or liability, including assumptions about risk, and the risks inherent in the inputs to valuation techniques. The Companies use valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs.

The accounting rules for fair value measurements and disclosures established a fair value hierarchy, that prioritizes the inputs to valuation techniques used to measure fair value in three broad levels. The rules require that assets and liabilities be classified in their entirety based on the level of input that is significant to the fair value measurement. Assessing the significance of a particular input may require judgment considering factors specific to the asset or liability and may affect the valuation of the asset or liability and their placement within the fair value hierarchy. The Companies classify fair value balances based on the fair value hierarchy defined by the accounting rules for fair value measurements and disclosures as follows:

•Level 1 – Consists of assets or liabilities whose value is based on unadjusted quoted prices in active markets at the measurement date. An active market is one in which transactions for assets or liabilities occur with sufficient frequency and volume to provide pricing information on an ongoing basis. This category includes contracts traded on active exchange markets valued using unadjusted prices quoted directly from the exchange.

•Level 2 – Consists of assets or liabilities valued using industry standard models and based on prices, other than quoted prices within Level 1, that are either directly or indirectly observable as of the measurement date. The industry standard models consider observable assumptions including time value, volatility factors and current market and contractual prices for the underlying commodities, in addition to other economic measures. This category includes contracts traded on active exchanges or in over-the-counter markets priced with industry standard models.

•Level 3 – Consists of assets or liabilities whose fair value is estimated based on internally developed models or methodologies using inputs that are generally less readily observable and supported by little, if any, market activity at the measurement date. Unobservable inputs are developed based on the best available information and subject to cost benefit constraints. This category includes contracts priced using models that are internally developed and contracts placed in illiquid markets. It also includes contracts that expire after the period of time for which quoted prices are available and internal models are used to determine a significant portion of the value.

New Financial Accounting Standards

In November 2023, the Financial Accounting Standards Board (FASB) issued amendments to the disclosure requirements for a public entity’s reportable segments through ASU 2023-07, “Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures." The amendments improve the disclosures about a public entity’s reportable segments and address requests from investors for additional, more detailed information about a reportable segment’s expenses. The amendments are effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. A public entity should apply these amendments retrospectively to all prior periods presented in the financial statements. The Companies do not expect the new guidance to have a material impact on their financial position, results of operations and liquidity.

In December 2023, the FASB issued amendments to the guidance on accounting for Income Taxes (Topic 740) through ASU 2023-09 to improve disclosures related to income taxes. The amendments focus on three key areas: rate reconciliation, income taxes paid, and income (or loss)/income tax expense (or benefit) from disaggregated continuing operations. For public entities, the amendments are effective for annual reporting periods beginning after December 15, 2024. Early adoption is permitted for annual financial statements. The Companies do not expect the new guidance to have a material impact on their financial position, results of operations and liquidity.

In November 2024, the FASB issued ASU 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40) to improve disclosures about a public business entity's expenses. The ASU addresses requests from investors for more detailed information about the types of expenses (including purchases of inventory, employee compensation, depreciation, amortization, and depletion) in commonly presented expense captions. The amendments require a public business entity to disclose, in the notes to the financial statements, specified information about certain costs and expenses at each interim and annual reporting period. The amendments are effective for annual reporting periods beginning after December 15, 2026, and interim reporting periods beginning after December 15, 2027. Early adoption is permitted. The Companies are in the process of evaluating the potential impact of the ASU on their financial position, results of operations and liquidity.