Summary of Significant Accounting Policies (Policies)	9 Months Ended
Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Principles of Consolidation	These unaudited condensed consolidated financial statements (the “financial statements”) include the accounts of Northrop Grumman Corporation and its subsidiaries and joint ventures or other investments for which we consolidate the financial results (herein referred to as “Northrop Grumman,” the “company,” “we,” “us,” or “our”). Intercompany accounts, transactions and profits are eliminated in consolidation. Investments in equity securities and joint ventures where the company has significant influence, but not control, are accounted for using the equity method.
Basis of Presentation	These financial statements are prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP” or “FAS”) and in accordance with the rules of the Securities and Exchange Commission (SEC) for interim reporting. The financial statements include adjustments of a normal recurring nature considered necessary by management for a fair presentation of the company’s unaudited condensed consolidated financial position, results of operations and cash flows. Results reported in these financial statements are not necessarily indicative of results that may be expected for the entire year. These financial statements should be read in conjunction with the information contained in the company’s 2022 Annual Report on Form 10-K. During the first quarter of 2023, we changed the presentation of the components of other comprehensive income (loss), net of tax in the Unaudited condensed consolidated statements of earnings and comprehensive income. Prior period amounts have been recast to conform to current period presentation. This change in presentation had no impact on our previously reported comprehensive income in total.
Fiscal Period Policy	Quarterly information is labeled using a calendar convention; that is, first quarter is consistently labeled as ending on March 31, second quarter as ending on June 30 and third quarter as ending on September 30. It is the company’s long-standing practice to establish actual interim closing dates using a “fiscal” calendar, in which we close our books on a Friday near these quarter-end dates in order to normalize the potentially disruptive effects of quarterly closings on business processes. This practice is only used at interim periods within a reporting year.
Accounting Estimates	Preparation of the financial statements requires management to make estimates and judgments that affect the reported amounts of assets and liabilities and the disclosure of contingencies at the date of the financial statements, as well as the reported amounts of sales and expenses during the reporting period. Estimates have been prepared using the most current and best available information; however, actual results could differ materially from those estimates.
Revenue from Contract with Customer	Contract Estimates Contract sales may include estimates of variable consideration, including cost or performance incentives (such as award and incentive fees), un-priced change orders, REAs and contract claims. Variable consideration is included in total estimated sales to the extent it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. We estimate variable consideration as the most likely amount to which we expect to be entitled. At the request of the National Aeronautics and Space Administration (NASA), Space Systems is preparing engineering change proposals (ECPs) for scope increases and other aspects of the Habitation and Logistics Outpost (HALO) contract largely stemming from evolving Lunar Gateway architecture and mission requirements. We expect the ECPs will address both work performed and work expected to be performed by the company resulting from scope changes previously approved by NASA, as well as changes NASA has requested the company to propose but has not yet directed the company to perform. The company plans to submit an ECP prior to the end of the year and begin negotiating with NASA on these various changes and other aspects of the HALO contract. The company’s third quarter results reflect our current best estimate of the outcome of the ECP negotiations assuming the terms of the current contract; however, if the outcome is less favorable than what we have assumed, it could have an adverse effect on our financial position, results of operations and/or cash flows. We recognize changes in estimated contract sales or costs and the resulting changes in contract profit on a cumulative basis. Net estimate-at-completion (EAC) adjustments represent the cumulative effect of the changes on current and prior periods; sales and operating margins in future periods are recognized as if the revised estimates had been used since contract inception. If it is determined that a loss is expected to result on an individual performance obligation, the entire amount of the estimable future loss, including an allocation of general and administrative expense, is charged against income in the period the loss is identified.Contract Assets and LiabilitiesFor each of the company’s contracts, the timing of revenue recognition, customer billings, and cash collections results in a net contract asset or liability at the end of each reporting period. Contract assets are equivalent to and reflected as Unbilled receivables in the unaudited condensed consolidated statements of financial position and are primarily related to long-term contracts where revenue recognized under the cost-to-cost method exceeds amounts billed to customers. Contract liabilities are equivalent to and reflected as Advance payments and billings in excess of costs incurred in the unaudited condensed consolidated statements of financial position.
Earnings Per Share	We calculate basic earnings per share by dividing net earnings by the weighted-average number of shares of common stock outstanding during each period.Diluted earnings per share include the dilutive effect of awards granted to employees under stock-based compensation plans.
Investments in Marketable Securities	The company holds a portfolio of marketable securities to partially fund non-qualified employee benefit plans. A portion of these securities are held in common/collective trust funds and are measured at fair value using net asset value (NAV) per share as a practical expedient; therefore, they are not categorized in the fair value hierarchy table
Derivative Financial Instruments and Hedging Activities	Where model-derived valuations are appropriate, the company utilizes the income approach to determine the fair value using internal models based on observable market inputs.
Fair Value of Long-term Debt	We calculated the fair value of long-term debt using Level 2 inputs, based on interest rates available for debt with terms and maturities similar to the company’s existing debt arrangements.
U.S. Government Cost Claims	From time to time, the company is advised of claims by the U.S. government concerning certain potential disallowed costs, plus, at times, penalties and interest. When such findings are presented, the company and U.S. government representatives engage in discussions to enable the company to evaluate the merits of these claims, as well as to assess the amounts being claimed. Where appropriate, provisions are made to reflect the company’s estimated exposure for such potential disallowed costs. Such provisions are reviewed periodically using the most recent information available.
Pension and Other Postretirement Plans	We fund our defined benefit pension plans annually in a manner consistent with the Employee Retirement Income Security Act of 1974, as amended by the Pension Protection Act of 2006
New Accounting Pronouncements, Policy	Accounting standards updates adopted and/or issued, but not effective until after September 30, 2023, are not expected to have a material effect on the company’s unaudited condensed consolidated financial position, annual results of operations and/or cash flows.

Summary of Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

These unaudited condensed consolidated financial statements (the “financial statements”) include the accounts of Northrop Grumman Corporation and its subsidiaries and joint ventures or other investments for which we consolidate the financial results (herein referred to as “Northrop Grumman,” the “company,” “we,” “us,” or “our”). Intercompany accounts, transactions and profits are eliminated in consolidation. Investments in equity securities and joint ventures where the company has significant influence, but not control, are accounted for using the equity method.

Basis of Presentation

These financial statements are prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP” or “FAS”) and in accordance with the rules of the Securities and Exchange Commission (SEC) for interim reporting. The financial statements include adjustments of a normal recurring nature considered necessary by management for a fair presentation of the company’s unaudited condensed consolidated financial position, results of operations and cash flows.

Results reported in these financial statements are not necessarily indicative of results that may be expected for the entire year. These financial statements should be read in conjunction with the information contained in the company’s 2022 Annual Report on Form 10-K. During the first quarter of 2023, we changed the presentation of the components of other comprehensive income (loss), net of tax in the Unaudited condensed consolidated statements of earnings and comprehensive income. Prior period amounts have been recast to conform to current period presentation. This change in presentation had no impact on our previously reported comprehensive income in total.

Fiscal Period Policy

Quarterly information is labeled using a calendar convention; that is, first quarter is consistently labeled as ending on March 31, second quarter as ending on June 30 and third quarter as ending on September 30. It is the company’s long-standing practice to establish actual interim closing dates using a “fiscal” calendar, in which we close our books on a Friday near these quarter-end dates in order to normalize the potentially disruptive effects of quarterly closings on business processes. This practice is only used at interim periods within a reporting year.

Accounting Estimates

Preparation of the financial statements requires management to make estimates and judgments that affect the reported amounts of assets and liabilities and the disclosure of contingencies at the date of the financial statements, as well as the reported amounts of sales and expenses during the reporting period. Estimates have been prepared using the most current and best available information; however, actual results could differ materially from those estimates.

Revenue from Contract with Customer

Contract Estimates

Contract sales may include estimates of variable consideration, including cost or performance incentives (such as award and incentive fees), un-priced change orders, REAs and contract claims. Variable consideration is included in total estimated sales to the extent it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. We estimate variable consideration as the most likely amount to which we expect to be entitled.

At the request of the National Aeronautics and Space Administration (NASA), Space Systems is preparing engineering change proposals (ECPs) for scope increases and other aspects of the Habitation and Logistics Outpost (HALO) contract largely stemming from evolving Lunar Gateway architecture and mission requirements. We expect the ECPs will address both work performed and work expected to be performed by the company resulting from scope changes previously approved by NASA, as well as changes NASA has requested the company to propose but has not yet directed the company to perform. The company plans to submit an ECP prior to the end of the year and begin negotiating with NASA on these various changes and other aspects of the HALO contract. The company’s third quarter results reflect our current best estimate of the outcome of the ECP negotiations assuming the terms of the current contract; however, if the outcome is less favorable than what we have assumed, it could have an adverse effect on our financial position, results of operations and/or cash flows.

We recognize changes in estimated contract sales or costs and the resulting changes in contract profit on a cumulative basis. Net estimate-at-completion (EAC) adjustments represent the cumulative effect of the changes on current and prior periods; sales and operating margins in future periods are recognized as if the revised estimates had been used since contract inception. If it is determined that a loss is expected to result on an individual performance

obligation, the entire amount of the estimable future loss, including an allocation of general and administrative expense, is charged against income in the period the loss is identified.Contract Assets and LiabilitiesFor each of the company’s contracts, the timing of revenue recognition, customer billings, and cash collections results in a net contract asset or liability at the end of each reporting period. Contract assets are equivalent to and reflected as Unbilled receivables in the unaudited condensed consolidated statements of financial position and are primarily related to long-term contracts where revenue recognized under the cost-to-cost method exceeds amounts billed to customers. Contract liabilities are equivalent to and reflected as Advance payments and billings in excess of costs incurred in the unaudited condensed consolidated statements of financial position.

Earnings Per Share

We calculate basic earnings per share by dividing net earnings by the weighted-average number of shares of common stock outstanding during each period.Diluted earnings per share include the dilutive effect of awards granted to employees under stock-based compensation plans.

Investments in Marketable Securities

The company holds a portfolio of marketable securities to partially fund non-qualified employee benefit plans. A portion of these securities are held in common/collective trust funds and are measured at fair value using net asset value (NAV) per share as a practical expedient; therefore, they are not categorized in the fair value hierarchy table

Derivative Financial Instruments and Hedging Activities

Where model-derived valuations are appropriate, the company utilizes the income approach to determine the fair value using internal models based on observable market inputs.

Fair Value of Long-term Debt

We calculated the fair value of long-term debt using Level 2 inputs, based on interest rates available for debt with terms and maturities similar to the company’s existing debt arrangements.

U.S. Government Cost Claims

From time to time, the company is advised of claims by the U.S. government concerning certain potential disallowed costs, plus, at times, penalties and interest. When such findings are presented, the company and U.S. government representatives engage in discussions to enable the company to evaluate the merits of these claims, as well as to assess the amounts being claimed. Where appropriate, provisions are made to reflect the company’s estimated exposure for such potential disallowed costs. Such provisions are reviewed periodically using the most recent information available.

Pension and Other Postretirement Plans

We fund our defined benefit pension plans annually in a manner consistent with the Employee Retirement Income Security Act of 1974, as amended by the Pension Protection Act of 2006

New Accounting Pronouncements, Policy

Accounting standards updates adopted and/or issued, but not effective until after September 30, 2023, are not expected to have a material effect on the company’s unaudited condensed consolidated financial position, annual results of operations and/or cash flows.