On January 12, 1999, Aerojet Rocketdyne and the U.S. government reached a settlement agreement ("Global Settlement") covering environmental costs associated with the Company's Sacramento site and its former Azusa site. Pursuant to the Global Settlement, the Company can recover up to 88% of its environmental remediation costs through the establishment of prices for Aerojet Rocketdyne's products and services sold to the U.S. government. Additionally, in conjunction with the sale of the EIS business in 2001, Aerojet Rocketdyne entered into an agreement with Northrop (the "Northrop Agreement") whereby Aerojet Rocketdyne is reimbursed by Northrop for a portion of environmental expenditures eligible for recovery under the Global Settlement, subject to an annual billing limitation of $6.0 million and a cumulative limitation of $189.7 million. The following table summarizes the Northrop Agreement activity (in millions): The cumulative expenditure limitation of $189.7 million under the Northrop Agreement was reached in June 2017. At that time, the Company was uncertain of the allowability and allocability of additional expenditures above that cumulative limitation and therefore did not recognize a recoverable asset for such amounts. In the third quarter of 2018, the Company and the U.S. government reached a determination that these expenditures are reimbursable under the Global Settlement and therefore recorded a one-time benefit of $43.0 million to recognize the recoverability of environmental expenditures at a rate of 88%. Environmental remediation costs are primarily incurred by the Company's Aerospace and Defense segment, and certain of these costs are recoverable from the Company's contracts with the U.S. government. The Company currently estimates approximately 12% of its future Aerospace and Defense segment environmental remediation costs will not likely be reimbursable and are expensed. Allowable environmental remediation costs are charged to the Company’s contracts with the U.S. government as the costs are incurred. Because these costs are recovered through forward-pricing arrangements, the ability of Aerojet Rocketdyne to continue recovering these costs from the U.S. government depends on Aerojet Rocketdyne’s sustained business volume from U.S. government contracts and programs. While the Company continues to seek an arrangement with the U.S. government to recover environmental expenditures in excess of the reimbursement ceiling identified in the Global Settlement, there can be no assurances that such a recovery will be obtained, or if not obtained, that such unreimbursed environmental expenditures will not have a materially adverse effect on the Company’s operating results, financial condition, and/or cash flows. The following table summarizes the financial information for the impact of environmental reserves and recoveries to the consolidated statements of operations: Environmental reserves and estimated recoveries impact on the consolidated statements of operations Total reimbursable costs under the Northrop Agreement $ 189.7  Amount reimbursed to the Company through December 31, 2020 (143.2) Receivable from Northrop included in the balance sheet at December 31, 2020 $ 46.5  Year Ended December 31, 2020 2019 2018 (In millions) Expense (benefit) to consolidated statement of operations $ 4.3  $ 2.1  $ (36.9) In addition to the items discussed above, the Company has and will from time to time enter into certain types of contracts that require the Company to indemnify parties against potential third-party and other claims. These contracts primarily relate to: (i) divestiture agreements, under which the Company may provide customary indemnification to purchasers of its businesses or assets including, for example, claims arising from the operation of the businesses prior to disposition, and liability to investigate and remediate environmental contamination existing prior to disposition; (ii) certain real estate leases, under which the Company may be required to indemnify property owners for claims arising from the use of the applicable premises; and (iii) certain agreements with officers and directors, under which the Company may be required to indemnify such persons for liabilities arising out of their relationship with the Company. The terms of such obligations vary. Generally, a maximum obligation is not explicitly stated. d. Arrangements with Off-Balance Sheet Risk As of December 31, 2020, arrangements with off-balance sheet risk consisted of:  • $27.6 million in outstanding commercial letters of credit, the majority of which may be renewed, primarily to collateralize obligations for environmental remediation and insurance coverage. • $53.5 million in outstanding surety bonds to primarily satisfy indemnification obligations for environmental remediation coverage. • Up to $120.0 million aggregate in guarantees by the Company of Aerojet Rocketdyne’s obligations to U.S. government agencies for environmental remediation activities. • Guarantees, jointly and severally, by the Company’s material domestic subsidiaries of their obligations under the Senior Credit Facility. 72 of future cleanup costs related to the Company’s operation of the Open Burn Unit from 2003-2009, and ARC assumed management for the ongoing remediation as required by the 2003 acquisition agreement. Estimated Recoveries