Commitments and Contingencies	3 Months Ended
Commitments and Contingencies	Mar. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Severance Agreements We have agreements with our executive officers and certain other key management personnel providing for severance benefits for such employees upon termination of their employment under certain circumstances. Guarantees In the ordinary course of business, we, at times, guarantee obligations of our subsidiaries under certain contracts. Generally, we are liable under such an arrangement only if our subsidiary fails to perform its obligations under the contract. Historically, we have not incurred any substantial liabilities as a consequence of these guarantees. Surety Bonds The terms of our construction contracts frequently require that we obtain from surety companies, and provide to our customers, surety bonds as a condition to the award of such contracts. These surety bonds are issued in return for premiums, which vary depending on the size and type of the bond, and secure our payment and performance obligations under such contracts. We have agreed to indemnify the surety companies for amounts, if any, paid by them in respect of surety bonds issued on our behalf. As of March 31, 2022, based on the percentage-of-completion of our projects covered by surety bonds, our aggregate estimated exposure, assuming defaults on all our then existing contractual obligations, was approximately $1.5 billion, which represents approximately 25% of our total remaining performance obligations. Surety bonds are sometimes provided to secure obligations for wages and benefits payable to or for certain of our employees, at the request of labor unions representing such employees. In addition, surety bonds may be issued as collateral for certain insurance obligations. As of March 31, 2022, we satisfied approximately $48.1 million of the collateral requirements of our insurance programs by utilizing surety bonds. We are not aware of any losses in connection with surety bonds that have been posted on our behalf, and we do not expect to incur significant losses in the foreseeable future. Hazardous Materials We are subject to regulation with respect to the handling of certain materials used in construction, which are classified as hazardous or toxic by federal, state, and local agencies. Our practice is to avoid participation in projects principally involving the remediation or removal of such materials. However, when remediation is required as part of our contract performance, we believe we comply with all applicable regulations governing the discharge of hazardous materials into the environment or otherwise relating to the protection of the environment. NOTE 12 - Commitments and Contingencies (continued) Government Contracts As a government contractor, we are subject to U.S. government audits and investigations relating to our operations, which such audits may result in fines, penalties and compensatory and treble damages, and possible suspension or debarment from doing business with the government. Based on currently available information, we believe the outcome of ongoing government disputes and investigations will not have a material impact on our financial position, results of operations, or liquidity. Legal Proceedings We are involved in several legal proceedings in which damages and claims have been asserted against us. We believe that we have a number of valid defenses to such proceedings and claims and intend to vigorously defend ourselves. We do not believe that any such matters will have a material adverse effect on our financial position, results of operations, or liquidity. We record a loss contingency if the potential loss from a proceeding or claim is considered probable and the amount can be reasonably estimated or a range of loss can be determined. We provide disclosure when it is reasonably possible that a loss will be incurred in excess of any recorded provision. Significant judgment is required in these determinations. As additional information becomes available, we reassess prior determinations and may change our estimates. Additional claims may be asserted against us in the future. Litigation is subject to many uncertainties, and the outcome of litigation is not predictable with assurance. It is possible that a litigation matter for which liabilities have not been recorded could be decided unfavorably to us, and that any such unfavorable decision could have a material adverse effect on our financial position, results of operations, or liquidity. Insurance Liabilities We have loss payment deductibles for certain workers’ compensation, automobile liability, general liability, and property claims, have self-insured retentions for certain other casualty claims, and are self-insured for employee-related healthcare claims. In addition, we maintain a wholly-owned captive insurance subsidiary to manage certain of our insurance liabilities. Losses are recorded based upon estimates of our liability for claims incurred and for claims incurred but not reported. The liabilities are derived from known facts, historical trends, and industry averages, utilizing the assistance of an independent third-party actuary to determine the best estimate for the majority of these obligations. As of March 31, 2022 and December 31, 2021, the estimated current portion of such undiscounted insurance liabilities, included in “Other accrued expenses and liabilities” in the accompanying Consolidated Balance Sheets, were $55.6 million and $61.5 million, respectively. The estimated non-current portion of such undiscounted insurance liabilities included in “Other long-term obligations” as of March 31, 2022 and December 31, 2021 were $216.2 million and $242.4 million, respectively. The current portion of anticipated insurance recoveries of $18.4 million and $26.4 million as of March 31, 2022 and December 31, 2021, respectively, were included in “Prepaid expenses and other” and the non-current portion of anticipated insurance recoveries of $66.6 million and $99.0 million as of March 31, 2022 and December 31, 2021, respectively, were included in “Other assets” in the accompanying Consolidated Balance Sheets. These balances decreased from December 31, 2021 as a result of the payment, by our insurers, of certain claims for which we previously maintained a reserve and corresponding insurance receivable.