Summary of Significant Accounting Policies	9 Months Ended
Summary of Significant Accounting Policies	Sep. 30, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Organization and Description of the Business Federal Signal Corporation was founded in 1901 and was reincorporated as a Delaware corporation in 1969. References herein to the “Company,” “we,” “our” or “us” refer collectively to Federal Signal Corporation and its subsidiaries. Products manufactured and services rendered by the Company are divided into two reportable segments: Environmental Solutions Group and Safety and Security Systems Group. The individual operating businesses are organized as such because they share certain characteristics, including technology, marketing, distribution and product application, which create long-term synergies. These segments are discussed in Note 11 – Segment Information. Basis of Presentation and Consolidation The accompanying unaudited condensed consolidated financial statements represent the consolidation of Federal Signal Corporation and its subsidiaries included herein and have been prepared by the Company pursuant to the rules and regulations of the United States (“U.S.”) Securities and Exchange Commission (the “SEC”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) have been condensed or omitted pursuant to such rules and regulations, although the Company believes that the disclosures presented herein are adequate to ensure the information presented is not misleading. Except as otherwise noted, these condensed consolidated financial statements have been prepared in accordance with the Company’s accounting policies described in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019, and should be read in conjunction with those consolidated financial statements and the notes thereto. These condensed consolidated financial statements include all normal and recurring adjustments that we considered necessary to present a fair statement of our results of operations, financial condition and cash flow. Intercompany balances and transactions have been eliminated in consolidation. In addition, certain prior-year amounts have been reclassified to conform to current-year presentation. The results reported in these condensed consolidated financial statements should not be regarded as necessarily indicative of results that may be expected for the entire year, which may differ materially due to, among other things, the risk factors described under Part I, Item 1A, Risk Factors, of the Company’s Annual Report on Form 10-K for the year ended December 31, 2019, which was filed with the SEC on February 27, 2020, and as updated in Part II, Item 1A, Risk Factors, of the Company’s Quarterly Reports on Form 10-Q for the quarterly periods ended March 31, 2020 and June 30, 2020, which were filed with the SEC on April 29, 2020 and July 29, 2020, respectively, and in this Form 10-Q. While we label our quarterly information using a calendar convention whereby our first, second and third quarters are labeled as ending on March 31, June 30 and September 30, respectively, it is our longstanding practice to establish interim quarterly closing dates based on a 13-week period ending on a Saturday, with our fiscal year ending on December 31. The effects of this practice are not material and exist only within a reporting year. Recent Accounting Pronouncements and Accounting Changes In June 2016, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) No. 2016-13, Financial Instruments – Credit Losses (Topic 326), Measurement of Credit Losses on Financial Statements, which requires the measurement of expected credit losses for financial instruments based on historical experience, current conditions, and reasonable forecasts. The amendments in this ASU are effective for fiscal years beginning after December 15, 2019 and interim periods within those fiscal years. The amendments in this ASU should be applied on a modified retrospective basis. The Company adopted this guidance effective January 1, 2020. The adoption of this ASU did not have a material impact on the Company’s consolidated financial statements. In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820), which eliminates certain disclosure requirements, such as the amount of, and reasons for, transfers between Level 1 and Level 2 of the fair value hierarchy. This ASU adds new disclosure requirements for Level 3 measurements, and is effective for fiscal years beginning after December 15, 2019 and interim periods within those fiscal years. The Company adopted this guidance effective January 1, 2020. The adoption of this ASU did not have a material impact on the Company’s disclosures in its consolidated financial statements. In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740), Simplifying the Accounting for Income Taxes, which is intended to simplify various aspects related to accounting for income taxes. ASU 2019-12 removes certain exceptions to the general principles in Topic 740 and also clarifies and amends existing guidance to improve consistent application. The amendments in this ASU are effective for fiscal years beginning after December 15, 2020 and interim periods within those fiscal years, with early adoption permitted. The amendments should be applied on a retrospective, modified retrospective or prospective basis, depending on the area covered by the update. The Company currently expects to adopt this guidance effective January 1, 2021 and does not expect that its adoption will have a material impact on the Company’s consolidated financial statements. In March 2020, the FASB issued ASU No. 2020-04, Reference Rate Reform (Topic 848), Facilitation of the Effects of Reference Rate Reform on Financial Reporting, which provides temporary optional expedients and exceptions for applying U.S. GAAP to contracts, hedging relationships and other transactions that reference London Interbank Offered Rate (“LIBOR”) or another reference rate expected to be discontinued because of reference rate reform. Among other things, for all types of hedging relationships, the guidance allows an entity to change the reference rate and other critical terms related to reference rate reform without having to remeasure the value or reassess a previous accounting determination. The amendments in this guidance should be applied on a prospective basis and, for companies with a fiscal year ending December 31, are effective from January 1, 2020 through December 31, 2022. The Company adopted this guidance effective January 1, 2020. When the transition occurs, the Company expects to apply this expedient to its existing interest rate swap that references LIBOR, and to any other new transactions that reference LIBOR or another reference rate that is discontinued, through December 31, 2022. The adoption of this ASU did not impact the Company’s consolidated financial statements. No other new accounting pronouncements issued, but not yet adopted, are expected to have a material impact on the Company’s results of operations, financial position or cash flow. Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect (i) the reported amounts of assets and liabilities, (ii) the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and (iii) the reported amounts of revenues and expenses during the reporting period. Actual results and outcomes may differ, including as a result of the risks and uncertainties associated with the COVID-19 pandemic and its effect on the global economy. Significant Accounting Policies There have been no changes to the Company’s significant accounting policies as disclosed in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019.