Contingencies	3 Months Ended
Mar. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Contingencies	Contingencies The Company is involved in various legal proceedings from time to time. The Company establishes reserves for specific legal proceedings when management determines that the likelihood of an unfavorable outcome is probable and the amount of loss can be reasonably estimated. The Company has also identified certain other legal matters where an unfavorable outcome is reasonably possible and/or for which no estimate of possible losses can be made. In these cases, the Company does not establish a reserve until it can reasonably estimate the loss. Legal fees are expensed as incurred. The outcomes of legal proceedings are inherently unpredictable, subject to significant uncertainties, and could be material to the Company's operating results and cash flows for a particular period. Privacy Class Action Litigation On September 11, 2017, the Company and a wholly-owned subsidiary, Full Circle Studies, Inc., (“Full Circle”), received demand letters on behalf of named plaintiffs and all others similarly situated alleging that the Company and Full Circle collected personal information from users under the age of 13 without verifiable parental consent in violation of Massachusetts law and the federal Children’s Online Privacy Protection Act. The letters alleged that the Company and Full Circle collected such personal information by embedding advertising software development kits ("SDKs") in applications created or developed by Disney. The letters sought monetary damages, attorneys’ fees and damages under Massachusetts law. On June 4, 2018, the plaintiffs filed amended complaints adding the Company and Full Circle as defendants in a purported class action against Disney, Twitter and other defendants, alleging violations of California’s constitutional right to privacy and intrusion upon seclusion law, New York’s deceptive trade practices statute, and Massachusetts’ deceptive trade practices and right to privacy statutes. The complaints allege damages in excess of $5 million, with any award to be apportioned among the defendants. The Company and Full Circle deny any wrongdoing or liability and intend to vigorously defend against these claims. Although the ultimate outcome of this matter is unknown, the Company believes that a material loss was not probable or estimable as of March 31, 2019. Securities Class Action Litigation On April 10, 2019, Sergii Bratusov, a purported shareholder of the Company, filed a putative class action complaint against the Company on behalf of all persons and entities that acquired securities of the Company between November 9, 2018 and March 29, 2019. The case, captioned Bratusov v. comScore, Inc., et al., Case No. 19 Civ. 03210, was filed in the U.S. District Court for the Southern District of New York and also names the Company's Chief Financial Officer, Gregory Fink, and the Company's former Chief Executive Officer, Bryan Wiener, as defendants. The complaint alleges that the Company, Mr. Wiener, and Mr. Fink violated Section 10(b) of the Exchange Act and Rule 10b-5 promulgated thereunder, by allegedly failing to disclose in public statements between November 2018 and March 2019 material information concerning unspecified difficulties implementing the Company's business strategy and the impact of these alleged difficulties on the Company's financial results. The complaint also alleges that Mr. Wiener and Mr. Fink, acting as control persons of the Company, violated Section 20(a) of the Exchange Act in connection with the Company's alleged failure to disclose material information. The complaint seeks a determination of the propriety of the class, compensatory damages and the award of reasonable costs and expenses incurred in the action. The defendants deny any wrongdoing or liability and intend to vigorously defend against these claims. Although the ultimate outcome of this matter is unknown, the Company believes that a material loss was not probable or estimable as of March 31, 2019. SEC Investigation The SEC is investigating allegations with respect to the Company regarding revenue recognition, internal controls, non-GAAP disclosures, tone at the top and whistleblower retaliation. The SEC has made no decisions regarding this matter including whether any securities laws have been violated. The Company is cooperating fully with the SEC and is seeking to resolve this matter as soon as possible. Export Controls Review In March 2018, the Company became aware of possible violations of U.S. export controls and economic sanctions laws and regulations involving the Company. The circumstances giving rise to these possible violations pertained to the Company’s collection of survey data from panelists within U.S. embargoed countries, as a part of the Company’s larger global survey efforts not intentionally targeted at such countries. The Company filed a joint initial notice of voluntary disclosure with the U.S. Department of the Treasury’s Office of Foreign Assets Control (“OFAC”) and the U.S. Commerce Department’s Bureau of Industry and Security (“BIS”) and commenced an internal review to identify the causes and scope of transactions that could constitute violations of the OFAC and BIS regulations. On May 31, 2018, the Company filed a final voluntary disclosure with OFAC and BIS. On September 10, 2018, the Company was notified that BIS did not find a violation of export regulations and closed the matter. If OFAC moves forward with this matter, the Company could be subject to fines or penalties. Although the ultimate outcome of this matter is unknown, the Company believes that a material loss was not probable or estimable as of March 31, 2019. Other Matters In addition to the matters described above, the Company is, and may become, a party to a variety of legal proceedings from time to time that arise in the normal course of the Company's business. While the results of such legal proceedings cannot be predicted with certainty, management believes that, based on current knowledge, the final outcome of any such current pending matters will not have a material adverse effect on the Company's financial position, results of operations or cash flows. Regardless of the outcome, legal proceedings can have an adverse effect on the Company because of defense costs, diversion of management resources and other factors. Indemnification The Company has entered into indemnification agreements with each of the Company's directors and certain officers, and the Company's amended and restated certificate of incorporation requires it to indemnify each of its officers and directors, to the fullest extent permitted by Delaware law, who was or is a party or is threatened to be made a party to any threatened, pending or completed action, suit or proceeding by reason of the fact that he or she is or was a director or officer of the Company. The Company has paid and continues to pay legal counsel fees incurred by the present and former directors and officers who are involved in legal proceedings that require indemnification. Similarly, certain of the Company's commercial contracts require it to indemnify contract counterparties under specified circumstances, and the Company may incur legal counsel fees and other costs in connection with these obligations.

Contingencies

The Company is involved in various legal proceedings from time to time. The Company establishes reserves for specific legal proceedings when management determines that the likelihood of an unfavorable outcome is probable and the amount of loss can be reasonably estimated. The Company has also identified certain other legal matters where an unfavorable outcome is reasonably possible and/or for which no estimate of possible losses can be made. In these cases, the Company does not establish a reserve until it can reasonably estimate the loss. Legal fees are expensed as incurred. The outcomes of legal proceedings are inherently unpredictable, subject to significant uncertainties, and could be material to the Company's operating results and cash flows for a particular period.

Privacy Class Action Litigation

On September 11, 2017, the Company and a wholly-owned subsidiary, Full Circle Studies, Inc., (“Full Circle”), received demand letters on behalf of named plaintiffs and all others similarly situated alleging that the Company and Full Circle collected personal information from users under the age of 13 without verifiable parental consent in violation of Massachusetts law and the federal Children’s Online Privacy Protection Act. The letters alleged that the Company and Full Circle collected such personal information by embedding advertising software development kits ("SDKs") in applications created or developed by Disney. The letters sought monetary damages, attorneys’ fees and damages under Massachusetts law. On June 4, 2018, the plaintiffs filed amended complaints adding the Company and Full Circle as defendants in a purported class action against Disney, Twitter and other defendants, alleging violations of California’s constitutional right to privacy and intrusion upon seclusion law, New York’s deceptive trade practices statute, and Massachusetts’ deceptive trade practices and right to privacy statutes. The complaints allege damages in excess of $5 million, with any award to be apportioned among the defendants. The Company and Full Circle deny any wrongdoing or liability and intend to vigorously defend against these claims. Although the ultimate outcome of this matter is unknown, the Company believes that a material loss was not probable or estimable as of March 31, 2019.

Securities Class Action Litigation

On April 10, 2019, Sergii Bratusov, a purported shareholder of the Company, filed a putative class action complaint against the Company on behalf of all persons and entities that acquired securities of the Company between November 9, 2018 and March 29, 2019. The case, captioned Bratusov v. comScore, Inc., et al., Case No. 19 Civ. 03210, was filed in the U.S. District Court for the Southern District of New York and also names the Company's Chief Financial Officer, Gregory Fink, and the Company's former Chief Executive Officer, Bryan Wiener, as defendants. The complaint alleges that the Company, Mr. Wiener, and Mr. Fink violated Section 10(b) of the Exchange Act and Rule 10b-5 promulgated thereunder, by allegedly failing to disclose in public statements between November 2018 and March 2019 material information concerning unspecified difficulties implementing the Company's business strategy and the impact of these alleged difficulties on the Company's financial results. The complaint also alleges that Mr. Wiener and Mr. Fink, acting as control persons of the Company, violated Section 20(a) of the Exchange Act in connection with the Company's alleged failure to disclose material information. The complaint seeks a determination of the propriety of the class, compensatory damages and the award of reasonable costs and expenses incurred in the action. The defendants deny any wrongdoing or liability and intend to vigorously defend against these claims. Although the ultimate outcome of this matter is unknown, the Company believes that a material loss was not probable or estimable as of March 31, 2019.

SEC Investigation

The SEC is investigating allegations with respect to the Company regarding revenue recognition, internal controls, non-GAAP disclosures, tone at the top and whistleblower retaliation. The SEC has made no decisions regarding this matter including whether any securities laws have been violated. The Company is cooperating fully with the SEC and is seeking to resolve this matter as soon as possible.

Export Controls Review

In March 2018, the Company became aware of possible violations of U.S. export controls and economic sanctions laws and regulations involving the Company. The circumstances giving rise to these possible violations pertained to the Company’s collection of survey data from panelists within U.S. embargoed countries, as a part of the Company’s larger global survey efforts not intentionally targeted at such countries. The Company filed a joint initial notice of voluntary disclosure with the U.S. Department of the Treasury’s Office of Foreign Assets Control (“OFAC”) and the U.S. Commerce Department’s Bureau of Industry and Security (“BIS”) and commenced an internal review to identify the causes and scope of transactions that could constitute violations of the OFAC and BIS regulations. On May 31, 2018, the Company filed a final voluntary disclosure with OFAC and BIS. On September 10, 2018, the Company was notified that BIS did not find a violation of export regulations and closed the matter. If OFAC moves forward with this matter, the Company could be subject to fines or penalties. Although the ultimate outcome of this matter is unknown, the Company believes that a material loss was not probable or estimable as of March 31, 2019.

Other Matters

In addition to the matters described above, the Company is, and may become, a party to a variety of legal proceedings from time to time that arise in the normal course of the Company's business. While the results of such legal proceedings cannot be predicted with certainty, management believes that, based on current knowledge, the final outcome of any such current pending matters will not have a material adverse effect on the Company's financial position, results of operations or cash flows. Regardless of the outcome, legal proceedings can have an adverse effect on the Company because of defense costs, diversion of management resources and other factors.

Indemnification

The Company has entered into indemnification agreements with each of the Company's directors and certain officers, and the Company's amended and restated certificate of incorporation requires it to indemnify each of its officers and directors, to the fullest extent permitted by Delaware law, who was or is a party or is threatened to be made a party to any threatened, pending or completed action, suit or proceeding by reason of the fact that he or she is or was a director or officer of the Company. The Company has paid and continues to pay legal counsel fees incurred by the present and former directors and officers who are involved in legal proceedings that require indemnification.

Similarly, certain of the Company's commercial contracts require it to indemnify contract counterparties under specified circumstances, and the Company may incur legal counsel fees and other costs in connection with these obligations.