Commitments and Contingencies	6 Months Ended
Jun. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies In the ordinary course of business, the Company from time to time enters into contracts containing indemnification obligations of the Company. These obligations may require the Company to make payments to another party upon the occurrence of certain events including the failure by the Company to meet its performance obligations under the contract. These contractual indemnification provisions are often standard contractual terms of the nature customarily found in the type of contracts entered into by the Company. In many cases, there are no stated or notional amounts included in the indemnification provisions. There are no amounts reflected on the Consolidated Balance Sheets as of June 30, 2020 and December 31, 2019 related to these indemnifications. Stanford Trust Company Litigation SEI has been named in seven lawsuits filed in Louisiana courts; four of the cases also name SPTC as a defendant. The underlying allegations in all actions relate to the purported role of SPTC in providing back-office services to Stanford Trust Company. The complaints allege that SEI and SPTC participated in some manner in the sale of “certificates of deposit” issued by Stanford International Bank so as to be a “seller” of the certificates of deposit for purposes of primary liability under the Louisiana Securities Law or so as to be secondarily liable under that statute for sales of certificates of deposit made by Stanford Trust Company. Two of the actions also include claims for violations of the Louisiana Racketeering Act and possibly conspiracy, and a third also asserts claims of negligence, breach of contract, breach of fiduciary duty, violations of the uniform fiduciaries law, negligent misrepresentation, detrimental reliance, violations of the Louisiana Racketeering Act, and conspiracy. The procedural status of the seven cases varies. The Lillie case, filed originally in the 19th Judicial District Court for the Parish of East Baton Rouge, was brought as a class action and is procedurally the most advanced of the cases. SEI and SPTC filed exceptions, which the Court granted in part, dismissing claims under the Louisiana Unfair Trade Practices Act and permitting the claims under the Louisiana Securities Law to go forward. On March 11, 2013, newly-added insurance carrier defendants removed the case to the United States District Court for the Middle District of Louisiana. On August 7, 2013, the Judicial Panel on Multidistrict Litigation transferred the matter to the Northern District of Texas where MDL 2099, In re: Stanford Entities Securities Litigation (“the Stanford MDL”), is pending. On September 22, 2015, the District Court on the motion of SEI and SPTC dismissed plaintiffs’ claims for primary liability under Section 714(A) of the Louisiana Securities Law, but declined to dismiss plaintiffs’ claims for secondary liability under Section 714(B) of the Louisiana Securities Law based on the allegations pled by plaintiffs. On November 4, 2015, the District Court granted SEI and SPTC's motion to dismiss plaintiffs' claims under Section 712(D) of the Louisiana Securities Law. Consequently, the only claims of plaintiffs remaining in Lillie are plaintiffs' claims for secondary liability against SEI and SPTC under Section 714(B) of the Louisiana Securities Law. On May 2, 2016, the District Court certified the class as being "all persons for whom Stanford Trust Company purchased or renewed Stanford Investment Bank Limited certificates of deposit in Louisiana between January 1, 2007 and February 13, 2009". Notice of the pendency of the class action was mailed to potential class members on October 4, 2016. On December 1, 2016, a group of plaintiffs who opted out of the Lillie class filed a complaint against SEI and SPTC in the United States District Court in the Middle District of Louisiana (“Ahders Complaint”), alleging claims essentially the same as those in Lillie. In January 2017, the Judicial Panel on Multidistrict Litigation transferred the Ahders proceeding to the Northern District of Texas and the Stanford MDL. During February 2017, SEI and SPTC filed their response to the Ahders Complaint, and in March 2017 the District Court for the Northern District of Texas approved the stipulated dismissal of all claims in this Complaint predicated on Section 712(D) or Section 714(A) of the Louisiana Securities Law. In both cases, as a result of the proceedings in the Northern District of Texas, only the plaintiffs’ secondary liability claims under Section 714(B) of the Louisiana Securities Law remain. Limited discovery and motions practice have occurred, including SEI and SPTC’s filing of a dispositive summary judgment motion in the Lillie proceeding. On January 31, 2019, the Judicial Panel on Multidistrict Litigation remanded the Lillie and Ahders proceedings to the Middle District of Louisiana. With respect to the Lillie proceeding, on July 9, 2019, the District Court issued an order granting SEI’s Summary Judgment Motion to dismiss the remaining Section 714(B) claim and denying Plaintiffs’ Motion for Continuance of SEI and SPTC’s Motion for Summary Judgment pursuant to Rule 56(d). On July 17, 2019, Plaintiffs filed a Motion for Reconsideration and/or New Trial. The Court denied Plaintiffs’ Motion for Reconsideration and/or New Trial and entered a Final Judgment in favor of SEI and SPTC on August 15, 2019. On August 27, 2019, Plaintiffs-Appellants filed a Notice of Appeal to the United States Court of Appeals for the Fifth Circuit of the District Court's dismissal of the Lillie matter. On November 20, 2019, Plaintiffs-Appellants filed a Motion in Support of the Notice of Appeal. On January 17, 2020, SEI and SPTC timely filed their brief in opposition to the Plaintiffs-Appellants' motion for appeal. On February 7, 2020, Plaintiffs- Appellants filed their reply brief. The parties are currently waiting for oral argument to be scheduled. With respect to the Ahders proceeding, on July 16, 2019, SEI and SPTC filed a Motion for Summary Judgment pursuant to Rule 56(d) to have the remaining Section 714(B) claim dismissed. On January 24, 2020, the District Court issued an order granting SEI’s Summary Judgment Motion to dismiss the remaining Section 714(B) claim. On March 17, 2020, Plaintiffs-Appellants filed a Notice of Appeal to the United States Court of Appeals for the Fifth Circuit of the District Court's dismissal of the Ahders matter. Similar to the Lillie matter, all motions and briefs in support of the parties’ positions have been filed and the parties are currently waiting for oral argument to be scheduled. Another case, filed in the 23rd Judicial District Court for the Parish of Ascension, also was removed to federal court and transferred by the Judicial Panel on Multidistrict Litigation to the Northern District of Texas and the Stanford MDL. The schedule for responding to that Complaint has not yet been established. Two additional cases remain in the Parish of East Baton Rouge. Plaintiffs filed petitions in 2010 and have granted SEI and SPTC indefinite extensions to respond. No material activity has taken place since. In two additional cases, filed in East Baton Rouge and brought by the same counsel who filed the Lillie action, virtually all of the litigation to date has involved motions practice and appellate litigation regarding the existence of federal subject matter jurisdiction under the federal Securities Litigation Uniform Standards Act (SLUSA). The matters were removed to the United States District Court for the Northern District of Texas and consolidated. The court then dismissed the action under SLUSA. The Court of Appeals for the Fifth Circuit reversed that order, and the Supreme Court of the United States affirmed the Court of Appeals judgment on February 26, 2014. The matters were remanded to state court and no material activity has taken place since that date. While the outcome of this litigation remains uncertain, SEI and SPTC believe that they have valid defenses to plaintiffs' claims and intend to defend the lawsuits vigorously. Because of uncertainty in the make-up of the Lillie class, the specific theories of liability that may survive a motion for summary judgment or other dispositive motion, the relative lack of discovery regarding damages, causation, mitigation and other aspects that may ultimately bear upon loss, the Company is not reasonably able to provide an estimate of loss, if any, with respect to the foregoing lawsuits. SS&C Advent Matter On February 28, 2020, SEI Global Services, Inc. ("SGSI"), a wholly-owned subsidiary of the Company, filed a complaint under seal in the United States District Court for the Eastern District of Pennsylvania against SS&C Advent ("Advent") and SS&C Technologies Holdings, Inc. ("SS&C") alleging that SS&C and Advent breached the terms of the contract between the parties and asking the Court to hold SS&C and Advent to their bargained-for obligations (the "Advent Matter"). In addition to Breach of Contract, the complaint also includes counts for Declaratory Judgment, Tortious Interference with Existing and Prospective Contractual Relations, Violation of the New York General Business Law Section 349, Violations of Section 2 of the Sherman Antitrust Act, Promissory Estoppel and Breach of the Covenant of Good Faith and Fair Dealing. SGSI seeks various forms of relief, including declaratory judgment, specific performance under the contract, and monetary damages, including treble damages and attorney’s fees. Following various procedural actions, including an amendment of the Company’s complaint to include additional breach of contract claims, SS&C and Advent filed a motion to dismiss the Company’s compliant. The oral argument regarding the motion to dismiss is currently scheduled for July 30, 2020. SEI does not believe that it will have to change providers under the current terms of its contract with SS&C or Advent and that the process of litigating its rights under this contract may be a multi-year process. Consequently, SEI does not believe that the Advent Matter will create any consequence to the services it provides to its clients in the near term. SEI believes that it has alternatives available to it that will enable it to continue to provide currently provided services to its clients in all material respects in the unlikely event that there ultimately is a negative outcome in the Advent Matter. SEI believes it has a strong basis for proving the actions it alleges in the Advent Matter and looks forward to the opportunity to assert its rights under contract. SEI expects the financial impact of litigating the Advent Matter to be immaterial. Other Matters The Company is also a party to various other actions and claims arising in the normal course of business that the Company does not believe are material. The Company believes that the ultimate resolution of these matters will not have a material adverse effect on the Company's financial position or the manner in which the Company conducts its business. Currently, the Company does not believe the amount of losses associated with these matters can be estimated. While the Company does not believe that the amount of such losses will, when liquidated or estimable, be material to its financial position, the assumptions may be incorrect and any such loss could have a material adverse effect on the Company's results of operations or the manner in which the Company conducts its business in the period(s) during which the underlying matters are resolved.

In the ordinary course of business, the Company from time to time enters into contracts containing indemnification obligations of the Company. These obligations may require the Company to make payments to another party upon the occurrence of certain events including the failure by the Company to meet its performance obligations under the contract. These contractual indemnification provisions are often standard contractual terms of the nature customarily found in the type of contracts entered into by the Company. In many cases, there are no stated or notional amounts included in the indemnification provisions. There are no amounts reflected on the Consolidated Balance Sheets as of June 30, 2020 and December 31, 2019 related to these indemnifications.

SEI has been named in seven lawsuits filed in Louisiana courts; four of the cases also name SPTC as a defendant. The underlying allegations in all actions relate to the purported role of SPTC in providing back-office services to Stanford Trust Company. The complaints allege that SEI and SPTC participated in some manner in the sale of “certificates of deposit” issued by Stanford International Bank so as to be a “seller” of the certificates of deposit for purposes of primary liability under the Louisiana Securities Law or so as to be secondarily liable under that statute for sales of certificates of deposit made by Stanford Trust Company. Two of the actions also include claims for violations of the Louisiana Racketeering Act and possibly conspiracy, and a third also asserts claims of negligence, breach of contract, breach of fiduciary duty, violations of the uniform fiduciaries law, negligent misrepresentation, detrimental reliance, violations of the Louisiana Racketeering Act, and conspiracy.

The procedural status of the seven cases varies. The Lillie case, filed originally in the 19th Judicial District Court for the Parish of East Baton Rouge, was brought as a class action and is procedurally the most advanced of the cases. SEI and SPTC filed exceptions, which the Court granted in part, dismissing claims under the Louisiana Unfair Trade Practices Act and permitting the claims under the Louisiana Securities Law to go forward. On March 11, 2013, newly-added insurance carrier defendants removed the case to the United States District Court for the Middle District of Louisiana. On August 7, 2013, the Judicial Panel on Multidistrict Litigation transferred the matter to the Northern District of Texas where MDL 2099,

In re: Stanford Entities Securities Litigation (“the Stanford MDL”), is pending. On September 22, 2015, the District Court on the motion of SEI and SPTC dismissed plaintiffs’ claims for primary liability under Section 714(A) of the Louisiana Securities Law, but declined to dismiss plaintiffs’ claims for secondary liability under Section 714(B) of the Louisiana Securities Law based on the allegations pled by plaintiffs. On November 4, 2015, the District Court granted SEI and SPTC's motion to dismiss plaintiffs' claims under Section 712(D) of the Louisiana Securities Law. Consequently, the only claims of plaintiffs remaining in Lillie are plaintiffs' claims for secondary liability against SEI and SPTC under Section 714(B) of the Louisiana Securities Law. On May 2, 2016, the District Court certified the class as being "all persons for whom Stanford Trust Company purchased or renewed Stanford Investment Bank Limited certificates of deposit in Louisiana between January 1, 2007 and February 13, 2009". Notice of the pendency of the class action was mailed to potential class members on October 4, 2016.

On December 1, 2016, a group of plaintiffs who opted out of the Lillie class filed a complaint against SEI and SPTC in the United States District Court in the Middle District of Louisiana (“Ahders Complaint”), alleging claims essentially the same as those in Lillie. In January 2017, the Judicial Panel on Multidistrict Litigation transferred the Ahders proceeding to the Northern District of Texas and the Stanford MDL. During February 2017, SEI and SPTC filed their response to the Ahders Complaint, and in March 2017 the District Court for the Northern District of Texas approved the stipulated dismissal of all claims in this Complaint predicated on Section 712(D) or Section 714(A) of the Louisiana Securities Law. In both cases, as a result of the proceedings in the Northern District of Texas, only the plaintiffs’ secondary liability claims under Section 714(B) of the Louisiana Securities Law remain. Limited discovery and motions practice have occurred, including SEI and SPTC’s filing of a dispositive summary judgment motion in the Lillie proceeding. On January 31, 2019, the Judicial Panel on Multidistrict Litigation remanded the Lillie and Ahders proceedings to the Middle District of Louisiana.

With respect to the Lillie proceeding, on July 9, 2019, the District Court issued an order granting SEI’s Summary Judgment Motion to dismiss the remaining Section 714(B) claim and denying Plaintiffs’ Motion for Continuance of SEI and SPTC’s Motion for Summary Judgment pursuant to Rule 56(d). On July 17, 2019, Plaintiffs filed a Motion for Reconsideration and/or New Trial. The Court denied Plaintiffs’ Motion for Reconsideration and/or New Trial and entered a Final Judgment in favor of SEI and SPTC on August 15, 2019. On August 27, 2019, Plaintiffs-Appellants filed a Notice of Appeal to the United States Court of Appeals for the Fifth Circuit of the District Court's dismissal of the Lillie matter. On November 20, 2019, Plaintiffs-Appellants filed a Motion in Support of the Notice of Appeal. On January 17, 2020, SEI and SPTC timely filed their brief in opposition to the Plaintiffs-Appellants' motion for appeal. On February 7, 2020, Plaintiffs- Appellants filed their reply brief. The parties are currently waiting for oral argument to be scheduled.

With respect to the Ahders proceeding, on July 16, 2019, SEI and SPTC filed a Motion for Summary Judgment pursuant to Rule 56(d) to have the remaining Section 714(B) claim dismissed. On January 24, 2020, the District Court issued an order granting SEI’s Summary Judgment Motion to dismiss the remaining Section 714(B) claim. On March 17, 2020, Plaintiffs-Appellants filed a Notice of Appeal to the United States Court of Appeals for the Fifth Circuit of the District Court's dismissal of the Ahders matter. Similar to the Lillie matter, all motions and briefs in support of the parties’ positions have been filed and the parties are currently waiting for oral argument to be scheduled.

Another case, filed in the 23rd Judicial District Court for the Parish of Ascension, also was removed to federal court and transferred by the Judicial Panel on Multidistrict Litigation to the Northern District of Texas and the Stanford MDL. The schedule for responding to that Complaint has not yet been established.

In two additional cases, filed in East Baton Rouge and brought by the same counsel who filed the Lillie action, virtually all of the litigation to date has involved motions practice and appellate litigation regarding the existence of federal subject matter jurisdiction under the federal Securities Litigation Uniform Standards Act (SLUSA). The matters were removed to the United States District Court for the Northern District of Texas and consolidated. The court then dismissed the action under SLUSA. The Court of Appeals for the Fifth Circuit reversed that order, and the Supreme Court of the United States affirmed the Court of Appeals judgment on February 26, 2014. The matters were remanded to state court and no material activity has taken place since that date.

While the outcome of this litigation remains uncertain, SEI and SPTC believe that they have valid defenses to plaintiffs' claims and intend to defend the lawsuits vigorously. Because of uncertainty in the make-up of the Lillie class, the specific theories of liability that may survive a motion for summary judgment or other dispositive motion, the relative lack of discovery regarding damages, causation, mitigation and other aspects that may ultimately bear upon loss, the Company is not reasonably able to provide an estimate of loss, if any, with respect to the foregoing lawsuits.

On February 28, 2020, SEI Global Services, Inc. ("SGSI"), a wholly-owned subsidiary of the Company, filed a complaint under seal in the United States District Court for the Eastern District of Pennsylvania against SS&C Advent ("Advent") and SS&C Technologies Holdings, Inc. ("SS&C") alleging that SS&C and Advent breached the terms of the contract between the parties and asking the Court to hold SS&C and Advent to their bargained-for obligations (the "Advent Matter"). In addition to Breach of Contract, the complaint also includes counts for Declaratory Judgment, Tortious Interference with Existing and Prospective Contractual Relations, Violation of the New York General Business Law Section 349, Violations of Section 2 of the Sherman Antitrust Act, Promissory Estoppel and Breach of the Covenant of Good Faith and Fair Dealing. SGSI seeks various forms of relief, including declaratory judgment, specific performance under the contract, and monetary damages, including treble damages and attorney’s fees.

Following various procedural actions, including an amendment of the Company’s complaint to include additional breach of contract claims, SS&C and Advent filed a motion to dismiss the Company’s compliant. The oral argument regarding the motion to dismiss is currently scheduled for July 30, 2020.

SEI does not believe that it will have to change providers under the current terms of its contract with SS&C or Advent and that the process of litigating its rights under this contract may be a multi-year process. Consequently, SEI does not believe that the Advent Matter will create any consequence to the services it provides to its clients in the near term. SEI believes that it has alternatives available to it that will enable it to continue to provide currently provided services to its clients in all material respects in the unlikely event that there ultimately is a negative outcome in the Advent Matter.

SEI believes it has a strong basis for proving the actions it alleges in the Advent Matter and looks forward to the opportunity to assert its rights under contract. SEI expects the financial impact of litigating the Advent Matter to be immaterial.

The Company is also a party to various other actions and claims arising in the normal course of business that the Company does not believe are material. The Company believes that the ultimate resolution of these matters will not have a material adverse effect on the Company's financial position or the manner in which the Company conducts its business. Currently, the Company does not believe the amount of losses associated with these matters can be estimated. While the Company does not believe that the amount of such losses will, when liquidated or estimable, be material to its financial position, the assumptions may be incorrect and any such loss could have a material adverse effect on the Company's results of operations or the manner in which the Company conducts its business in the period(s) during which the underlying matters are resolved.