Commitments And Contingencies	6 Months Ended
Jun. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments And Contingencies	Commitments and Contingencies In the normal course of business, the Company is party to various claims and legal proceedings. 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 still pending before the District Court 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, alleging claims essentially the same as those in Lillie. In January 2017, the Judicial Panel on Multidistrict Litigation transferred the proceeding to the Northern District of Texas and the Stanford MDL. During February 2017, SEI filed its response to the 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. Another one of the cases, 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. The plaintiffs in two of the cases remaining in the Parish of East Baton Rouge have granted SEI and SPTC indefinite extensions to respond to the petitions. In the 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 subjection matter jurisdiction under the federal Securities Litigation Uniform Standards Act (SLUSA). After the matter was removed to the United States District Court for the Northern District of Texas, that court 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 matter was 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 November 26, 2014, a Writ of Summons was issued to two of our subsidiaries, SEI Investments - Global Fund Services Limited (GFSL) and SEI Investments - Depositary & Custodial Services (Ireland) Limited (D&C), to appear before the Court of First Instance Antwerp, Belgium. The plaintiffs in this case allege that through their initial investments in collective investment funds domiciled in Netherlands and subsequent transfer of claim rights to a Belgium domiciled partnership, they are beneficial owners of a portfolio of life settlement policies (the Portfolio) which lapsed due to a failure to make premium payments. The plaintiffs seek to recover jointly and severally from nine defendants including GFSL and D&C, damages of approximately $84 million. GFSL and D&C’s involvement in the litigation appears to arise out of their historical provision of administration and custody services, respectively, to the Strategic Life Settlement Fund PLC, who, together with its managers, appear to be the principal defendants in this claim. On December 4, 2015, the Belgium Court dismissed plaintiff's claims for a lack of jurisdiction. On December 22, 2015, the plaintiffs appealed the dismissal. The appeal is still pending. While the outcome of this action is uncertain given its early phase and the lack of specific theories of liability asserted against GFSL and D&C, each of GFSL and D&C believe that they have valid defenses to plaintiffs’ claims and intend to defend the lawsuit vigorously, and GFSL and D&C are not reasonably able to provide an estimate of the ultimate loss, if any, with respect to this lawsuit.

Commitments and Contingencies

In the normal course of business, the Company is party to various claims and legal proceedings.

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 still pending before the District Court 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, alleging claims essentially the same as those in Lillie. In January 2017, the Judicial Panel on Multidistrict Litigation transferred the proceeding to the Northern District of Texas and the Stanford MDL. During February 2017, SEI filed its response to the 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.

Another one of the cases, 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.

The plaintiffs in two of the cases remaining in the Parish of East Baton Rouge have granted SEI and SPTC indefinite extensions to respond to the petitions.

In the 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 subjection matter jurisdiction under the federal Securities Litigation Uniform Standards Act (SLUSA). After the matter was removed to the United States District Court for the Northern District of Texas, that court 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 matter was 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 November 26, 2014, a Writ of Summons was issued to two of our subsidiaries, SEI Investments - Global Fund Services Limited (GFSL) and SEI Investments - Depositary & Custodial Services (Ireland) Limited (D&C), to appear before the Court of First Instance Antwerp, Belgium. The plaintiffs in this case allege that through their initial investments in collective investment funds domiciled in Netherlands and subsequent transfer of claim rights to a Belgium domiciled partnership, they are beneficial owners of a portfolio of life settlement policies (the Portfolio) which lapsed due to a failure to make premium payments. The plaintiffs seek to recover jointly and severally from nine defendants including GFSL and D&C, damages of approximately $84 million. GFSL and D&C’s involvement in the litigation appears to arise out of their historical provision of administration and custody services, respectively, to the Strategic Life Settlement Fund PLC, who, together with its managers, appear to be the principal defendants in this claim. On December 4, 2015, the Belgium Court dismissed plaintiff's claims for a lack of jurisdiction. On December 22, 2015, the plaintiffs appealed the dismissal. The appeal is still pending.

While the outcome of this action is uncertain given its early phase and the lack of specific theories of liability asserted against GFSL and D&C, each of GFSL and D&C believe that they have valid defenses to plaintiffs’ claims and intend to defend the lawsuit vigorously, and GFSL and D&C are not reasonably able to provide an estimate of the ultimate loss, if any, with respect to this lawsuit.