Subsequent Events	6 Months Ended
Jun. 30, 2011
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	13. SUBSEQUENT EVENTS Other than the subsequent events disclosed below, we determined that there were no other subsequent events required to be disclosed or recorded as of June 30, 2011 in our financial statements. On July 8, 2011, S1 Corporation and its wholly owned subsidiary, S1, Inc. (collectively, the “Company”), entered into a Settlement and License Agreement (the “Agreement”) with Leon Stambler (“Stambler”), which settled all claims brought against the Company arising in the civil action filed on May 28, 2010 in the United States District Court for the Eastern District of Texas (the “Court”) captioned Leon Stambler v. Intuit Inc., et al. (the “Litigation”). The Litigation was originally disclosed in our Quarterly Report on Form 10-Q for the quarter ended June 30, 2010. Pursuant to the terms of the Agreement (i) Stambler agreed to grant the Company a license for the use of certain patents (the “Stambler Patents”), (ii) the Company and Stambler agreed to release each other from any and all claims accruing prior to or as of the effective time of the Agreement related in whole or in part to the Litigation or the Stambler Patents, and (iii) the Company agreed to pay Stambler a one-time payment of $260,000 which we have accrued as of June 30, 2011. On July 11, 2011, the Court dismissed the Company, with prejudice, from the Litigation. On July 26, 2011, the Company received an unsolicited written proposal from ACI Worldwide, Inc. (“ACI”) to acquire the Company for $9.50 per share in a mix of cash and common stock of ACI. On that date, the company publicly announced that it had received ACI’s unsolicited proposal and that the Company’s board of directors would evaluate the terms of ACI’s proposal in a manner consistent with its obligations under the Merger Agreement and applicable Delaware law. On August 2, 2011, the Company announced that its board of directors, after thorough consideration and consultation with its legal and financial advisors, had rejected ACI’s proposal and affirmed its commitment to the Company’s pending business combination with Fundtech. Later that day, ACI publicly reaffirmed its proposal. On July 29, 2011, a putative stockholder class action was filed in the Court of Chancery of the State of Delaware by Michael Levitan against the Company and the individual members of the Company’s board of directors. The complaint, which appears to proceed from the erroneous assumption that the Company has entered into an agreement to be acquired by ACI, alleges, among other things, that the Company’s directors breached their fiduciary duties in connection with such a proposed acquisition of the Company by ACI. Among other things, the complaint seeks to enjoin the Company and its directors from completing a transaction with ACI or, alternatively, recission of the transaction proposed by ACI in the event the Company and ACI were able to consummate such a transaction. The Company believes that the claims against the Company set forth in the complaint are without merit, and the Company intends to vigorously defend against such claims once properly served with the complaint. However, at this time, we cannot determine the final resolution of the lawsuit or when it might be resolved. We will continue to assess the potential impact, if any, on our financial condition, results of operations or cash flows.

13. SUBSEQUENT EVENTS

Other than the subsequent events disclosed below, we determined that there were no other subsequent events required to be disclosed or recorded as of June 30, 2011 in our financial statements.

On July 8, 2011, S1 Corporation and its wholly owned subsidiary, S1, Inc. (collectively, the “Company”), entered into a Settlement and License Agreement (the “Agreement”) with Leon Stambler (“Stambler”), which settled all claims brought against the Company arising in the civil action filed on May 28, 2010 in the United States District Court for the Eastern District of Texas (the “Court”) captioned Leon Stambler v. Intuit Inc., et al. (the “Litigation”). The Litigation was originally disclosed in our Quarterly Report on Form 10-Q for the quarter ended June 30, 2010. Pursuant to the terms of the Agreement (i) Stambler agreed to grant the Company a license for the use of certain patents (the “Stambler Patents”), (ii) the Company and Stambler agreed to release each other from any and all claims accruing prior to or as of the effective time of the Agreement related in whole or in part to the Litigation or the Stambler Patents, and (iii) the Company agreed to pay Stambler a one-time payment of $260,000 which we have accrued as of June 30, 2011. On July 11, 2011, the Court dismissed the Company, with prejudice, from the Litigation.

On July 26, 2011, the Company received an unsolicited written proposal from ACI Worldwide, Inc. (“ACI”) to acquire the Company for $9.50 per share in a mix of cash and common stock of ACI. On that date, the company publicly announced that it had received ACI’s unsolicited proposal and that the Company’s board of directors would evaluate the terms of ACI’s proposal in a manner consistent with its obligations under the Merger Agreement and applicable Delaware law. On August 2, 2011, the Company announced that its board of directors, after thorough consideration and consultation with its legal and financial advisors, had rejected ACI’s proposal and affirmed its commitment to the Company’s pending business combination with Fundtech. Later that day, ACI publicly reaffirmed its proposal.

On July 29, 2011, a putative stockholder class action was filed in the Court of Chancery of the State of Delaware by Michael Levitan against the Company and the individual members of the Company’s board of directors. The complaint, which appears to proceed from the erroneous assumption that the Company has entered into an agreement to be acquired by ACI, alleges, among other things, that the Company’s directors breached their fiduciary duties in connection with such a proposed acquisition of the Company by ACI. Among other things, the complaint seeks to enjoin the Company and its directors from completing a transaction with ACI or, alternatively, recission of the transaction proposed by ACI in the event the Company and ACI were able to consummate such a transaction. The Company believes that the claims against the Company set forth in the complaint are without merit, and the Company intends to vigorously defend against such claims once properly served with the complaint. However, at this time, we cannot determine the final resolution of the lawsuit or when it might be resolved. We will continue to assess the potential impact, if any, on our financial condition, results of operations or cash flows.