Description of Business	12 Months Ended
Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	Description of Business DST Systems, Inc. and consolidated subsidiaries (“we,” “our,” “us,” the “Company” or “DST”) use proprietary software applications to provide sophisticated information processing and servicing solutions, through strategically unified business processing and data management, to clients globally within the asset management, brokerage, retirement, healthcare and other markets. Our wholly-owned data centers provide the secure technology infrastructure necessary to support our solutions. On January 11, 2018, we entered into an Agreement and Plan of Merger (the “Merger Agreement”) wherein SS&C Technologies Holdings, Inc. (“SS&C”) will acquire DST (the “Merger”). Under the terms of the agreement, SS&C will purchase DST in an all-cash transaction for $84.00 per share plus the assumption of debt, equating to an enterprise value of approximately $5.4 billion. The Company has agreed to customary covenants in the Merger Agreement, including with respect to the Company’s operation of its business prior to the closing of the transaction or termination of the agreement, such as restrictions on making certain acquisitions and divestitures, entering into certain contracts, incurring certain indebtedness and expenditures, paying dividends, repurchasing stock and taking other specified actions. The transaction is subject to DST stockholder approval, clearances by the relevant regulatory authorities and other customary closing conditions and is currently expected to close by the end of the second quarter 2018; however, there can be no assurances as to the actual closing or the timing of the closing. Under certain circumstances, we would be required to pay a termination fee of $165.0 million to SS&C in the event the Merger Agreement with SS&C is terminated. In March 2017, we acquired State Street Corporation’s (“State Street”) ownership interest in our joint ventures Boston Financial Data Services, Inc. (“BFDS”) and International Financial Data Services U.K. Limited (“IFDS U.K.”), as well as other investments and real estate held by International Financial Data Services, L.P. (“IFDS L.P.”). BFDS and IFDS U.K. were consolidated in our financial results from the date control of these entities was obtained. See Note 3, “Significant Business Transactions,” for additional information. Beginning in 2017, DST established a new reportable segment structure that separates the previously reported Financial Services segment into two new segments, Domestic Financial Services and International Financial Services, based upon the geographical location of the revenue-generating business. The activity within the previously reported Investments and Other segment has now been included in either the Domestic or International Financial Services segments based on the business supported. The Healthcare Services segment remains unchanged. The new segment presentation is reflective of how management is now operating the business and making resource allocations following the acquisitions of the remaining interests in BFDS and IFDS U.K., as well as the recent reductions in non-core investment assets. The Company’s operating business units are now reported as three operating segments (Domestic Financial Services, International Financial Services and Healthcare Services). Prior periods have been revised to reflect the new reportable operating segments. In May 2017, our Board of Directors declared a two-for-one stock split of DST’s outstanding common stock effected in the form of a stock dividend, which was paid on June 8, 2017 to shareholders of record at the close of business on May 26, 2017. In connection with the stock split, 16.5 million treasury shares were used to settle a portion of the distribution. All share and per share data, excluding treasury shares, have been retroactively adjusted for all periods presented to reflect the stock split, as if the stock split had occurred at the beginning of the earliest period presented. We sold our North American Customer Communications business on July 1, 2016 and sold our United Kingdom (“U.K.”) Customer Communications business on May 4, 2017. We have classified the results of the Customer Communications businesses sold as discontinued operations in our consolidated financial statements for all periods presented. See Note 4, “Discontinued Operations,” for additional information.

Description of Business

DST Systems, Inc. and consolidated subsidiaries (“we,” “our,” “us,” the “Company” or “DST”) use proprietary software applications to provide sophisticated information processing and servicing solutions, through strategically unified business processing and data management, to clients globally within the asset management, brokerage, retirement, healthcare and other markets. Our wholly-owned data centers provide the secure technology infrastructure necessary to support our solutions.

On January 11, 2018, we entered into an Agreement and Plan of Merger (the “Merger Agreement”) wherein SS&C Technologies Holdings, Inc. (“SS&C”) will acquire DST (the “Merger”). Under the terms of the agreement, SS&C will purchase DST in an all-cash transaction for $84.00 per share plus the assumption of debt, equating to an enterprise value of approximately $5.4 billion. The Company has agreed to customary covenants in the Merger Agreement, including with respect to the Company’s operation of its business prior to the closing of the transaction or termination of the agreement, such as restrictions on making certain acquisitions and divestitures, entering into certain contracts, incurring certain indebtedness and expenditures, paying dividends, repurchasing stock and taking other specified actions. The transaction is subject to DST stockholder approval, clearances by the relevant regulatory authorities and other customary closing conditions and is currently expected to close by the end of the second quarter 2018; however, there can be no assurances as to the actual closing or the timing of the closing. Under certain circumstances, we would be required to pay a termination fee of $165.0 million to SS&C in the event the Merger Agreement with SS&C is terminated.

In March 2017, we acquired State Street Corporation’s (“State Street”) ownership interest in our joint ventures Boston Financial Data Services, Inc. (“BFDS”) and International Financial Data Services U.K. Limited (“IFDS U.K.”), as well as other investments and real estate held by International Financial Data Services, L.P. (“IFDS L.P.”). BFDS and IFDS U.K. were consolidated in our financial results from the date control of these entities was obtained. See Note 3, “Significant Business Transactions,” for additional information.

Beginning in 2017, DST established a new reportable segment structure that separates the previously reported Financial Services segment into two new segments, Domestic Financial Services and International Financial Services, based upon the geographical location of the revenue-generating business. The activity within the previously reported Investments and Other segment has now been included in either the Domestic or International Financial Services segments based on the business supported. The Healthcare Services segment remains unchanged. The new segment presentation is reflective of how management is now operating the business and making resource allocations following the acquisitions of the remaining interests in BFDS and IFDS U.K., as well as the recent reductions in non-core investment assets. The Company’s operating business units are now reported as three operating segments (Domestic Financial Services, International Financial Services and Healthcare Services). Prior periods have been revised to reflect the new reportable operating segments.

In May 2017, our Board of Directors declared a two-for-one stock split of DST’s outstanding common stock effected in the form of a stock dividend, which was paid on June 8, 2017 to shareholders of record at the close of business on May 26, 2017. In connection with the stock split, 16.5 million treasury shares were used to settle a portion of the distribution. All share and per share data, excluding treasury shares, have been retroactively adjusted for all periods presented to reflect the stock split, as if the stock split had occurred at the beginning of the earliest period presented.

We sold our North American Customer Communications business on July 1, 2016 and sold our United Kingdom (“U.K.”) Customer Communications business on May 4, 2017. We have classified the results of the Customer Communications businesses sold as discontinued operations in our consolidated financial statements for all periods presented. See Note 4, “Discontinued Operations,” for additional information.