Annual Total Returns - FidelitySAIInternationalIndexFund-PRO - FidelitySAIInternationalIndexFund-PRO - Fidelity SAI International Index Fund - Fidelity SAI International Index Fund	Dec. 30, 2024
Bar Chart Table:
Annual Return, Inception Date	Jan. 05, 2016
Annual Return 2017	25.04%
Annual Return 2018	(13.55%)
Annual Return 2019	22.06%
Annual Return 2020	8.16%
Annual Return 2021	11.26%
Annual Return 2022	(14.17%)
Annual Return 2023	18.24%

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If the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. Provide annual total returns beginning with the earliest calendar year. Calculate annual returns using the Instructions to Item 8(a), except that the calculations should be based on calendar years. If a Fund's shares are sold subject to a sales load or account fees, state that sales loads or account fees are not reflected in the bar chart and that, if these amounts were reflected, returns would be less than those shown. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets). When a Multiple Class Fund offering one or more Classes offers a new Class in a prospectus that does not offer the shares of any other Class, include the bar chart with annual total returns for any other existing Class for the first year that the Class is offered. Explain in a footnote that the returns are for a Class that is not offered in the prospectus that would have substantially similar annual returns because the shares are invested in the same portfolio of securities and the annual returns would differ only to the extent that the Classes do not have the same expenses. Include return information for the other Class reflected in the bar chart in the performance table.

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