Shareholder Fees {- Fidelity® SAI U.S. Large Cap Index Fund}	Sep. 29, 2020 USD ($)
07.31 Fidelity SAI U.S. Large Cap Index Fund PRO-08 \| Fidelity® SAI U.S. Large Cap Index Fund
Shareholder Fees:
(fees paid directly from your investment)	none

Other Expenses

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form
-Number N-1A
-Chapter A
-Section 3
-Subsection table
-Paragraph 1
-Subparagraph 10

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