Expense Example {- Fidelity® SAI U.S. Large Cap Index Fund} - 07.31 Fidelity SAI U.S. Large Cap Index Fund PRO-08 - Fidelity® SAI U.S. Large Cap Index Fund - Fidelity SAI U.S. Large Cap Index Fund-Default	Sep. 29, 2020 USD ($)
Expense Example:
1 year	$ 2
3 years	7
5 years	12
10 years	$ 28