v3.26.1
Shareholder Report, Holdings (Details)
Apr. 30, 2026
Fidelity ZERO Total Market Index Fund | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 7.00%
Fidelity ZERO Total Market Index Fund | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 5.80%
Fidelity ZERO Total Market Index Fund | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 4.40%
Fidelity ZERO Total Market Index Fund | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 3.80%
Fidelity ZERO Total Market Index Fund | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 3.30%
Fidelity ZERO Total Market Index Fund | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.90%
Fidelity ZERO Total Market Index Fund | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.60%
Fidelity ZERO Total Market Index Fund | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.90%
Fidelity ZERO Total Market Index Fund | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.50%
Fidelity ZERO Total Market Index Fund | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity ZERO Total Market Index Fund | MSFinancialsSectorMember  
Holdings [Line Items]  
Percent of Net Asset Value 12.40%
Fidelity ZERO Total Market Index Fund | Information Technology Member  
Holdings [Line Items]  
Percent of Net Asset Value 33.20%
Fidelity ZERO Total Market Index Fund | Healthcare Sector  
Holdings [Line Items]  
Percent of Net Asset Value 8.90%
Fidelity ZERO Total Market Index Fund | Real Estate Sector  
Holdings [Line Items]  
Percent of Net Asset Value 2.30%
Fidelity ZERO Total Market Index Fund | Industrial Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 10.10%
Fidelity ZERO Total Market Index Fund | Materials Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.30%
Fidelity ZERO Total Market Index Fund | Consumer Discretionary Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 9.90%
Fidelity ZERO Total Market Index Fund | Consumer Staples Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 4.60%
Fidelity ZERO Total Market Index Fund | Communications Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 10.10%
Fidelity ZERO Total Market Index Fund | Energy Sector  
Holdings [Line Items]  
Percent of Net Asset Value 3.60%
Fidelity ZERO Total Market Index Fund | Utilities Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.30%
Fidelity ZERO Total Market Index Fund | United States  
Holdings [Line Items]  
Percent of Net Asset Value 99.60%
Fidelity ZERO Total Market Index Fund | Netherlands  
Holdings [Line Items]  
Percent of Net Asset Value 0.20%
Fidelity ZERO Total Market Index Fund | Switzerland  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity ZERO Total Market Index Fund | Australia  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity ZERO Total Market Index Fund | United Kingdom  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity ZERO Total Market Index Fund | Canada  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity ZERO Total Market Index Fund | Korea, Republic of  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity ZERO Total Market Index Fund | Thailand  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity ZERO Total Market Index Fund | Puerto Rico  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity ZERO Total Market Index Fund | AACommonStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 99.70%
Fidelity ZERO Total Market Index Fund | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.30%
Fidelity ZERO Large Cap Index Fund | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 7.80%
Fidelity ZERO Large Cap Index Fund | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 6.40%
Fidelity ZERO Large Cap Index Fund | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 4.90%
Fidelity ZERO Large Cap Index Fund | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 4.10%
Fidelity ZERO Large Cap Index Fund | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 3.60%
Fidelity ZERO Large Cap Index Fund | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 3.20%
Fidelity ZERO Large Cap Index Fund | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.80%
Fidelity ZERO Large Cap Index Fund | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.10%
Fidelity ZERO Large Cap Index Fund | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.70%
Fidelity ZERO Large Cap Index Fund | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity ZERO Large Cap Index Fund | MSFinancialsSectorMember  
Holdings [Line Items]  
Percent of Net Asset Value 11.80%
Fidelity ZERO Large Cap Index Fund | Information Technology Member  
Holdings [Line Items]  
Percent of Net Asset Value 35.20%
Fidelity ZERO Large Cap Index Fund | Healthcare Sector  
Holdings [Line Items]  
Percent of Net Asset Value 8.50%
Fidelity ZERO Large Cap Index Fund | Real Estate Sector  
Holdings [Line Items]  
Percent of Net Asset Value 1.80%
Fidelity ZERO Large Cap Index Fund | Industrial Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 9.10%
Fidelity ZERO Large Cap Index Fund | Materials Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.10%
Fidelity ZERO Large Cap Index Fund | Consumer Discretionary Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 9.70%
Fidelity ZERO Large Cap Index Fund | Consumer Staples Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 4.80%
Fidelity ZERO Large Cap Index Fund | Communications Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 10.80%
Fidelity ZERO Large Cap Index Fund | Energy Sector  
Holdings [Line Items]  
Percent of Net Asset Value 3.50%
Fidelity ZERO Large Cap Index Fund | Utilities Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.30%
Fidelity ZERO Large Cap Index Fund | United States  
Holdings [Line Items]  
Percent of Net Asset Value 99.60%
Fidelity ZERO Large Cap Index Fund | Netherlands  
Holdings [Line Items]  
Percent of Net Asset Value 0.20%
Fidelity ZERO Large Cap Index Fund | Switzerland  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity ZERO Large Cap Index Fund | Australia  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity ZERO Large Cap Index Fund | United Kingdom  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity ZERO Large Cap Index Fund | Canada  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity ZERO Large Cap Index Fund | Korea, Republic of  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity ZERO Large Cap Index Fund | AACommonStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 99.60%
Fidelity ZERO Large Cap Index Fund | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity ZERO International Index Fund | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 4.40%
Fidelity ZERO International Index Fund | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.00%
Fidelity ZERO International Index Fund | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity ZERO International Index Fund | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity ZERO International Index Fund | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity ZERO International Index Fund | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity ZERO International Index Fund | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity ZERO International Index Fund | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
Fidelity ZERO International Index Fund | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
Fidelity ZERO International Index Fund | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
Fidelity ZERO International Index Fund | MSFinancialsSectorMember  
Holdings [Line Items]  
Percent of Net Asset Value 24.70%
Fidelity ZERO International Index Fund | Information Technology Member  
Holdings [Line Items]  
Percent of Net Asset Value 18.30%
Fidelity ZERO International Index Fund | Healthcare Sector  
Holdings [Line Items]  
Percent of Net Asset Value 6.60%
Fidelity ZERO International Index Fund | Real Estate Sector  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity ZERO International Index Fund | Industrial Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 15.10%
Fidelity ZERO International Index Fund | Materials Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 6.90%
Fidelity ZERO International Index Fund | Consumer Discretionary Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 8.10%
Fidelity ZERO International Index Fund | Consumer Staples Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 4.90%
Fidelity ZERO International Index Fund | Communications Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 4.10%
Fidelity ZERO International Index Fund | Energy Sector  
Holdings [Line Items]  
Percent of Net Asset Value 4.80%
Fidelity ZERO International Index Fund | Utilities Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 3.30%
Fidelity ZERO International Index Fund | United States  
Holdings [Line Items]  
Percent of Net Asset Value 6.90%
Fidelity ZERO International Index Fund | Australia  
Holdings [Line Items]  
Percent of Net Asset Value 4.80%
Fidelity ZERO International Index Fund | United Kingdom  
Holdings [Line Items]  
Percent of Net Asset Value 6.50%
Fidelity ZERO International Index Fund | Canada  
Holdings [Line Items]  
Percent of Net Asset Value 7.80%
Fidelity ZERO International Index Fund | Korea, Republic of  
Holdings [Line Items]  
Percent of Net Asset Value 6.30%
Fidelity ZERO International Index Fund | Japan  
Holdings [Line Items]  
Percent of Net Asset Value 15.90%
Fidelity ZERO International Index Fund | Taiwan  
Holdings [Line Items]  
Percent of Net Asset Value 8.30%
Fidelity ZERO International Index Fund | China  
Holdings [Line Items]  
Percent of Net Asset Value 6.20%
Fidelity ZERO International Index Fund | Germany  
Holdings [Line Items]  
Percent of Net Asset Value 4.80%
Fidelity ZERO International Index Fund | OtherMember  
Holdings [Line Items]  
Percent of Net Asset Value 32.50%
Fidelity ZERO International Index Fund | AACommonStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 97.80%
Fidelity ZERO International Index Fund | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.80%
Fidelity ZERO International Index Fund | AAPreferredStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity ZERO Extended Market Index Fund | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.50%
Fidelity ZERO Extended Market Index Fund | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.50%
Fidelity ZERO Extended Market Index Fund | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity ZERO Extended Market Index Fund | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity ZERO Extended Market Index Fund | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity ZERO Extended Market Index Fund | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity ZERO Extended Market Index Fund | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity ZERO Extended Market Index Fund | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity ZERO Extended Market Index Fund | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity ZERO Extended Market Index Fund | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.30%
Fidelity ZERO Extended Market Index Fund | MSFinancialsSectorMember  
Holdings [Line Items]  
Percent of Net Asset Value 17.20%
Fidelity ZERO Extended Market Index Fund | Information Technology Member  
Holdings [Line Items]  
Percent of Net Asset Value 14.80%
Fidelity ZERO Extended Market Index Fund | Healthcare Sector  
Holdings [Line Items]  
Percent of Net Asset Value 13.30%
Fidelity ZERO Extended Market Index Fund | Real Estate Sector  
Holdings [Line Items]  
Percent of Net Asset Value 6.80%
Fidelity ZERO Extended Market Index Fund | Industrial Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 19.10%
Fidelity ZERO Extended Market Index Fund | Materials Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 3.80%
Fidelity ZERO Extended Market Index Fund | Consumer Discretionary Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 11.10%
Fidelity ZERO Extended Market Index Fund | Consumer Staples Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 3.10%
Fidelity ZERO Extended Market Index Fund | Communications Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 3.30%
Fidelity ZERO Extended Market Index Fund | Energy Sector  
Holdings [Line Items]  
Percent of Net Asset Value 4.60%
Fidelity ZERO Extended Market Index Fund | Utilities Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.70%
Fidelity ZERO Extended Market Index Fund | United States  
Holdings [Line Items]  
Percent of Net Asset Value 98.30%
Fidelity ZERO Extended Market Index Fund | Switzerland  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity ZERO Extended Market Index Fund | Canada  
Holdings [Line Items]  
Percent of Net Asset Value 0.20%
Fidelity ZERO Extended Market Index Fund | Thailand  
Holdings [Line Items]  
Percent of Net Asset Value 0.50%
Fidelity ZERO Extended Market Index Fund | Puerto Rico  
Holdings [Line Items]  
Percent of Net Asset Value 0.30%
Fidelity ZERO Extended Market Index Fund | Japan  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity ZERO Extended Market Index Fund | OtherMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity ZERO Extended Market Index Fund | Bermuda  
Holdings [Line Items]  
Percent of Net Asset Value 0.20%
Fidelity ZERO Extended Market Index Fund | Sweden  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity ZERO Extended Market Index Fund | Singapore  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity ZERO Extended Market Index Fund | AACommonStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 99.80%
Fidelity ZERO Extended Market Index Fund | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.20%
Fidelity Series International Index Fund | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.60%
Fidelity Series International Index Fund | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity Series International Index Fund | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Series International Index Fund | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Series International Index Fund | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Series International Index Fund | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.20%
Fidelity Series International Index Fund | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.20%
Fidelity Series International Index Fund | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
Fidelity Series International Index Fund | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
Fidelity Series International Index Fund | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Series International Index Fund | MSFinancialsSectorMember  
Holdings [Line Items]  
Percent of Net Asset Value 24.60%
Fidelity Series International Index Fund | Information Technology Member  
Holdings [Line Items]  
Percent of Net Asset Value 9.30%
Fidelity Series International Index Fund | Healthcare Sector  
Holdings [Line Items]  
Percent of Net Asset Value 10.20%
Fidelity Series International Index Fund | Real Estate Sector  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity Series International Index Fund | Industrial Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 19.20%
Fidelity Series International Index Fund | Materials Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 6.20%
Fidelity Series International Index Fund | Consumer Discretionary Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 8.20%
Fidelity Series International Index Fund | Consumer Staples Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 6.70%
Fidelity Series International Index Fund | Communications Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 3.70%
Fidelity Series International Index Fund | Energy Sector  
Holdings [Line Items]  
Percent of Net Asset Value 3.90%
Fidelity Series International Index Fund | Utilities Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 4.00%
Fidelity Series International Index Fund | United States  
Holdings [Line Items]  
Percent of Net Asset Value 11.40%
Fidelity Series International Index Fund | Netherlands  
Holdings [Line Items]  
Percent of Net Asset Value 4.80%
Fidelity Series International Index Fund | Switzerland  
Holdings [Line Items]  
Percent of Net Asset Value 4.60%
Fidelity Series International Index Fund | Australia  
Holdings [Line Items]  
Percent of Net Asset Value 7.40%
Fidelity Series International Index Fund | United Kingdom  
Holdings [Line Items]  
Percent of Net Asset Value 10.90%
Fidelity Series International Index Fund | Japan  
Holdings [Line Items]  
Percent of Net Asset Value 22.50%
Fidelity Series International Index Fund | Germany  
Holdings [Line Items]  
Percent of Net Asset Value 8.80%
Fidelity Series International Index Fund | OtherMember  
Holdings [Line Items]  
Percent of Net Asset Value 17.80%
Fidelity Series International Index Fund | France  
Holdings [Line Items]  
Percent of Net Asset Value 8.20%
Fidelity Series International Index Fund | Spain  
Holdings [Line Items]  
Percent of Net Asset Value 3.60%
Fidelity Series International Index Fund | AACommonStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 97.10%
Fidelity Series International Index Fund | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.60%
Fidelity Series International Index Fund | AAPreferredStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.30%
Fidelity SAI Japan Stock Index Fund | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 4.10%
Fidelity SAI Japan Stock Index Fund | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 3.70%
Fidelity SAI Japan Stock Index Fund | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.90%
Fidelity SAI Japan Stock Index Fund | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.90%
Fidelity SAI Japan Stock Index Fund | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.70%
Fidelity SAI Japan Stock Index Fund | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.60%
Fidelity SAI Japan Stock Index Fund | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.50%
Fidelity SAI Japan Stock Index Fund | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.50%
Fidelity SAI Japan Stock Index Fund | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.10%
Fidelity SAI Japan Stock Index Fund | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.10%
Fidelity SAI Japan Stock Index Fund | MSFinancialsSectorMember  
Holdings [Line Items]  
Percent of Net Asset Value 17.20%
Fidelity SAI Japan Stock Index Fund | Information Technology Member  
Holdings [Line Items]  
Percent of Net Asset Value 16.20%
Fidelity SAI Japan Stock Index Fund | Healthcare Sector  
Holdings [Line Items]  
Percent of Net Asset Value 6.00%
Fidelity SAI Japan Stock Index Fund | Real Estate Sector  
Holdings [Line Items]  
Percent of Net Asset Value 2.30%
Fidelity SAI Japan Stock Index Fund | Industrial Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 26.10%
Fidelity SAI Japan Stock Index Fund | Materials Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 3.80%
Fidelity SAI Japan Stock Index Fund | Consumer Discretionary Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 14.60%
Fidelity SAI Japan Stock Index Fund | Consumer Staples Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 3.90%
Fidelity SAI Japan Stock Index Fund | Communications Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 6.70%
Fidelity SAI Japan Stock Index Fund | Energy Sector  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
Fidelity SAI Japan Stock Index Fund | Utilities Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
Fidelity SAI Japan Stock Index Fund | United States  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity SAI Japan Stock Index Fund | Japan  
Holdings [Line Items]  
Percent of Net Asset Value 99.00%
Fidelity SAI Japan Stock Index Fund | AACommonStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 99.00%
Fidelity SAI Japan Stock Index Fund | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity SAI International Small Cap Index Fund | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity SAI International Small Cap Index Fund | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.50%
Fidelity SAI International Small Cap Index Fund | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.50%
Fidelity SAI International Small Cap Index Fund | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.50%
Fidelity SAI International Small Cap Index Fund | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity SAI International Small Cap Index Fund | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.30%
Fidelity SAI International Small Cap Index Fund | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.30%
Fidelity SAI International Small Cap Index Fund | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.30%
Fidelity SAI International Small Cap Index Fund | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.30%
Fidelity SAI International Small Cap Index Fund | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.30%
Fidelity SAI International Small Cap Index Fund | MSFinancialsSectorMember  
Holdings [Line Items]  
Percent of Net Asset Value 12.80%
Fidelity SAI International Small Cap Index Fund | Information Technology Member  
Holdings [Line Items]  
Percent of Net Asset Value 9.30%
Fidelity SAI International Small Cap Index Fund | Healthcare Sector  
Holdings [Line Items]  
Percent of Net Asset Value 4.90%
Fidelity SAI International Small Cap Index Fund | Real Estate Sector  
Holdings [Line Items]  
Percent of Net Asset Value 10.20%
Fidelity SAI International Small Cap Index Fund | Industrial Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 24.10%
Fidelity SAI International Small Cap Index Fund | Materials Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 11.80%
Fidelity SAI International Small Cap Index Fund | Consumer Discretionary Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 11.00%
Fidelity SAI International Small Cap Index Fund | Consumer Staples Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 4.90%
Fidelity SAI International Small Cap Index Fund | Communications Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 3.60%
Fidelity SAI International Small Cap Index Fund | Energy Sector  
Holdings [Line Items]  
Percent of Net Asset Value 3.50%
Fidelity SAI International Small Cap Index Fund | Utilities Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.60%
Fidelity SAI International Small Cap Index Fund | Switzerland  
Holdings [Line Items]  
Percent of Net Asset Value 4.30%
Fidelity SAI International Small Cap Index Fund | Australia  
Holdings [Line Items]  
Percent of Net Asset Value 10.50%
Fidelity SAI International Small Cap Index Fund | United Kingdom  
Holdings [Line Items]  
Percent of Net Asset Value 10.90%
Fidelity SAI International Small Cap Index Fund | Japan  
Holdings [Line Items]  
Percent of Net Asset Value 35.70%
Fidelity SAI International Small Cap Index Fund | Germany  
Holdings [Line Items]  
Percent of Net Asset Value 3.90%
Fidelity SAI International Small Cap Index Fund | OtherMember  
Holdings [Line Items]  
Percent of Net Asset Value 18.40%
Fidelity SAI International Small Cap Index Fund | Sweden  
Holdings [Line Items]  
Percent of Net Asset Value 4.60%
Fidelity SAI International Small Cap Index Fund | France  
Holdings [Line Items]  
Percent of Net Asset Value 3.80%
Fidelity SAI International Small Cap Index Fund | Israel  
Holdings [Line Items]  
Percent of Net Asset Value 5.10%
Fidelity SAI International Small Cap Index Fund | Italy  
Holdings [Line Items]  
Percent of Net Asset Value 2.80%
Fidelity SAI International Small Cap Index Fund | AACommonStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 98.40%
Fidelity SAI International Small Cap Index Fund | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity SAI International Small Cap Index Fund | AAPreferredStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.30%
Fidelity SAI Canada Equity Index Fund | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 8.30%
Fidelity SAI Canada Equity Index Fund | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 6.10%
Fidelity SAI Canada Equity Index Fund | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 4.90%
Fidelity SAI Canada Equity Index Fund | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 4.00%
Fidelity SAI Canada Equity Index Fund | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 3.50%
Fidelity SAI Canada Equity Index Fund | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 3.40%
Fidelity SAI Canada Equity Index Fund | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 3.30%
Fidelity SAI Canada Equity Index Fund | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 3.10%
Fidelity SAI Canada Equity Index Fund | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 3.10%
Fidelity SAI Canada Equity Index Fund | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 3.00%
Fidelity SAI Canada Equity Index Fund | MSFinancialsSectorMember  
Holdings [Line Items]  
Percent of Net Asset Value 38.10%
Fidelity SAI Canada Equity Index Fund | Information Technology Member  
Holdings [Line Items]  
Percent of Net Asset Value 8.40%
Fidelity SAI Canada Equity Index Fund | Real Estate Sector  
Holdings [Line Items]  
Percent of Net Asset Value 0.20%
Fidelity SAI Canada Equity Index Fund | Industrial Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 9.30%
Fidelity SAI Canada Equity Index Fund | Materials Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 15.10%
Fidelity SAI Canada Equity Index Fund | Consumer Discretionary Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 3.20%
Fidelity SAI Canada Equity Index Fund | Consumer Staples Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 3.50%
Fidelity SAI Canada Equity Index Fund | Communications Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
Fidelity SAI Canada Equity Index Fund | Energy Sector  
Holdings [Line Items]  
Percent of Net Asset Value 18.70%
Fidelity SAI Canada Equity Index Fund | Utilities Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.60%
Fidelity SAI Canada Equity Index Fund | United States  
Holdings [Line Items]  
Percent of Net Asset Value 0.50%
Fidelity SAI Canada Equity Index Fund | Canada  
Holdings [Line Items]  
Percent of Net Asset Value 96.20%
Fidelity SAI Canada Equity Index Fund | Brazil  
Holdings [Line Items]  
Percent of Net Asset Value 1.90%
Fidelity SAI Canada Equity Index Fund | Chile  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity SAI Canada Equity Index Fund | Zambia  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity SAI Canada Equity Index Fund | CongoDemocraticRepublicOfMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.20%
Fidelity SAI Canada Equity Index Fund | AACommonStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 99.80%
Fidelity SAI Canada Equity Index Fund | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.20%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.70%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.30%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.10%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.90%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.90%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.80%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.80%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.80%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.70%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | MSFinancialsSectorMember  
Holdings [Line Items]  
Percent of Net Asset Value 25.20%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | Information Technology Member  
Holdings [Line Items]  
Percent of Net Asset Value 10.10%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | Healthcare Sector  
Holdings [Line Items]  
Percent of Net Asset Value 9.00%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | Real Estate Sector  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | Industrial Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 10.60%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | Materials Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | Consumer Discretionary Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 6.70%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | Consumer Staples Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 9.60%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | Communications Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 9.80%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | Energy Sector  
Holdings [Line Items]  
Percent of Net Asset Value 5.70%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | Utilities Sector Member  
Holdings [Line Items]  
Percent of Net Asset Value 8.20%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | United States  
Holdings [Line Items]  
Percent of Net Asset Value 11.40%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | Netherlands  
Holdings [Line Items]  
Percent of Net Asset Value 2.50%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | United Kingdom  
Holdings [Line Items]  
Percent of Net Asset Value 6.10%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | Canada  
Holdings [Line Items]  
Percent of Net Asset Value 9.30%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | Japan  
Holdings [Line Items]  
Percent of Net Asset Value 19.50%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | Taiwan  
Holdings [Line Items]  
Percent of Net Asset Value 10.20%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | China  
Holdings [Line Items]  
Percent of Net Asset Value 12.20%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | OtherMember  
Holdings [Line Items]  
Percent of Net Asset Value 18.00%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | India  
Holdings [Line Items]  
Percent of Net Asset Value 7.90%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | Saudi Arabia  
Holdings [Line Items]  
Percent of Net Asset Value 2.90%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | AACommonStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 99.30%
Fidelity SAI Global ex U.S. Low Volatility Index Fund | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%