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Label Element Value
Risk/Return: rr_RiskReturnAbstract  
Registrant Name dei_EntityRegistrantName FIDELITY HASTINGS STREET TRUST
Prospectus Date rr_ProspectusDate Mar. 01, 2017
12.31 Fidelity Series Emerging Markets Debt Fund Series PRO-03 | Fidelity® Series Emerging Markets Debt Fund  
Risk/Return: rr_RiskReturnAbstract  
Operating Expenses Caption [Text] rr_OperatingExpensesCaption

Annual Operating Expenses

(expenses that you pay each year as a % of the value of your investment)

Expenses Restated to Reflect Current [Text] rr_ExpensesRestatedToReflectCurrent Adjusted to reflect current fees.
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption

Sell All Shares

12.31 Fidelity Series Emerging Markets Debt Fund Series PRO-03 | Fidelity® Series Emerging Markets Debt Fund | Fidelity Series Emerging Markets Debt Fund-Series Class  
Risk/Return: rr_RiskReturnAbstract  
Management fee rr_ManagementFeesOverAssets none
Distribution and/or Service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.01% [1]
Total annual operating expenses rr_ExpensesOverAssets 0.01%
1 year rr_ExpenseExampleYear01 $ 1
3 years rr_ExpenseExampleYear03 3
5 years rr_ExpenseExampleYear05 6
10 years rr_ExpenseExampleYear10 $ 13
[1] Adjusted to reflect current fees.