v3.26.1
S000000853 [Member] Annual Fund Operating Expenses - Parnassus Mid Cap Fund
Dec. 31, 2025
Prospectus [Line Items]  
Fee Waiver or Reimbursement over Assets, Date of Termination May 1, 2027
Investor Shares  
Prospectus [Line Items]  
Management Fees (as a percentage of Assets) 0.72%
Distribution and Service (12b-1) Fees 0.00%
Component1 Other Expenses 0.25%
Component2 Other Expenses 0.06%
Other Expenses (as a percentage of Assets): 0.31%
Expenses (as a percentage of Assets) 1.03%
Fee Waiver or Reimbursement 0.08%
Net Expenses (as a percentage of Assets) 0.95% [1]
Institutional Shares  
Prospectus [Line Items]  
Management Fees (as a percentage of Assets) 0.72%
Distribution and Service (12b-1) Fees 0.00%
Component1 Other Expenses 0.00%
Component2 Other Expenses 0.05%
Other Expenses (as a percentage of Assets): 0.05%
Expenses (as a percentage of Assets) 0.77%
Fee Waiver or Reimbursement 0.02%
Net Expenses (as a percentage of Assets) 0.75% [1]
[1] The investment adviser has contractually agreed to reimburse the Fund for expenses to the extent necessary to limit total annual fund operating expenses to 0.95% of net assets for the Parnassus Mid Cap Fund—Investor Shares and to 0.75% of net assets for the Parnassus Mid Cap Fund—Institutional Shares. This agreement will not be terminated prior to May 1, 2027 and may be continued indefinitely by the investment adviser on a year‑to‑year basis.