S000000856 [Member] Fees and Expenses - Parnassus Core Equity Fund	Dec. 31, 2025
Prospectus [Line Items]
Expense Heading [Optional Text]	Fees and Expenses
Expense Narrative [Text Block]	This table describes the fees and expenses that you may pay if you buy, hold and sell shares of the Parnassus Core Equity Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and example below.
Operating Expenses Caption [Optional Text]	Annual Fund Operating Expenses (%)(expenses that you pay each year as a percentageof the value of your investment)
Expense Footnotes [Text Block]	For additional information about the Parnassus Core Equity Fund’s expenses, please see “Financial Highlights” in the prospectus.
Expense Example [Heading]	Example
Expense Example Narrative [Text Block]	This example is intended to help you compare the cost of investing in the Parnassus Core Equity Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The example also assumes that your investment has a 5% return each year, and that the Fund’s operating expenses are equal to the total annual fund operating expenses after expense reimbursement for the first year and the total annual fund operating expenses for the remaining years. Although your actual costs may be higher or lower, under these assumptions, your costs would be:
Portfolio Turnover [Heading]	Portfolio Turnover
Portfolio Turnover [Text Block]	The Parnassus Core Equity Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 28.5% of the average value of its portfolio.
Portfolio Turnover, Rate	28.50%

S000000856 [Member] Fees and Expenses - Parnassus Core Equity Fund

Dec. 31, 2025

Fees and Expenses

This table describes the fees and expenses that you may pay if you buy, hold and sell shares of the Parnassus Core Equity Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and example below.

Operating Expenses Caption [Optional Text]

Annual Fund Operating Expenses (%)(expenses that you pay each year as a percentageof the value of your investment)

Expense Footnotes [Text Block]

For additional information about the Parnassus Core Equity Fund’s expenses, please see “Financial Highlights” in the prospectus.

Expense Example [Heading]

Example

Expense Example Narrative [Text Block]

This example is intended to help you compare the cost of investing in the Parnassus Core Equity Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The example also

assumes that your investment has a 5% return each year, and that the Fund’s operating expenses are equal to the total annual fund operating expenses after expense reimbursement for the first year and the total annual fund operating expenses for the remaining years. Although your actual costs may be higher or lower, under these assumptions, your costs would be:

Portfolio Turnover [Heading]

Portfolio Turnover

Portfolio Turnover [Text Block]

The Parnassus Core Equity Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 28.5% of the average value of its portfolio.

Portfolio Turnover, Rate

28.50%