Label

Element

Value

Risk/Return:

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Registrant Name

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PENN SERIES FUNDS INC

Prospectus Date

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May 01, 2015

Penn Series Money Market Fund

Risk/Return:

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Risk/Return [Heading]

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FUND SUMMARY:  MONEY MARKET FUND

Objective [Heading]

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Investment Objective

Objective, Primary [Text Block]

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The Money Market Fund (the “Fund”) seeks to preserve capital and achieve the highest income consistent with high liquidity.

Expense [Heading]

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Fund Fees and Expenses

Expense Narrative [Text Block]

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This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. Additional fees and expenses will be applied at the variable annuity contract or variable life insurance policy (each, a “variable contract”) level. Those fees and expenses are described in your variable contract prospectus. If the information below were to reflect the deduction of variable contract charges, fees and expenses would be higher.

Operating Expenses Caption [Text]

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

Expenses Restated to Reflect Current [Text]

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The expense information in the table has been restated to reflect an increase in the Fund’s Investment Advisory Fee approved by Fund shareholders on February 13, 2014 and effective May 1, 2014.

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

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This example is intended to help you compare the cost of investing in the 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 remain the same. Although your actual costs and returns might be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

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Principal Investment Strategy

Strategy Narrative [Text Block]

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The Fund will invest in a diversified portfolio of high-quality money market instruments, which are rated within the two highest credit categories assigned by recognized rating organizations or, if not rated, are of comparable investment quality as determined by Penn Mutual Asset Management, Inc. ("PMAM" or the "Adviser"). Investments include commercial paper, U.S. Treasury securities, bank certificates of deposit and repurchase agreements. The Adviser seeks to invest in money market instruments that present minimal credit risks. Important factors in selecting investments include a company's profitability, ability to generate funds, capital adequacy, and liquidity of the investment. The Fund will invest only in securities that mature in 397 days or less, as calculated in accordance with applicable law. The Fund's policy is to seek to maintain a stable price of $1.00 per share.

Risk [Heading]

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Principal Risks of Investing

Risk Narrative [Text Block]

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Counterparty Risk.  The possibility that a party to a transaction involving the Fund may fail to meet its obligations thereby causing the Fund to lose money or the benefit of the transaction or preventing the Fund from selling or buying other securities to implement its investment strategies.

Credit Risk.  The possibility that an issuer of a debt security held by the Fund defaults on its payment obligations. While the Fund tries to minimize this risk by investing in high-quality securities, the credit quality of such securities may change rapidly in certain market environments and in response to certain market events, such as a decline in the credit quality of an issuer.

Interest Rate Risk.  The possibility that the prices of the Fund’s fixed income investments will decline due to rising interest rates.

Investment Risk.  You may lose money by investing in the Fund. Although the Fund seeks to preserve the value of your investment at $1.00 per share, there is no guarantee that the Fund will be able to do so.

Liquidity Risk.  The possibility that the market for certain of the Fund’s investments may become illiquid under adverse or volatile market or economic conditions, making those investments difficult to sell at an advantageous price. The market price of certain investments may fall dramatically if there is no liquid trading market for the investments. It also may be difficult for the Fund to purchase a desired investment at an advantageous price under such circumstances.

New Regulatory Risk.  In July 2014, the SEC adopted money market fund reform intended to address potential systemic risks associated with money market funds and to improve transparency for money market fund investors. In an effort to comply with the new requirements, the Fund may take certain steps that will impact its investment strategy, which could impact the return potential of the Fund.

Redemption Risk.  The possibility that large redemptions may cause the Fund to sell its securities at inopportune times resulting in a loss to the Fund.

U.S. Government Securities Risk.  The possibility that the U.S. government will not provide financial assistance in support of securities issued by certain of its agencies and instrumentalities and held by the Fund if it is not obligated to do because such securities are not issued or guaranteed by the U.S. Treasury. A default by a U.S. government agency or instrumentality could cause the Fund’s share price or yield to fall.

Risk Money Market Fund [Text]

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Although the Fund seeks to preserve the value of your investment at $1.00 per share, there is no guarantee that the Fund will be able to do so.

Bar Chart and Performance Table [Heading]

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Performance Information

Performance Narrative [Text Block]

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The bar chart and table below show the performance of the Fund both year-by-year and as an average over different periods of time. The bar chart and table demonstrate the variability of performance over time and provide an indication of the risks and volatility of an investment in the Fund. Past performance does not necessarily indicate how the Fund will perform in the future. This performance information does not include the impact of any charges deducted under your variable contract. If it did, returns would be lower. The current yield of the Money Market Fund for the seven-day period ended December 31, 2014 was 0.01%.

Performance Information Illustrates Variability of Returns [Text]

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The bar chart and table below show the performance of the Fund both year-by-year and as an average over different periods of time. The bar chart and table demonstrate the variability of performance over time and provide an indication of the risks and volatility of an investment in the Fund.

Performance Past Does Not Indicate Future [Text]

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Past performance does not necessarily indicate how the Fund will perform in the future.

Bar Chart Does Not Reflect Sales Loads [Text]

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This performance information does not include the impact of any charges deducted under your variable contract. If it did, returns would be lower.

Bar Chart Closing [Text Block]

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Best Quarter	Worst Quarter
1.25%	0.00%
9/30/2007	12/31/2009

Performance Table Heading

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Average Annual Total Return (for Periods Ended December 31, 2014)

Money Market Seven Day Yield, Caption [Text]

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The current yield of the Money Market Fund for the seven-day period ended December 31, 2014 was 0.01%.

Penn Series Money Market Fund | Money Market Fund

Risk/Return:

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Investment Advisory Fees

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0.33%

^[1]

Distribution (12b-1) Fees

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none

Other Expenses

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0.28%

Total Annual Fund Operating Expenses

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0.61%

^[1]

1 Year

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62

3 Years

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195

5 Years

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340

10 Years

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762

2005

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2.81%

2006

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4.66%

2007

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4.97%

2008

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2.66%

2009

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0.43%

2010

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0.01%

2011

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0.01%

2012

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0.01%

2013

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0.01%

2014

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0.01%

Highest Quarterly Return, Label

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Best Quarter

Highest Quarterly Return, Date

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Sep. 30, 2007

Highest Quarterly Return

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1.25%

Lowest Quarterly Return, Label

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Worst Quarter

Lowest Quarterly Return, Date

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Dec. 31, 2009

Lowest Quarterly Return

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0.00%

1 Year

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0.01%

5 Years

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0.01%

10 Years

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1.54%

Money Market Seven Day Yield

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0.01%

[1] The expense information in the table has been restated to reflect an increase in the Fund's Investment Advisory Fee approved by Fund shareholders on February 13, 2014 and effective May 1, 2014.