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 Large Core Growth Fund

Risk/Return:

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Risk/Return [Heading]

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FUND SUMMARY:  LARGE CORE GROWTH FUND

Objective [Heading]

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Investment Objective

Objective, Primary [Text Block]

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The investment objective of the Large Core Growth Fund (the “Fund”) is to seek to achieve long-term growth of capital (capital appreciation).

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 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)

Portfolio Turnover [Heading]

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Portfolio Turnover

Portfolio Turnover [Text Block]

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The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover may indicate higher transaction costs. These costs, which are not reflected in the 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 83% of the average value of its portfolio.

Portfolio Turnover, Rate

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83.00%

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 attempts to achieve its investment objective by investing primarily in common and preferred stocks of large capitalization U.S. companies. Under normal circumstances, the Fund invests at least 80% of its net assets, plus the amount of any borrowings for investment purposes, in securities of large capitalization companies. For purposes of this policy, large capitalization companies have market capitalizations that fall within the market capitalization range of companies in the Russell 1000^® Growth Index at the time of purchase (as of March 31, 2015, this range was between $212.3 million and $725 billion). Because the Fund’s definition of large capitalization companies is dynamic, the lower and upper limits on market capitalization will change with the markets.

The Fund invests principally in equity securities of large capitalization companies that offer the potential for capital growth, with an emphasis on identifying companies that have the prospect for improving sales and earnings growth rates, enjoy a competitive advantage and have effective management with a history of making investments that are in the best interests of shareholders. The Sub-Adviser employs a rigorous bottom-up research process to identify solid investment opportunities. The Sub-Adviser seeks to construct a well diversified portfolio in order to reduce risk while enhancing return.

The Sub-Adviser may sell a security based on several factors, with valuation the key element. The Sub-Adviser may sell a security if the investment reaches its target price, there is a change in the security’s fundamentals or when better investment opportunities emerge.

The Fund may also invest in U.S. dollar-denominated and U.S. exchange-traded foreign equities, American Depositary Receipts (“ADRs”), real estate investment trusts (“REITs”), shares of other investment companies and exchange-traded funds (“ETFs”), and cash instruments maturing in one year or less.

The Fund may buy and sell portfolio securities actively. If it does, its portfolio turnover rate and transaction costs will rise, which may lower fund performance.

Risk [Heading]

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Principal Risks of Investing

Risk Narrative [Text Block]

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Currency Risk.  The possibility that the value of the Fund’s assets may be affected favorably or unfavorably by currency exchange rates, currency exchange control regulations, and restrictions or prohibitions on the repatriation of foreign currencies.

Depositary Receipt Risk.  The possibility that the Fund’s investments in foreign companies through depositary receipts will expose the Fund to the same risks as direct investment in securities of foreign issuers. In addition, investments in ADRs may be less liquid than the underlying shares in their primary trading market, and the value of securities underlying ADRs may change materially at times when U.S. markets are not open for trading.

Foreign Investment Risk.  The possibility that the Fund’s investments in foreign securities may be adversely affected by political, social, and economic conditions affecting foreign issuers, greater volatility, reduced liquidity, or decreases in foreign currency values relative to the U.S. dollar.

“Growth” Investing Risk.  The possibility that the Fund’s investments in securities of companies perceived to be “growth” companies may underperform when value investing is in favor and may be more volatile than other securities because they are more sensitive to investor perceptions of the issuing company’s growth of earnings potential. Also, because growth companies usually invest a high portion of earnings in their businesses, growth stocks may lack the dividends of some value stocks that can cushion stock prices in a falling market.

Large-Cap Securities Risk.  The possibility that the Fund’s investments in larger companies may underperform relative to those of smaller companies. Larger more established companies may be unable to respond quickly to new competitive challenges such as changes in technology and consumer tastes and may not be able to attain the high growth rate of successful smaller companies, especially during extended periods of economic expansion.

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.

Market Risk.  The possibility that the values of, and/or the income generated by, securities held by the Fund may decline, sometimes unpredictably, due to general market conditions or other factors, including those directly involving the issuers of such securities. Security markets are volatile and may decline significantly in response to adverse issuer, regulatory, political, or economic developments. Different sectors of the market and different security types may react differently to such developments.

Other Investment Company Risk.  The possibility that investments by the Fund in shares of other investment companies will subject the Fund to the risks associated with those investment companies. Fund shareholders will also indirectly bear a proportionate share of any underlying investment company’s fees and expenses in addition to paying the Fund’s expenses.

Portfolio Turnover Risk.  The possibility that the Fund may frequently buy and sell portfolio securities, which may increase transaction costs to the Fund and cause the Fund’s performance to be less than you expect.

REITs Risk.  The possibility that the Fund’s investments in REITs will subject the Fund to the risks associated with the direct ownership of real estate, including fluctuations in the value of underlying properties, changes in interest rates and risks related to general or local economic conditions. REITs are dependent upon management skills and generally may not be diversified. REITs are also subject to heavy cash flow dependency, defaults by borrowers or tenants and self-liquidation.

An investment in the Fund may be appropriate for investors who are willing to accept the risks and uncertainties of investing in common and preferred stocks in the hope of achieving long-term growth of capital.

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 by showing how the Fund’s average annual total returns for various periods compare with those of a broad-based securities market index. 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.

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 by showing how the Fund’s average annual total returns for various periods compare with those of a broad-based securities market index.

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
18.51%	-17.53%
3/31/2012	9/30/2011

Performance Table Heading

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

Penn Series Large Core Growth Fund | Large Core Growth Fund

Risk/Return:

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Investment Advisory Fees

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0.60%

Distribution (12b-1) Fees

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none

Other Expenses

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0.27%

Total Annual Fund Operating Expenses

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0.87%

1 Year

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89

3 Years

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278

5 Years

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482

10 Years

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1,073

2009

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35.89%

2010

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17.27%

2011

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(5.01%)

2012

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16.15%

2013

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37.91%

2014

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7.73%

Highest Quarterly Return, Label

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Best Quarter

Highest Quarterly Return, Date

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Mar. 31, 2012

Highest Quarterly Return

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18.51%

Lowest Quarterly Return, Label

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Worst Quarter

Lowest Quarterly Return, Date

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Sep. 30, 2011

Lowest Quarterly Return

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(17.53%)

1 Year

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7.73%

5 Years

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13.96%

Since Inception

rr_AverageAnnualReturnSinceInception

7.76%

Inception Date

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Aug. 25, 2008

Penn Series Large Core Growth Fund | Russell 1000® Growth Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

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1 Year

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13.05%

5 Years

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15.81%

Since Inception

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10.86%

Inception Date

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Aug. 25, 2008