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 Cap Growth Fund

Risk/Return:

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Risk/Return [Heading]

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FUND SUMMARY:  LARGE CAP GROWTH FUND

Objective [Heading]

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Investment Objective

Objective, Primary [Text Block]

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The investment objective of the Large Cap Growth Fund (the “Fund”) is to seek long-term 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)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

April 30, 2016

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 25% of the average value of its portfolio.

Portfolio Turnover, Rate

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25.00%

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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Under normal circumstances, the Fund invests at least 80% of its net assets, plus the amount of any borrowings for investment purposes, in common stocks of U.S. companies with large market capitalizations. For purposes of this policy, large capitalization companies have market capitalizations of more than $3 billion at the time of purchase. The Sub-Adviser focuses on investing the Fund's assets in the stocks of companies it believes to have above average earnings growth potential compared to other companies (i.e., growth companies). Growth companies tend to have stock prices that are high relative to their earnings, dividends, book value, or other financial measures. While the Fund primarily invests in the common stocks of large capitalization companies, the Fund may invest a portion of its net assets (no more than 20%) in small and medium capitalization companies with market capitalizations of less than $3 billion at the time of purchase. The Fund also may invest up to 20% of its net assets in foreign securities at the time of purchase. The Fund may participate in initial public offerings ("IPOs").

The Sub-Adviser uses a bottom-up investment approach to buying and selling investments for the Fund. Investments are selected primarily based on fundamental analysis of individual issuers and their potential in light of their financial condition, and market, economic, political, and regulatory conditions. Factors considered may include analysis of an issuer's earnings, cash flows, competitive position, and management ability. Quantitative models that systematically evaluate an issuer's valuation, price and earnings momentum, earnings quality, and other factors may also be considered.

Due to its investment strategy, the Fund may buy and sell securities frequently, which may result in higher transaction costs and 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.

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.

IPOs Risk.  The possibility that the Fund’s performance may be affected by the purchase of securities issued in initial public offerings (IPOs) that have little to no trading history, limited issuer information, increased volatility and may not be available to the extent desired. The prices of securities bought in IPOs may rise and fall rapidly, often because of investor perceptions rather than economic reasons.

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.

Management Risk.  The possibility that the investment decisions, techniques, analyses or models implemented by the Fund’s Sub-Adviser in seeking to achieve the Fund’s investment objective may not produce the returns expected, may cause the Fund’s shares to lose value or may cause the Fund to underperform relevant benchmarks or other funds with similar investment objectives.

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.

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.

Small- and Mid-Cap Securities Risk.  The possibility that the Fund’s investments in small- and mid-cap securities may be subject to greater risk and higher volatility than are customarily associated with investing in larger more established companies. Securities issued by small- and mid-sized companies, which can include start-up companies, tend to be more vulnerable than larger and more established companies to adverse business and economic developments. Such companies generally have narrower product lines, more limited financial resources and more limited markets for their stock as compared with larger companies. As a result, the value of such securities also may be more volatile than the securities of larger companies, and the Fund’s portfolio may experience difficulty in purchasing or selling such securities at the desired time and price or in the desired amount.

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

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. They represent the performance of the Fund’s previous managers for the period prior to May 1, 2013. Since May 1, 2013, Massachusetts Financial Services Company has been responsible for the Fund’s day-to-day portfolio management. 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. They represent the performance of the Fund’s previous managers for the period prior to May 1, 2013. Since May 1, 2013, Massachusetts Financial Services Company has been responsible for the Fund’s day-to-day portfolio management. 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
17.05%	-26.16%
3/31/2012	12/31/2008

Performance Table Heading

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

Penn Series Large Cap Growth Fund | Large Cap Growth Fund

Risk/Return:

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Investment Advisory Fees

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0.55%

Distribution (12b-1) Fees

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none

Other Expenses

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0.35%

Total Annual Fund Operating Expenses

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0.90%

Less Fee Waiver and/or Expense Reimbursement

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0.01%

^[1]

Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement

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0.89%

^[1]

1 Year

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91

3 Years

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284

5 Years

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493

10 Years

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1,096

2005

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1.20%

2006

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3.70%

2007

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4.71%

2008

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(43.82%)

2009

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37.54%

2010

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12.44%

2011

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(6.77%)

2012

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10.25%

2013

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23.09%

2014

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11.29%

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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17.05%

Lowest Quarterly Return, Label

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Worst Quarter

Lowest Quarterly Return, Date

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Dec. 31, 2008

Lowest Quarterly Return

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(26.16%)

1 Year

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11.29%

5 Years

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9.63%

10 Years

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3.00%

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

Risk/Return:

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1 Year

rr_AverageAnnualReturnYear01

13.05%

5 Years

rr_AverageAnnualReturnYear05

15.81%

10 Years

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8.49%

[1] Penn Mutual and the Adviser have contractually agreed to waive a portion of their fees and/or reimburse expenses to the extent necessary to keep the Fund's Total Annual Operating Expenses from exceeding 0.89% of average daily net assets (excluding nonrecurring account fees, fees on portfolio transactions, such as exchange fees, dividends and interest on securities sold short, acquired fund fees and expenses, interest, taxes, brokerage commissions, other expenditures which are capitalized in accordance with generally accepted accounting principles, and other non-routine expenses or extraordinary expenses not incurred in the ordinary course of the Fund's business) through April 30, 2016. The agreement may be terminated prior to April 30, 2016 only by a majority vote of the Company's Board of Directors for any reason and at any time.