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 Growth Stock Fund

Risk/Return:

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Risk/Return [Heading]

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FUND SUMMARY:  LARGE GROWTH STOCK FUND

Objective [Heading]

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Investment Objective

Objective, Primary [Text Block]

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The investment objective of the Large Growth Stock Fund (the “Fund”) is to achieve long-term growth of capital and increase of future income.

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 38% of the average value of its portfolio.

Portfolio Turnover, Rate

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38.00%

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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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 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 $200 million and $724.8 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 will invest primarily in common stocks of well established companies the Sub-Adviser believes have long-term growth potential. In selecting the Fund's investments, the Sub-Adviser seeks investments in companies that have the ability to pay increasing dividends through strong cash flow. The Sub-Adviser's approach looks for companies with an above-average rate of earnings growth and a lucrative niche in the economy that gives them the ability to sustain earnings momentum even during times of slow economic growth. The Sub-Adviser believes when a company increases its earnings faster than both inflation and the overall economy, the market will eventually reward it with a higher stock price. The Fund may sell securities for a variety of reasons, such as to secure gains, limit losses, or redeploy assets into more promising opportunities.

In pursuing its investment objective, the Sub-Adviser has the discretion to purchase some securities that do not meet its normal investment criteria, as described above, when it perceives an unusual opportunity for gain. Those situations might arise when the Sub-Adviser believes a security could increase in value for a variety of reasons, including a change in management, an extraordinary corporate event, a new product introduction or innovation, or a favorable competitive development.

While most assets will be invested in exchange-listed U.S. common stocks, other securities may also be purchased, including foreign stocks (up to 30% of total assets), convertible securities, and preferred stocks, in keeping with the Fund's objectives.

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.

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.

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.

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 earning above-average long-term growth of capital and income.

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
19.01%	-23.79%
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 Growth Stock Fund | Large Growth Stock Fund

Risk/Return:

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Investment Advisory Fees

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0.72%

^[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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1.00%

^[1]

1 Year

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102

3 Years

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318

5 Years

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552

10 Years

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1,225

2005

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6.14%

2006

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13.01%

2007

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9.16%

2008

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(41.87%)

2009

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42.93%

2010

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16.79%

2011

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(1.55%)

2012

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18.75%

2013

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39.11%

2014

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8.36%

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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19.01%

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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(23.79%)

1 Year

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8.36%

5 Years

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15.53%

10 Years

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8.39%

Penn Series Large Growth Stock 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%

10 Years

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8.49%

[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.