Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	PAX WORLD FUNDS SERIES TRUST I
Prospectus Date	rr_ProspectusDate	May 01, 2012
Pax World High Yield Bond Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Pax World High Yield Bond Fund (the “High Yield Bond Fund”) Summary of Key Information
Objective [Heading]	rr_ObjectiveHeading	Investment Objectives
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The High Yield Bond Fund’s primary investment objective is to seek high current income.
Objective, Secondary [Text Block]	rr_ObjectiveSecondaryTextBlock	As a secondary investment objective the High Yield Bond Fund seeks capital appreciation.
Expense [Heading]	rr_ExpenseHeading	Fees & Expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The table below describes the fees and expenses that investors may pay if they buy and hold Individual Investor Class, Institutional Class or R Class shares of the High Yield Bond Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment):
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that are deducted from High Yield Bond Fund assets):
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	December 31, 2012
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The 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 shares are held in a taxable account. These transaction costs, which are not reflected in “Annual Fund Operating Expenses” or in the “Example of Expenses,” affect the High Yield Bond Fund’s performance. During the High Yield Bond Fund’s most recent fiscal year, the High Yield Bond Fund’s portfolio turnover rate was 49% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	49.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example of Expenses
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in Individual Investor Class, Institutional Class and R Class shares of the High Yield Bond Fund with the cost of investing in other mutual funds. The table assumes that an investor invests $10,000 in Individual Investor Class, Institutional Class or R Class shares of the High Yield Bond Fund for the time periods indicated and then redeems all of his or her shares at the end of those periods. The table also assumes that the investment has a 5% return each year, that all dividends and distributions are reinvested and that the High Yield Bond Fund’s operating expenses remain the same throughout those periods. Although an investor’s actual expenses may be higher or lower than those shown in the table, based on these assumptions his or her expenses would be:
Strategy [Heading]	rr_StrategyHeading	Principal Investment Strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The High Yield Bond Fund follows a sustainable investing approach, combining rigorous financial analysis with equally rigorous environmental, social and governance (ESG) analysis in order to identify investments. Under normal market conditions, the High Yield Bond Fund invests at least 80% of its assets (plus any borrowings for investment purposes) in high‒yield, fixed income securities (such as bonds, notes or debentures) that are rated below BBB‒ by Standard & Poor’s Ratings Group or below Baa3 by Moody’s Investors Service, similarly rated by another major rating service, or unrated and determined by the High Yield Bond Fund’s investment adviser to be of comparable quality. These fixed income securities are commonly referred to as “junk bonds”. In determining which securities to buy for the High Yield Bond Fund, the portfolio manager seeks to establish if each security’s return is appropriate for its level of risk. In making this determination, the portfolio manager generally performs fundamental credit analysis. The High Yield Bond Fund may invest up to 40% of its assets in securities of non‒U.S. issuers, including investments in emerging markets. The High Yield Bond Fund may utilize derivatives for hedging and for investment purposes. The High Yield Bond Fund avoids investing in companies that its investment adviser determines are significantly involved in the manufacture of weapons or weapons‒related products, manufacture tobacco products or engage in unethical business practices.
Risk [Heading]	rr_RiskHeading	Principal Risks
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	Market Risk Conditions in a broad or specialized market, a sector thereof or an individual industry may adversely affect security prices, thereby reducing the value of the Fund’s investments. Derivatives Risk Derivatives involve special risks and may result in losses. The values of derivatives can be very volatile, especially in unusual market conditions, and that volatility can be exacerbated by the use of leverage, which is common for derivative strategies. Derivatives may be illiquid, and may also be subject to the risk of nonperformance by a transaction counterparty. The Fund may not be able to enter into, or terminate, a derivatives position when desired. Derivatives are also subject to mispricing and improper valuation, and may increase the amount of taxes payable by shareholders. Non-U. S. Securities Risk Non-U.S. securities may have less liquidity and more volatile prices than domestic securities, which can make it difficult for the Fund to sell such securities at desired times or prices. Non-U.S. markets may differ from U.S. markets in material and adverse ways. For example, securities transaction expenses generally are higher, transaction settlement may be slower, recourse in the event of default may be more limited and taxes and currency exchange controls may limit amounts available for distribution to shareholders. Non-U.S. investments are also subject to the effects of local political, social, diplomatic or economic events. Interest Rate Risk The value of debt securities tends to decrease when nominal interest rates rise. Longer-duration securities tend to be more sensitive to interest rate changes, and thus more volatile, than shorter-duration securities. Credit Risk Changing economic conditions may adversely affect an obligated entity’s actual or perceived ability to pay interest or principal on a fixed income security when due, which in turn can adversely affect the price of or income derived from the security. Reinvestment Risk Income from the Fund’s investments may decline if the Fund is forced to invest the proceeds from matured, called or otherwise dis- posed of debt securities or convertible securities at interest rates that are below the Fund’s earnings rate at that time. Small-and Medium-Sized Capitalization Company Risk Securities of small‒ and medium-sized companies may have less liquidity and more volatile prices than securities of larger companies, which can make it difficult for the Fund to sell such securities at desired times or prices. High Yield Securities Risk High yield securities (“junk bonds”) are considered predominately speculative with respect to the issuer’s continuing ability to make principal and interest payments when due. Investments in such securities tend to increase the Fund’s exposure to interest rate risk, credit risk and liquidity risk. As with all mutual funds, investors may lose money by investing in the High Yield Bond Fund. The foregoing descriptions are only summaries. Please see “About the Funds ‒ Risks” on page 68 for more detailed descriptions of the foregoing risks.
Risk Lose Money [Text]	rr_RiskLoseMoney	As with all mutual funds, investors may lose money by investing in the High Yield Bond Fund.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance Information
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart below presents the calendar year total returns for Individual Investor Class shares of the High Yield Bond Fund before taxes. The bar chart is intended to provide some indication of the risk of investing in the High Yield Bond Fund by showing changes in the High Yield Bond Fund’s performance from year to year. As with all mutual funds, past performance (before and after taxes) is not necessarily an indication of future performance.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart is intended to provide some indication of the risk of investing in the High Yield Bond Fund by showing changes in the High Yield Bond Fund’s performance from year to year.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The performance table is intended to provide some indication of the risks of investment in the High Yield Bond Fund by showing how the High Yield Bond Fund’s average annual total returns compare with the returns of a broad-based securities market index and a performance average of other similar mutual funds, each over a one-year, five-year and ten-year period.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	800.767.1729
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.paxworld.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	As with all mutual funds, past performance (before and after taxes) is not necessarily an indication of future performance.
Bar Chart [Heading]	rr_BarChartHeading	Individual Investor Class Annual Return(%)
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Calender Year End For the periods shown in the bar chart: Best quarter: 2nd quarter 2009, 11.79%                                                             Worst quarter: 4th quarter 2008, -17.51%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are estimated using the highest historical individual federal marginal income tax rates and do not reflect the effect of local, state or foreign taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns will depend on a shareholder’s own tax situation and may differ from those shown. After-tax returns may not be relevant to shareholders who hold their shares through tax-deferred arrangements (such as 401(k) plans and individual retirement accounts).
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax performance is presented only for Individual Investor Class Shares for the Fund. After-tax returns for Institutional Class and R Class shares may vary.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The performance table below presents the average annual total returns for Individual Investor Class, Institutional Class and R Class shares of the High Yield Bond Fund. The performance table is intended to provide some indication of the risks of investment in the High Yield Bond Fund by showing how the High Yield Bond Fund’s average annual total returns compare with the returns of a broad-based securities market index and a performance average of other similar mutual funds, each over a one-year, five-year and ten-year period. After-tax performance is presented only for Individual Investor Class Shares for the Fund. After-tax returns for Institutional Class and R Class shares may vary. After-tax returns are estimated using the highest historical individual federal marginal income tax rates and do not reflect the effect of local, state or foreign taxes. Actual after-tax returns will depend on a shareholder’s own tax situation and may differ from those shown. After-tax returns may not be relevant to shareholders who hold their shares through tax-deferred arrangements (such as 401(k) plans and individual retirement accounts). As with all mutual funds, past performance (before and after taxes) is not necessarily an indication of future performance.
Caption	rr_AverageAnnualReturnCaption	Periods ended December 31, 2011
Pax World High Yield Bond Fund | Individual Investor Class
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees (fees paid directly from your investment)	rr_ShareholderFeeOther	none
Management Fee	rr_ManagementFeesOverAssets	0.50%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.22%
Acquired Fund Fees	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.98%	[1]
1 year	rr_ExpenseExampleYear01	100
3 year	rr_ExpenseExampleYear03	312
5 year	rr_ExpenseExampleYear05	542
10 year	rr_ExpenseExampleYear10	1,201
2002	rr_AnnualReturn2002	(0.51%)
2003	rr_AnnualReturn2003	16.90%
2004	rr_AnnualReturn2004	10.00%
2005	rr_AnnualReturn2005	2.32%
2006	rr_AnnualReturn2006	10.11%
2007	rr_AnnualReturn2007	5.80%
2008	rr_AnnualReturn2008	(20.61%)
2009	rr_AnnualReturn2009	38.70%
2010	rr_AnnualReturn2010	10.35%
2011	rr_AnnualReturn2011	2.00%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	11.79%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(17.51%)
1 year	rr_AverageAnnualReturnYear01	2.00%	[2]
5 year	rr_AverageAnnualReturnYear05	5.56%	[2]
10 year	rr_AverageAnnualReturnYear10	6.57%	[2]
Pax World High Yield Bond Fund | Institutional Class
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees (fees paid directly from your investment)	rr_ShareholderFeeOther	none
Management Fee	rr_ManagementFeesOverAssets	0.50%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.22%
Acquired Fund Fees	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.73%	[1]
1 year	rr_ExpenseExampleYear01	75
3 year	rr_ExpenseExampleYear03	233
5 year	rr_ExpenseExampleYear05	406
10 year	rr_ExpenseExampleYear10	906
1 year	rr_AverageAnnualReturnYear01	2.10%	[2],[3]
5 year	rr_AverageAnnualReturnYear05	5.74%	[2],[3]
10 year	rr_AverageAnnualReturnYear10	6.75%	[2],[3]
Pax World High Yield Bond Fund | R Class
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees (fees paid directly from your investment)	rr_ShareholderFeeOther	none
Management Fee	rr_ManagementFeesOverAssets	0.50%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.50%
Other Expenses	rr_OtherExpensesOverAssets	0.22%
Acquired Fund Fees	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.23%	[1]
1 year	rr_ExpenseExampleYear01	125
3 year	rr_ExpenseExampleYear03	390
5 year	rr_ExpenseExampleYear05	676
10 year	rr_ExpenseExampleYear10	1,489
1 year	rr_AverageAnnualReturnYear01	1.87%	[2],[4]
5 year	rr_AverageAnnualReturnYear05	5.30%	[2],[4]
10 year	rr_AverageAnnualReturnYear10	6.44%	[2],[4]
Return After Taxes | Pax World High Yield Bond Fund | Individual Investor Class
Risk/Return:	rr_RiskReturnAbstract
1 year	rr_AverageAnnualReturnYear01	(0.91%)	[2]
5 year	rr_AverageAnnualReturnYear05	2.47%	[2]
10 year	rr_AverageAnnualReturnYear10	3.69%	[2]
Return After Taxes and Distributions and Sale of Fund Shares | Pax World High Yield Bond Fund | Individual Investor Class
Risk/Return:	rr_RiskReturnAbstract
1 year	rr_AverageAnnualReturnYear01	1.63%	[2]
5 year	rr_AverageAnnualReturnYear05	2.95%	[2]
10 year	rr_AverageAnnualReturnYear10	3.92%	[2]
BofA Merrill Lynch U.S. High Yield BB-B (Constrained 2%) Index | Pax World High Yield Bond Fund
Risk/Return:	rr_RiskReturnAbstract
1 year	rr_AverageAnnualReturnYear01	5.43%	[5],[6]
5 year	rr_AverageAnnualReturnYear05	6.85%	[5],[6]
10 year	rr_AverageAnnualReturnYear10	7.96%	[5],[6]
Lipper High Current Yield Bond Funds Index | Pax World High Yield Bond Fund
Risk/Return:	rr_RiskReturnAbstract
1 year	rr_AverageAnnualReturnYear01	2.85%	[5],[7]
5 year	rr_AverageAnnualReturnYear05	5.13%	[5],[7]
10 year	rr_AverageAnnualReturnYear10	7.08%	[5],[7]

[1] The High Yield Bond Fund's investment adviser has contractually agreed to reimburse expenses (excluding Acquired Fund Fees and Expenses, if any) allocable to Individual Class, Institutional Class and R Class shares of the High Yield Bond Fund to the extent such expenses exceed 0.99%, 0.74% and 1.24% of the average daily net assets of Individual Investor Class, Institutional Class and R Class shares, respectively. This reimbursement arrangement may not be amended or terminated without the approval of the Fund's Board of Trustees before December 31, 2012.

[2] The Fund's adviser assumed certain expenses during the period; total returns would have been lower had these expenses not been assumed. Total return figures include reinvested dividends and capital gains distributions, and changes in principal value, and, other than for Individual investor Class Shares, do not reflect the taxes that a shareholder might pay on Fund distributions or on the redemption of Fund shares. These figures represent past performance, which is no guarantee of future results. Investment return and principal value of an investment will fluctuate so that an investor's shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than the performance data quoted. For more recent month-end performance data, please visit www.paxworld.com or call 800.767.1729.

[3] Inception of Institutional Class shares is June 1, 2004. The performance information shown for Institutional Class shares includes the performance of Individual Investor Class shares for the period prior to Institutional Class inception. Expenses have not been adjusted to reflect the expenses allocable to Institutional Class shares. If such expenses were reflected, the returns would be higher than those shown.

[4] Inception of R Class shares is April 2, 2007. The performance information shown for R Class shares includes the performance of Individual Investor Class shares for the period prior to R Class inception. Expenses have not been adjusted to reflect the expenses allocable to R Class shares. If such expenses were reflected, the returns would be lower than those shown.

[5] Unlike the High Yield Bond Fund, the BofA Merrill Lynch U.S. High Yield BB-B (Constrained 2%) Index and the Lipper High Current Yield Bond Funds Index are not investments, are not professionally managed, have no policy of sustainable investing and (with the exception of the Lipper High Current Yield Bond Funds Index) do not reflect deductions for fees, expenses or taxes.

[6] The BofA Merrill Lynch U.S. High Yield BB-B (Constrained 2%) Index tracks the performance of BB- and B-rated fixed income securities publicly issued in the major domestic or eurobond markets, with total index allocation to an individual issuer limited to 2%. The benchmark of High Yield Bond Fund was changed to the BofA Merrill Lynch U.S. High Yield BB-B (Constrained 2%) Index effective June 30, 2010. Pax World believes the BofA Merrill Lynch U.S. High Yield BB-B (Constrained 2%) Index more closely corresponds to the investments of the Fund.

[7] The Lipper High Current Yield Bond Funds Index tracks the results of the 30 largest mutual funds in the Lipper High Current Yield Bond Funds Average. The Lipper High Current Yield Bond Funds Average is a total return performance average of mutual funds tracked by Lipper, Inc. that aim at high (relative) current yield from fixed income securities, have no quality or maturity restrictions and tend to invest in lower grade debt issues. The Lipper High Current Yield Bond Funds Index is not what is typically considered an "index" because it tracks the performance of other mutual funds rather than changes in the value of a group of securities, a securities index or some other traditional economic indicator.