2.2.0.25truefalse000101 - Document - Risk/Return Summary {Unlabeled} - (T. Rowe Price New Horizons Fund, Inc.)falsefalsetrue1falsefalsetruefalse{dei_LegalEntityAxis} : S000002106 Member 5/1/2011 - 5/1/2011 Duration_5_1_2011_To_5_1_2011_dei_LegalEntityAxis_cik000080248_S000002106Memberhttp://www.sec.gov/CIK0000080248duration2011-05-01T00:00:002011-05-01T00:00:00falsefalsecik000080248_S000002106Memberdei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldicik000080248_S000002106Memberdei_LegalEntityAxisexplicitMemberUnit1Standardhttp://www.xbrl.org/2003/instancepurexbrli03false0rr_RiskReturnHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div class="MetaData"> New Horizons Fund   <a name="_Toc290467942"> </a> SUMMARY</div>falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringRisk/Return Summary Investment Objectives/Goals Include the following information, in plain English under rule 421(d) under the Securities Act, in the order and subject matter indicatedReference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 2 falsefalseRisk/Return [Heading]4false0rr_ObjectiveHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div class="MetaData"> Investment Objective</div>falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringInvestment Objectives/Goals. Disclose the Fund's investment objectives or goals. A Fund also may identify its type or category (e.g., that it is a Money Market Fund or a balanced fund).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 2 -Subsection a falsefalseObjective [Heading]5false0rr_ObjectivePrimaryTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div> <div class="MetaData"> The fund seeks long-term capital growth by investing primarily in common stocks of small, rapidly growing companies.</div> </div>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringInvestment Objectives/Goals. Disclose the Fund's investment objectives or goals. A Fund also may identify its type or category (e.g., that it is a Money Market Fund or a balanced fund).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 2 -Subsection a falsefalseObjective, Primary [Text Block]6false0rr_ExpenseHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div class="MetaData"> Fees and Expenses  </div>falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringRisk/Return Summary Fee Table Includes the following information, in plain English under rule 421(d) under the Securities Act, after Item 2 Fees and expenses of the Fund This table describes the fees and expenses that you may pay if you buy and hold shared of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $[_____] in [name of fund family] funds. Shareholder Fees (fees paid directly from your investment) Example 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 you redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return per year and that the Fund's operating expenses remained the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be You would pay the following expenses if you did not redeem your shares The Example does not reflect sales charges (loads) on reinvested dividends [and other distributions]. If these sales charges (loads) were included, your costs would be higher. Portfolio Turnover 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 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 __% of the average value of its whole portfolio. Instructions. A.3.instructions.6 New Funds. For purposes of this Item, a "New Fund" is a Fund that does not include in Form N-1A financial statements reporting operating results or that includes financial statements for the Fund's initial fiscal year reporting operating results for a period of 6 months or less. The following Instructions apply to New Funds.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph d -Subsection instructions falsefalseExpense [Heading]7false0rr_ExpenseNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div> <div class="MetaData"> <div class="MetaData"> <div>This table describes the fees and expenses that you may pay if you buy and hold shares of the fund. </div> <div>  </div></div> <div align="left"> <table style="border-bottom: medium none; border-left: medium none; width: 344.299pt; border-collapse: collapse; margin-left: 0.4pt; border-top: medium none; border-right: medium none;" class="MetaData" border="0" cellspacing="0" cellpadding="0"> <tr><td class="MetaData"> Fees and expenses of the fund</td></tr></table></div></div> </div>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringThis table describes the fees and expenses that you may pay if you buy and hold shared of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $[_____] in [name of fund family] funds. Include the narrative explanations in the order indicated. A Fund may modify the narrative explanations if the explanation contains comparable information to that shown.The narrative explanation regarding sales charge discounts is only required by a Fund that offers such discounts and should specify the minimum level of investment required to qualify for a discount. Modify the narrative explanation to state that Fund shares are sold on a national securities exchange at the end of the time periods indicated, and that brokerage commissions for buying and selling Fund shares through a broker are not reflected.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph b -Subsection instructions falsefalseExpense Narrative [Text Block]8false0rr_ShareholderFeesCaptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div class="MetaData">   Shareholder fees (fees paid directly from your investment)</div>falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringShareholder Fees (fees paid directly from your investment).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subsection table falsefalseShareholder Fees Caption [Text]9false0rr_ShareholderFeesTableTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div> <div style="display:none;" >~ http://www.troweprice.com/role/ScheduleShareholderFeesTRowePriceNewHorizonsFundInc column period compact * column dei_LegalEntityAxis compact cik000080248_S000002106Member column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> </div>falsefalse<div> <div style="display:none;" >~ http://www.troweprice.com/role/ScheduleShareholderFeesTRowePriceNewHorizonsFundInc column period compact * column dei_LegalEntityAxis compact cik000080248_S000002106Member column rr_ProspectusShareClassAxis compact * row primary compact * ~</div> </div>falsehttp://www.troweprice.com/role/ScheduleShareholderFeesTRowePriceNewHorizonsFundIncfalsefalse000102 - Schedule - Shareholder Fees - {T. Rowe Price New Horizons Fund, Inc.}truefalsefalse1falseColumnperiodPeriod*Columndei_LegalEntityAxisAxiscik000080248_S000002106MemberColumnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*duration2011-05-01T00:00:002011-05-01T00:00:00falsefalseT. Rowe Price New Horizons Fund, Inc.dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldicik000080248_S000002106Memberdei_LegalEntityAxisexplicitMemberfalsefalseT. Rowe Price New Horizons Fund, Inc.rr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldicik000080248_C000005478Memberrr_ProspectusShareClassAxisexplicitMemberT. Rowe Price New Horizons Fund, Inc.T. Rowe Price New Horizons Fund, Inc.Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170falseUSDfalsefalse$1falseRowprimaryElement*5false0rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPricerrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truetruetrue00falsefalsefalsetruefalseOtherrr:NonNegativePure4TypepureMaximum Deferred Sales Charge (Load) (as a percentage of ____) A.3.instructions.2.a.i "Maximum Deferred Sales Charge (Load)" includes the maximum total deferred sales charge (load) payable upon redemption, in installments, or both, expressed as a percentage of the amount or amounts stated in response to Item 7(a), except that, for a sales charge (load) based on net asset value at the time of purchase, show the sales charge (load) as a percentage of the offering price at the time of purchase. A Fund may include in a footnote to the table, if applicable, a tabular presentation showing the amount of deferred sales charges (loads) over time or a narrative explanation of the sales charges (loads) (e.g., __% in the first year after purchase, declining to __% in the __ year and eliminated thereafter). A.3.instructions.2.a.ii If more than one type of sales charge (load) is imposed (e.g., a deferred sales charge (load) and a front-end sales charge (load)), the first caption in the table should read "Maximum Sales Charge (Load)" and show the maximum cumulative percentage. 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A Fund may include in a footnote to the table, if applicable, a tabular presentation showing the amount of deferred sales charges (loads) over time or a narrative explanation of the sales charges (loads) (e.g., __% in the first year after purchase, declining to __% in the __ year and eliminated thereafter). A.3.instructions.2.a.ii If more than one type of sales charge (load) is imposed (e.g., a deferred sales charge (load) and a front-end sales charge (load)), the first caption in the table should read "Maximum Sales Charge (Load)" and show the maximum cumulative percentage. 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"Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 4 -Subsection table falsefalseRedemption Fee0rr_RedemptionFeetruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue00falsefalsefalsetruefalseOthernanafalsefalseRedemption Fee4falseRowprimaryElement*8false0rr_MaximumAccountFeerrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue1010[1]falsefalsefalsetruefalseMonetaryrr:NonNegativeMonetaryTypemonetaryInclude the caption "Maximum Account Fees" only if the Fund charges these fees. A Fund may omit other captions if the Fund does not charge the fees or expenses covered by the captions. Disclose account fees that may be charged to a typical investor in the Fund; fees that apply to only a limited number of shareholders based on their particular circumstances need not be disclosed. Include a caption describing the maximum account fee (e.g., "Maximum Account Maintenance Fee" or "Maximum Cash Management Fee"). State the maximum annual account fee as either a fixed dollar amount or a percentage of assets. Include in a parenthetical to the caption the basis on which any percentage is calculated. If an account fee is charged only to accounts that do not meet a certain threshold (e.g., accounts under $5)Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph c -Subsection instructions falsefalseMaximum Account Fee0rr_MaximumAccountFeetruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse[1]1truefalsetrue1010falsefalsefalsetruefalseOthernanafalsefalseMaximum Account Fee1 Nonretirement accounts with less than a $2,000 balance (with certain exceptions) may be subject to an annual $10 fee.14Shareholder Fees - (USD $)UnKnownUnKnownUnKnownUnKnownfalsetrueColumnperiodPeriod*Columndei_LegalEntityAxisAxiscik000080248_S000002106MemberColumnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*RowprimaryElement*falsefalsefalseOtherus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to ShareholderFeesData.No authoritative reference available.falsefalseShareholder Fees [Table]10false0rr_OperatingExpensesCaptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Annual fund operating expenses(expenses that you pay each year as a percentage of the value of your investment)falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringAnnual Fund Operating Expenses (ongoing expenses that you pay each year as a percentage of the value of your investment)Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 7 -Subsection table falsefalseOperating Expenses Caption [Text]11false0rr_AnnualFundOperatingExpensesTableTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div> <div style="display:none;" >~ http://www.troweprice.com/role/ScheduleAnnualFundOperatingExpensesTRowePriceNewHorizonsFundIncX column period compact * column dei_LegalEntityAxis compact cik000080248_S000002106Member row primary compact * ~</div> </div>falsefalse<div> <div style="display:none;" >~ http://www.troweprice.com/role/ScheduleAnnualFundOperatingExpensesTRowePriceNewHorizonsFundIncX column period compact * column dei_LegalEntityAxis compact cik000080248_S000002106Member row primary compact * ~</div> </div>falsehttp://www.troweprice.com/role/ScheduleAnnualFundOperatingExpensesTRowePriceNewHorizonsFundIncXfalsefalse000103 - Schedule - Annual Fund Operating Expenses - {T. 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Rowe Price New Horizons Fund, Inc.Standard0falseUSDfalsefalse$1falseRowprimaryElement*5false0rr_ManagementFeesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truetruetrue0.00650.0065falsefalsefalsetruefalseOtherrr:NonNegativePure4TypepureManagement Fees include investment advisory fees (including any fees based on the Fund's performance), any other management fees payable to the investment adviser or its affiliates, and administrative fees payable to the investment adviser or its affiliates that are not included as "Other Expenses."Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 3 -Subparagraph a -Subsection instructions falsefalseManagement fees0rr_ManagementFeesOverAssetstruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00650.0065falsefalsefalsetruefalseOthernanafalsefalseManagement fees2falseRowprimaryElement*6false0rr_DistributionAndService12b1FeesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truetruetrue0.00000.0000falsefalsefalsetruefalseOtherrr:NonNegativePure4TypepureDistribution [and/or Service] (12b-1) Fees" include all distribution or other expenses incurred during the most recent fiscal year under a plan adopted pursuant to rule 12b-1 [17 CFR 270.12b-1]. Under an appropriate caption or a subcaption of "Other Expenses," disclose the amount of any distribution or similar expenses deducted from the Fund's assets other than pursuant to a rule 12b-1 plan.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 9 -Subsection table falsefalseDistribution and service (12b-1) fees0rr_DistributionAndService12b1FeesOverAssetstruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00000.0000falsefalsefalsetruefalseOthernanafalsefalseDistribution and service (12b-1) fees3falseRowprimaryElement*7false0rr_OtherExpensesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truetruetrue0.00160.0016falsefalsefalsetruefalseOtherrr:NonNegativePure4Typepure"Other Expenses" include all expenses not otherwise disclosed in the table that are deducted from the Fund's assets or charged to all shareholder accounts. The amount of expenses deducted from the Fund's assets are the amounts shown as expenses in the Fund's statement of operations (including increases resulting from complying with paragraph 2(g) of rule 6-07 of Regulation S-X [17 CFR 210.6-07]). "Other Expenses" do not include extraordinary expenses as determined under generally accepted accounting principles (see Accounting Principles Board Opinion No. 30). If extraordinary expenses were incurred that materially affected the Fund's "Other Expenses," disclose in a footnote to the table what "Other Expenses" would have been had the extraordinary expenses been included.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 3 -Subparagraph c -Clause i -Subsection instructions falsefalseOther expenses0rr_OtherExpensesOverAssetstruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00160.0016falsefalsefalsetruefalseOthernanafalsefalseOther expenses4falseRowprimaryElement*8false0rr_NetExpensesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalsetotallabel1truetruetrue0.00810.0081falsefalsefalsetruefalseOtherrr:NonNegativePure4TypepureTotal Annual Fund Operating Expenses.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 11 -Subsection table truefalseTotal annual fund operating expenses0rr_NetExpensesOverAssetstruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00810.0081falsefalsefalsetruefalseOthernanafalsefalseTotal annual fund operating expenses14Annual Fund Operating Expenses - UnKnownUnKnownUnKnownUnKnownfalsetrueColumnperiodPeriod*Columndei_LegalEntityAxisAxiscik000080248_S000002106MemberColumnunitUnit*RowprimaryElement*falsefalsefalseOtherus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to OperatingExpensesData.No authoritative reference available.falsefalseAnnual Fund Operating Expenses [Table]12false0rr_ExpenseExampleHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Example falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringHeading for Expense Example.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 4 -Subsection instructions falsefalseExpense Example [Heading]13false0rr_ExpenseExampleNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div> 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 may be higher or lower, based on these assumptions your costs would be: </div>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringThe Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 1 -Subsection example falsefalseExpense Example Narrative [Text Block]14false0rr_ExpenseExampleWithRedemptionTableTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div> <div style="display:none;" >~ http://www.troweprice.com/role/ScheduleExpenseExampleNoRedemptionTransposedTRowePriceNewHorizonsFundInc row period compact * row primary compact * column dei_LegalEntityAxis compact cik000080248_S000002106Member column rr_ProspectusShareClassAxis compact * ~</div> </div>falsefalse<div> <div style="display:none;" >~ http://www.troweprice.com/role/ScheduleExpenseExampleNoRedemptionTransposedTRowePriceNewHorizonsFundInc row period compact * row primary compact * column dei_LegalEntityAxis compact cik000080248_S000002106Member column rr_ProspectusShareClassAxis compact * ~</div> </div>truehttp://www.troweprice.com/role/ScheduleExpenseExampleNoRedemptionTransposedTRowePriceNewHorizonsFundIncfalsefalse000105 - Schedule - Expense Example, No Redemption {Transposed} - {T. Rowe Price New Horizons Fund, Inc.}truefalsefalse1falseColumnperiodPeriod*ColumnprimaryElement*5false0rr_ExpenseExampleNoRedemptionYear01rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsetrue8383falsefalsefalsetruefalseMonetaryrr:NonNegativeMonetaryTypemonetaryYou would pay the following expenses if you did not redeem your shares. Include the second 1-, 3-, 5-, and 10-year periods and related narrative explanation only if a sales charge (load) or other fee is charged upon redemption.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 2 -Subparagraph 1 -Subsection example falsefalse1 yearduration2011-05-01T00:00:002011-05-01T00:00:00falseUSDfalsefalse$2falseColumnperiodPeriod*ColumnprimaryElement*6false0rr_ExpenseExampleNoRedemptionYear03rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsetrue259259falsefalsefalsetruefalseMonetaryrr:NonNegativeMonetaryTypemonetaryYou would pay the following expenses if you did not redeem your shares. Include the second 1-, 3-, 5-, and 10-year periods and related narrative explanation only if a sales charge (load) or other fee is charged upon redemption.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 2 -Subparagraph 1 -Subsection example falsefalse3 yearsduration2011-05-01T00:00:002011-05-01T00:00:00falseUSDfalsefalse$3falseColumnperiodPeriod*ColumnprimaryElement*7false0rr_ExpenseExampleNoRedemptionYear05rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsetrue450450falsefalsefalsetruefalseMonetaryrr:NonNegativeMonetaryTypemonetaryYou would pay the following expenses if you did not redeem your shares. Include the second 1-, 3-, 5-, and 10-year periods and related narrative explanation only if a sales charge (load) or other fee is charged upon redemption.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 4 -Subparagraph f -Subsection instructions falsefalse5 yearsduration2011-05-01T00:00:002011-05-01T00:00:00falseUSDfalsefalse$4falseColumnperiodPeriod*ColumnprimaryElement*8false0rr_ExpenseExampleNoRedemptionYear10rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsetrue10021002falsefalsefalsetruefalseMonetaryrr:NonNegativeMonetaryTypemonetaryYou would pay the following expenses if you did not redeem your shares. Include the second 1-, 3-, 5-, and 10-year periods and related narrative explanation only if a sales charge (load) or other fee is charged upon redemption.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 4 -Subparagraph f -Subsection instructions falsefalse10 yearsduration2011-05-01T00:00:002011-05-01T00:00:00falseUSDfalsefalse$1falseRowdei_LegalEntityAxisAxiscik000080248_S000002106MemberRowrr_ProspectusShareClassAxisAxis*RowunitUnit*falsefalseT. Rowe Price New Horizons Fund, Inc.dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldicik000080248_S000002106Memberdei_LegalEntityAxisexplicitMemberfalsefalseT. Rowe Price New Horizons Fund, Inc.rr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldicik000080248_C000005478Memberrr_ProspectusShareClassAxisexplicitMemberT. Rowe Price New Horizons Fund, Inc.T. Rowe Price New Horizons Fund, Inc.Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso421700truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue8383falsefalsefalsetruefalse2truefalsetrue259259falsefalsefalsetruefalse3truefalsetrue450450falsefalsefalsetruefalse4truefalsetrue10021002falsefalsefalsetruefalseOthernanafalsefalseT. Rowe Price New Horizons Fund, Inc.41Expense Example, No Redemption - (USD $)UnKnownUnKnownUnKnownUnKnownfalsetrueColumnperiodPeriod*ColumnprimaryElement*Rowdei_LegalEntityAxisAxiscik000080248_S000002106MemberRowrr_ProspectusShareClassAxisAxis*RowunitUnit*falsefalsefalseOtherus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to ExpenseExample.No authoritative reference available.falsefalseExpense Example, With Redemption [Table]15false0rr_PortfolioTurnoverHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Portfolio Turnover falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringDisclose the portfolio turnover rate provided in response to Item 14(a) for the most recent fiscal year (or for such shorter period as the Fund has been in operation). Disclose the period for which the information is provided if less than a full fiscal year. A Fund that is a Money Market Fund may omit the portfolio turnover information required by this Item.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 5 -Subsection instructions falsefalsePortfolio Turnover [Heading]16false0rr_PortfolioTurnoverTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div> 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 fund shares are held in a taxable account. These costs, which are not reflected in 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 46.1%  of the average value of its portfolio. </div>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringDisclose the portfolio turnover rate provided in response to Item 14(a) for the most recent fiscal year (or for such shorter period as the Fund has been in operation). Disclose the period for which the information is provided if less than a full fiscal year. A Fund that is a Money Market Fund may omit the portfolio turnover information required by this Item.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 3 -Subsection example falsefalsePortfolio Turnover [Text Block]17false0rr_StrategyHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div class="MetaData"> Investments, Risks, and Performance Principal Investment Strategies  </div>falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringPrincipal investment strategies of the Fund. Summarize how the Fund intends to achieve its investment objectives by identifying the Fund's principal investment strategies (including the type or types of securities in which the Fund invests or will invest principally) and any policy to concentrate in securities of issuers in a particular industry or group of industries.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection a falsefalseStrategy [Heading]18false0rr_StrategyNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div> <div class="MetaData">  The fund will invest primarily in a diversified group of small, emerging growth companies, preferably early in the corporate life cycle before a company becomes widely recognized by the investment community. The fund may also invest in companies that offer the possibility of accelerating earnings growth because of rejuvenated management, new products, or structural changes in the economy. We will not necessarily sell a position in a company that has grown beyond the developing stage if the company still fits the fund's other investment criteria. When choosing stocks, T. Rowe Price analysts look for small growth companies that exhibit some or all of the following: ·     have effective management; ·     operate in fertile growth areas; ·     demonstrate effective research, product development, and marketing; ·     provide efficient service; ·     possess pricing flexibility; and ·     employ sound financial and accounting policies. In pursuing its investment objective, the fund has the discretion to deviate from its normal investment criteria, as previously described, and purchase securities that the fund's management believes will provide an opportunity for substantial appreciation. These situations might arise when the fund's management believes a security could increase in value for a variety of reasons, including an extraordinary corporate event, a new product introduction or innovation, a favorable competitive development, or a change in management. While most assets will typically be invested in U.S. common stocks, the fund may invest in foreign stocks in keeping with the fund's objectives. The fund may sell securities for a variety of reasons, such as to secure gains, limit losses, or redeploy assets into more promising opportunities.</div> </div>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringPrincipal investment strategies of the Fund. 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The fund's share price fluctuates, which means you could lose money by investing in the fund.The principal risks of investing in this fund are summarized as follows: Active management risk   The fund is subject to the risk that the investment adviser's judgments about the attractiveness, value, or potential appreciation of the fund's investments may prove to be incorrect. If the securities selected and strategies employed by the fund fail to produce the intended results, the fund could underperform other funds with similar objectives and investment strategies. Risks of stock investing   Stocks generally fluctuate in value more than bonds and may decline significantly over short time periods. There is a chance that stock prices overall will decline because stock markets tend to move in cycles, with periods of rising prices and falling prices. The value of a stock in which the fund invests may decline due to general weakness in the stock market or because of factors that affect a company or a particular industry. Investment style risk   Different investment styles tend to shift in and out of favor, depending on market conditions and investor sentiment. The fund's growth approach to investing could cause it to underperform other stock funds that employ a different investment style. Growth stocks tend to be more volatile than value stocks and their prices usually fluctuate more dramatically than the overall stock market. A stock with growth characteristics can have sharp price declines due to decreases in current or expected earnings and may lack dividends that can help cushion its share price in a declining market. Market capitalization risk   Investing primarily in issuers within the same market capitalization category carries the risk that the category may be out of favor due to current market conditions or investor sentiment. Because the fund invests primarily in securities issued by small-cap companies, it is likely to be more volatile than a fund that focuses on securities issued by larger companies. Small-sized companies often have less experienced management, narrower product lines, more limited financial resources, and less publicly available information than larger companies. In addition, smaller companies are typically more sensitive to changes in overall economic conditions and their securities may be difficult to trade. Foreign investing risk   This is the risk that the fund's investments in foreign securities may be adversely affected by political and economic conditions overseas, reduced liquidity, or decreases in foreign currency values relative to the U.S. dollar. </div></div> </div>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringNarrative Risk Disclosure. 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The fund's past performance (before and after taxes) is not necessarily an indication of future performance. The fund can also experience short-term performance swings, as shown by the best and worst calendar quarter returns during the years depicted. In addition, the average annual total returns table shows hypothetical after-tax returns to suggest how taxes paid by a shareholder may influence returns. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. 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Rowe Price New Horizons Fund, Inc.dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldicik000080248_S000002106Memberdei_LegalEntityAxisexplicitMemberfalsefalseT. Rowe Price New Horizons Fund, Inc.rr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldicik000080248_C000005478Memberrr_ProspectusShareClassAxisexplicitMembertruefalseBefore Taxesrr_PerformanceMeasureAxisrr_PerformanceMeasureDomainrr_PerformanceMeasureAxisexplicitMemberT. Rowe Price New Horizons Fund, Inc.T. Rowe Price New Horizons Fund, Inc.Before TaxesUnit12Standardhttp://www.xbrl.org/2003/iso4217USDiso421700truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.34670.3467falsefalsefalsetruefalse2truetruetrue0.06240.0624falsefalsefalsetruefalse3truetruetrue0.06640.0664falsefalsefalsetruefalseOthernanafalsefalseT. Rowe Price New Horizons Fund, Inc.2falseRowdei_LegalEntityAxisAxiscik000080248_S000002106MemberRowrr_ProspectusShareClassAxisAxis*Rowrr_PerformanceMeasureAxisAxis*RowunitUnit*falsefalseT. 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Rowe Price New Horizons Fund, Inc.After Taxes on Distributions and Sale of Fund SharesStandard00truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.23270.2327falsefalsefalsetruefalse2truetruetrue0.05200.0520falsefalsefalsetruefalse3truetruetrue0.05710.0571falsefalsefalsetruefalseOthernanafalsefalseT. Rowe Price New Horizons Fund, Inc. After Taxes on Distributions and Sale of Fund Shares4falseRowdei_LegalEntityAxisAxiscik000080248_S000002106MemberRowrr_ProspectusShareClassAxisAxis*Rowrr_PerformanceMeasureAxisAxis*RowunitUnit*falsefalseT. Rowe Price New Horizons Fund, Inc.dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldicik000080248_S000002106Memberdei_LegalEntityAxisexplicitMembertruefalseShare Classesrr_ProspectusShareClassAxisrr_ShareClassDomainrr_ProspectusShareClassAxisexplicitMemberfalsefalseS&P 500 Indexrr_PerformanceMeasureAxisxbrldihttp://xbrl.org/2006/xbrldicik000080248_SP500Memberrr_PerformanceMeasureAxisexplicitMemberT. Rowe Price New Horizons Fund, Inc.Share ClassesS&P 500 IndexStandard00truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.15060.1506falsefalsefalsetruefalse2truetruetrue0.02290.0229falsefalsefalsetruefalse3truetruetrue0.01410.0141falsefalsefalsetruefalseOthernanafalsefalseT. Rowe Price New Horizons Fund, Inc. S&P 500 Index5falseRowdei_LegalEntityAxisAxiscik000080248_S000002106MemberRowrr_ProspectusShareClassAxisAxis*Rowrr_PerformanceMeasureAxisAxis*RowunitUnit*falsefalseT. Rowe Price New Horizons Fund, Inc.dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldicik000080248_S000002106Memberdei_LegalEntityAxisexplicitMembertruefalseShare Classesrr_ProspectusShareClassAxisrr_ShareClassDomainrr_ProspectusShareClassAxisexplicitMemberfalsefalseRussell 2000 Indexrr_PerformanceMeasureAxisxbrldihttp://xbrl.org/2006/xbrldicik000080248_Russell2000Memberrr_PerformanceMeasureAxisexplicitMemberT. Rowe Price New Horizons Fund, Inc.Share ClassesRussell 2000 IndexStandard00truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.26850.2685falsefalsefalsetruefalse2truetruetrue0.04470.0447falsefalsefalsetruefalse3truetruetrue0.06330.0633falsefalsefalsetruefalseOthernanafalsefalseT. Rowe Price New Horizons Fund, Inc. Russell 2000 Index6falseRowdei_LegalEntityAxisAxiscik000080248_S000002106MemberRowrr_ProspectusShareClassAxisAxis*Rowrr_PerformanceMeasureAxisAxis*RowunitUnit*falsefalseT. Rowe Price New Horizons Fund, Inc.dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldicik000080248_S000002106Memberdei_LegalEntityAxisexplicitMembertruefalseShare Classesrr_ProspectusShareClassAxisrr_ShareClassDomainrr_ProspectusShareClassAxisexplicitMemberfalsefalseRussell 2000 Growth Indexrr_PerformanceMeasureAxisxbrldihttp://xbrl.org/2006/xbrldicik000080248_Russell2000GrowthAndRussell2000ValueIndexesMemberrr_PerformanceMeasureAxisexplicitMemberT. Rowe Price New Horizons Fund, Inc.Share ClassesRussell 2000 Growth IndexStandard00truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.29090.2909falsefalsefalsetruefalse2truetruetrue0.05300.0530falsefalsefalsetruefalse3truetruetrue0.03780.0378falsefalsefalsetruefalseOthernanafalsefalseT. Rowe Price New Horizons Fund, Inc. Russell 2000 Growth Index36Average Annual Total Returns - UnKnownUnKnownUnKnownUnKnownfalsetrueColumnperiodPeriod*ColumnprimaryElement*Rowdei_LegalEntityAxisAxiscik000080248_S000002106MemberRowrr_ProspectusShareClassAxisAxis*Rowrr_PerformanceMeasureAxisAxis*RowunitUnit*falsefalsefalseOtherus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to PerformanceTableData.No authoritative reference available.falsefalsePerformance [Table]28false0rr_PerformanceTableClosingTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div> <div class="MetaData"> Updated performance information is available through troweprice.com or may be obtained by calling 1-800-225-5132.</div> </div>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringIf the Fund has annual returns for at least one calendar year, provide a table showing the Fund's (A) average annual total return; (B) average annual total return (after taxes on distributions); and (C) average annual total return (after taxes on distributions and redemption). A Money Market Fund should show only the returns described in clause (A) of the preceding sentence. All returns should be shown for 1-, 5-, and 10- calendar year periods ending on the date of the most recently completed calendar year (or for the life of the Fund, if shorter), but only for periods subsequent to the effective date of the Fund's registration statement. The table also shouldshow the returns of an appropriate broadbased securities market index as defined in Instruction 5 to Item 22(b)(7) for the same periods. A Fund that has been in existence for more than 10 years also may include returns for the life of the Fund. A Money Market Fund may provide the Fund's 7-day yield ending on the date of the most recent calendar year or disclose a toll-free (or collect) telephone number that investors can use to obtain the Fund's current 7-day yield. For a Fund (other than a Money Market Fund or a Fund described in General Instruction C.3.(d)(iii)), provide the information in the following table with the specified captions AVERAGE ANNUAL TOTAL RETURNS (For the periods ended December 31, _____)Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph iii -Subsection b falsefalsePerformance Table Closing [Text Block]126Risk/Return Summary - (T. Rowe Price New Horizons Fund, Inc.) (T. Rowe Price New Horizons Fund, Inc.)UnKnownUnKnownUnKnownUnKnownfalsetrue