2.2.0.25 true Sheet 000001 - Document - Document and Entity Information {Elements} Document and Entity Information http://www.troweprice.com/role/DocumentDocumentAndEntityInformationElements false R1.xml false Sheet 000101 - Document - Risk/Return Summary {Unlabeled} - (T. Rowe Price New Horizons Fund, Inc.) Risk/Return Summary - (T. Rowe Price New Horizons Fund, Inc.) http://www.troweprice.com/role/DocumentRiskReturnSummaryUnlabeledTRowePriceNewHorizonsFundInc true R2.xml false Sheet 000108 - Disclosure - Risk/Return Detail Data {Elements} - (T. Rowe Price New Horizons Fund, Inc.) Risk/Return Detail Data - (T. Rowe Price New Horizons Fund, Inc.) http://www.troweprice.com/role/DisclosureRiskReturnDetailDataElementsTRowePriceNewHorizonsFundInc false R8.xml false Sheet 040000 - Disclosure - Risk/Return Detail Data {Elements} Risk/Return Detail Data http://xbrl.sec.gov/rr/role/RiskReturnDetailData false R9.xml false Book All Reports All Reports false 1 8 7 0 2 70 true false Duration_5_1_2011_To_5_1_2011 8 Duration_5_1_2011_To_5_1_2011_dei_LegalEntityAxis_cik000080248_S000002106Member_rr_PerformanceMeasureAxis_rr_AfterTaxesOnDistributionsAndSalesMember_rr_ProspectusShareClassAxis_cik000080248_C000005478Member 3 Duration_5_1_2011_To_5_1_2011_dei_LegalEntityAxis_cik000080248_S000002106Member_rr_PerformanceMeasureAxis_cik000080248_Russell2000Member 3 Duration_5_1_2011_To_5_1_2011_dei_LegalEntityAxis_cik000080248_S000002106Member_rr_PerformanceMeasureAxis_rr_AfterTaxesOnDistributionsMember_rr_ProspectusShareClassAxis_cik000080248_C000005478Member 3 Duration_5_1_2011_To_5_1_2011_dei_LegalEntityAxis_cik000080248_S000002106Member_rr_PerformanceMeasureAxis_cik000080248_Russell2000GrowthAndRussell2000ValueIndexesMember 3 Duration_5_1_2011_To_5_1_2011_dei_LegalEntityAxis_cik000080248_S000002106Member 35 Duration_5_1_2011_To_5_1_2011_dei_LegalEntityAxis_cik000080248_S000002106Member_rr_ProspectusShareClassAxis_cik000080248_C000005478Member 27 Duration_5_1_2011_To_5_1_2011_dei_LegalEntityAxis_cik000080248_S000002106Member_rr_PerformanceMeasureAxis_cik000080248_SP500Member 3 true true