3.6.0.2 html 68 92 1 true 47 0 false 2 false false R1.htm 000000 - Document - Document and Entity Information {Elements} Sheet http://www.blackrock.com/role/DocumentDocumentandEntityInformationElements Document and Entity Information 1 false true R2.htm 000011 - Document - Risk/Return Summary {Unlabeled} - BLACKROCK GLOBAL OPPORTUNITIES PORTFOLIO Sheet http://www.blackrock.com/role/DocumentRiskReturnSummaryUnlabeledBLACKROCKGLOBALOPPORTUNITIESPORTFOLIO Risk/Return Summary- BLACKROCK GLOBAL OPPORTUNITIES PORTFOLIO 2 false false R9.htm 000019 - Disclosure - Risk/Return Detail Data {Elements} - BLACKROCK GLOBAL OPPORTUNITIES PORTFOLIO Sheet http://www.blackrock.com/role/DisclosureRiskReturnDetailDataElementsBLACKROCKGLOBALOPPORTUNITIESPORTFOLIO Risk/Return Detail Data- BLACKROCK GLOBAL OPPORTUNITIES PORTFOLIO 3 false true R10.htm 000021 - Document - Risk/Return Summary {Unlabeled} - BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO (Investor A, B, C and Institutional) Sheet http://www.blackrock.com/role/DocumentRiskReturnSummaryUnlabeledBLACKROCKINTERNATIONALOPPORTUNITIESPORTFOLIOInvestorABCandInstitutional Risk/Return Summary- BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO (Investor A, B, C and Institutional) 4 false false R17.htm 000029 - Disclosure - Risk/Return Detail Data {Elements} - BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO (Investor A, B, C and Institutional) Sheet http://www.blackrock.com/role/DisclosureRiskReturnDetailDataElementsBLACKROCKINTERNATIONALOPPORTUNITIESPORTFOLIOInvestorABCandInstitutional Risk/Return Detail Data- BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO (Investor A, B, C and Institutional) 5 false true R18.htm 000031 - Document - Risk/Return Summary {Unlabeled} - BLACKROCK U.S. OPPORTUNITIES PORTFOLIO (Investor A, B, C and Institutional) Sheet http://www.blackrock.com/role/DocumentRiskReturnSummaryUnlabeledBLACKROCKUSOPPORTUNITIESPORTFOLIOInvestorABCandInstitutional Risk/Return Summary- BLACKROCK U.S. OPPORTUNITIES PORTFOLIO (Investor A, B, C and Institutional) 6 false false R25.htm 000039 - Disclosure - Risk/Return Detail Data {Elements} - BLACKROCK U.S. OPPORTUNITIES PORTFOLIO (Investor A, B, C and Institutional) Sheet http://www.blackrock.com/role/DisclosureRiskReturnDetailDataElementsBLACKROCKUSOPPORTUNITIESPORTFOLIOInvestorABCandInstitutional Risk/Return Detail Data- BLACKROCK U.S. OPPORTUNITIES PORTFOLIO (Investor A, B, C and Institutional) 7 false true R26.htm 000041 - Document - Risk/Return Summary {Unlabeled} - BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO (Investor A, B, C, Institutional and Class R) Sheet http://www.blackrock.com/role/DocumentRiskReturnSummaryUnlabeledBLACKROCKHEALTHSCIENCESOPPORTUNITIESPORTFOLIOInvestorABCInstitutionalandClassR Risk/Return Summary- BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO (Investor A, B, C, Institutional and Class R) 8 false false R33.htm 000049 - Disclosure - Risk/Return Detail Data {Elements} - BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO (Investor A, B, C, Institutional and Class R) Sheet http://www.blackrock.com/role/DisclosureRiskReturnDetailDataElementsBLACKROCKHEALTHSCIENCESOPPORTUNITIESPORTFOLIOInvestorABCInstitutionalandClassR Risk/Return Detail Data- BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO (Investor A, B, C, Institutional and Class R) 9 false true R34.htm 000051 - Document - Risk/Return Summary {Unlabeled} - BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO (Investor A, C, Institutional and Class R) Sheet http://www.blackrock.com/role/DocumentRiskReturnSummaryUnlabeledBLACKROCKSCIENCETECHNOLOGYOPPORTUNITIESPORTFOLIOInvestorACInstitutionalandClassR Risk/Return Summary- BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO (Investor A, C, Institutional and Class R) 10 false false R41.htm 000059 - Disclosure - Risk/Return Detail Data {Elements} - BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO (Investor A, C, Institutional and Class R) Sheet http://www.blackrock.com/role/DisclosureRiskReturnDetailDataElementsBLACKROCKSCIENCETECHNOLOGYOPPORTUNITIESPORTFOLIOInvestorACInstitutionalandClassR Risk/Return Detail Data- BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO (Investor A, C, Institutional and Class R) 11 false true R42.htm 000061 - Document - Risk/Return Summary {Unlabeled} - BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO (Service) Sheet http://www.blackrock.com/role/DocumentRiskReturnSummaryUnlabeledBLACKROCKINTERNATIONALOPPORTUNITIESPORTFOLIOService Risk/Return Summary- BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO (Service) 12 false false R47.htm 000069 - Disclosure - Risk/Return Detail Data {Elements} - BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO (Service) Sheet http://www.blackrock.com/role/DisclosureRiskReturnDetailDataElementsBLACKROCKINTERNATIONALOPPORTUNITIESPORTFOLIOService Risk/Return Detail Data- BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO (Service) 13 false true R48.htm 000071 - Document - Risk/Return Summary {Unlabeled} - BLACKROCK U.S. OPPORTUNITIES PORTFOLIO (Service) Sheet http://www.blackrock.com/role/DocumentRiskReturnSummaryUnlabeledBLACKROCKUSOPPORTUNITIESPORTFOLIOService Risk/Return Summary- BLACKROCK U.S. OPPORTUNITIES PORTFOLIO (Service) 14 false false R53.htm 000079 - Disclosure - Risk/Return Detail Data {Elements} - BLACKROCK U.S. OPPORTUNITIES PORTFOLIO (Service) Sheet http://www.blackrock.com/role/DisclosureRiskReturnDetailDataElementsBLACKROCKUSOPPORTUNITIESPORTFOLIOService Risk/Return Detail Data- BLACKROCK U.S. OPPORTUNITIES PORTFOLIO (Service) 15 false true R54.htm 000081 - Document - Risk/Return Summary {Unlabeled} - BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO (Service) Sheet http://www.blackrock.com/role/DocumentRiskReturnSummaryUnlabeledBLACKROCKHEALTHSCIENCESOPPORTUNITIESPORTFOLIOService Risk/Return Summary- BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO (Service) 16 false false R59.htm 000089 - Disclosure - Risk/Return Detail Data {Elements} - BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO (Service) Sheet http://www.blackrock.com/role/DisclosureRiskReturnDetailDataElementsBLACKROCKHEALTHSCIENCESOPPORTUNITIESPORTFOLIOService Risk/Return Detail Data- BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO (Service) 17 false true R60.htm 000091 - Document - Risk/Return Summary {Unlabeled} - BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO (Service) Sheet http://www.blackrock.com/role/DocumentRiskReturnSummaryUnlabeledBLACKROCKSCIENCETECHNOLOGYOPPORTUNITIESPORTFOLIOService Risk/Return Summary- BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO (Service) 18 false false R65.htm 000099 - Disclosure - Risk/Return Detail Data {Elements} - BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO (Service) Sheet http://www.blackrock.com/role/DisclosureRiskReturnDetailDataElementsBLACKROCKSCIENCETECHNOLOGYOPPORTUNITIESPORTFOLIOService Risk/Return Detail Data- BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO (Service) 19 false true R66.htm 000101 - Document - Risk/Return Summary {Unlabeled} - BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO (Class K) Sheet http://www.blackrock.com/role/DocumentRiskReturnSummaryUnlabeledBLACKROCKHEALTHSCIENCESOPPORTUNITIESPORTFOLIOClassK Risk/Return Summary- BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO (Class K) 20 false false R71.htm 000109 - Disclosure - Risk/Return Detail Data {Elements} - BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO (Class K) Sheet http://www.blackrock.com/role/DisclosureRiskReturnDetailDataElementsBLACKROCKHEALTHSCIENCESOPPORTUNITIESPORTFOLIOClassK Risk/Return Detail Data- BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO (Class K) 21 false false R72.htm 040000 - Disclosure - Risk/Return Detail Data {Elements} Sheet http://xbrl.sec.gov/rr/role/RiskReturnDetailData Risk/Return Detail Data 22 false false All Reports Book All Reports bf13-20170127.xml bf13-20170127.xsd bf13-20170127_cal.xml bf13-20170127_def.xml bf13-20170127_lab.xml bf13-20170127_pre.xml BarChart1.png BarChart2.png BarChart3.png BarChart4.png BarChart5.png BarChart6.png BarChart7.png BarChart8.png BarChart9.png BarChart10.png true true