000000 - Document - Document and Entity Information link:presentationLink link:calculationLink link:definitionLink 000011 - Document - Risk/Return Supplement {Unlabeled} - BlackRock Funds II link:presentationLink link:calculationLink link:definitionLink 000012 - Schedule - Shareholder Fees {- BLACKROCK PREPARED PORTFOLIO 2015} link:presentationLink link:calculationLink link:definitionLink 000013 - Schedule - Annual Fund Operating Expenses {- BLACKROCK PREPARED PORTFOLIO 2015} link:presentationLink link:calculationLink link:definitionLink 000014 - Schedule - Expense Example {Transposed} {- BLACKROCK PREPARED PORTFOLIO 2015} link:presentationLink link:calculationLink link:definitionLink 000015 - Schedule - Expense Example, No Redemption {Transposed} {- BLACKROCK PREPARED PORTFOLIO 2015} link:presentationLink link:calculationLink link:definitionLink 000016 - Schedule - Annual Total Returns - BLACKROCK PREPARED PORTFOLIO 2015 [BarChart] link:presentationLink link:calculationLink link:definitionLink 000017 - Schedule - Average Annual Total Returns {Transposed} {- BLACKROCK PREPARED PORTFOLIO 2015} link:presentationLink link:calculationLink link:definitionLink 000018 - Document - Risk/Return Detail {Unlabeled} - BLACKROCK PREPARED PORTFOLIO 2015 link:presentationLink link:calculationLink link:definitionLink 000019 - Disclosure - Risk/Return Detail Data {Elements} - BlackRock Funds II link:presentationLink link:calculationLink link:definitionLink