2.4.0.8000020 - Document - Risk/Return Summary (MainStay High Yield Corporate Bond Fund) {Unlabeled}falsefalsetrue1false falsefalseContext_Custom_31-Oct-2012_DocumentInformationDocumentAxis_S000006896SummaryMember_LegalEntityAxis_S000006896Memberhttp://www.sec.gov/CIK0000787441duration2012-10-31T00:00:002012-10-31T00:00:001false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00MainStay High Yield Corporate Bond Fund (Prospectus Summary) | MainStay High Yield Corporate Bond Fundfalsefalsefalse1false truefalseContext_Custom_31-Oct-2012_DocumentInformationDocumentAxis_S000006896SummaryMember_LegalEntityAxis_S000006896Memberhttp://www.sec.gov/CIK0000787441duration2012-10-31T00:00:002012-10-31T00:00:00falsefalsecik0000787441_S000006896SummaryMemberdei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldicik0000787441_S000006896SummaryMemberdei_DocumentInformationDocumentAxisexplicitMemberfalsefalsecik0000787441_S000006896Memberdei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldicik0000787441_S000006896Memberdei_LegalEntityAxisexplicitMembernanafalse0MainStay High Yield Corporate Bond Fund (Prospectus Summary) | MainStay High Yield Corporate Bond Fund2false 5rr_RiskReturnHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<div><div style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 20pt; font-weight: bold;"><font style="font-family: times new roman,times;"><a name="4"></a><font style="font-family: sans-serif; font-weight: bold;"></font><font size="2">MainStay High Yield Corporate Bond Fund</font></font></div></div>falsefalsefalsexbrli: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: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 2 false0Risk/Return, Heading3false 5rr_ObjectiveHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<p style="margin: 0in 0in 10pt;" class="msonormal"><b style="mso-bidi-font-weight: normal;"><font style="font-family: times new roman,times;" size="2">Investment Objective</font></b></p>falsefalsefalsexbrli: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: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 2 -Subsection a false0Investment Objective, Heading4false 5rr_ObjectivePrimaryTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<div style="text-align: left; text-transform: none; text-indent: 0px; font: 10pt sans-serif; white-space: normal; letter-spacing: normal; color: #000000; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><font style="font-family: times new roman,times;; font-family:times new roman,times" size="2">The Fund seeks maximum current income through investment in a diversified portfolio of high-yield debt securities.</font></div>falsefalsefalsenonnum:textBlockItemTypenaInvestment 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: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 2 -Subsection a false0investment Objective, Primary5false 5rr_ObjectiveSecondaryTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<div><font style="font-family: times new roman,times;; font-family:times new roman,times" size="2">Capital appreciation is a secondary objective.</font></div>falsefalsefalsenonnum:textBlockItemTypenaInvestment 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: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 2 -Subsection a false0Objective, Secondary [Text Block]6false 5rr_ExpenseHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<p style="margin: 0in 0in 10pt;" class="msonormal"><font style="font-family: times new roman,times;" size="2"><b>Fees and Expenses of the Fund</b></font></p>falsefalsefalsexbrli: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: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 1 -Subparagraph d false0Expense [Heading]7false 5rr_ExpenseNarrativeTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<div><div style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 10pt; font-weight: normal;"><font style="font-family: times new roman,times; ; font-family: times new roman,times;" size="2">The table below describes the fees and expenses that you may pay if you buy and hold shares of the Fund.</font></div></div>falsefalsefalsenonnum:textBlockItemTypenaThis 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: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 1 -Subparagraph b false0Expense, Narrative8false 5rr_ShareholderFeesCaptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<div style="line-height: normal; margin: 0in 0in 6pt;" class="msonormal"><font style="font-family: times new roman,times;" size="2"><b>Shareholder Fees</b> (fees paid directly from your investment)</font></div>falsefalsefalsexbrli:stringItemTypestringShareholder Fees (fees paid directly from your investment).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection table -Paragraph 1 false0Shareholder Fees, Caption9false 5rr_ShareholderFeesTableTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<div style='display: none;'> ~ http://www.mainstayfunds.com/role/ShareholderFeesMainstayHighYieldCorporateBondFund column dei_DocumentInformationDocumentAxis compact cik0000787441_S000006896SummaryMember column dei_LegalEntityAxis compact cik0000787441_S000006896Member row primary compact * ~ </div>falsefalse<div style='display: none;'> ~ http://www.mainstayfunds.com/role/ShareholderFeesMainstayHighYieldCorporateBondFund column dei_DocumentInformationDocumentAxis compact cik0000787441_S000006896SummaryMember column dei_LegalEntityAxis compact cik0000787441_S000006896Member row primary compact * ~ </div>falsehttp://www.mainstayfunds.com/role/ShareholderFeesMainstayHighYieldCorporateBondFund000030 - Schedule - Shareholder Fees MainStay High Yield Corporate Bond Fundtruefalsefalse1falseColumnperiodPeriod*Columndei_DocumentInformationDocumentAxisAxiscik0000787441_S000006896SummaryMemberColumndei_LegalEntityAxisAxiscik0000787441_S000006896MemberColumnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*duration2012-10-31T00:00:002012-10-31T00:00:00falsefalsedei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldicik0000787441_S000006896SummaryMemberdei_DocumentInformationDocumentAxisexplicitMemberfalsefalsedei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldicik0000787441_S000006896Memberdei_LegalEntityAxisexplicitMemberfalsefalseClass R6rr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldicik0000787441_C000127160Memberrr_ProspectusShareClassAxisexplicitMemberClass R6pureStandardhttp://www.xbrl.org/2003/instancepurexbrli0Standard0 USDfalsefalseduration2012-10-31T00:00:002012-10-31T00:00:00$1falseRowprimaryElement*3false 5rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPricerr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabelrr: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. Show the percentage amounts and the terms of each sales charge (load) comprising that figure on separate lines below.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection table -Paragraph 1 -Subparagraph 1 false0Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) 0rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPricerr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr: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. Show the percentage amounts and the terms of each sales charge (load) comprising that figure on separate lines below.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection table -Paragraph 1 -Subparagraph 1 false0Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)2falseRowprimaryElement*4false 5rr_MaximumDeferredSalesChargeOverOfferingPricerr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabelrr: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. Show the percentage amounts and the terms of each sales charge (load) comprising that figure on separate lines below.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph a -Clause i false0Maximum Deferred Sales Charge (Load) (as a percentage of the lesser of the original offering price or redemption proceeds) 0rr_MaximumDeferredSalesChargeOverOfferingPricerr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr: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. Show the percentage amounts and the terms of each sales charge (load) comprising that figure on separate lines below.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph a -Clause i false0Maximum Deferred Sales Charge (Load) (as a percentage of the lesser of the original offering price or redemption proceeds)falseShareholder Fees MainStay High Yield Corporate Bond Fund UnKnownUnKnownUnKnownUnKnownfalsefalsefalseSheet12011207ColumnperiodPeriod*Columndei_DocumentInformationDocumentAxisAxiscik0000787441_S000006896SummaryMemberColumndei_LegalEntityAxisAxiscik0000787441_S000006896MemberColumnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*RowprimaryElement*falsenonnum:textBlockItemTypenaContains a command for the SEC Viewer for the role corresponding to ShareholderFeesData.No definition available.false0Shareholder Fees [Table]10false 5rr_OperatingExpensesCaptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<div style="line-height: normal; margin: 0in 0in 6pt;" class="msonormal"><font style="font-family: times new roman,times;" size="2"><b>Annual Fund Operating Expenses</b><b></b>(expenses that you pay each year as a percentage of the value of your investment)</font></div>falsefalsefalsexbrli:stringItemTypestringAnnual Fund Operating Expenses (ongoing expenses that you pay each year as a percentage of the value of your investment)Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection table -Paragraph 1 -Subparagraph 7 false0Operating Expenses, Caption11false 5rr_AnnualFundOperatingExpensesTableTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<div style='display: none;'> ~ http://www.mainstayfunds.com/role/AnnualFundOperatingExpensesMainstayHighYieldCorporateBondFund column dei_DocumentInformationDocumentAxis compact cik0000787441_S000006896SummaryMember column dei_LegalEntityAxis compact cik0000787441_S000006896Member row primary compact * ~ </div>falsefalse<div style='display: none;'> ~ http://www.mainstayfunds.com/role/AnnualFundOperatingExpensesMainstayHighYieldCorporateBondFund column dei_DocumentInformationDocumentAxis compact cik0000787441_S000006896SummaryMember column dei_LegalEntityAxis compact cik0000787441_S000006896Member row primary compact * ~ </div>falsehttp://www.mainstayfunds.com/role/AnnualFundOperatingExpensesMainstayHighYieldCorporateBondFund000040 - Schedule - Annual Fund Operating Expensestruefalsefalse1falseColumnperiodPeriod*Columndei_DocumentInformationDocumentAxisAxiscik0000787441_S000006896SummaryMemberColumndei_LegalEntityAxisAxiscik0000787441_S000006896MemberColumnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*duration2012-10-31T00:00:002012-10-31T00:00:00falsefalsedei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldicik0000787441_S000006896SummaryMemberdei_DocumentInformationDocumentAxisexplicitMemberfalsefalsedei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldicik0000787441_S000006896Memberdei_LegalEntityAxisexplicitMemberfalsefalseClass R6rr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldicik0000787441_C000127160Memberrr_ProspectusShareClassAxisexplicitMemberClass R6pureStandardhttp://www.xbrl.org/2003/instancepurexbrli0Standard0 USDfalsefalseduration2012-10-31T00:00:002012-10-31T00:00:00$1falseRowprimaryElement*3false 5rr_ManagementFeesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabelrr: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: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 3 -Subparagraph a false0Management Fees (as an annual percentage of the Fund's average daily net assets) 0rr_ManagementFeesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel[1]1truetruetrue0.00550.0055falsefalsefalserr: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: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 3 -Subparagraph a false0Management Fees (as an annual percentage of the Fund's average daily net assets)2falseRowprimaryElement*4false 5rr_DistributionAndService12b1FeesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabelrr: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: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection table -Paragraph 1 -Subparagraph 9 false0Distribution and/or Service (12b-1) Fees 0rr_DistributionAndService12b1FeesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr: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: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection table -Paragraph 1 -Subparagraph 9 false0Distribution and/or Service (12b-1) Fees3falseRowprimaryElement*5false 5rr_OtherExpensesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabelrr: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: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 3 -Subparagraph c -Clause i false0Other Expenses 0rr_OtherExpensesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue0.00040.0004falsefalsefalserr: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: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 3 -Subparagraph c -Clause i false0Other Expenses4falseRowprimaryElement*6false 5rr_ExpensesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalsetotalLabelrr:NonNegativePure4TypepureTotal Annual Fund Operating Expenses. If the Fund is a Feeder Fund, reflect the aggregate expenses of the Feeder Fund and the Master Fund in a single fee table using the captions provided. In a footnote to the fee table, state that the table and Example reflect the expenses of both the Feeder and Master Funds. If the prospectus offers more than one Class of a Multiple Class Fund or more than one Feeder Fund that invests in the same Master Fund, provide a separate response for each Class or Feeder Fund. Base the percentages of "Annual Fund Operating Expenses" on amounts incurred during the Fund's most recent fiscal year, but include in expenses amounts that would have been incurred absent expense reimbursement or fee waiver arrangements. If the Fund has changed its fiscal year and, as a result, the most recent fiscal year is less than three months, use the fiscal year prior to the most recent fiscal year as the basis for determining "Annual Fund Operating Expenses."Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 3 -Subparagraph d true0Total Annual Fund Operating Expenses 0rr_ExpensesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalsetotalLabel1truetruetrue0.00590.0059falsefalsefalserr:NonNegativePure4TypepureTotal Annual Fund Operating Expenses. If the Fund is a Feeder Fund, reflect the aggregate expenses of the Feeder Fund and the Master Fund in a single fee table using the captions provided. In a footnote to the fee table, state that the table and Example reflect the expenses of both the Feeder and Master Funds. If the prospectus offers more than one Class of a Multiple Class Fund or more than one Feeder Fund that invests in the same Master Fund, provide a separate response for each Class or Feeder Fund. Base the percentages of "Annual Fund Operating Expenses" on amounts incurred during the Fund's most recent fiscal year, but include in expenses amounts that would have been incurred absent expense reimbursement or fee waiver arrangements. If the Fund has changed its fiscal year and, as a result, the most recent fiscal year is less than three months, use the fiscal year prior to the most recent fiscal year as the basis for determining "Annual Fund Operating Expenses."Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 3 -Subparagraph d true0Total Annual Fund Operating Expenses1The management fee is as follows: 0.60% on assets up to $500 million; 0.55% on assets from $500 million to $5 billion; 0.525% on assets from $5 billion to $7 billion; and 0.50% on assets in excess of $7 billion, plus a fee for fund accounting services previously provided by New York Life Investment Management LLC under a separate fund accounting agreement. This addition to the management fee amounted to 0.01% of the Fund's average daily net assets, but did not result in a net increase in Total Annual Fund Operating Expenses.falseAnnual Fund Operating Expenses UnKnownUnKnownUnKnownUnKnownfalsefalsefalseSheet14031409ColumnperiodPeriod*Columndei_DocumentInformationDocumentAxisAxiscik0000787441_S000006896SummaryMemberColumndei_LegalEntityAxisAxiscik0000787441_S000006896MemberColumnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*RowprimaryElement*falsenonnum:textBlockItemTypenaContains a command for the SEC Viewer for the role corresponding to OperatingExpensesData.No definition available.false0Annual Fund Operating Expenses [Table]12false 5rr_ExpenseExampleHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<div><font style="font-family: times new roman,times;" size="2"><b>Example</b></font></div>falsefalsefalsexbrli:stringItemTypestringHeading for Expense Example.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 4 false0Expense Example, Heading13false 5rr_ExpenseExampleNarrativeTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<div><font style="font-family: times new roman,times; ; font-family: times new roman,times;" size="2">The 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.</font></div>falsefalsefalsenonnum:textBlockItemTypenaThe 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: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection example -Paragraph 1 -Subparagraph 1 false0Expense Example Narrative [Text Block]14false 5rr_ExpenseExampleByYearCaptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<div><font style="font-family: times new roman,times; ; font-family: times new roman,times;" size="2">Although your actual costs may be higher or lower, based on these assumptions your costs would be:</font></div>falsefalsefalsexbrli:stringItemTypestringThe 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. 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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.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 4 false2Expense Example, With Redemption, 1 Year USDfalsefalse$2falseColumnprimaryElement*4false 5rr_ExpenseExampleYear03rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabelrr:NonNegativeMonetaryTypemonetaryThe 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.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection example -Paragraph 1 -Subparagraph 2 false2Expense Example, With Redemption, 3 Years USDfalsefalse$3falseColumnprimaryElement*5false 5rr_ExpenseExampleYear05rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabelrr:NonNegativeMonetaryTypemonetaryThe 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.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection example -Paragraph 1 -Subparagraph 2 false2Expense Example, With Redemption, 5 Years USDfalsefalse$4falseColumnprimaryElement*6false 5rr_ExpenseExampleYear10rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabelrr:NonNegativeMonetaryTypemonetaryThe 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. 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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: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 5 false0Portfolio Turnover, Heading17false 5rr_PortfolioTurnoverTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<div><div style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 10pt; font-weight: normal;"><font style="font-family: times new roman,times;" size="2">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 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 29% of the average value of its portfolio.</font></div></div>falsefalsefalsenonnum:textBlockItemTypenaDisclose 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: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection example -Paragraph 3 false0Portfolio Turnover18false 5rr_StrategyHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<p style="margin: 0in 0in 10pt;" class="msonormal"><b style="mso-bidi-font-weight: normal;"><font style="font-family: times new roman,times;" size="2">Principal Investment Strategies</font></b></p>falsefalsefalsexbrli: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: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection a false0Investment Strategy, Heading19false 5rr_StrategyNarrativeTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<div><p style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 10pt; font-weight: normal;"><font style="font-family: times new roman,times;" size="2">The Fund, under normal circumstances, invests at least 80% of its assets (net assets plus any borrowings for investment purposes) in high-yield corporate debt securities, including all types of high-yield domestic and foreign corporate debt securities that are rated below investment grade by an independent rating agency, such as Standard &amp; Poor's or Moody's Investors Service, Inc., or that are unrated but are considered to be of comparable quality by MacKay Shields LLC, the Fund's Subadvisor.</font></p><p style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 10pt; font-weight: normal;"><font style="font-family: times new roman,times;" size="2">Some securities that are rated below investment grade by independent rating agencies are commonly referred to as "junk bonds." These securities are sometimes considered speculative. If independent rating agencies assign different ratings to the same security, the Fund will use the lower rating for purposes of determining the security's credit quality.</font></p><p style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 10pt; font-weight: normal;"><font style="font-family: times new roman,times;" size="2">The Fund's high-yield investments may also include convertible corporate securities and loan participation interests (e.g., bank debt). The Fund may invest up to 20% of its net assets in common stocks and other equity-related securities.&#160;</font>&#160;</p><p style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 10pt; font-weight: normal;"><font style="font-family: times new roman,times;" size="2">The Fund may hold cash or invest in short-term instruments during times when the Subadvisor is unable to identify attractive high-yield securities. </font></p><p style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 10pt; font-weight: normal;"><font style="font-family: times new roman,times;" size="2">In times of unusual or adverse market, economic or political conditions, the Fund may invest without limit in investment grade securities and may invest in U.S. government securities or other high quality money market instruments. Periods of unusual or adverse market, economic or political conditions may exist in some cases, for up to a year. To the extent the Fund is invested in cash, investment grade debt or other high quality instruments, the yield on these investments tends to be lower than the yield on other investments normally purchased by the Fund. Although investing heavily in these investments may help to preserve the Fund's assets, it may not be consistent with the Fund's primary investment objective and may limit the Fund's ability to achieve a high level of income.</font></p><p style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 10pt; font-weight: normal;"><font style="font-family: times new roman,times;" size="2"><font style="font-family: sans-serif; font-weight: bold;">Investment Process:</font> The Subadvisor seeks to identify investment opportunities through analyzing individual companies and evaluates each company's competitive position, financial condition, and business prospects. The Fund only invests in companies in which the Subadvisor has judged that there is sufficient asset coverage&#8212;that is, the Subadvisor's subjective appraisal of a company's value divided by the value of its debt, with the intent of maximizing default-adjusted income and returns.</font></p><div style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 10pt; font-weight: normal;"><font style="font-family: times new roman,times;" size="2">The Subadvisor may sell a security if it no longer believes the security will contribute to meeting the investment objectives of the Fund. In considering whether to sell a security, the Subadvisor may evaluate, among other things, meaningful changes in the issuer's financial condition and competitiveness.</font></div></div>falsefalsefalsenonnum:textBlockItemTypenaPrincipal 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: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection a false0Investment Strategy, Narrative20false 5rr_RiskHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<div style="text-align: left; font-style: normal; text-indent: 2.9pt; font-family: sans-serif; font-size: 10pt; font-weight: bold;"><font style="font-family: times new roman,times; ; font-family: times new roman,times;">Principal Risks</font></div>falsefalsefalsexbrli:stringItemTypestringNarrative Risk Disclosure.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 1 false0Risk, Heading21false 5rr_RiskNarrativeTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<div><p style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 10pt; font-weight: normal;"><font style="font-family: times new roman,times; ; font-family: times new roman,times;" size="2"><font style="font-family: sans-serif; font-weight: bold;">Loss of Money Risk:</font> Before considering an investment in the Fund, you should understand that you could lose money. </font></p><p style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 10pt; font-weight: normal;"><font style="font-family: times new roman,times; ; font-family: times new roman,times;" size="2"><font style="font-family: sans-serif; font-weight: bold;">Market Changes Risk:</font> The value of the Fund's investments may change because of broad changes in the markets in which the Fund invests, which could cause the Fund to underperform other funds with similar objectives. From time to time, markets may experience periods of acute stress that may result in increased volatility. Such market conditions tend to add significantly to the risk of short-term volatility in the net asset value of the Fund's shares.</font></p><p style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 10pt; font-weight: normal;"><font style="font-family: times new roman,times;" size="2"><font style="font-family: sans-serif; font-weight: bold;">Management Risk:</font></font><font style="font-family: times new roman,times; ; font-family: times new roman,times;" size="2"> The investment strategies, practices and risk analysis used by the Subadvisor may not produce the desired results.</font></p><p style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 10pt; font-weight: normal;"><font style="font-family: times new roman,times; ; font-family: times new roman,times;" size="2"><font style="font-family: sans-serif; font-weight: bold;">Debt Securities Risk:</font> The risks of investing in debt securities include (without limitation): (i) credit risk, i.e., the issuer may not repay the loan created by the issuance of that debt security; (ii) maturity risk, i.e., a debt security with a longer maturity may fluctuate in value more than one with a shorter maturity; (iii) market risk, i.e., low demand for debt securities may negatively impact their price; (iv) interest rate risk, i.e., when interest rates go up, the value of a debt security goes down, and when interest rates go down, the value of a debt security goes up; (v) selection risk, i.e., the securities selected by the Subadvisor may underperform the market or other securities selected by other funds; and (vi) call risk, i.e., during a period of falling interest rates, the issuer may redeem a security by repaying it early, which may reduce the Fund&#8217;s income if the proceeds are reinvested at lower interest rates. </font></p><p style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 10pt; font-weight: normal;"><font style="font-family: times new roman,times; ; font-family: times new roman,times;" size="2">Interest rates in the United States are at, or near, historic lows, which may increase the Fund&#8217;s exposure to risks associated with rising rates. Moreover, rising interest rates may lead to decreased liquidity in the bond markets, making it more difficult for the Fund to sell its bond holdings at a time when theSubadvisor might wish to sell. Decreased market liquidity also may make it more difficult to value some or all of the Fund&#8217;s bond holdings. Please see &#8220;Liquidity and Valuation Risk&#8221; below for more information.</font></p><p style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 10pt; font-weight: normal;"><font style="font-family: times new roman,times; ; font-family: times new roman,times;" size="2"><font style="font-family: sans-serif; font-weight: bold;">High-Yield Securities Risk:</font> Investments in high-yield securities or non-investment grade securities (commonly referred to as "junk bonds") are sometimes considered speculative because they present a greater risk of loss than higher quality securities. Such securities may, under certain circumstances, be less liquid than higher rated securities. These securities pay investors a premium (a high interest rate or yield) because of the increased risk of loss. These securities can also be subject to greater price volatility. In times of unusual or adverse market, economic or political conditions, these securities may experience higher than normal default rates.</font></p><p style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 10pt; font-weight: normal;"><font style="font-family: times new roman,times; ; font-family: times new roman,times;" size="2"><font style="font-family: sans-serif; font-weight: bold;">Liquidity and Valuation Risk:</font> Securities purchased by the Fund that are liquid at the time of purchase may subsequently become illiquid due to, among other things, events relating to the issuer of the securities, market events, economic conditions, investor perceptions or lack of market participants. The lack of an active trading market may make it difficult to obtain an accurate price for a security. If market conditions make it difficult to value securities, the Fund may value these securities using more subjective methods, such as fair value pricing. In such cases, the value determined for a security could be different than the value realized upon such security's sale. Please see &#8220;Fair Valuation and Portfolio Holdings Disclosure &#8211; Determining the MainStay Funds&#8217; Share Prices and the Valuation of Securities&#8221; in the Shareholder Guide for more information. As a result, an investor could pay more than the market value when buying Fund shares or receive less than the market value when selling Fund shares. Liquidity risk may also refer to the risk that the Fund may not be able to pay redemption proceeds within the allowable time period because of unusual market conditions, unusually high volume of redemptions, or other reasons. To meet redemption requests, the Fund may be forced to sell securities at an unfavorable time and/or under unfavorable conditions.</font></p><p style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 10pt; font-weight: normal;"><font style="font-family: times new roman,times; ; font-family: times new roman,times;" size="2"><font style="font-family: sans-serif; font-weight: bold;">Loan Participation Interest Risk:</font> There may not be a readily available market for loan participation interests, which in some cases could result in the Fund disposing of such a security at a substantial discount from face value or holding such a security until maturity. In addition, there is also the credit risk of the underlying corporate borrower as well as the lending institution or other participant from whom the Fund purchased the loan participation interests.</font></p><p style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 10pt; font-weight: normal;"><font style="font-family: times new roman,times; ; font-family: times new roman,times;" size="2"><font style="font-family: sans-serif; font-weight: bold;">Floating Rate Loans Risk:</font> The floating rate loans in which the Fund invests are usually rated below investment grade (commonly referred to as "junk bonds") and are generally considered speculative because they present a greater risk of loss, including default, than higher quality debt securities. Moreover, such securities may, under certain circumstances, be less liquid than higher quality debt securities. Although certain floating rate loans are collateralized, there is no guarantee that the value of the collateral will be sufficient to repay the loan. In times of unusual or adverse market, economic or political conditions, floating rate loans may experience higher than normal default rates. In the event of a recession or serious credit event, among other eventualities, the Fund's investments in floating rate loans are more likely to decline.</font></p><p style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 10pt; font-weight: normal;"><font style="font-family: times new roman,times; ; font-family: times new roman,times;" size="2"><font style="font-family: sans-serif; font-weight: bold;">Convertible Securities Risk:</font> Convertible securities may be subordinate to other securities. In part, the total return for a convertible security depends upon the performance of the underlying stock into which it can be converted. Also, issuers of convertible securities are often not as strong financially as those issuing securities with higher credit ratings, are more likely to encounter financial difficulties and typically are more vulnerable to changes in the economy, such as a recession or a sustained period of rising interest rates, which could affect their ability to make interest and principal payments. If an issuer stops making interest and/or principal payments, the Fund could lose its entire investment.</font></p><p style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 10pt; font-weight: normal;"><font style="font-family: times new roman,times; ; font-family: times new roman,times;" size="2"><font style="font-family: sans-serif; font-weight: bold;">Foreign Securities Risk:</font> Investments in foreign securities may be riskier than investments in U.S. securities. Differences between U.S. and foreign regulatory regimes and securities markets, including less stringent investor protections and disclosure standards of some foreign markets, less liquid trading markets and political and economic developments in foreign countries, may affect the value of the Fund's investments in foreign securities. Foreign securities may also subject the Fund's investments to changes in currency rates. These risks may be greater with respect to securities of companies that conduct their business activities in emerging markets or whose securities are traded principally in emerging markets.</font></p><div style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 10pt; font-weight: normal;"><font style="font-family: times new roman,times; ; font-family: times new roman,times;" size="2"><font style="font-family: sans-serif; font-weight: bold;">Equity Securities Risk:</font> Investments in common stocks and other equity securities are particularly subject to the risk of changing economic, stock market, industry and company conditions and the risks inherent in the portfolio manager's ability to anticipate such changes that can adversely affect the value of the Fund's holdings. Opportunity for greater gain often comes with greater risk of loss.</font></div></div>falsefalsefalsenonnum:textBlockItemTypenaNarrative Risk Disclosure. A Fund may, in responding to this Item, describe the types of investors for whom the Fund is intended or the types of investment goals that may be consistent with an investment in the Fund.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 1 -Subparagraph i -Clause instruction false0Risk, Narrative22false 5rr_BarChartAndPerformanceTableHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<div><div style="text-align: left; font-style: normal; text-indent: 2.9pt; font-family: sans-serif; font-size: 10pt; font-weight: bold;"><font style="font-family: times new roman,times;" size="2">Past Performance</font></div></div>falsefalsefalsexbrli:stringItemTypestringRisk/Return Bar Chart and Table.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 false0Bar Chart and Performance Table, Heading23false 5rr_PerformanceNarrativeTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<div><p style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 10pt; font-weight: normal;"><font style="font-family: times new roman,times;" size="2">The following bar chart and tables indicate some of the risks of investing in the Fund. The bar chart shows you how the Fund's calendar year performance has varied over the last ten years. The average annual total returns table shows how the Fund's average annual total returns (before and after taxes) for the one-, five- and ten-year periods compare to those of a broad-based securities market index. The Fund has selected the Credit Suisse High Yield Index<font style="font-style: normal; font-family: sans-serif; font-size: 6pt; font-weight: normal;"></font>as its primary benchmark. The Credit Suisse High Yield Index is a market-weighted index that includes publicly traded bonds rated below BBB by S&amp;P and Baa by Moody's. </font></p><div style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 10pt; font-weight: normal;"><font style="font-family: times new roman,times;" size="2">Performance data for the classes varies based on differences in their fee and expense structures. Performance figures for Class R6 shares, first offered on June 17, 2013, include the historical performance of Class I shares. Performance for Class I shares, which were first offered on January 2, 2004, include the historical performance of Class B shares through January 1, 2004, adjusted for differences in fees and expenses. Unadjusted, the performance for Class I shares would likely have been different. Performance for Class R6 shares would also likely have been different because of expenses attributable to each share class. Past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. Please visit mainstayinvestments.com for more recent performance information.</font></div></div>falsefalsefalsenonnum:textBlockItemTypenaRisk/Return Bar Chart and Table.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 false0Performance Narrative [Text Block]24false 5rr_BarChartNarrativeTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<div><font style="font-family: times new roman,times;" size="2">The bar chart shows you how the Fund's calendar year performance has varied over the last ten years.</font></div>falsefalsefalsenonnum:textBlockItemTypenaProvide a brief explanation of how the information illustrates the variability of the Fund's returns (e.g., by stating that the information provides some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual returns for 1, 5, and 10 years compare with those of a broad measure of market performance). Provide a statement to the effect that the Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph i false0Bar Chart, Narrative25false 5rr_BarChartHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<div style="text-align: left; text-transform: none; text-indent: 0px; font: bold 10pt sans-serif; white-space: normal; letter-spacing: normal; color: #000000; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><font style="font-family: times new roman,times;">Annual Returns, Class R6 Shares <font style="font-style: normal; font-family: sans-serif; font-weight: normal;; font-family:times new roman,times" size="2">(by calendar year 2003-2012)</font></font></div>falsefalsefalsexbrli:stringItemTypestringRisk/Return Bar Chart and Table.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 false0Bar Chart, Heading26false 5rr_BarChartTableTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<div style='display: none;'> ~ http://www.mainstayfunds.com/role/Annualtotalreturnsbarchart column dei_DocumentInformationDocumentAxis compact cik0000787441_S000006896SummaryMember column dei_LegalEntityAxis compact cik0000787441_S000006896Member row primary compact * ~ </div>falsefalseBarChart1.jpg<div style='display: none;'> ~ http://www.mainstayfunds.com/role/Annualtotalreturnsbarchart column dei_DocumentInformationDocumentAxis compact cik0000787441_S000006896SummaryMember column dei_LegalEntityAxis compact cik0000787441_S000006896Member row primary compact * ~ </div>falsehttp://www.mainstayfunds.com/role/Annualtotalreturnsbarchart000060 - Schedule - Annual Total Returnstruefalsefalse1falseColumnperiodPeriod*Columndei_DocumentInformationDocumentAxisAxiscik0000787441_S000006896SummaryMemberColumndei_LegalEntityAxisAxiscik0000787441_S000006896MemberColumnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*duration2012-10-31T00:00:002012-10-31T00:00:00falsefalsedei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldicik0000787441_S000006896SummaryMemberdei_DocumentInformationDocumentAxisexplicitMemberfalsefalsedei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldicik0000787441_S000006896Memberdei_LegalEntityAxisexplicitMemberfalsefalseClass R6rr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldicik0000787441_C000127160Memberrr_ProspectusShareClassAxisexplicitMemberClass R6pureStandardhttp://www.xbrl.org/2003/instancepurexbrli0Standard0 USDfalsefalseduration2012-10-31T00:00:002012-10-31T00:00:00$1falseRowprimaryElement*3false3false 5rr_AnnualReturn2003rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruefalse0.37960.3796falsefalsefalsexbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph instructions -Clause 3 -Exhibit a false0Annual Return 2003 5rr_AnnualReturn2003rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabelxbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph instructions -Clause 3 -Exhibit a false0Annual Return 2003 0rr_AnnualReturn2003rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruefalse0.37960.3796falsefalsefalsexbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph instructions -Clause 3 -Exhibit a false0Annual Return 20032falseRowprimaryElement*4false4false 5rr_AnnualReturn2004rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruefalse0.12770.1277falsefalsefalsexbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph instructions -Clause 3 -Exhibit a false0Annual Return 2004 5rr_AnnualReturn2004rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabelxbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph instructions -Clause 3 -Exhibit a false0Annual Return 2004 0rr_AnnualReturn2004rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruefalse0.12770.1277falsefalsefalsexbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph instructions -Clause 3 -Exhibit a false0Annual Return 20043falseRowprimaryElement*5false5false 5rr_AnnualReturn2005rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruefalse0.03570.0357falsefalsefalsexbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph ii false0Annual Return 2005 5rr_AnnualReturn2005rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabelxbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph ii false0Annual Return 2005 0rr_AnnualReturn2005rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruefalse0.03570.0357falsefalsefalsexbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph ii false0Annual Return 20054falseRowprimaryElement*6false6false 5rr_AnnualReturn2006rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruefalse0.11960.1196falsefalsefalsexbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph ii false0Annual Return 2006 5rr_AnnualReturn2006rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabelxbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph ii false0Annual Return 2006 0rr_AnnualReturn2006rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruefalse0.11960.1196falsefalsefalsexbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph ii false0Annual Return 20065falseRowprimaryElement*7false7false 5rr_AnnualReturn2007rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruefalse0.02250.0225falsefalsefalsexbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph instructions -Clause 3 -Exhibit a false0Annual Return 2007 5rr_AnnualReturn2007rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabelxbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph instructions -Clause 3 -Exhibit a false0Annual Return 2007 0rr_AnnualReturn2007rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruefalse0.02250.0225falsefalsefalsexbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph instructions -Clause 3 -Exhibit a false0Annual Return 20076falseRowprimaryElement*8false8false 5rr_AnnualReturn2008rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruefalse-0.2389-0.2389falsefalsefalsexbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph ii false0Annual Return 2008 5rr_AnnualReturn2008rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabelxbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph ii false0Annual Return 2008 0rr_AnnualReturn2008rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruefalse-0.2389-0.2389falsefalsefalsexbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph ii false0Annual Return 20087falseRowprimaryElement*9false9false 5rr_AnnualReturn2009rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruefalse0.42760.4276falsefalsefalsexbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph instructions -Clause 3 -Exhibit a false0Annual Return 2009 5rr_AnnualReturn2009rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabelxbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph instructions -Clause 3 -Exhibit a false0Annual Return 2009 0rr_AnnualReturn2009rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruefalse0.42760.4276falsefalsefalsexbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph instructions -Clause 3 -Exhibit a false0Annual Return 20098falseRowprimaryElement*10false10false 5rr_AnnualReturn2010rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruefalse0.12450.1245falsefalsefalsexbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph ii false0Annual Return 2010 5rr_AnnualReturn2010rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabelxbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph ii false0Annual Return 2010 0rr_AnnualReturn2010rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruefalse0.12450.1245falsefalsefalsexbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph ii false0Annual Return 20109falseRowprimaryElement*11false11false 5rr_AnnualReturn2011rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruefalse0.06030.0603falsefalsefalsexbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph instructions -Clause 3 -Exhibit a false0Annual Return 2011 5rr_AnnualReturn2011rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabelxbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph instructions -Clause 3 -Exhibit a false0Annual Return 2011 0rr_AnnualReturn2011rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruefalse0.06030.0603falsefalsefalsexbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph instructions -Clause 3 -Exhibit a false0Annual Return 201110falseRowprimaryElement*12false12false 5rr_AnnualReturn2012rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruefalse0.13270.1327falsefalsefalsexbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph ii false0Annual Return 2012 5rr_AnnualReturn2012rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabelxbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph ii false0Annual Return 2012 0rr_AnnualReturn2012rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruefalse0.13270.1327falsefalsefalsexbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph ii false0Annual Return 2012falseAnnual Total Returns UnKnownUnKnownUnKnownUnKnownfalsefalsefalseSheet11009110015ColumnperiodPeriod*Columndei_DocumentInformationDocumentAxisAxiscik0000787441_S000006896SummaryMemberColumndei_LegalEntityAxisAxiscik0000787441_S000006896MemberColumnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*RowprimaryElement*falsenonnum:textBlockItemTypenaContains a command for the SEC Viewer for the role corresponding to BarChartData.No definition available.false0Bar Chart [Table]27false 5rr_BarChartClosingTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<table style="width: 35%; clear: both;" cellspacing="0" cellpadding="0"><tr><td style="border-bottom: #000000 0.75pt solid; vertical-align: bottom;" colspan="2"><p style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 10pt; font-weight: bold;"><font style="font-family: times new roman,times;" size="2">Best Quarter</font></p></td><td style="border-bottom: #000000 0.75pt solid; font-size: 1pt; vertical-align: top;"><font style="font-family: times new roman,times;" size="2">&#160;</font></td></tr><tr><td style="border-bottom: #000000 0.25pt solid; vertical-align: bottom;"><p style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 8pt; font-weight: normal;"><font style="font-family: times new roman,times;" size="2">2Q/09</font></p></td><td style="border-bottom: #000000 0.25pt solid; vertical-align: bottom;"><p style="text-align: right; font-style: normal; font-family: sans-serif; font-size: 8pt; font-weight: normal;"><font style="font-family: times new roman,times;" size="2">17.34</font></p></td><td style="border-bottom: #000000 0.25pt solid; vertical-align: bottom;"><p style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 8pt; font-weight: normal;"><font style="font-family: times new roman,times;" size="2">%</font></p></td></tr><tr><td style="border-bottom: #000000 0.75pt solid; vertical-align: bottom;" colspan="2"><p style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 10pt; font-weight: bold;"><font style="font-family: times new roman,times;" size="2">Worst Quarter</font></p></td><td style="border-bottom: #000000 0.75pt solid; font-size: 1pt; vertical-align: top;"><font style="font-family: times new roman,times;" size="2">&#160;</font></td></tr><tr><td style="border-bottom: #000000 0.25pt solid; vertical-align: bottom;"><p style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 8pt; font-weight: normal;"><font style="font-family: times new roman,times;" size="2">4Q/08</font></p></td><td style="border-bottom: #000000 0.25pt solid; vertical-align: bottom;"><p style="text-align: right; font-style: normal; font-family: sans-serif; font-size: 8pt; font-weight: normal;"><font style="font-family: times new roman,times;" size="2">-17.22</font></p></td><td style="border-bottom: #000000 0.25pt solid; vertical-align: bottom;"><p style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 8pt; font-weight: normal;"><font style="font-family: times new roman,times;" size="2">%</font></p></td></tr></table><div><div style="font-style: normal; font-weight: normal;"><font style="font-family: times new roman,times;" size="2">&#160;</font></div><p></p><p style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 10pt; font-weight: normal;"><font style="font-family: times new roman,times;" size="2">As of March 31, 2013, the Class R6 shares of the Fund would have had a year-to-date return of 2.61%.</font></p></div>falsefalsefalsenonnum:textBlockItemTypenaIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph ii false0Bar Chart Closing [Text Block]28false 5rr_AverageAnnualReturnCaptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsetruefalse00<div style="line-height: normal; margin: 0in 0in 6pt;" class="msonormal"><font style="font-family: times new roman,times;" size="2"><b>Average Annual Total Returns</b> (for the periods ended December 31, 2012)</font></div>falsefalsefalsexbrli:stringItemTypestringThis item represents Average Anuual Total Returns. If a Multiple Class Fund offers a Class in the prospectus that converts into another Class after a stated period, compute average annual total returns in the table by using the returns of the other Class for the period after conversion.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph instructions -Clause 5 false0Average Annual Returns, Caption29false 5rr_PerformanceTableTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<div style='display: none;'> ~ http://www.mainstayfunds.com/role/AverageAnnualTotalReturnsMainstayHighYieldCorporateBondFundTransposed column dei_DocumentInformationDocumentAxis compact cik0000787441_S000006896SummaryMember column dei_LegalEntityAxis compact cik0000787441_S000006896Member column rr_ProspectusShareClassAxis compact * column rr_PerformanceMeasureAxis compact * row primary compact * ~ </div>falsefalse<div style='display: none;'> ~ http://www.mainstayfunds.com/role/AverageAnnualTotalReturnsMainstayHighYieldCorporateBondFundTransposed column dei_DocumentInformationDocumentAxis compact cik0000787441_S000006896SummaryMember column dei_LegalEntityAxis compact cik0000787441_S000006896Member column rr_ProspectusShareClassAxis compact * column rr_PerformanceMeasureAxis compact * row primary compact * ~ </div>truehttp://www.mainstayfunds.com/role/AverageAnnualTotalReturnsMainstayHighYieldCorporateBondFundTransposed000070 - Schedule - Average Annual Total Returns {Transposed}truefalsefalse1falseColumnprimaryElement*3false 5rr_AverageAnnualReturnLabelrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabelxbrli:stringItemTypestringThis item represents Average Anuual Total Returns. If a Multiple Class Fund offers a Class in the prospectus that converts into another Class after a stated period, compute average annual total returns in the table by using the returns of the other Class for the period after conversion.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph iii -Clause 1 -Exhibit 2 false0Average Annual Returns, Label USDfalsefalse$2falseColumnprimaryElement*4false 5rr_AverageAnnualReturnYear01rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabelxbrli:pureItemTypepureReturn Before Taxes.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph iii -Clause 1 -Exhibit 2 false0Average Annual Returns, 1 Year USDfalsefalse$3falseColumnprimaryElement*5false 5rr_AverageAnnualReturnYear05rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabelxbrli:pureItemTypepureReturn Before Taxes.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph iii -Clause 1 -Exhibit 2 false0Average Annual Returns, 5 Years USDfalsefalse$4falseColumnprimaryElement*6false 5rr_AverageAnnualReturnYear10rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabelxbrli:pureItemTypepureReturn Before Taxes.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph iii -Clause 1 -Exhibit 2 false0Average Annual Returns, 10 Years USDfalsefalse$1falseRowperiodPeriod*Rowdei_DocumentInformationDocumentAxisAxiscik0000787441_S000006896SummaryMemberRowdei_LegalEntityAxisAxiscik0000787441_S000006896MemberRowrr_ProspectusShareClassAxisAxis*Rowrr_PerformanceMeasureAxisAxis*RowunitUnit*duration2012-10-31T00:00:002012-10-31T00:00:00falsefalsedei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldicik0000787441_S000006896SummaryMemberdei_DocumentInformationDocumentAxisexplicitMemberfalsefalsedei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldicik0000787441_S000006896Memberdei_LegalEntityAxisexplicitMemberfalsefalseClass R6rr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldicik0000787441_C000127160Memberrr_ProspectusShareClassAxisexplicitMembertruefalseBefore Taxesrr_PerformanceMeasureAxisrr_PerformanceMeasureDomainrr_PerformanceMeasureAxisexplicitMemberClass R6Before TaxespureStandardhttp://www.xbrl.org/2003/instancepurexbrli0Standard0 0truefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00<div><div style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 8pt; font-weight: normal;"><font style="font-family: times new roman,times; ; font-family: times new roman,times;" size="2">Class R6 Return Before Taxes</font></div></div>falsefalsefalse2truetruetrue0.13270.1327falsefalsefalse3truetruetrue0.07970.0797falsefalsefalse4truetruetrue0.10470.1047falsefalsefalsenanafalse0Class R62falseRowperiodPeriod*Rowdei_DocumentInformationDocumentAxisAxiscik0000787441_S000006896SummaryMemberRowdei_LegalEntityAxisAxiscik0000787441_S000006896MemberRowrr_ProspectusShareClassAxisAxis*Rowrr_PerformanceMeasureAxisAxis*RowunitUnit*duration2012-10-31T00:00:002012-10-31T00:00:00falsefalsedei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldicik0000787441_S000006896SummaryMemberdei_DocumentInformationDocumentAxisexplicitMemberfalsefalsedei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldicik0000787441_S000006896Memberdei_LegalEntityAxisexplicitMemberfalsefalseClass R6rr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldicik0000787441_C000127160Memberrr_ProspectusShareClassAxisexplicitMemberfalsefalseAfter Taxes on Distributionsrr_PerformanceMeasureAxisxbrldihttp://xbrl.org/2006/xbrldirr_AfterTaxesOnDistributionsMemberrr_PerformanceMeasureAxisexplicitMemberClass R6After Taxes on DistributionspureStandardhttp://www.xbrl.org/2003/instancepurexbrli0Standard0 0truefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00<p style="margin: 0in 0in 10pt;" class="msonormal"><font style="font-family: times new roman,times;" size="2">Class R6 Return After Taxes on Distributions</font></p>falsefalsefalse2truetruetrue0.10450.1045falsefalsefalse3truetruetrue0.05070.0507falsefalsefalse4truetruetrue0.07530.0753falsefalsefalsenanafalse0Class R6 After Taxes on Distributions3falseRowperiodPeriod*Rowdei_DocumentInformationDocumentAxisAxiscik0000787441_S000006896SummaryMemberRowdei_LegalEntityAxisAxiscik0000787441_S000006896MemberRowrr_ProspectusShareClassAxisAxis*Rowrr_PerformanceMeasureAxisAxis*RowunitUnit*duration2012-10-31T00:00:002012-10-31T00:00:00falsefalsedei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldicik0000787441_S000006896SummaryMemberdei_DocumentInformationDocumentAxisexplicitMemberfalsefalsedei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldicik0000787441_S000006896Memberdei_LegalEntityAxisexplicitMemberfalsefalseClass R6rr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldicik0000787441_C000127160Memberrr_ProspectusShareClassAxisexplicitMemberfalsefalseAfter Taxes on Distributions and Salesrr_PerformanceMeasureAxisxbrldihttp://xbrl.org/2006/xbrldirr_AfterTaxesOnDistributionsAndSalesMemberrr_PerformanceMeasureAxisexplicitMemberClass R6After Taxes on Distributions and SalespureStandardhttp://www.xbrl.org/2003/instancepurexbrli0Standard0 0truefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00<div><div style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 8pt; font-weight: normal;"><div><font style="font-family: times new roman,times;" size="2">Class R6 Return After Taxes on Distributions and Sale of Fund Shares</font></div></div></div>falsefalsefalse2truetruetrue0.08540.0854falsefalsefalse3truetruetrue0.05030.0503falsefalsefalse4truetruetrue0.07320.0732falsefalsefalsenanafalse0Class R6 After Taxes on Distributions and Sales4falseRowperiodPeriod*Rowdei_DocumentInformationDocumentAxisAxiscik0000787441_S000006896SummaryMemberRowdei_LegalEntityAxisAxiscik0000787441_S000006896MemberRowrr_ProspectusShareClassAxisAxis*Rowrr_PerformanceMeasureAxisAxis*RowunitUnit*duration2012-10-31T00:00:002012-10-31T00:00:00falsefalsedei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldicik0000787441_S000006896SummaryMemberdei_DocumentInformationDocumentAxisexplicitMemberfalsefalsedei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldicik0000787441_S000006896Memberdei_LegalEntityAxisexplicitMembertruefalseShare Classesrr_ProspectusShareClassAxisrr_ShareClassDomainrr_ProspectusShareClassAxisexplicitMemberfalsefalseCredit Suisse High Yield Indexrr_PerformanceMeasureAxisxbrldihttp://xbrl.org/2006/xbrldicik0000787441_RRINDEX00001Memberrr_PerformanceMeasureAxisexplicitMemberShare ClassesCredit Suisse High Yield IndexpureStandardhttp://www.xbrl.org/2003/instancepurexbrli0Standard0 0truefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00<div><div style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 8pt; font-weight: normal;"><font style="font-family: times new roman,times; ; font-family: times new roman,times;" size="2">Credit Suisse High Yield Index (reflects no deductions for fees, expenses, or taxes)</font></div></div>falsefalsefalse2truetruetrue0.14710.1471falsefalsefalse3truetruetrue0.09530.0953falsefalsefalse4truetruetrue0.10250.1025falsefalsefalsenanafalse0Credit Suisse High Yield IndexfalseAverage Annual Total Returns UnKnownUnKnownUnKnownUnKnownfalsefalsefalseSheet44121244056ColumnprimaryElement*RowperiodPeriod*Rowdei_DocumentInformationDocumentAxisAxiscik0000787441_S000006896SummaryMemberRowdei_LegalEntityAxisAxiscik0000787441_S000006896MemberRowrr_ProspectusShareClassAxisAxis*Rowrr_PerformanceMeasureAxisAxis*RowunitUnit*falsenonnum:textBlockItemTypenaContains a command for the SEC Viewer for the role corresponding to PerformanceTableData.No definition available.false0Performance [Table]30false 5rr_PerformanceTableClosingTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<div><div style="text-align: left; font-style: normal; font-family: sans-serif; font-size: 10pt; font-weight: normal;"><font style="font-family: times new roman,times;" size="2">After-tax returns are calculated using the highest individual federal marginal income tax rates in effect at the time of each distribution or capital gain or upon the sale of fund shares, and do not reflect the impact of state and local taxes. In some cases, the return after taxes may exceed the return before taxes due to an assumed tax benefit from any losses on a sale of shares at the end of the measurement period. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns are not relevant if you hold your shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns shown are for Class R6 shares. After-tax returns for the other share classes may vary.</font></div></div>falsefalsefalsenonnum:textBlockItemTypenaIf 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 should show the returns of an appropriate broad-based 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: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph iii false0Performance Table, ClosingfalseRisk/Return Summary (MainStay High Yield Corporate Bond Fund) (MainStay High Yield Corporate Bond Fund (Prospectus Summary), MainStay High Yield Corporate Bond Fund)UnKnownUnKnownUnKnownUnKnowntruefalsefalseSheethttp://www.mainstayfunds.com/role/Riskreturnsummarymainstayhighyieldcorporatebondfundunlabeled130