2.4.0.8000019 - Disclosure - Risk/Return Detail Data {Elements} - BMO Aggregate Bond Fundtruetruefalse1false falsefalseDuration_29Dec2011_28Dec2012http://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:001true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:2false 3dei_EntityRegistrantNamedei_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00BMO FUNDS, INC.falsefalsefalsexbrli:normalizedStringItemTypenormalizedstringThe exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation 12B -Number 240 -Section 12b -Subsection 1 false0Registrant Name3false 3rr_ProspectusDaterr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002012-12-28falsefalsetruexbrli:dateItemTypedateThe date of the prospectus.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 1 -Subsection a -Paragraph 3 false0Prospectus Date4false 3mfibmo_SupplementTextBlockmfibmo_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<center>BMO FUNDS, INC.</center>Prospectus SupplementJune 14, 2013To Prospectus Dated December 29, 2012, as supplemented April 9, 2013 and May 10, 2013 BMO Funds is making certain updates to its Prospectus. Accordingly, the Funds Prospectus is revised as follows, effective immediately:Elimination of Redemption Fee for Certain BMO FundsThe 2.00% redemption fee relating to redemptions or exchanges of shares held less than 30 days after the purchase of such shares is eliminated for the following Funds: BMO Low Volatility Equity Fund, BMO Large-Cap Value Fund, BMO Dividend Income Fund, BMO Large-Cap Growth Fund, BMO Mid-Cap Value Fund, BMO Mid-Cap Growth Fund, BMO Small-Cap Value Fund, BMO Small-Cap Growth Fund, BMO Short Tax-Free Fund, BMO Short-Term Income Fund, BMO Short-Intermediate Bond Fund, BMO Intermediate Tax-Free Fund, BMO Government Income Fund, BMO TCH Corporate Income Fund, BMO Aggregate Bond Fund, BMO TCH Core Plus Bond Fund, and BMO Monegy High Yield Bond Fund. Accordingly, the line item for Redemption Fee in the table under Fund SummaryFees and Expenses of the Fund in the Prospectus for each of the above-referenced Funds is hereby changed from 2.00% to None.falsefalsefalsenonnum:textBlockItemTypenaSupplement.No definition available.false0Supplement [Text Block]5false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2false truefalseDuration_29Dec2011_28Dec2012BMOLargeCapValueFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Large-Cap Value Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOLargeCapValueFundMemberdei_LegalEntityAxisexplicitMembernanafalse0BMO Large-Cap Value Fund6true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:7false 3mfibmo_SupplementTextBlockmfibmo_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<center>BMO FUNDS, INC.</center>Prospectus SupplementJune 14, 2013To Prospectus Dated December 29, 2012, as supplemented April 9, 2013 and May 10, 2013 BMO Funds is making certain updates to its Prospectus. Accordingly, the Funds Prospectus is revised as follows, effective immediately:Elimination of Redemption Fee for Certain BMO FundsThe 2.00% redemption fee relating to redemptions or exchanges of shares held less than 30 days after the purchase of such shares is eliminated for the following Funds: BMO Low Volatility Equity Fund, BMO Large-Cap Value Fund, BMO Dividend Income Fund, BMO Large-Cap Growth Fund, BMO Mid-Cap Value Fund, BMO Mid-Cap Growth Fund, BMO Small-Cap Value Fund, BMO Small-Cap Growth Fund, BMO Short Tax-Free Fund, BMO Short-Term Income Fund, BMO Short-Intermediate Bond Fund, BMO Intermediate Tax-Free Fund, BMO Government Income Fund, BMO TCH Corporate Income Fund, BMO Aggregate Bond Fund, BMO TCH Core Plus Bond Fund, and BMO Monegy High Yield Bond Fund. Accordingly, the line item for Redemption Fee in the table under Fund SummaryFees and Expenses of the Fund in the Prospectus for each of the above-referenced Funds is hereby changed from 2.00% to None.falsefalsefalsenonnum:textBlockItemTypenaSupplement.No definition available.false0Supplement [Text Block]8false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse3false truefalseDuration_29Dec2011_28Dec2012C000049007_MemberBMOLargeCapValueFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Large-Cap Value Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOLargeCapValueFundMemberdei_LegalEntityAxisexplicitMemberfalsefalseClass Yrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049007Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO Large-Cap Value Fund | Class Y9true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:10false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)11false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse4false truefalseDuration_29Dec2011_28Dec2012C000049008_MemberBMOLargeCapValueFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Large-Cap Value Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOLargeCapValueFundMemberdei_LegalEntityAxisexplicitMemberfalsefalseClass Irr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049008Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO Large-Cap Value Fund | Class I12true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:13false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)14false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse5false truefalseDuration_29Dec2011_28Dec2012BMOLargeCapGrowthFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Large-Cap Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOLargeCapGrowthFundMemberdei_LegalEntityAxisexplicitMembernanafalse0BMO Large-Cap Growth Fund15true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:16false 3mfibmo_SupplementTextBlockmfibmo_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<center>BMO FUNDS, INC.</center>Prospectus SupplementJune 14, 2013To Prospectus Dated December 29, 2012, as supplemented April 9, 2013 and May 10, 2013 BMO Funds is making certain updates to its Prospectus. Accordingly, the Funds Prospectus is revised as follows, effective immediately:Elimination of Redemption Fee for Certain BMO FundsThe 2.00% redemption fee relating to redemptions or exchanges of shares held less than 30 days after the purchase of such shares is eliminated for the following Funds: BMO Low Volatility Equity Fund, BMO Large-Cap Value Fund, BMO Dividend Income Fund, BMO Large-Cap Growth Fund, BMO Mid-Cap Value Fund, BMO Mid-Cap Growth Fund, BMO Small-Cap Value Fund, BMO Small-Cap Growth Fund, BMO Short Tax-Free Fund, BMO Short-Term Income Fund, BMO Short-Intermediate Bond Fund, BMO Intermediate Tax-Free Fund, BMO Government Income Fund, BMO TCH Corporate Income Fund, BMO Aggregate Bond Fund, BMO TCH Core Plus Bond Fund, and BMO Monegy High Yield Bond Fund. Accordingly, the line item for Redemption Fee in the table under Fund SummaryFees and Expenses of the Fund in the Prospectus for each of the above-referenced Funds is hereby changed from 2.00% to None.falsefalsefalsenonnum:textBlockItemTypenaSupplement.No definition available.false0Supplement [Text Block]17false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse6false truefalseDuration_29Dec2011_28Dec2012C000049007_MemberBMOLargeCapGrowthFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Large-Cap Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOLargeCapGrowthFundMemberdei_LegalEntityAxisexplicitMemberfalsefalseClass Yrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049007Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO Large-Cap Growth Fund | Class Y18true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:19false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)20false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse7false truefalseDuration_29Dec2011_28Dec2012C000049008_MemberBMOLargeCapGrowthFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Large-Cap Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOLargeCapGrowthFundMemberdei_LegalEntityAxisexplicitMemberfalsefalseClass Irr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049008Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO Large-Cap Growth Fund | Class I21true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:22false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)23false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse8false truefalseDuration_29Dec2011_28Dec2012BMOMidCapValueFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Mid-Cap Value Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOMidCapValueFundMemberdei_LegalEntityAxisexplicitMembernanafalse0BMO Mid-Cap Value Fund24true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:25false 3mfibmo_SupplementTextBlockmfibmo_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<center>BMO FUNDS, INC.</center>Prospectus SupplementJune 14, 2013To Prospectus Dated December 29, 2012, as supplemented April 9, 2013 and May 10, 2013 BMO Funds is making certain updates to its Prospectus. Accordingly, the Funds Prospectus is revised as follows, effective immediately:Elimination of Redemption Fee for Certain BMO FundsThe 2.00% redemption fee relating to redemptions or exchanges of shares held less than 30 days after the purchase of such shares is eliminated for the following Funds: BMO Low Volatility Equity Fund, BMO Large-Cap Value Fund, BMO Dividend Income Fund, BMO Large-Cap Growth Fund, BMO Mid-Cap Value Fund, BMO Mid-Cap Growth Fund, BMO Small-Cap Value Fund, BMO Small-Cap Growth Fund, BMO Short Tax-Free Fund, BMO Short-Term Income Fund, BMO Short-Intermediate Bond Fund, BMO Intermediate Tax-Free Fund, BMO Government Income Fund, BMO TCH Corporate Income Fund, BMO Aggregate Bond Fund, BMO TCH Core Plus Bond Fund, and BMO Monegy High Yield Bond Fund. Accordingly, the line item for Redemption Fee in the table under Fund SummaryFees and Expenses of the Fund in the Prospectus for each of the above-referenced Funds is hereby changed from 2.00% to None.falsefalsefalsenonnum:textBlockItemTypenaSupplement.No definition available.false0Supplement [Text Block]26false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse9false truefalseDuration_29Dec2011_28Dec2012C000049007_MemberBMOMidCapValueFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Mid-Cap Value Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOMidCapValueFundMemberdei_LegalEntityAxisexplicitMemberfalsefalseClass Yrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049007Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO Mid-Cap Value Fund | Class Y27true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:28false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)29false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse10false truefalseDuration_29Dec2011_28Dec2012C000049008_MemberBMOMidCapValueFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Mid-Cap Value Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOMidCapValueFundMemberdei_LegalEntityAxisexplicitMemberfalsefalseClass Irr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049008Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO Mid-Cap Value Fund | Class I30true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:31false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)32false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse11false truefalseDuration_29Dec2011_28Dec2012BMOMidCapGrowthFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Mid-Cap Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOMidCapGrowthFundMemberdei_LegalEntityAxisexplicitMembernanafalse0BMO Mid-Cap Growth Fund33true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:34false 3mfibmo_SupplementTextBlockmfibmo_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<center>BMO FUNDS, INC.</center>Prospectus SupplementJune 14, 2013To Prospectus Dated December 29, 2012, as supplemented April 9, 2013 and May 10, 2013 BMO Funds is making certain updates to its Prospectus. Accordingly, the Funds Prospectus is revised as follows, effective immediately:Elimination of Redemption Fee for Certain BMO FundsThe 2.00% redemption fee relating to redemptions or exchanges of shares held less than 30 days after the purchase of such shares is eliminated for the following Funds: BMO Low Volatility Equity Fund, BMO Large-Cap Value Fund, BMO Dividend Income Fund, BMO Large-Cap Growth Fund, BMO Mid-Cap Value Fund, BMO Mid-Cap Growth Fund, BMO Small-Cap Value Fund, BMO Small-Cap Growth Fund, BMO Short Tax-Free Fund, BMO Short-Term Income Fund, BMO Short-Intermediate Bond Fund, BMO Intermediate Tax-Free Fund, BMO Government Income Fund, BMO TCH Corporate Income Fund, BMO Aggregate Bond Fund, BMO TCH Core Plus Bond Fund, and BMO Monegy High Yield Bond Fund. Accordingly, the line item for Redemption Fee in the table under Fund SummaryFees and Expenses of the Fund in the Prospectus for each of the above-referenced Funds is hereby changed from 2.00% to None.falsefalsefalsenonnum:textBlockItemTypenaSupplement.No definition available.false0Supplement [Text Block]35false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse12false truefalseDuration_29Dec2011_28Dec2012C000049007_MemberBMOMidCapGrowthFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Mid-Cap Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOMidCapGrowthFundMemberdei_LegalEntityAxisexplicitMemberfalsefalseClass Yrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049007Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO Mid-Cap Growth Fund | Class Y36true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:37false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)38false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse13false truefalseDuration_29Dec2011_28Dec2012C000049008_MemberBMOMidCapGrowthFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Mid-Cap Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOMidCapGrowthFundMemberdei_LegalEntityAxisexplicitMemberfalsefalseClass Irr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049008Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO Mid-Cap Growth Fund | Class I39true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:40false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)41false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse14false truefalseDuration_29Dec2011_28Dec2012BMOSmallCapGrowthFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Small-Cap Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOSmallCapGrowthFundMemberdei_LegalEntityAxisexplicitMembernanafalse0BMO Small-Cap Growth Fund42true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:43false 3mfibmo_SupplementTextBlockmfibmo_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<center>BMO FUNDS, INC.</center>Prospectus SupplementJune 14, 2013To Prospectus Dated December 29, 2012, as supplemented April 9, 2013 and May 10, 2013 BMO Funds is making certain updates to its Prospectus. Accordingly, the Funds Prospectus is revised as follows, effective immediately:Elimination of Redemption Fee for Certain BMO FundsThe 2.00% redemption fee relating to redemptions or exchanges of shares held less than 30 days after the purchase of such shares is eliminated for the following Funds: BMO Low Volatility Equity Fund, BMO Large-Cap Value Fund, BMO Dividend Income Fund, BMO Large-Cap Growth Fund, BMO Mid-Cap Value Fund, BMO Mid-Cap Growth Fund, BMO Small-Cap Value Fund, BMO Small-Cap Growth Fund, BMO Short Tax-Free Fund, BMO Short-Term Income Fund, BMO Short-Intermediate Bond Fund, BMO Intermediate Tax-Free Fund, BMO Government Income Fund, BMO TCH Corporate Income Fund, BMO Aggregate Bond Fund, BMO TCH Core Plus Bond Fund, and BMO Monegy High Yield Bond Fund. Accordingly, the line item for Redemption Fee in the table under Fund SummaryFees and Expenses of the Fund in the Prospectus for each of the above-referenced Funds is hereby changed from 2.00% to None.falsefalsefalsenonnum:textBlockItemTypenaSupplement.No definition available.false0Supplement [Text Block]44false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse15false truefalseDuration_29Dec2011_28Dec2012C000049007_MemberBMOSmallCapGrowthFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Small-Cap Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOSmallCapGrowthFundMemberdei_LegalEntityAxisexplicitMemberfalsefalseClass Yrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049007Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO Small-Cap Growth Fund | Class Y45true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:46false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)47false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse16false truefalseDuration_29Dec2011_28Dec2012C000049008_MemberBMOSmallCapGrowthFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Small-Cap Growth Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOSmallCapGrowthFundMemberdei_LegalEntityAxisexplicitMemberfalsefalseClass Irr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049008Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO Small-Cap Growth Fund | Class I48true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:49false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)50false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse17false truefalseDuration_29Dec2011_28Dec2012BMOGovernmentIncomeFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Government Income Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOGovernmentIncomeFundMemberdei_LegalEntityAxisexplicitMembernanafalse0BMO Government Income Fund51true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:52false 3mfibmo_SupplementTextBlockmfibmo_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<center>BMO FUNDS, INC.</center>Prospectus SupplementJune 14, 2013To Prospectus Dated December 29, 2012, as supplemented April 9, 2013 and May 10, 2013 BMO Funds is making certain updates to its Prospectus. Accordingly, the Funds Prospectus is revised as follows, effective immediately:Elimination of Redemption Fee for Certain BMO FundsThe 2.00% redemption fee relating to redemptions or exchanges of shares held less than 30 days after the purchase of such shares is eliminated for the following Funds: BMO Low Volatility Equity Fund, BMO Large-Cap Value Fund, BMO Dividend Income Fund, BMO Large-Cap Growth Fund, BMO Mid-Cap Value Fund, BMO Mid-Cap Growth Fund, BMO Small-Cap Value Fund, BMO Small-Cap Growth Fund, BMO Short Tax-Free Fund, BMO Short-Term Income Fund, BMO Short-Intermediate Bond Fund, BMO Intermediate Tax-Free Fund, BMO Government Income Fund, BMO TCH Corporate Income Fund, BMO Aggregate Bond Fund, BMO TCH Core Plus Bond Fund, and BMO Monegy High Yield Bond Fund. Accordingly, the line item for Redemption Fee in the table under Fund SummaryFees and Expenses of the Fund in the Prospectus for each of the above-referenced Funds is hereby changed from 2.00% to None.falsefalsefalsenonnum:textBlockItemTypenaSupplement.No definition available.false0Supplement [Text Block]53false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse18false truefalseDuration_29Dec2011_28Dec2012C000049007_MemberBMOGovernmentIncomeFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Government Income Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOGovernmentIncomeFundMemberdei_LegalEntityAxisexplicitMemberfalsefalseClass Yrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049007Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO Government Income Fund | Class Y54true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:55false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)56false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse19false truefalseDuration_29Dec2011_28Dec2012C000049008_MemberBMOGovernmentIncomeFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Government Income Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOGovernmentIncomeFundMemberdei_LegalEntityAxisexplicitMemberfalsefalseClass Irr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049008Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO Government Income Fund | Class I57true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:58false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)59false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse20false truefalseDuration_29Dec2011_28Dec2012BMOShortIntermediateBondFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Short-Intermediate Bond Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOShortIntermediateBondFundMemberdei_LegalEntityAxisexplicitMembernanafalse0BMO Short-Intermediate Bond Fund60true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:61false 3mfibmo_SupplementTextBlockmfibmo_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<center>BMO FUNDS, INC.</center>Prospectus SupplementJune 14, 2013To Prospectus Dated December 29, 2012, as supplemented April 9, 2013 and May 10, 2013 BMO Funds is making certain updates to its Prospectus. Accordingly, the Funds Prospectus is revised as follows, effective immediately:Elimination of Redemption Fee for Certain BMO FundsThe 2.00% redemption fee relating to redemptions or exchanges of shares held less than 30 days after the purchase of such shares is eliminated for the following Funds: BMO Low Volatility Equity Fund, BMO Large-Cap Value Fund, BMO Dividend Income Fund, BMO Large-Cap Growth Fund, BMO Mid-Cap Value Fund, BMO Mid-Cap Growth Fund, BMO Small-Cap Value Fund, BMO Small-Cap Growth Fund, BMO Short Tax-Free Fund, BMO Short-Term Income Fund, BMO Short-Intermediate Bond Fund, BMO Intermediate Tax-Free Fund, BMO Government Income Fund, BMO TCH Corporate Income Fund, BMO Aggregate Bond Fund, BMO TCH Core Plus Bond Fund, and BMO Monegy High Yield Bond Fund. Accordingly, the line item for Redemption Fee in the table under Fund SummaryFees and Expenses of the Fund in the Prospectus for each of the above-referenced Funds is hereby changed from 2.00% to None.falsefalsefalsenonnum:textBlockItemTypenaSupplement.No definition available.false0Supplement [Text Block]62false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse21false truefalseDuration_29Dec2011_28Dec2012C000049007_MemberBMOShortIntermediateBondFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Short-Intermediate Bond Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOShortIntermediateBondFundMemberdei_LegalEntityAxisexplicitMemberfalsefalseClass Yrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049007Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO Short-Intermediate Bond Fund | Class Y63true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:64false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)65false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse22false truefalseDuration_29Dec2011_28Dec2012C000049008_MemberBMOShortIntermediateBondFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Short-Intermediate Bond Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOShortIntermediateBondFundMemberdei_LegalEntityAxisexplicitMemberfalsefalseClass Irr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049008Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO Short-Intermediate Bond Fund | Class I66true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:67false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)68false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse23false truefalseDuration_29Dec2011_28Dec2012BMOIntermediateTaxFreeFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Intermediate Tax-Free Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOIntermediateTaxFreeFundMemberdei_LegalEntityAxisexplicitMembernanafalse0BMO Intermediate Tax-Free Fund69true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:70false 3mfibmo_SupplementTextBlockmfibmo_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<center>BMO FUNDS, INC.</center>Prospectus SupplementJune 14, 2013To Prospectus Dated December 29, 2012, as supplemented April 9, 2013 and May 10, 2013 BMO Funds is making certain updates to its Prospectus. Accordingly, the Funds Prospectus is revised as follows, effective immediately:Elimination of Redemption Fee for Certain BMO FundsThe 2.00% redemption fee relating to redemptions or exchanges of shares held less than 30 days after the purchase of such shares is eliminated for the following Funds: BMO Low Volatility Equity Fund, BMO Large-Cap Value Fund, BMO Dividend Income Fund, BMO Large-Cap Growth Fund, BMO Mid-Cap Value Fund, BMO Mid-Cap Growth Fund, BMO Small-Cap Value Fund, BMO Small-Cap Growth Fund, BMO Short Tax-Free Fund, BMO Short-Term Income Fund, BMO Short-Intermediate Bond Fund, BMO Intermediate Tax-Free Fund, BMO Government Income Fund, BMO TCH Corporate Income Fund, BMO Aggregate Bond Fund, BMO TCH Core Plus Bond Fund, and BMO Monegy High Yield Bond Fund. Accordingly, the line item for Redemption Fee in the table under Fund SummaryFees and Expenses of the Fund in the Prospectus for each of the above-referenced Funds is hereby changed from 2.00% to None.falsefalsefalsenonnum:textBlockItemTypenaSupplement.No definition available.false0Supplement [Text Block]71false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse24false truefalseDuration_29Dec2011_28Dec2012C000049007_MemberBMOIntermediateTaxFreeFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Intermediate Tax-Free Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOIntermediateTaxFreeFundMemberdei_LegalEntityAxisexplicitMemberfalsefalseClass Yrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049007Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO Intermediate Tax-Free Fund | Class Y72true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:73false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)74false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse25false truefalseDuration_29Dec2011_28Dec2012C000049008_MemberBMOIntermediateTaxFreeFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Intermediate Tax-Free Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOIntermediateTaxFreeFundMemberdei_LegalEntityAxisexplicitMemberfalsefalseClass Irr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049008Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO Intermediate Tax-Free Fund | Class I75true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:76false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)77false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse26false truefalseDuration_29Dec2011_28Dec2012BMOShortTermIncomeFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Short-Term Income Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOShortTermIncomeFundMemberdei_LegalEntityAxisexplicitMembernanafalse0BMO Short-Term Income Fund78true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:79false 3mfibmo_SupplementTextBlockmfibmo_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<center>BMO FUNDS, INC.</center>Prospectus SupplementJune 14, 2013To Prospectus Dated December 29, 2012, as supplemented April 9, 2013 and May 10, 2013 BMO Funds is making certain updates to its Prospectus. Accordingly, the Funds Prospectus is revised as follows, effective immediately:Elimination of Redemption Fee for Certain BMO FundsThe 2.00% redemption fee relating to redemptions or exchanges of shares held less than 30 days after the purchase of such shares is eliminated for the following Funds: BMO Low Volatility Equity Fund, BMO Large-Cap Value Fund, BMO Dividend Income Fund, BMO Large-Cap Growth Fund, BMO Mid-Cap Value Fund, BMO Mid-Cap Growth Fund, BMO Small-Cap Value Fund, BMO Small-Cap Growth Fund, BMO Short Tax-Free Fund, BMO Short-Term Income Fund, BMO Short-Intermediate Bond Fund, BMO Intermediate Tax-Free Fund, BMO Government Income Fund, BMO TCH Corporate Income Fund, BMO Aggregate Bond Fund, BMO TCH Core Plus Bond Fund, and BMO Monegy High Yield Bond Fund. Accordingly, the line item for Redemption Fee in the table under Fund SummaryFees and Expenses of the Fund in the Prospectus for each of the above-referenced Funds is hereby changed from 2.00% to None.falsefalsefalsenonnum:textBlockItemTypenaSupplement.No definition available.false0Supplement [Text Block]80false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse27false truefalseDuration_29Dec2011_28Dec2012C000049007_MemberBMOShortTermIncomeFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Short-Term Income Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOShortTermIncomeFundMemberdei_LegalEntityAxisexplicitMemberfalsefalseClass Yrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049007Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO Short-Term Income Fund | Class Y81true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:82false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)83false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse28false truefalseDuration_29Dec2011_28Dec2012C000049008_MemberBMOShortTermIncomeFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Short-Term Income Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOShortTermIncomeFundMemberdei_LegalEntityAxisexplicitMemberfalsefalseClass Irr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049008Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO Short-Term Income Fund | Class I84true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:85false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)86false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse29false truefalseDuration_29Dec2011_28Dec2012S000017748_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Aggregate Bond Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_S000017748Memberdei_LegalEntityAxisexplicitMembernanafalse0BMO Aggregate Bond Fund87true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:88false 3mfibmo_SupplementTextBlockmfibmo_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<center>BMO FUNDS, INC.</center>Prospectus SupplementJune 14, 2013To Prospectus Dated December 29, 2012, as supplemented April 9, 2013 and May 10, 2013 BMO Funds is making certain updates to its Prospectus. Accordingly, the Funds Prospectus is revised as follows, effective immediately:Elimination of Redemption Fee for Certain BMO FundsThe 2.00% redemption fee relating to redemptions or exchanges of shares held less than 30 days after the purchase of such shares is eliminated for the following Funds: BMO Low Volatility Equity Fund, BMO Large-Cap Value Fund, BMO Dividend Income Fund, BMO Large-Cap Growth Fund, BMO Mid-Cap Value Fund, BMO Mid-Cap Growth Fund, BMO Small-Cap Value Fund, BMO Small-Cap Growth Fund, BMO Short Tax-Free Fund, BMO Short-Term Income Fund, BMO Short-Intermediate Bond Fund, BMO Intermediate Tax-Free Fund, BMO Government Income Fund, BMO TCH Corporate Income Fund, BMO Aggregate Bond Fund, BMO TCH Core Plus Bond Fund, and BMO Monegy High Yield Bond Fund. Accordingly, the line item for Redemption Fee in the table under Fund SummaryFees and Expenses of the Fund in the Prospectus for each of the above-referenced Funds is hereby changed from 2.00% to None.falsefalsefalsenonnum:textBlockItemTypenaSupplement.No definition available.false0Supplement [Text Block]89false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse30false truefalseDuration_29Dec2011_28Dec2012S000017748_MemberC000049007_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Aggregate Bond Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_S000017748Memberdei_LegalEntityAxisexplicitMemberfalsefalseClass Yrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049007Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO Aggregate Bond Fund | Class Y90true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:91false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)92false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse31false truefalseDuration_29Dec2011_28Dec2012S000017748_MemberC000049008_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Aggregate Bond Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_S000017748Memberdei_LegalEntityAxisexplicitMemberfalsefalseClass Irr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049008Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO Aggregate Bond Fund | Class I93true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:94false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)95false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse32false truefalseDuration_29Dec2011_28Dec2012BMOTCHCorePlusBondFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO TCH Core Plus Bond Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOTCHCorePlusBondFundMemberdei_LegalEntityAxisexplicitMembernanafalse0BMO TCH Core Plus Bond Fund96true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:97false 3mfibmo_SupplementTextBlockmfibmo_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<center>BMO FUNDS, INC.</center>Prospectus SupplementJune 14, 2013To Prospectus Dated December 29, 2012, as supplemented April 9, 2013 and May 10, 2013 BMO Funds is making certain updates to its Prospectus. Accordingly, the Funds Prospectus is revised as follows, effective immediately:Elimination of Redemption Fee for Certain BMO FundsThe 2.00% redemption fee relating to redemptions or exchanges of shares held less than 30 days after the purchase of such shares is eliminated for the following Funds: BMO Low Volatility Equity Fund, BMO Large-Cap Value Fund, BMO Dividend Income Fund, BMO Large-Cap Growth Fund, BMO Mid-Cap Value Fund, BMO Mid-Cap Growth Fund, BMO Small-Cap Value Fund, BMO Small-Cap Growth Fund, BMO Short Tax-Free Fund, BMO Short-Term Income Fund, BMO Short-Intermediate Bond Fund, BMO Intermediate Tax-Free Fund, BMO Government Income Fund, BMO TCH Corporate Income Fund, BMO Aggregate Bond Fund, BMO TCH Core Plus Bond Fund, and BMO Monegy High Yield Bond Fund. Accordingly, the line item for Redemption Fee in the table under Fund SummaryFees and Expenses of the Fund in the Prospectus for each of the above-referenced Funds is hereby changed from 2.00% to None.falsefalsefalsenonnum:textBlockItemTypenaSupplement.No definition available.false0Supplement [Text Block]98false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse33false truefalseDuration_29Dec2011_28Dec2012C000049007_MemberBMOTCHCorePlusBondFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO TCH Core Plus Bond Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOTCHCorePlusBondFundMemberdei_LegalEntityAxisexplicitMemberfalsefalseClass Yrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049007Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO TCH Core Plus Bond Fund | Class Y99true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:100false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)101false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse34false truefalseDuration_29Dec2011_28Dec2012C000049008_MemberBMOTCHCorePlusBondFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO TCH Core Plus Bond Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOTCHCorePlusBondFundMemberdei_LegalEntityAxisexplicitMemberfalsefalseClass Irr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049008Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO TCH Core Plus Bond Fund | Class I102true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:103false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)104false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse35false truefalseDuration_29Dec2011_28Dec2012BMOTCHCorporateIncomeFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO TCH Corporate Income Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOTCHCorporateIncomeFundMemberdei_LegalEntityAxisexplicitMembernanafalse0BMO TCH Corporate Income Fund105true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:106false 3mfibmo_SupplementTextBlockmfibmo_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<center>BMO FUNDS, INC.</center>Prospectus SupplementJune 14, 2013To Prospectus Dated December 29, 2012, as supplemented April 9, 2013 and May 10, 2013 BMO Funds is making certain updates to its Prospectus. Accordingly, the Funds Prospectus is revised as follows, effective immediately:Elimination of Redemption Fee for Certain BMO FundsThe 2.00% redemption fee relating to redemptions or exchanges of shares held less than 30 days after the purchase of such shares is eliminated for the following Funds: BMO Low Volatility Equity Fund, BMO Large-Cap Value Fund, BMO Dividend Income Fund, BMO Large-Cap Growth Fund, BMO Mid-Cap Value Fund, BMO Mid-Cap Growth Fund, BMO Small-Cap Value Fund, BMO Small-Cap Growth Fund, BMO Short Tax-Free Fund, BMO Short-Term Income Fund, BMO Short-Intermediate Bond Fund, BMO Intermediate Tax-Free Fund, BMO Government Income Fund, BMO TCH Corporate Income Fund, BMO Aggregate Bond Fund, BMO TCH Core Plus Bond Fund, and BMO Monegy High Yield Bond Fund. Accordingly, the line item for Redemption Fee in the table under Fund SummaryFees and Expenses of the Fund in the Prospectus for each of the above-referenced Funds is hereby changed from 2.00% to None.falsefalsefalsenonnum:textBlockItemTypenaSupplement.No definition available.false0Supplement [Text Block]107false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse36false truefalseDuration_29Dec2011_28Dec2012C000049007_MemberBMOTCHCorporateIncomeFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO TCH Corporate Income Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOTCHCorporateIncomeFundMemberdei_LegalEntityAxisexplicitMemberfalsefalseClass Yrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049007Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO TCH Corporate Income Fund | Class Y108true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:109false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)110false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse37false truefalseDuration_29Dec2011_28Dec2012C000049008_MemberBMOTCHCorporateIncomeFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO TCH Corporate Income Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOTCHCorporateIncomeFundMemberdei_LegalEntityAxisexplicitMemberfalsefalseClass Irr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049008Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO TCH Corporate Income Fund | Class I111true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:112false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)113false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse38false truefalseDuration_29Dec2011_28Dec2012BMOSmallCapValueFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Small-Cap Value Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOSmallCapValueFundMemberdei_LegalEntityAxisexplicitMembernanafalse0BMO Small-Cap Value Fund114true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:115false 3mfibmo_SupplementTextBlockmfibmo_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<center>BMO FUNDS, INC.</center>Prospectus SupplementJune 14, 2013To Prospectus Dated December 29, 2012, as supplemented April 9, 2013 and May 10, 2013 BMO Funds is making certain updates to its Prospectus. Accordingly, the Funds Prospectus is revised as follows, effective immediately:Elimination of Redemption Fee for Certain BMO FundsThe 2.00% redemption fee relating to redemptions or exchanges of shares held less than 30 days after the purchase of such shares is eliminated for the following Funds: BMO Low Volatility Equity Fund, BMO Large-Cap Value Fund, BMO Dividend Income Fund, BMO Large-Cap Growth Fund, BMO Mid-Cap Value Fund, BMO Mid-Cap Growth Fund, BMO Small-Cap Value Fund, BMO Small-Cap Growth Fund, BMO Short Tax-Free Fund, BMO Short-Term Income Fund, BMO Short-Intermediate Bond Fund, BMO Intermediate Tax-Free Fund, BMO Government Income Fund, BMO TCH Corporate Income Fund, BMO Aggregate Bond Fund, BMO TCH Core Plus Bond Fund, and BMO Monegy High Yield Bond Fund. Accordingly, the line item for Redemption Fee in the table under Fund SummaryFees and Expenses of the Fund in the Prospectus for each of the above-referenced Funds is hereby changed from 2.00% to None.falsefalsefalsenonnum:textBlockItemTypenaSupplement.No definition available.false0Supplement [Text Block]116false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse39false truefalseDuration_29Dec2011_28Dec2012C000049007_MemberBMOSmallCapValueFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Small-Cap Value Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOSmallCapValueFundMemberdei_LegalEntityAxisexplicitMemberfalsefalseClass Yrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049007Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO Small-Cap Value Fund | Class Y117true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:118false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)119false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse40false truefalseDuration_29Dec2011_28Dec2012C000049008_MemberBMOSmallCapValueFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Small-Cap Value Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOSmallCapValueFundMemberdei_LegalEntityAxisexplicitMemberfalsefalseClass Irr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049008Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO Small-Cap Value Fund | Class I120true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:121false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)122false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse41false truefalseDuration_29Dec2011_28Dec2012BMODividendIncomeFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Dividend Income Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMODividendIncomeFundMemberdei_LegalEntityAxisexplicitMembernanafalse0BMO Dividend Income Fund123true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:124false 3mfibmo_SupplementTextBlockmfibmo_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<center>BMO FUNDS, INC.</center>Prospectus SupplementJune 14, 2013To Prospectus Dated December 29, 2012, as supplemented April 9, 2013 and May 10, 2013 BMO Funds is making certain updates to its Prospectus. Accordingly, the Funds Prospectus is revised as follows, effective immediately:Elimination of Redemption Fee for Certain BMO FundsThe 2.00% redemption fee relating to redemptions or exchanges of shares held less than 30 days after the purchase of such shares is eliminated for the following Funds: BMO Low Volatility Equity Fund, BMO Large-Cap Value Fund, BMO Dividend Income Fund, BMO Large-Cap Growth Fund, BMO Mid-Cap Value Fund, BMO Mid-Cap Growth Fund, BMO Small-Cap Value Fund, BMO Small-Cap Growth Fund, BMO Short Tax-Free Fund, BMO Short-Term Income Fund, BMO Short-Intermediate Bond Fund, BMO Intermediate Tax-Free Fund, BMO Government Income Fund, BMO TCH Corporate Income Fund, BMO Aggregate Bond Fund, BMO TCH Core Plus Bond Fund, and BMO Monegy High Yield Bond Fund. Accordingly, the line item for Redemption Fee in the table under Fund SummaryFees and Expenses of the Fund in the Prospectus for each of the above-referenced Funds is hereby changed from 2.00% to None.falsefalsefalsenonnum:textBlockItemTypenaSupplement.No definition available.false0Supplement [Text Block]125false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse42false truefalseDuration_29Dec2011_28Dec2012C000049007_MemberBMODividendIncomeFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Dividend Income Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMODividendIncomeFundMemberdei_LegalEntityAxisexplicitMemberfalsefalseClass Yrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049007Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO Dividend Income Fund | Class Y126true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:127false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)128false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse43false truefalseDuration_29Dec2011_28Dec2012C000049008_MemberBMODividendIncomeFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Dividend Income Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMODividendIncomeFundMemberdei_LegalEntityAxisexplicitMemberfalsefalseClass Irr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049008Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO Dividend Income Fund | Class I129true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:130false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)131false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse44false truefalseDuration_29Dec2011_28Dec2012BMOMonegyHighYieldBondFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Monegy High Yield Bond Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOMonegyHighYieldBondFundMemberdei_LegalEntityAxisexplicitMembernanafalse0BMO Monegy High Yield Bond Fund132true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:133false 3mfibmo_SupplementTextBlockmfibmo_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<center>BMO FUNDS, INC.</center>Prospectus SupplementJune 14, 2013To Prospectus Dated December 29, 2012, as supplemented April 9, 2013 and May 10, 2013 BMO Funds is making certain updates to its Prospectus. Accordingly, the Funds Prospectus is revised as follows, effective immediately:Elimination of Redemption Fee for Certain BMO FundsThe 2.00% redemption fee relating to redemptions or exchanges of shares held less than 30 days after the purchase of such shares is eliminated for the following Funds: BMO Low Volatility Equity Fund, BMO Large-Cap Value Fund, BMO Dividend Income Fund, BMO Large-Cap Growth Fund, BMO Mid-Cap Value Fund, BMO Mid-Cap Growth Fund, BMO Small-Cap Value Fund, BMO Small-Cap Growth Fund, BMO Short Tax-Free Fund, BMO Short-Term Income Fund, BMO Short-Intermediate Bond Fund, BMO Intermediate Tax-Free Fund, BMO Government Income Fund, BMO TCH Corporate Income Fund, BMO Aggregate Bond Fund, BMO TCH Core Plus Bond Fund, and BMO Monegy High Yield Bond Fund. Accordingly, the line item for Redemption Fee in the table under Fund SummaryFees and Expenses of the Fund in the Prospectus for each of the above-referenced Funds is hereby changed from 2.00% to None.falsefalsefalsenonnum:textBlockItemTypenaSupplement.No definition available.false0Supplement [Text Block]134false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse45false truefalseDuration_29Dec2011_28Dec2012C000049007_MemberBMOMonegyHighYieldBondFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Monegy High Yield Bond Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOMonegyHighYieldBondFundMemberdei_LegalEntityAxisexplicitMemberfalsefalseClass Yrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049007Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO Monegy High Yield Bond Fund | Class Y135true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:136false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)137false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse46false truefalseDuration_29Dec2011_28Dec2012C000049008_MemberBMOMonegyHighYieldBondFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Monegy High Yield Bond Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOMonegyHighYieldBondFundMemberdei_LegalEntityAxisexplicitMemberfalsefalseClass Irr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049008Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO Monegy High Yield Bond Fund | Class I138true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:139false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)140false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse47false truefalseDuration_29Dec2011_28Dec2012BMOLowVolatilityEquityFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Low Volatility Equity Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOLowVolatilityEquityFundMemberdei_LegalEntityAxisexplicitMembernanafalse0BMO Low Volatility Equity Fund141true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:142false 3mfibmo_SupplementTextBlockmfibmo_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<center>BMO FUNDS, INC.</center>Prospectus SupplementJune 14, 2013To Prospectus Dated December 29, 2012, as supplemented April 9, 2013 and May 10, 2013 BMO Funds is making certain updates to its Prospectus. Accordingly, the Funds Prospectus is revised as follows, effective immediately:Elimination of Redemption Fee for Certain BMO FundsThe 2.00% redemption fee relating to redemptions or exchanges of shares held less than 30 days after the purchase of such shares is eliminated for the following Funds: BMO Low Volatility Equity Fund, BMO Large-Cap Value Fund, BMO Dividend Income Fund, BMO Large-Cap Growth Fund, BMO Mid-Cap Value Fund, BMO Mid-Cap Growth Fund, BMO Small-Cap Value Fund, BMO Small-Cap Growth Fund, BMO Short Tax-Free Fund, BMO Short-Term Income Fund, BMO Short-Intermediate Bond Fund, BMO Intermediate Tax-Free Fund, BMO Government Income Fund, BMO TCH Corporate Income Fund, BMO Aggregate Bond Fund, BMO TCH Core Plus Bond Fund, and BMO Monegy High Yield Bond Fund. Accordingly, the line item for Redemption Fee in the table under Fund SummaryFees and Expenses of the Fund in the Prospectus for each of the above-referenced Funds is hereby changed from 2.00% to None.falsefalsefalsenonnum:textBlockItemTypenaSupplement.No definition available.false0Supplement [Text Block]143false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse48false truefalseDuration_29Dec2011_28Dec2012C000049007_MemberBMOLowVolatilityEquityFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Low Volatility Equity Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOLowVolatilityEquityFundMemberdei_LegalEntityAxisexplicitMemberfalsefalseClass Yrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049007Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO Low Volatility Equity Fund | Class Y144true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:145false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)146false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse49false truefalseDuration_29Dec2011_28Dec2012C000049008_MemberBMOLowVolatilityEquityFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Low Volatility Equity Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOLowVolatilityEquityFundMemberdei_LegalEntityAxisexplicitMemberfalsefalseClass Irr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049008Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO Low Volatility Equity Fund | Class I147true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:148false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)149false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse50false truefalseDuration_29Dec2011_28Dec2012BMOShortTaxFreeFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Short Tax-Free Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOShortTaxFreeFundMemberdei_LegalEntityAxisexplicitMembernanafalse0BMO Short Tax-Free Fund150true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:151false 3mfibmo_SupplementTextBlockmfibmo_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<center>BMO FUNDS, INC.</center>Prospectus SupplementJune 14, 2013To Prospectus Dated December 29, 2012, as supplemented April 9, 2013 and May 10, 2013 BMO Funds is making certain updates to its Prospectus. Accordingly, the Funds Prospectus is revised as follows, effective immediately:Elimination of Redemption Fee for Certain BMO FundsThe 2.00% redemption fee relating to redemptions or exchanges of shares held less than 30 days after the purchase of such shares is eliminated for the following Funds: BMO Low Volatility Equity Fund, BMO Large-Cap Value Fund, BMO Dividend Income Fund, BMO Large-Cap Growth Fund, BMO Mid-Cap Value Fund, BMO Mid-Cap Growth Fund, BMO Small-Cap Value Fund, BMO Small-Cap Growth Fund, BMO Short Tax-Free Fund, BMO Short-Term Income Fund, BMO Short-Intermediate Bond Fund, BMO Intermediate Tax-Free Fund, BMO Government Income Fund, BMO TCH Corporate Income Fund, BMO Aggregate Bond Fund, BMO TCH Core Plus Bond Fund, and BMO Monegy High Yield Bond Fund. Accordingly, the line item for Redemption Fee in the table under Fund SummaryFees and Expenses of the Fund in the Prospectus for each of the above-referenced Funds is hereby changed from 2.00% to None.falsefalsefalsenonnum:textBlockItemTypenaSupplement.No definition available.false0Supplement [Text Block]152false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse51false truefalseDuration_29Dec2011_28Dec2012C000049007_MemberBMOShortTaxFreeFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Short Tax-Free Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOShortTaxFreeFundMemberdei_LegalEntityAxisexplicitMemberfalsefalseClass Yrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049007Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO Short Tax-Free Fund | Class Y153true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:154false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)155false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse52false truefalseDuration_29Dec2011_28Dec2012C000049008_MemberBMOShortTaxFreeFund_Memberhttp://www.sec.gov/CIK0000889366duration2011-12-29T00:00:002012-12-28T00:00:00falsefalseBMO Short Tax-Free Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_BMOShortTaxFreeFundMemberdei_LegalEntityAxisexplicitMemberfalsefalseClass Irr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldimfibmo_C000049008Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0BMO Short Tax-Free Fund | Class I156true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:157false 3rr_RedemptionFeeOverRedemptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue00falsefalsefalserr:NonPositivePure4Typepure"Redemption Fee" (as a percentage of amount redeemed, if applicable) If the Fund is an Exchange-Traded Fund and issues or redeems shares in creation units of not less than 25,000 shares each, exclude any fees charged for the purchase and redemption of the Fund's creation units. "Redemption Fee" includes a fee charged for any redemption of the Fund's shares, but does not include a deferred sales charge (load) imposed upon redemption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph b false0Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)falseRisk/Return Detail Data - BMO Aggregate Bond FundUnKnownUnKnownUnKnownUnKnowntruefalsefalseSheethttp://www.bmofundsus.com/role/DisclosureRiskReturnDetailDataElementsBMOAggregateBondFund1157