Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

BMO FUNDS, INC.

Prospectus Date

rr_ProspectusDate

Dec. 29, 2014

BMO Prime Money Market Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

BMO Prime Money Market Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective:

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

To provide current income consistent with stability of principal.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses of the Fund

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

December 31, 2015

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees

Total Annual Fund Operating Expenses shown will not correlate to the Fund’s ratio of expenses to average net assets appearing in the Financial Highlights tables, which do not include Acquired Fund Fees and Expenses.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses are as shown in the table and remain the same. Although your actual costs and returns may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund invests in high quality, short-term money market instruments, such as short-term commercial paper, corporate bonds and notes, asset-backed securities, bank instruments, demand and variable rate demand instruments, U.S. government obligations, municipal securities, repurchase agreements, and funding agreements. The Fund may invest in U.S. dollar-denominated instruments issued by foreign governments, corporations and financial institutions. The securities in which the Fund invests must be rated in one of the two highest short-term rating categories by one or more nationally recognized statistical rating organizations or be determined by the Adviser to be of comparable quality to securities having such ratings (except that U.S. Government securities and shares of other registered money market funds are not subject to this requirement). The Adviser uses a “bottom-up” approach, which evaluates debt securities of individual companies against the context of broader market factors such as the cyclical trend in interest rates, the shape of the yield curve, and debt security supply factors. The Fund invests in compliance with industry-standard regulatory requirements for money market funds for the quality, maturity, diversification, and liquidity of investments.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

An investment in the Fund is not a deposit of BMO Harris Bank N.A., or any of its affiliates, and is not insured or guaranteed by the FDIC or any other government agency. Although the Fund seeks to preserve the value of your investment at $1.00 per share, it is possible to lose money by investing in the Fund. In addition, the Fund is subject to the following risks.

Interest Rate Risks. Prices of fixed income securities rise and fall in response to changes in the interest rate paid by similar securities. Generally, when interest rates rise, prices of fixed income securities fall. Interest rate changes have a greater effect on the price of fixed income securities with longer maturities.

Credit Risks. Credit risk is the possibility that an issuer or counterparty will default on a security or repurchase agreement by failing to pay interest or principal when due. If an issuer defaults, the Fund may lose money. Lower credit ratings correspond to higher credit risk.

Call Risks. If the securities in which the Fund invests are redeemed by the issuer before maturity (or “called”), the Fund may have to reinvest the proceeds in securities that pay a lower interest rate, which may decrease the Fund’s yield. This will most likely happen when interest rates are declining.

Liquidity Risks. Liquidity risk refers to the possibility that the Fund may not be able to sell or buy a security or close out an investment contract at a favorable price or time. Consequently, the Fund may have to accept a lower price to sell a security, sell other securities to raise cash, or give up an investment opportunity, any of which could have a negative effect on the Fund’s performance. Infrequent trading of securities also may lead to an increase in their price volatility. Additionally, significant redemptions by large investors in the Fund could have a material adverse effect on the Fund’s other shareholders and the net asset value could be affected by forced selling during periods of high redemption pressures and/or illiquid markets.

Asset-Backed Securities Risks. Asset-backed securities are subject to risks of prepayment. The Fund’s yield will be reduced if cash from prepaid securities is reinvested in securities with lower interest rates. Asset-backed securities may decline in value because of defaults on the underlying obligations.

Government Obligations Risks. No assurance can be given that the U.S. government will provide financial support to U.S. government-sponsored agencies or instrumentalities where it is not obligated to do so by law. As a result, there is risk that these entities will default on a financial obligation.

Municipal Securities Risks. Municipal bonds are subject to risks based on many factors, including economic and regulatory developments, changes or proposed changes in the federal and state tax structure, deregulation, court rulings, and other factors. The value of municipal securities may be affected more by supply and demand factors or the creditworthiness of the issuer than by market interest rates. Repayment of municipal securities depends on the ability of the issuer or project backing such securities to generate taxes or revenues. There is a risk that interest may be taxable on a municipal security that is otherwise expected to produce tax-exempt interest.

Foreign Securities Risks. The value of instruments of foreign issuers may be adversely affected by political, regulatory, and economic developments, which developments may be similar to or greater than those experienced by domestic issuers. In addition, financial information relating to foreign issuers may be more limited than financial information generally available for domestic issuers.

Sovereign Debt Risks. Sovereign debt instruments are subject to the risk that a governmental entity may be unable to pay interest or repay principal on its sovereign debt due to cash flow problems, insufficient foreign currency reserves, or political concerns. If a governmental entity defaults on an obligation, the Fund may have limited recourse against the defaulting government and may lose its investment. Financial markets have recently experienced increased volatility due to the uncertainty surrounding the sovereign debt of certain European countries.

Regulatory Changes Risk. The SEC recently adopted regulations that substantially change the way in which money market funds may be operated. The Fund is reviewing the regulations and their impact, including liquidity of an investment in the Fund and the Fund’s ability to maintain a stable net asset value per share. These changes may result in reduced yields from the Fund.

Management Risks. The Adviser’s judgments about the attractiveness, value, and potential appreciation of the Fund’s investments may prove to be incorrect. Accordingly, no guarantee exists that the investment techniques used by the Fund’s managers will produce the desired results.

Risk Lose Money [Text]

rr_RiskLoseMoney

Although the Fund seeks to preserve the value of your investment at $1.00 per share, it is possible to lose money by investing in the Fund.

Risk Money Market Fund [Text]

rr_RiskMoneyMarketFund

Although the Fund seeks to preserve the value of your investment at $1.00 per share, it is possible to lose money by investing in the Fund.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a deposit of BMO Harris Bank N.A., or any of its affiliates, and is not insured or guaranteed by the FDIC or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Fund Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The bar chart and table show the historical performance of the Fund’s shares and provide some indication of the risks of investing in the Fund. The bar chart shows how the Fund’s total returns have varied from year to year, while the table compares the Fund’s average annual total returns to the returns of an average of money funds with similar objectives and an index of funds with similar investment objectives. Please keep in mind that past performance does not represent how the Fund will perform in the future. Investors may obtain the Fund’s current 7-Day Net Yield or updated performance information at www.bmofunds.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart and table show the historical performance of the Fund’s shares and provide some indication of the risks of investing in the Fund. The bar chart shows how the Fund’s total returns have varied from year to year, while the table compares the Fund’s average annual total returns to the returns of an average of money funds with similar objectives and an index of funds with similar investment objectives.

Performance Additional Market Index [Text]

rr_PerformanceAdditionalMarketIndex

The iMoneyNet, Inc. Money Fund Report Averages (MFRA) is an average of money funds with investment objectives similar to that of the Fund.

The Lipper Money Market Instrument Funds Index (LMMFI) tracks the total return performance of the 30 largest mutual funds included in this Lipper category.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.bmofunds.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Please keep in mind that past performance does not represent how the Fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Class Y—Annual Total Returns (calendar years 2004-2013)

Bar Chart Closing [Text Block]

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The return for the Class Y shares of the Fund from January 1, 2014 through September 30, 2014 was 0.01%.

During the periods shown in the bar chart for the Fund:

	Quarter Ended		Returns
Best quarter		9/30/2007		1.26	%
Worst quarter		3/31/2013		0.00	%

7-Day Net Yield as of December 31, 2013 was 0.01%

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns through 12/31/13

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

The iMoneyNet, Inc. Money Fund Report Averages (MFRA) is an average of money funds with investment objectives similar to that of the Fund.

The Lipper Money Market Instrument Funds Index (LMMFI) tracks the total return performance of the 30 largest mutual funds included in this Lipper category.

Money Market Seven Day Yield, Caption [Text]

rr_MoneyMarketSevenDayYieldCaption

7-Day Net Yield as of December 31, 2013

Money Market Seven Day Yield

rr_MoneyMarketSevenDayYield

0.01%

BMO Prime Money Market Fund | Class Y

Risk/Return:

rr_RiskReturnAbstract

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum Deferred Sales Charge (Load) (as a percentage of shares redeemed within 18 months of purchase)

rr_MaximumDeferredSalesChargeOverOther

none

Redemption Fee

rr_RedemptionFeeOverRedemption

none

Management Fees

rr_ManagementFeesOverAssets

0.14%

Distribution (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.31%

Acquired Fund Fees and Expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.01%

^[1]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

0.46%

^[2]

1 Year

rr_ExpenseExampleYear01

47

3 Years

rr_ExpenseExampleYear03

148

5 Years

rr_ExpenseExampleYear05

258

10 Years

rr_ExpenseExampleYear10

579

2004

rr_AnnualReturn2004

1.03%

2005

rr_AnnualReturn2005

2.91%

2006

rr_AnnualReturn2006

4.75%

2007

rr_AnnualReturn2007

5.01%

2008

rr_AnnualReturn2008

2.75%

2009

rr_AnnualReturn2009

0.44%

2010

rr_AnnualReturn2010

0.02%

2011

rr_AnnualReturn2011

0.01%

2012

rr_AnnualReturn2012

0.01%

2013

rr_AnnualReturn2013

0.01%

Year to Date Return, Label

rr_YearToDateReturnLabel

The return for the Class Y shares of the Fund from January 1, 2014 through September 30, 2014

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Sep. 30, 2014

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

0.01%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2007

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

1.26%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Mar. 31, 2013

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

0.00%

1 Year

rr_AverageAnnualReturnYear01

0.01%

5 Year

rr_AverageAnnualReturnYear05

0.10%

10 Year

rr_AverageAnnualReturnYear10

1.68%

Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 23, 1992

BMO Prime Money Market Fund | Class I

Risk/Return:

rr_RiskReturnAbstract

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum Deferred Sales Charge (Load) (as a percentage of shares redeemed within 18 months of purchase)

rr_MaximumDeferredSalesChargeOverOther

none

Redemption Fee

rr_RedemptionFeeOverRedemption

none

Management Fees

rr_ManagementFeesOverAssets

0.14%

Distribution (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.06%

Acquired Fund Fees and Expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.01%

^[1]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

0.21%

^[2]

1 Year

rr_ExpenseExampleYear01

22

3 Years

rr_ExpenseExampleYear03

68

5 Years

rr_ExpenseExampleYear05

118

10 Years

rr_ExpenseExampleYear10

268

1 Year

rr_AverageAnnualReturnYear01

0.04%

5 Year

rr_AverageAnnualReturnYear05

0.26%

10 Year

rr_AverageAnnualReturnYear10

1.89%

Inception Date

rr_AverageAnnualReturnInceptionDate

Apr. 03, 2000

BMO Prime Money Market Fund | MFRA (reflects deduction of fees and no deduction for sales charges or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

0.02%

5 Year

rr_AverageAnnualReturnYear05

0.06%

10 Year

rr_AverageAnnualReturnYear10

1.48%

BMO Prime Money Market Fund | LMMFI (reflects deduction of fees and no deduction for sales charges or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

0.01%

5 Year

rr_AverageAnnualReturnYear05

0.06%

10 Year

rr_AverageAnnualReturnYear10

1.53%

[1] Acquired Fund Fees and Expenses represent the pro rata expense indirectly incurred by the Fund as a result of its investment in other investment companies. Total Annual Fund Operating Expenses shown will not correlate to the Fund’s ratio of expenses to average net assets appearing in the Financial Highlights tables, which do not include Acquired Fund Fees and Expenses.

[2] BMO Asset Management Corp. (Adviser) has agreed to waive or reduce its investment advisory fee and reimburse expenses to the extent necessary to prevent class total annual operating expenses (excluding interest, taxes, brokerage commissions, other investment-related costs, and extraordinary expenses, such as litigation and other expenses not incurred in the ordinary course of the Fund's business, and Acquired Fund Fees and Expenses) from exceeding 0.45% for Class Y and 0.20% for Class I through December 31, 2015. This expense limitation agreement may not be terminated prior to December 31, 2015 without the consent of the Fund's Board of Directors, unless terminated due to the termination of the investment advisory agreement.