Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

BMO FUNDS, INC.

Prospectus Date

rr_ProspectusDate

Dec. 29, 2014

BMO Small-Cap Value Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

BMO Small-Cap Value Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective:

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

To provide capital appreciation.

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. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Class A shares of certain BMO Funds. More information about these and other discounts is available from your financial professional and under “How to Buy Shares – Sales Charge” on page 110 of this Prospectus and under “How to Buy Shares – Waivers and Reductions of Sales Charges – Class A Shares” beginning on page 111 of this Prospectus and “How to Buy Shares” beginning on page B-43 of the Fund’s Statement of Additional Information.

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

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund incurs transaction costs, such as commissions, when it buys and sells securities (or turns over its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 43% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

43.00%

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

The Maximum Deferred Sales Charge on Class A shares is applied only to purchases of $1,000,000 or more that are redeemed within 18 months of purchase.

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Class A shares of certain BMO Funds.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

50,000

Other Expenses, New Fund, Based on Estimates [Text]

rr_OtherExpensesNewFundBasedOnEstimates

"Other Expenses" for the Class A, R3, and R6 shares are based on estimated amounts for the current fiscal year.

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. The costs in the one-year example and for the first year of the three-, five-, and ten-year examples reflect the Adviser’s agreement to waive fees and reimburse expenses through December 31, 2015. 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 at least 80% of its assets in value oriented common stocks of small-sized U.S. companies similar in size, at the time of purchase, to those within the Russell 2000^® Value Index. The largest company by market capitalization in the Russell 2000^® Value Index was approximately $4.3 billion as of October 31, 2014 and the median market capitalization of companies in the Index as of the same period was $632 million.

The Adviser uses a disciplined investment process that identifies companies that it believes have good value relative to their assets, sustainable cash flow, acceptable levels of debt, and potential for improving their business fundamentals. In addition, these companies may have under-appreciated assets, or be involved in company turnarounds or corporate restructurings.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

The Fund cannot assure that it will achieve its investment objective. 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. The net asset value of the Fund will vary and you could lose money by investing in the Fund. In addition, the Fund is subject to the following risks.

Stock Market Risks. The Fund is subject to fluctuations in the stock market, which has periods of increasing and decreasing values. Stocks are more volatile than debt securities. The value of equity securities purchased by the Fund may decline if the financial condition of the companies in which the Fund invests declines or if overall market and economic conditions deteriorate. If the value of the Fund’s investments goes down, you may lose money.

Sector Risks. Companies with similar characteristics, such as those within the same industry, may be grouped together in broad categories called sectors. To the extent the Fund invests its assets in a particular sector, the Fund’s performance may be more susceptible to any economic, business, or other developments that generally affect that sector.

Style Risks. Investments in value stocks are subject to the risk that their intrinsic values may never be realized by the market, that a stock judged to be undervalued may actually be appropriately priced, or that their prices may decline, even though in theory they are already undervalued. Value stocks can react differently to issuer, political, market, and economic developments than the market as a whole, and other types of stocks (e.g., growth stocks).

Small-Cap Company Risks. Generally, the smaller the market capitalization of a company, the fewer the number of shares traded daily, the less liquid its stock, and the more volatile its price. Companies with smaller market capitalizations also tend to have unproven track records, a limited product or service base, and limited access to capital. These factors also increase risks and make these companies more likely to fail than companies with larger market capitalizations.

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.

Corporate Restructuring Risks. Securities of companies that are involved in company turnarounds or corporate restructurings may present special risk because of the high degree of uncertainty that can be associated with such events. It is possible that the market price of securities of companies involved in company turnarounds or corporate restructurings may be subject to significant and unpredictable fluctuations.

Risk Lose Money [Text]

rr_RiskLoseMoney

The net asset value of the Fund will vary and you could 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 before taxes have varied from year to year, while the table compares the Fund’s average annual total returns to the returns of a broad measure of market performance and an index of funds with similar investment objectives. Please keep in mind that past performance, before and after taxes, does not represent how the Fund will perform in the future. Investors may obtain updated performance information for the Fund 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 before taxes have varied from year to year, while the table compares the Fund’s average annual total returns to the returns of a broad measure of market performance and an index of funds with similar investment objectives.

Performance One Year or Less [Text]

rr_PerformanceOneYearOrLess

Because Class A, Class R3, and Class R6 shares have not been offered for a full calendar year, the information provided represents returns of Class I shares.

Performance Additional Market Index [Text]

rr_PerformanceAdditionalMarketIndex

The Russell 2000^® Value Index is a market- weighted, value-oriented index of those small companies included in the Russell 2000^® Index with lower price-to-book ratios and lower forecasted growth values.

The Lipper Small-Cap Core Funds Index (LSCCFI) tracks the total return performance of the 30 largest funds included in this 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, before and after taxes, does not represent how the Fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Class I—Annual Total Returns (calendar years 2012-2013)

Bar Chart Does Not Reflect Sales Loads [Text]

rr_BarChartDoesNotReflectSalesLoads

The bar chart does not reflect the payment of any sales charges. If these charges had been reflected, the returns shown would have been lower.

Bar Chart Footnotes [Text Block]

rr_BarChartFootnotesTextBlock

* The bar chart does not reflect the payment of any sales charges. If these charges had been reflected, the returns shown would have been lower.

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

The return for the Class I shares of the Fund from January 1, 2014 through September 30, 2014 was (0.95)%.

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

	Quarter Ended		Returns
Best quarter		3/31/2013		13.97	%
Worst quarter		6/30/2012		(4.95)	%

Bar Chart, Reason Selected Class Different from Immediately Preceding Period [Text]

rr_BarChartReasonSelectedClassDifferentFromImmediatelyPrecedingPeriod

The bar chart previously reflected the performance of the Class Y shares. On April 21, 2015, the Fund's Class Y shares were converted to Class A shares. As a result of the conversion, performance set forth in the bar chart reflects the performance of the Class I shares rather than the Class Y shares. The Fund no longer offers Class Y shares.

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns through 12/31/13

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the highest historical individual marginal federal income tax rates and do not reflect the effect of any applicable state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

After-tax returns shown are not relevant to investors holding shares through tax-deferred programs, such as IRAs or 401(k) plans.

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax returns are shown only for Class I, and after-tax returns for Class A, Class R3, and Class R6 will vary.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

After-tax returns are calculated using the highest historical individual marginal federal income tax rates and do not reflect the effect of any applicable state and local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns shown are not relevant to investors holding shares through tax-deferred programs, such as IRAs or 401(k) plans. After-tax returns are shown only for Class I, and after-tax returns for Class A, Class R3, and Class R6 will vary.

The Russell 2000^® Value Index is a market- weighted, value-oriented index of those small companies included in the Russell 2000^® Index with lower price-to-book ratios and lower forecasted growth values.

The Lipper Small-Cap Core Funds Index (LSCCFI) tracks the total return performance of the 30 largest funds included in this category.

Performance Table Footnotes, Reason Performance Information for Class Different from Immediately Preceding Period [Text]

rr_PerformanceTableFootnotesReasonPerformanceInformationForClassDifferentFromImmediatelyPrecedingPeriod

The table previously reflected the performance of the Class Y shares. On April 21, 2015, the Fund’s Class Y shares were converted to Class A shares. As a result of the conversion, performance set forth in the table reflects the performance of the Class I shares rather than the Class Y shares. The Fund no longer offers Class Y shares.

BMO Small-Cap Value 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

^[1]

Redemption Fee

rr_RedemptionFeeOverRedemption

none

Management Fees

rr_ManagementFeesOverAssets

0.69%

Distribution (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.46%

^[2]

Acquired Fund Fees and Expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.01%

^[3]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.16%

Fee Waiver and Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

(0.16%)

^[4]

Total Annual Fund Operating Expenses After Fee Waiver and Expense Reimbursement

rr_NetExpensesOverAssets

1.00%

^[4]

1 Year

rr_ExpenseExampleYear01

102

3 Years

rr_ExpenseExampleYear03

353

5 Years

rr_ExpenseExampleYear05

623

10 Years

rr_ExpenseExampleYear10

1,395

2012

rr_AnnualReturn2012

25.82%

^[5]

2013

rr_AnnualReturn2013

34.41%

^[5]

Year to Date Return, Label

rr_YearToDateReturnLabel

The return for the Class I 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

(0.95%)

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2013

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

13.97%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Jun. 30, 2012

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(4.95%)

1 Year

rr_AverageAnnualReturnYear01

34.41%

^[6],[7]

Since Inception

rr_AverageAnnualReturnSinceInception

16.90%

^[6],[7]

Inception Date

rr_AverageAnnualReturnInceptionDate

Feb. 28, 2011

^[6],[7]

BMO Small-Cap Value Fund | Class A

Risk/Return:

rr_RiskReturnAbstract

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

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

5.00%

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

rr_MaximumDeferredSalesChargeOverOther

1.00%

^[1]

Redemption Fee

rr_RedemptionFeeOverRedemption

none

Management Fees

rr_ManagementFeesOverAssets

0.69%

Distribution (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other Expenses

rr_OtherExpensesOverAssets

0.46%

^[2]

Acquired Fund Fees and Expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.01%

^[3]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.41%

Fee Waiver and Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

(0.16%)

^[4]

Total Annual Fund Operating Expenses After Fee Waiver and Expense Reimbursement

rr_NetExpensesOverAssets

1.25%

^[4]

1 Year

rr_ExpenseExampleYear01

621

3 Years

rr_ExpenseExampleYear03

909

5 Years

rr_ExpenseExampleYear05

1,218

10 Years

rr_ExpenseExampleYear10

2,093

BMO Small-Cap Value Fund | Class R3

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

^[1]

Redemption Fee

rr_RedemptionFeeOverRedemption

none

Management Fees

rr_ManagementFeesOverAssets

0.69%

Distribution (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

0.50%

Other Expenses

rr_OtherExpensesOverAssets

0.46%

^[2]

Acquired Fund Fees and Expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.01%

^[3]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.66%

Fee Waiver and Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

(0.16%)

^[4]

Total Annual Fund Operating Expenses After Fee Waiver and Expense Reimbursement

rr_NetExpensesOverAssets

1.50%

^[4]

1 Year

rr_ExpenseExampleYear01

153

3 Years

rr_ExpenseExampleYear03

508

5 Years

rr_ExpenseExampleYear05

887

10 Years

rr_ExpenseExampleYear10

1,952

BMO Small-Cap Value Fund | Class R6

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

^[1]

Redemption Fee

rr_RedemptionFeeOverRedemption

none

Management Fees

rr_ManagementFeesOverAssets

0.69%

Distribution (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.31%

^[2]

Acquired Fund Fees and Expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.01%

^[3]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.01%

Fee Waiver and Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

(0.16%)

^[4]

Total Annual Fund Operating Expenses After Fee Waiver and Expense Reimbursement

rr_NetExpensesOverAssets

0.85%

^[4]

1 Year

rr_ExpenseExampleYear01

87

3 Years

rr_ExpenseExampleYear03

306

5 Years

rr_ExpenseExampleYear05

542

10 Years

rr_ExpenseExampleYear10

1,222

BMO Small-Cap Value Fund | Return After Taxes on Distributions | Class I

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

30.13%

^[6],[7]

Since Inception

rr_AverageAnnualReturnSinceInception

15.39%

^[6],[7]

BMO Small-Cap Value Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class I

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

20.61%

^[6],[7]

Since Inception

rr_AverageAnnualReturnSinceInception

12.88%

^[6],[7]

BMO Small-Cap Value Fund | Russell 2000® Value Index (reflects no deduction of fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

34.52%

^[7]

Since Inception

rr_AverageAnnualReturnSinceInception

13.38%

^[7]

BMO Small-Cap Value Fund | LSCCFI (reflects deduction of fees and no deduction for sales charges or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

36.13%

^[7]

Since Inception

rr_AverageAnnualReturnSinceInception

13.88%

^[7]

[1] The Maximum Deferred Sales Charge on Class A shares is applied only to purchases of $1,000,000 or more that are redeemed within 18 months of purchase.

[2] "Other Expenses" for the Class A, R3, and R6 shares are based on estimated amounts for the current fiscal year.

[3] 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.

[4] 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 0.99% for Class I, 1.24% for Class A, 1.49% for Class R3, and 0.84% for Class R6 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.

[5] The bar chart previously reflected the performance of the Class Y shares. On April 21, 2015, the Fund's Class Y shares were converted to Class A shares. As a result of the conversion, performance set forth in the bar chart reflects the performance of the Class I shares rather than the Class Y shares. The Fund no longer offers Class Y shares.

[6] The table previously reflected the performance of the Class Y shares. On April 21, 2015, the Fund's Class Y shares were converted to Class A shares. As a result of the conversion, performance set forth in the table reflects the performance of the Class I shares rather than the Class Y shares. The Fund no longer offers Class Y shares.

[7] Because Class A, Class R3, and Class R6 shares have not been offered for a full calendar year, the information provided represents returns of Class I shares. Class A (without the reflection of the payment of sales charges), Class R3, and Class R6 shares would have substantially similar annual returns because the shares are invested in the same portfolio of securities. However, the performance of Class A, R3, and R6 shares will be different from the Class I shares (Class A and Class R3 shares' performance will be lower and Class R6 shares' performance will be higher) because they have different Total Annual Fund Operating Expenses. In addition, Class A shares charge a front-end sales charge, which also will lower the performance of Class A shares.