Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	MARSHALL FUNDS INC d/b/a BMO FUNDS
Prospectus Date	rr_ProspectusDate	Dec. 28, 2012
BMO Short Tax-Free Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	BMO Short Tax-Free Fund
Objective [Heading]	rr_ObjectiveHeading	Investment Objective:
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	To provide current income exempt from federal income tax consistent with preservation of capital.
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, 2013
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.
Other Expenses, New Fund, Based on Estimates [Text]	rr_OtherExpensesNewFundBasedOnEstimates	“Other Expenses” are based on estimated amounts for the Fund’s current fiscal year because it is a new fund.
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-year example reflect the Adviser’s agreement to waive fees and/or reimburse expenses through December 31, 2013. 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 municipal securities, the income from which is exempt from federal income tax (including the federal alternative minimum tax (AMT)). Fund investments include municipal securities with a minimum rating in the lowest investment grade category (i.e., rated BBB or Baa, or higher, or unrated and considered by the Adviser to be comparable in quality) at the time of purchase. Municipal securities include debt obligations of states, territories, and possessions of the U.S., and political subdivisions and financing authorities of these entities that provide income exempt from federal income tax (including federal AMT). The Adviser selects Fund investments after assessing factors such as the cyclical trend in interest rates, the shape of the municipal yield curve, tax rates, sector valuation, and municipal bond supply factors. The Fund normally maintains an average dollar-weighted effective maturity of one to three years. Effective maturity takes into account the possibility that a bond may have prepayments or may be called by the issuer before its stated maturity date.
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. 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 will default on a security 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. Bonds rated lower than BBB or Baa have speculative characteristics. 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. 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 the interest on an otherwise tax-exempt municipal security may be subject to federal income tax. 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. Sector Risks. The Fund may invest its assets in municipal securities that finance similar projects, such as those relating to education, health care, transportation, and utilities. 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.
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	Performance information is not included because the Fund does not have one full calendar year of performance as of the date of this Prospectus.
Performance One Year or Less [Text]	rr_PerformanceOneYearOrLess	Performance information is not included because the Fund does not have one full calendar year of performance as of the date of this Prospectus.
BMO Short Tax-Free Fund | Class Y
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)	rr_RedemptionFeeOverRedemption	2.00%
Management Fees	rr_ManagementFeesOverAssets	0.25%
Distribution (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.78%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.03%
Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.48%)	[2]
Total Annual Fund Operating Expenses After Fee Waiver and Expense Reimbursement	rr_NetExpensesOverAssets	0.55%	[2]
1 Year	rr_ExpenseExampleYear01	56
3 Years	rr_ExpenseExampleYear03	280
BMO Short Tax-Free Fund | Class I
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Redemption Fee (as a percentage of amount redeemed, for shares held less than 30 days)	rr_RedemptionFeeOverRedemption	2.00%
Management Fees	rr_ManagementFeesOverAssets	0.25%
Distribution (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.53%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.78%
Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.38%)	[2]
Total Annual Fund Operating Expenses After Fee Waiver and Expense Reimbursement	rr_NetExpensesOverAssets	0.40%	[2]
1 Year	rr_ExpenseExampleYear01	41
3 Years	rr_ExpenseExampleYear03	211

[1] “Other Expenses” are based on estimated amounts for the Fund’s current fiscal year because it is a new fund.

[2] BMO Asset Management Corp. (Adviser) has agreed to waive or reduce its investment advisory fee or reimburse expenses to the extent necessary to prevent 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) from exceeding 0.55% for Class Y and 0.40% for Class I through December 31, 2013. The Adviser may not terminate this arrangement prior to December 31, 2013 unless the investment advisory agreement is terminated.