Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Prospectus Date	rr_ProspectusDate	Jan. 28, 2011
Oakmark Fund (Prospectus Summary): \| Oakmark Fund
Risk/Return:	rr_RiskReturnAbstract
Supplement Text	ck0000872323_SupplementTextBlock	HARRIS ASSOCIATES INVESTMENT TRUST Supplement dated June 30, 2011 to the Prospectus of The Oakmark Funds dated January 28, 2011, as previously supplemented on May 11, 2011 For Oakmark Fund, the following replaces the table entitled "Shareholder Fees" on page 1 of the prospectus.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Oakmark Fund \| Class I
Risk/Return:	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	OAKMX
Maximum sales charge (load) imposed on purchases	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum deferred sales charge (load)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Redemption fee (as a percentage of amount redeemed on shares held for 90 days or less)	rr_RedemptionFeeOverRedemption	none
Exchange fee	rr_ExchangeFee	none
Oakmark Fund \| Class II
Risk/Return:	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	OARMX
Maximum sales charge (load) imposed on purchases	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum deferred sales charge (load)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Redemption fee (as a percentage of amount redeemed on shares held for 90 days or less)	rr_RedemptionFeeOverRedemption	none
Exchange fee	rr_ExchangeFee	none

Maximum Deferred Sales Charge (Load) (as a percentage of ____) A.3.instructions.2.a.i "Maximum Deferred Sales Charge (Load)" includes the maximum total deferred sales charge (load) payable upon redemption, in installments, or both, expressed as a percentage of the amount or amounts stated in response to Item 7(a), except that, for a sales charge (load) based on net asset value at the time of purchase, show the sales charge (load) as a percentage of the offering price at the time of purchase. A Fund may include in a footnote to the table, if applicable, a tabular presentation showing the amount of deferred sales charges (loads) over time or a narrative explanation of the sales charges (loads) (e.g., __% in the first year after purchase, declining to __% in the __ year and eliminated thereafter). A.3.instructions.2.a.ii If more than one type of sales charge (load) is imposed (e.g., a deferred sales charge (load) and a front-end sales charge (load)), the first caption in the table should read "Maximum Sales Charge (Load)" and show the maximum cumulative percentage. Show the percentage amounts and the terms of each sales charge (load) comprising that figure on separate lines below.

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