485BPOS

As filed with the Securities and Exchange Commission on February 14, 2012

Securities Act registration no. 33-38953

Investment Company Act file no. 811-06279

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-1A

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933   x

Post-Effective Amendment No. 43 x

and

REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT OF 1940   x

Amendment No.  45 x

HARRIS ASSOCIATES INVESTMENT TRUST

(Registrant)

Two North La Salle Street, Suite 500

Chicago, Illinois 60602-3790

Telephone number 312/621-0600

Janet L. Reali	Paulita A. Pike
Harris Associates L.P.	K&L Gates LLP
Two North La Salle Street, #500	70 West Madison Street, #3100
Chicago, Illinois 60602	Chicago, Illinois 60602

(Agents for service)

It is proposed that this filing will become effective:

x    immediately upon filing pursuant to rule 485(b)

o    on                            pursuant to rule 485(b)

o    60 days after filing pursuant to rule 485(a)(1)

o    on                            pursuant to rule 485(a)(1)

o    75 days after filing pursuant to rule 485(a)(2)

o    on                            pursuant to rule 485(a)(2)

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933 and the Investment Company Act of 1940, the Registrant certifies that it meets all of the requirements for effectiveness of this post-effective amendment pursuant to Rule 485(b) under the Securities Act of 1933 and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Chicago and State of Illinois on February 14, 2012.

HARRIS ASSOCIATES INVESTMENT TRUST
By	/s/ Kristi L. Rowsell
	Kristi L. Rowsell, President

Pursuant to the requirements of the Securities Act of 1933, this post-effective amendment to the registration statement has been signed below by the following persons in the capacities and on the date indicated.

Signature	Title	Date
/s/ Michael J. Friduss*	Trustee
Michael J. Friduss
/s/ Thomas H. Hayden*	Trustee
Thomas H. Hayden
/s/ Christine M. Maki*	Trustee
Christine M. Maki
/s/ Allan J. Reich*	Trustee
Allan J. Reich
/s/ Steven S. Rogers*	Trustee	February 14, 2012
Steven S. Rogers
/s/ Burton W. Ruder*	Trustee
Burton W. Ruder
/s/ Peter S. Voss*	Trustee
Peter S. Voss
/s/ Gary N. Wilner*	Trustee
Gary N. Wilner
/s/ Kristi L. Rowsell	Trustee and President (Principal Executive Officer)
Kristi L. Rowsell
/s/ Thomas E. Herman	Principal Financial Officer
Thomas E. Herman

By	/s/ Janet L. Reali
	Janet L. Reali
	Secretary

* Janet L. Reali signs this document on behalf of the individuals noted pursuant to the powers of attorney filed on January 28, 2010 as exhibit(q) to Post-effective Amendment no. 39 on Form N-1A (File No. 33-38953) and incorporated by reference herein.

Index of Exhibits

Exhibit
Number	Exhibits
EX-101.INS	XBRL Instance Document
EX-101.SCH	XBRL Taxonomy Extension Schema Document
EX-101.CAL	XBRL Taxonomy Extension Calculation Linkbase
EX-101.DEF	XBRL Taxonomy Extension Definition Linkbase
EX-101.LAB	XBRL Taxonomy Extension Labels Linkbase
EX-101.PRE	XBRL Taxonomy Extension Presentation Linkbase

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	Jan. 27, 2012
Oakmark International Small Cap Fund (Prospectus Summary) | Oakmark International Small Cap Fund
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	OAKMARK INTERNATIONAL SMALL CAP FUND
Investment Objective, Heading	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	Oakmark International Small Cap Fund seeks long-term capital appreciation.
Expense, Heading	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense, Narrative	rr_ExpenseNarrativeTextBlock	Below are the fees and expenses that you would pay if you buy and hold shares of the Fund.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses, Caption	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover, Heading	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover	rr_PortfolioTurnoverTextBlock	The Fund pays 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 46% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	46.00%
Expense Example, Heading	rr_ExpenseExampleHeading	Example.
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 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 remain the same.
Expense Example, By Year, Caption	rr_ExpenseExampleByYearCaption	Although your actual returns and costs may be higher or lower, based on these assumptions your expenses would be:
Investment Strategy, Heading	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGY
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	The Fund invests primarily in a diversified portfolio of common stocks of non-U.S. companies. Under normal market conditions, the Fund invests at least 80% of its net assets (plus any borrowings for investment purposes) in the stocks of "small cap companies." A small cap company is one whose market capitalization is less than $5 billion at the time of investment. The Fund may invest in non-U.S. markets throughout the world, including emerging markets. Ordinarily, the Fund will invest in the securities of at least five countries outside the U.S. There are no geographic limits on the Fund's non-U.S. investments. The Fund uses a value investment philosophy in selecting equity securities. This investment philosophy is based upon the belief that, over time, a company's stock price converges with the company's intrinsic or true business value. By "true business value," we mean an estimate of the price a knowledgeable buyer would pay to acquire the entire business. We believe that investing in securities priced significantly below their true business value presents the best opportunity to achieve the Fund's investment objective. The Fund's investment adviser, Harris Associates L.P. (the "Adviser"), uses this value philosophy to identify companies that it believes have discounted stock prices compared to the companies' true business values. In assessing such companies, the Adviser looks for the following characteristics, although not all of the companies selected will have these attributes: (1) free cash flows and intelligent investment of excess cash; (2) earnings that are growing and are reasonably predictable; and (3) high level of manager ownership. Key Tenets of the Oakmark Investment Philosophy: 1. Buy businesses that are trading at a significant discount to the Adviser's estimate of the company's intrinsic value. At the time the Adviser buys a company, the Adviser wants the company's stock to be inexpensive relative to what it believes the entire business is worth. 2. Invest with companies expected to grow shareholder value over time. Value investors can sometimes fall into the trap of buying a stock that is inexpensive for a reason-because the company just does not grow. The Adviser looks for good quality, growing businesses with positive free cash flow and intelligent investment of cash. 3. Invest with management teams that think and act as owners. The Adviser seeks out companies with management teams that understand the dynamics of per share value growth and are focused on achieving such growth. Stock ownership and incentives that align managements' interests with those of shareholders are key components of this analysis. In making its investment decisions, the Adviser uses a "bottom-up" approach focused on individual companies, rather than focusing on specific economic factors or specific industries. In order to select investments that meet the criteria described above, the Adviser uses independent, in-house research to analyze each company. As part of this selection process, the Adviser's analysts typically visit companies and conduct other research on the companies and their industries. Once the Adviser determines that a stock is selling at a significant discount and that the company has the additional qualities mentioned above, the Adviser may consider buying that stock for the Fund. The Adviser usually sells a stock when the price approaches its estimated worth. This means the Adviser sets specific "buy" and "sell" targets for each stock held by the Fund. The Adviser also monitors each holding and adjusts those price targets as warranted to reflect changes in a company's fundamentals. The Adviser believes that holding a relatively small number of stocks allows its "best ideas" to have a meaningful impact on the Fund's performance. Therefore, the Fund's portfolio typically holds thirty to seventy stocks rather than hundreds.
Risk, Heading	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk, Narrative	rr_RiskNarrativeTextBlock	As an investor in the Fund, you should have a long-term perspective and be able to tolerate potentially wide fluctuations in the value of your Fund shares. Your investment in the Fund is subject to risks, including the possibility that the value of the Fund's portfolio holdings may fluctuate in response to events specific to the companies in which the Fund invests, as well as economic, political or social events in the U.S. or abroad. As a result, when you redeem your Fund shares, they may be worth more or less than you paid for them. Although the Fund makes every effort to achieve its objective, it cannot guarantee it will attain that objective. The principal risks of investing in the Fund are: Market Risk. The Fund is subject to market risk-the risk that securities markets and individual securities will increase or decrease in value. Market risk applies to every market and every security. Security prices may fluctuate widely over short or extended periods in response to market or economic news and conditions, and securities markets also tend to move in cycles. If there is a general decline in the securities markets, it is possible your investment may lose value regardless of the individual results of the companies in which the Fund invests. The magnitude of up and down price or market fluctuations over time is sometimes referred to as "volatility," which, at times, can be significant. In addition, different asset classes and geographic markets may experience periods of significant correlation with each other. As a result of this correlation, the securities and markets in which the Fund invests may experience volatility due to market, economic, political or social events and conditions that may not readily appear to directly relate to such securities, the securities' issuer or the markets in which they trade. Common Stock Risk. Common stocks are subject to greater fluctuations in market value than other asset classes as a result of such factors as a company's business performance, investor perceptions, stock market trends and general economic conditions. The rights of common stockholders are subordinate to all other claims on a company's assets including debt holders and preferred stockholders; therefore, the Fund could lose money if a company in which it invests becomes financially distressed. Focused Portfolio Risk. The Fund's portfolio tends to be invested in a relatively small number of stocks. As a result, the appreciation or depreciation of any one security held by the Fund will have a greater impact on the Fund's net asset value than it would if the Fund invested in a larger number of securities. Although that strategy has the potential to generate attractive returns over time, it also increases the Fund's volatility. Value Style Risk. Investing in "value" stocks presents the risk that the stocks may never reach what the Adviser believes are their full market values, either because the market fails to recognize what the Adviser considers to be the companies' true business values or because the Adviser misjudged those values. In addition, value stocks may fall out of favor with investors and underperform growth stocks during given periods. Non-U.S. Securities Risk. Investments in securities issued by entities based outside the United States involve risks relating to political, social and economic developments abroad, as well as risks resulting from the differences between the regulations to which U.S. and non-U.S. issuers and markets are subject. These risks may result in the Fund experiencing rapid and extreme value changes due to currency controls; different accounting, auditing, financial reporting, and legal standards and practices; political and diplomatic changes and developments; expropriation; changes in tax policy; a lack of available public information regarding non-U.S. issuers; greater market volatility; a lack of sufficient market liquidity; differing securities market structures; higher transaction costs; and various administrative difficulties, such as delays in clearing and settling portfolio transactions or in receiving payment of dividends. These risks may be heightened in connection with investments in issuers located in developing and emerging countries, and in issuers in more developed countries that conduct substantial business in such developing and emerging countries. Fluctuations in the exchange rates between currencies may negatively affect an investment in non-U.S. securities. The Fund may hedge its exposure to foreign currencies. Although hedging may be used to protect the Fund from adverse currency movements, the use of such hedges may reduce or eliminate the potentially positive effect of currency revaluations on the Fund's total return, and there is no guarantee that the Fund's hedging strategy will be successful. Small Cap Securities Risk. Investments in small cap companies may be riskier than investments in larger, more established companies. The securities of smaller companies may trade less frequently and in smaller volumes, and as a result, may be less liquid than securities of larger companies. In addition, smaller companies may be more vulnerable to economic, market and industry changes. As a result, share price changes may be more sudden or erratic than the prices of other equity securities, especially over the short term. Because smaller companies may have limited product lines, markets or financial resources or may depend on a few key employees, they may be more susceptible to particular economic events or competitive factors than large capitalization companies. Your investment in the Fund is not a deposit in a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You may lose money by investing in the Fund. The likelihood of loss may be greater if you invest for a shorter period of time.
Risk, Lose Money	rr_RiskLoseMoney	You may lose money by investing in the Fund.
Risk, Not Insured Depository Institution	rr_RiskNotInsuredDepositoryInstitution	Your investment in the Fund is not a deposit in a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance, Narrative	rr_PerformanceNarrativeTextBlock	The Fund's past performance (before and after taxes), as provided by the bar chart and performance table that follow, is not an indication of how the Fund will perform in the future. This information can help you evaluate the potential risk and reward of investing in the Fund by showing changes in the performance of the Fund's Class I Shares from year to year. The information illustrates the volatility of the Fund's historical returns and shows how the Fund's annual average returns compare with a broad measure of market performance. Updated performance information is available at oakmark.com or by calling 1-800-OAKMARK.
Performance, Information Illustrates Variability of Returns	rr_PerformanceInformationIllustratesVariabilityOfReturns	The information illustrates the volatility of the Fund's historical returns and shows how the Fund's annual average returns compare with a broad measure of market performance.
Performance, Availability Phone Number	rr_PerformanceAvailabilityPhone	1-800-OAKMARK
Performance, Availability Website Address	rr_PerformanceAvailabilityWebSiteAddress	oakmark.com
Bar Chart, Heading	rr_BarChartHeading	Class I Shares Total Returns for Years Ended December 31 (%)
Bar Chart, Narrative	rr_BarChartNarrativeTextBlock	Since 2002, the highest and lowest quarterly returns for the Fund's Class I Shares were: • Highest quarterly return: 43.7%, during the quarter ended June 30, 2009 • Lowest quarterly return: -27.3%, during the  quarter ended December 31, 2008
Performance Table, Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table, Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	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 who hold their shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts or individual retirement accounts.
Performance Table, One Class of after Tax Shown	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown only for Class I shares. After-tax returns for Class II shares will vary from returns shown for Class I.
Performance Table, Explanation after Tax Higher	rr_PerformanceTableExplanationAfterTaxHigher	In some cases, the after-tax returns may exceed the return before taxes due to an assumed tax benefit from any losses on a sale of Fund shares at the end of the measurement period.
Performance Table, Closing	rr_PerformanceTableClosingTextBlock	The Morgan Stanley Capital International (MSCI) World ex U.S. Small Cap Index is an unmanaged index that measures the equity market performance of small cap companies in developed markets excluding the U.S. The Index is a free float-adjusted market capitalization index. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of 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 who hold their shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts or individual retirement accounts. In some cases, the after-tax returns may exceed the return before taxes due to an assumed tax benefit from any losses on a sale of Fund shares at the end of the measurement period. After-tax returns are shown only for Class I shares. After-tax returns for Class II shares will vary from returns shown for Class I.
Average Annual Returns, Caption	rr_AverageAnnualReturnCaption	Average Annual Total Returns for Periods Ended December 31, 2011
Oakmark International Small Cap Fund (Prospectus Summary) | Oakmark International Small Cap Fund | MSCI World ex U.S. Small Cap Index
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	MSCI World ex U.S. Small Cap Index
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	(12.21%)
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	(4.09%)
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	5.14%
Oakmark International Small Cap Fund (Prospectus Summary) | Oakmark International Small Cap Fund | Class I
Risk Return [Abstract]	rr_RiskReturnAbstract
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	(2.00%)
Exchange fee	rr_ExchangeFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	1.15%
Distribution (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.23%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.38%
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	140
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	437
Expense Example, With Redemption, 5 Years	rr_ExpenseExampleYear05	755
Expense Example, With Redemption, 10 Years	rr_ExpenseExampleYear10	1,657
Annual Return 2002	rr_AnnualReturn2002	(5.12%)
Annual Return 2003	rr_AnnualReturn2003	52.41%
Annual Return 2004	rr_AnnualReturn2004	28.95%
Annual Return 2005	rr_AnnualReturn2005	21.26%
Annual Return 2006	rr_AnnualReturn2006	34.90%
Annual Return 2007	rr_AnnualReturn2007	(8.33%)
Annual Return 2008	rr_AnnualReturn2008	(45.71%)
Annual Return 2009	rr_AnnualReturn2009	67.45%
Annual Return 2010	rr_AnnualReturn2010	21.53%
Annual Return 2011	rr_AnnualReturn2011	(16.44%)
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest quarterly return:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	43.70%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest quarterly return:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(27.30%)
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	International Small Cap Fund - Class I Return before taxes
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	(16.44%)
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	(3.28%)
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	9.95%
Oakmark International Small Cap Fund (Prospectus Summary) | Oakmark International Small Cap Fund | Class I | After Taxes on Distributions
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	International Small Cap Fund - Class I Return after taxes on distributions
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	(16.34%)
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	(4.53%)
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	8.54%
Oakmark International Small Cap Fund (Prospectus Summary) | Oakmark International Small Cap Fund | Class I | After Taxes on Distributions and Sales
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	International Small Cap Fund - Class I Return after taxes on distributions and sale of Fund shares
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	(10.55%)
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	(2.82%)
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	8.77%
Oakmark International Small Cap Fund (Prospectus Summary) | Oakmark International Small Cap Fund | Class II
Risk Return [Abstract]	rr_RiskReturnAbstract
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	(2.00%)
Exchange fee	rr_ExchangeFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	1.15%
Distribution (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.57%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.72%
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	175
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	542
Expense Example, With Redemption, 5 Years	rr_ExpenseExampleYear05	933
Expense Example, With Redemption, 10 Years	rr_ExpenseExampleYear10	2,030
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	International Small Cap Fund - Class II Return before taxes
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	(16.72%)
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	(3.52%)
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	9.74%

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Oakmark International Fund (Prospectus Summary) | Oakmark International Fund

OAKMARK INTERNATIONAL FUND

INVESTMENT OBJECTIVE

Oakmark International Fund seeks long-term capital appreciation.

FEES AND EXPENSES OF THE FUND

Below are the fees and expenses that you would pay if you buy and hold shares of
the Fund.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees Oakmark International Fund	Class I	Class II
Maximum sales charge (load) imposed on purchases	none	none
Maximum deferred sales charge (load)	none	none
Redemption fee (as a percentage of amount redeemed on shares held for 90 days or less)	2.00%	2.00%
Exchange fee	none	none

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

Annual Fund Operating Expenses Oakmark International Fund	Class I	Class II
Management fees	0.90%	0.90%
Distribution (12b-1) Fees	none	none
Other expenses	0.16%	0.55%
Total Annual Fund Operating Expenses	1.06%	1.45%

Example.

The Example is intended to help you compare the cost of investing in
the Fund with the cost of investing in other mutual funds. The example assumes
that you invest $10,000 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
remain the same.

Although your actual returns and costs may be higher or lower, based on these assumptions your expenses would be:

Expense Example Oakmark International Fund (USD $)	Class I	Class II
Expense Example, With Redemption, 1 Year	108	148
Expense Example, With Redemption, 3 Years	337	459
Expense Example, With Redemption, 5 Years	585	792
Expense Example, With Redemption, 10 Years	1,294	1,735

Portfolio Turnover

The Fund pays 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 45%
of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGY

The Fund invests primarily in a diversified portfolio of common stocks of
non-U.S. companies. The Fund may invest in non-U.S. markets throughout the
world, including emerging markets. Ordinarily, the Fund will invest in the
securities of at least five countries outside the U.S. There are no geographic
limits on the Fund's non-U.S. investments. The Fund may invest in securities of
large-, mid-, and small-capitalization companies.

The Fund uses a value investment philosophy in selecting equity securities. This
investment philosophy is based upon the belief that, over time, a company's
stock price converges with the company's intrinsic or true business value. By
"true business value," we mean an estimate of the price a knowledgeable buyer
would pay to acquire the entire business. We believe that investing in
securities priced significantly below their true business value presents the
best opportunity to achieve the Fund's investment objective.

The Fund's investment adviser, Harris Associates L.P. (the "Adviser"), uses this
value philosophy to identify companies that it believes have discounted stock
prices compared to the companies' true business values. In assessing such
companies, the Adviser looks for the following characteristics, although not all
of the companies selected will have these attributes: (1) free cash flows and
intelligent investment of excess cash; (2) earnings that are growing and are
reasonably predictable; and (3) high level of manager ownership.

Key Tenets of the Oakmark Investment Philosophy:

1. Buy businesses that are trading at a significant discount to the Adviser's
estimate of the company's intrinsic value. At the time the Adviser buys a
company, the Adviser wants the company's stock to be inexpensive relative to
what it believes the entire business is worth.

2. Invest with companies expected to grow shareholder value over time. Value
investors can sometimes fall into the trap of buying a stock that is inexpensive
for a reason-because the company just does not grow. The Adviser looks for good
quality, growing businesses with positive free cash flow and intelligent
investment of cash.

3. Invest with management teams that think and act as owners. The Adviser seeks
out companies with management teams that understand the dynamics of per share
value growth and are focused on achieving such growth. Stock ownership and
incentives that align managements' interests with those of shareholders are key
components of this analysis.

In making its investment decisions, the Adviser uses a "bottom-up" approach
focused on individual companies, rather than focusing on specific economic
factors or specific industries. In order to select investments that meet the
criteria described above, the Adviser uses independent, in-house research to
analyze each company. As part of this selection process, the Adviser's analysts
typically visit companies and conduct other research on the companies and their
industries.

Once the Adviser determines that a stock is selling at a significant discount
and that the company has the additional qualities mentioned above, the Adviser
may consider buying that stock for the Fund. The Adviser usually sells a stock
when the price approaches its estimated worth. This means the Adviser sets
specific "buy" and "sell" targets for each stock held by the Fund. The Adviser
also monitors each holding and adjusts those price targets as warranted to
reflect changes in a company's fundamentals.

The Adviser believes that holding a relatively small number of stocks allows its
"best ideas" to have a meaningful impact on the Fund's performance. Therefore,
the Fund's portfolio typically holds thirty to sixty stocks rather than
hundreds.

PRINCIPAL INVESTMENT RISKS

As an investor in the Fund, you should have a long-term perspective and be able
to tolerate potentially wide fluctuations in the value of your Fund shares. Your
investment in the Fund is subject to risks, including the possibility that the
value of the Fund's portfolio holdings may fluctuate in response to events
specific to the companies in which the Fund invests, as well as economic,
political or social events in the U.S. or abroad. As a result, when you redeem
your Fund shares, they may be worth more or less than you paid for them.

Although the Fund makes every effort to achieve its objective, it cannot
guarantee it will attain that objective. The principal risks of investing in the
Fund are:

Market Risk. The Fund is subject to market risk-the risk that securities markets
and individual securities will increase or decrease in value. Market risk
applies to every market and every security. Security prices may fluctuate widely
over short or extended periods in response to market or economic news and
conditions, and securities markets also tend to move in cycles. If there is a
general decline in the securities markets, it is possible your investment may
lose value regardless of the individual results of the companies in which the
Fund invests. The magnitude of up and down price or market fluctuations over
time is sometimes referred to as "volatility," which, at times, can be
significant. In addition, different asset classes and geographic markets may
experience periods of significant correlation with each other. As a result of
this correlation, the securities and markets in which the Fund invests may
experience volatility due to market, economic, political or social events and
conditions that may not readily appear to directly relate to such securities,
the securities' issuer or the markets in which they trade.

Common Stock Risk. Common stocks are subject to greater fluctuations in market
value than other asset classes as a result of such factors as a company's
business performance, investor perceptions, stock market trends and general
economic conditions. The rights of common stockholders are subordinate to all
other claims on a company's assets including debt holders and preferred
stockholders; therefore, the Fund could lose money if a company in which it
invests becomes financially distressed.

Focused Portfolio Risk. The Fund's portfolio tends to be invested in a
relatively small number of stocks. As a result, the appreciation or depreciation
of any one security held by the Fund will have a greater impact on the Fund's
net asset value than it would if the Fund invested in a larger number of
securities. Although that strategy has the potential to generate attractive
returns over time, it also increases the Fund's volatility.

Small and Mid Cap Securities Risk. Investments in small and mid cap companies
may be riskier than investments in larger, more established companies. The
securities of smaller companies may trade less frequently and in smaller
volumes, and as a result, may be less liquid than securities of larger
companies. In addition, smaller companies may be more vulnerable to economic,
market and industry changes. As a result, share price changes may be more sudden
or erratic than the prices of other equity securities, especially over the short
term. Because smaller companies may have limited product lines, markets or
financial resources or may depend on a few key employees, they may be more
susceptible to particular economic events or competitive factors than large
capitalization companies.

Value Style Risk. Investing in "value" stocks presents the risk that the stocks
may never reach what the Adviser believes are their full market values, either
because the market fails to recognize what the Adviser considers to be the
companies' true business values or because the Adviser misjudged those values.
In addition, value stocks may fall out of favor with investors and underperform
growth stocks during given periods.

Non-U.S. Securities Risk. Investments in securities issued by entities based
outside the United States involve risks relating to political, social and
economic developments abroad, as well as risks resulting from the differences
between the regulations to which U.S. and non-U.S. issuers and markets are
subject. These risks may result in the Fund experiencing rapid and extreme value
changes due to currency controls; different accounting, auditing, financial
reporting, and legal standards and practices; political and diplomatic changes
and developments; expropriation; changes in tax policy; a lack of available
public information regarding non-U.S. issuers; greater market volatility; a lack
of sufficient market liquidity; differing securities market structures; higher
transaction costs; and various administrative difficulties, such as delays in
clearing and settling portfolio transactions or in receiving payment of
dividends. These risks may be heightened in connection with investments in
issuers located in developing and emerging countries, and in issuers in more
developed countries that conduct substantial business in such developing and
emerging countries. Fluctuations in the exchange rates between currencies may
negatively affect an investment in non-U.S. securities. The Fund may hedge its
exposure to foreign currencies. Although hedging may be used to protect the Fund
from adverse currency movements, the use of such hedges may reduce or eliminate
the potentially positive effect of currency revaluations on the Fund's total
return, and there is no guarantee that the Fund's hedging strategy will be
successful.

Your investment in the Fund is not a deposit in a bank and is not insured or
guaranteed by the Federal Deposit Insurance Corporation or any other government
agency. You may lose money by investing in the Fund. The likelihood of loss may
be greater if you invest for a shorter period of time.

PERFORMANCE INFORMATION

The Fund's past performance (before and after taxes), as provided by the bar
chart and performance table that follow, is not an indication of how the Fund
will perform in the future. This information can help you evaluate the potential
risk and reward of investing in the Fund by showing changes in the performance
of the Fund's Class I Shares from year to year. The information illustrates the
volatility of the Fund's historical returns and shows how the Fund's annual
average returns compare with those of a broad measure of market performance.
Updated performance information is available at oakmark.com or by calling
1-800-OAKMARK.

Since 2002, the highest and lowest quarterly returns for the Fund's Class I Shares were:
• Highest quarterly return: 33.2%, during the quarter ended June 30, 2009
• Lowest quarterly return: -22.9%, during the quarter ended September 30, 2002

Class I Shares Total Returns for Years Ended December 31 (%)

Average Annual Total Returns for Periods Ended December 31, 2011

Average Annual Total Returns Oakmark International Fund	Average Annual Returns, Label	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Class I	International Fund - Class I Return before taxes	(14.07%)	(1.75%)	7.46%
Class I After Taxes on Distributions	International Fund - Class I Return after taxes on distributions	(14.06%)	(2.68%)	6.60%
Class I After Taxes on Distributions and Sales	International Fund - Class I Return after taxes on distributions and sale of Fund shares	(8.91%)	(1.52%)	6.58%
Class II	International Fund - Class II Return before taxes	(14.38%)	(2.06%)	7.10%
MSCI World ex U.S. Index	MSCI World ex U.S. Index (does not reflect the deduction of fees, expenses or taxes)	(12.21%)	(4.09%)	5.14%

The Morgan Stanley Capital International (MSCI) World ex U.S. Index is an
unmanaged index that includes countries throughout the world, in proportion to
world stock market capitalization, but excludes U.S. companies. All returns
reflect reinvested dividends.

After-tax returns are calculated using the historical highest individual federal
marginal income tax rates and do not reflect the impact of 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 who hold
their shares through tax-deferred arrangements, such as 401(k) plans, qualified
plans, education savings accounts or individual retirement accounts. In some
cases, the after-tax returns may exceed the return before taxes due to an
assumed tax benefit from any losses on a sale of Fund shares at the end of the
measurement period. After-tax returns are shown only for Class I shares.
After-tax returns for Class II shares will vary from returns shown for Class I.

XML

Oakmark Select Fund (Prospectus Summary) | Oakmark Select Fund

OAKMARK SELECT FUND

INVESTMENT OBJECTIVE

Oakmark Select Fund seeks long-term capital appreciation.

FEES AND EXPENSES OF THE FUND

Below are the fees and expenses that you would pay if you buy and hold shares of
the Fund.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees Oakmark Select Fund	Class I	Class II
Maximum sales charge (load) imposed on purchases	none	none
Maximum deferred sales charge (load)	none	none
Redemption fee (as a percentage of amount redeemed on shares held for 90 days or less)	none	none
Exchange fee	none	none

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

Annual Fund Operating Expenses Oakmark Select Fund	Class I	Class II
Management fees	0.94%	0.94%
Distribution (12b-1) Fees	none	none
Other expenses	0.13%	0.44%
Total Annual Fund Operating Expenses	1.07%	1.38%

Example.

The Example is intended to help you compare the cost of investing in
the Fund with the cost of investing in other mutual funds. The Example assumes
that you invest $10,000 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
remain the same.

Although your actual returns and costs may be higher or lower, based on these assumptions your expenses would be:

Expense Example Oakmark Select Fund (USD $)	Class I	Class II
Expense Example, With Redemption, 1 Year	109	140
Expense Example, With Redemption, 3 Years	340	437
Expense Example, With Redemption, 5 Years	590	755
Expense Example, With Redemption, 10 Years	1,306	1,657

Portfolio Turnover

The Fund pays 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 16%
of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGY

The Fund invests primarily in common stocks of U.S. companies. The Fund is
non-diversified, which means that it may invest a greater portion of its assets
in a more limited number of issuers than a diversified fund. The Fund could own
as few as twelve securities, but generally will have approximately twenty
securities in its portfolio. The Fund may invest in the securities of large-,
mid-, and small-capitalization companies.

The Fund uses a value investment philosophy in selecting equity securities. This
investment philosophy is based upon the belief that, over time, a company's
stock price converges with the company's intrinsic or true business value. By
"true business value," we mean an estimate of the price a knowledgeable buyer
would pay to acquire the entire business. We believe that investing in
securities priced significantly below their true business value presents the
best opportunity to achieve the Fund's investment objective.

The Fund's investment adviser, Harris Associates L.P. (the "Adviser"), uses this
value philosophy to identify companies that it believes have discounted stock
prices compared to the companies' true business values. In assessing such
companies, the Adviser looks for the following characteristics, although not all
of the companies selected will have these attributes: (1) free cash flows and
intelligent investment of excess cash; (2) earnings that are growing and are
reasonably predictable; and (3) high level of manager ownership.

Key Tenets of the Oakmark Investment Philosophy:

1. Buy businesses that are trading at a significant discount to the Adviser's
estimate of the company's intrinsic value. At the time the Adviser buys a
company, the Adviser wants the company's stock to be inexpensive relative to
what it believes the entire business is worth.

2. Invest with companies expected to grow shareholder value over time. Value
investors can sometimes fall into the trap of buying a stock that is inexpensive
for a reason-because the company just does not grow. The Adviser looks for good
quality, growing businesses with positive free cash flow and intelligent
investment of cash.

3. Invest with management teams that think and act as owners. The Adviser seeks
out companies with management teams that understand the dynamics of per share
value growth and are focused on achieving such growth. Stock ownership and
incentives that align managements' interests with those of shareholders are key
components of this analysis.

In making its investment decisions, the Adviser uses a "bottom-up" approach
focused on individual companies, rather than focusing on specific economic
factors or specific industries. In order to select investments that meet the
criteria described above, the Adviser uses independent, in-house research to
analyze each company. As part of this selection process, the Adviser's analysts
typically visit companies and conduct other research on the companies and their
industries.

Once the Adviser determines that a stock is selling at a significant discount
and that the company has the additional qualities mentioned above, the Adviser
may consider buying that stock for the Fund. The Adviser usually sells a stock
when the price approaches its estimated worth. This means the Adviser sets
specific "buy" and "sell" targets for each stock held by the Fund. The Adviser
also monitors each holding and adjusts those price targets as warranted to
reflect changes in a company's fundamentals.

PRINCIPAL INVESTMENT RISKS

As an investor in the Fund, you should have a long-term perspective and be able
to tolerate potentially wide fluctuations in the value of your Fund shares. Your
investment in the Fund is subject to risks, including the possibility that the
value of the Fund's portfolio holdings may fluctuate in response to events
specific to the companies in which the Fund invests, as well as economic,
political or social events in the U.S. or abroad. As a result, when you redeem
your Fund shares, they may be worth more or less than you paid for them.

Although the Fund makes every effort to achieve its objective, it cannot
guarantee it will attain that objective. The principal risks of investing in the
Fund are:

Market Risk. The Fund is subject to market risk-the risk that securities markets
and individual securities will increase or decrease in value. Market risk
applies to every market and every security. Security prices may fluctuate widely
over short or extended periods in response to market or economic news and
conditions, and securities markets also tend to move in cycles. If there is a
general decline in the securities markets, it is possible your investment may
lose value regardless of the individual results of the companies in which the
Fund invests. The magnitude of up and down price or market fluctuations over
time is sometimes referred to as "volatility," which, at times, can be
significant. In addition, different asset classes and geographic markets may
experience periods of significant correlation with each other. As a result of
this correlation, the securities and markets in which the Fund invests may
experience volatility due to market, economic, political or social events and
conditions that may not readily appear to directly relate to such securities,
the securities' issuer or the markets in which they trade.

Common Stock Risk. Common stocks are subject to greater fluctuations in market
value than other asset classes as a result of such factors as a company's
business performance, investor perceptions, stock market trends and general
economic conditions. The rights of common stockholders are subordinate to all
other claims on a company's assets including debt holders and preferred
stockholders; therefore, the Fund could lose money if a company in which it
invests becomes financially distressed.

Small and Mid Cap Securities Risk. Investments in small and mid cap companies
may be riskier than investments in larger, more established companies. The
securities of smaller companies may trade less frequently and in smaller
volumes, and as a result, may be less liquid than securities of larger
companies. In addition, smaller companies may be more vulnerable to economic,
market and industry changes. As a result, share price changes may be more sudden
or erratic than the prices of other equity securities, especially over the short
term. Because smaller companies may have limited product lines, markets or
financial resources or may depend on a few key employees, they may be more
susceptible to particular economic events or competitive factors than large
capitalization companies.

Value Style Risk. Investing in "value" stocks presents the risk that the stocks
may never reach what the Adviser believes are their full market values, either
because the market fails to recognize what the Adviser considers to be the
companies' true business values or because the Adviser misjudged those values.
In addition, value stocks may fall out of favor with investors and underperform
growth stocks during given periods.

Non-Diversification Risk. A non-diversified fund may be subject to greater risk
than a diversified fund because changes in the financial condition or market
assessment of a single issuer may cause greater fluctuation in the value of a
non-diversified fund's shares. Lack of broad diversification also may cause a
non-diversified fund to be more susceptible to economic, political or regulatory
events than a diversified fund. A non-diversification strategy may increase the
Fund's volatility.

Your investment in the Fund is not a deposit in a bank and is not insured or
guaranteed by the Federal Deposit Insurance Corporation or any other government
agency. You may lose money by investing in the Fund. The likelihood of loss may
be greater if you invest for a shorter period of time.

PERFORMANCE INFORMATION

The Fund's past performance (before and after taxes), as provided by the bar
chart and performance table that follow, is not an indication of how the Fund
will perform in the future. This information can help you evaluate the potential
risk and reward of investing in the Fund by showing changes in the performance
of the Fund's Class I Shares from year to year. The information illustrates the
volatility of the Fund's historical returns and shows how the Fund's annual
average returns compare with those of a broad measure of market performance.
Updated performance information is available at oakmark.com or by calling
1-800-OAKMARK.

Since 2002, the highest and lowest quarterly returns for the Fund's Class I Shares were:
• Highest quarterly return: 25.7%, during the quarter ended June 30, 2009
• Lowest quarterly return: -20.2%, during the quarter ended December 31, 2008

Class I Shares Total Returns for Years Ended December 31 (%)

Average Annual Total Returns for Periods Ended December 31, 2011

Average Annual Total Returns Oakmark Select Fund	Average Annual Returns, Label	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Class I	Select Fund - Class I Return before taxes	2.15%	(0.67%)	3.62%
Class I After Taxes on Distributions	Select Fund - Class I Return after taxes on distributions	2.12%	(1.09%)	3.12%
Class I After Taxes on Distributions and Sales	Select Fund - Class I Return after taxes on distributions and sale of Fund shares	1.44%	(0.61%)	3.11%
Class II	Select Fund - Class II Return before taxes	1.82%	(0.92%)	3.34%
S&P 500	S&P 500 (does not reflect the deduction of fees, expenses or taxes)	2.11%	(0.25%)	2.92%

The S&P 500 Index is a widely quoted, unmanaged, market-weighted stock market
index that includes 500 of the largest companies publicly traded in the U.S. All
returns reflect reinvested dividends.

After-tax returns are calculated using the historical highest individual federal
marginal income tax rates and do not reflect the impact of 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
who hold their shares through tax-deferred arrangements, such as 401(k) plans,
qualified plans, education savings accounts or individual retirement accounts.
In some cases, the after-tax returns may exceed the return before taxes due to
an assumed tax benefit from any losses on a sale of Fund shares at the end of
the measurement period. After-tax returns are shown only for Class I shares.
After-tax returns for Class II shares will vary from returns shown for Class I.

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	Jan. 27, 2012
Oakmark International Fund (Prospectus Summary) | Oakmark International Fund
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	OAKMARK INTERNATIONAL FUND
Investment Objective, Heading	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	Oakmark International Fund seeks long-term capital appreciation.
Expense, Heading	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense, Narrative	rr_ExpenseNarrativeTextBlock	Below are the fees and expenses that you would pay if you buy and hold shares of the Fund.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses, Caption	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover, Heading	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover	rr_PortfolioTurnoverTextBlock	The Fund pays 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 45% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	45.00%
Expense Example, Heading	rr_ExpenseExampleHeading	Example.
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 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 remain the same.
Expense Example, By Year, Caption	rr_ExpenseExampleByYearCaption	Although your actual returns and costs may be higher or lower, based on these assumptions your expenses would be:
Investment Strategy, Heading	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGY
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	The Fund invests primarily in a diversified portfolio of common stocks of non-U.S. companies. The Fund may invest in non-U.S. markets throughout the world, including emerging markets. Ordinarily, the Fund will invest in the securities of at least five countries outside the U.S. There are no geographic limits on the Fund's non-U.S. investments. The Fund may invest in securities of large-, mid-, and small-capitalization companies. The Fund uses a value investment philosophy in selecting equity securities. This investment philosophy is based upon the belief that, over time, a company's stock price converges with the company's intrinsic or true business value. By "true business value," we mean an estimate of the price a knowledgeable buyer would pay to acquire the entire business. We believe that investing in securities priced significantly below their true business value presents the best opportunity to achieve the Fund's investment objective. The Fund's investment adviser, Harris Associates L.P. (the "Adviser"), uses this value philosophy to identify companies that it believes have discounted stock prices compared to the companies' true business values. In assessing such companies, the Adviser looks for the following characteristics, although not all of the companies selected will have these attributes: (1) free cash flows and intelligent investment of excess cash; (2) earnings that are growing and are reasonably predictable; and (3) high level of manager ownership. Key Tenets of the Oakmark Investment Philosophy: 1. Buy businesses that are trading at a significant discount to the Adviser's estimate of the company's intrinsic value. At the time the Adviser buys a company, the Adviser wants the company's stock to be inexpensive relative to what it believes the entire business is worth. 2. Invest with companies expected to grow shareholder value over time. Value investors can sometimes fall into the trap of buying a stock that is inexpensive for a reason-because the company just does not grow. The Adviser looks for good quality, growing businesses with positive free cash flow and intelligent investment of cash. 3. Invest with management teams that think and act as owners. The Adviser seeks out companies with management teams that understand the dynamics of per share value growth and are focused on achieving such growth. Stock ownership and incentives that align managements' interests with those of shareholders are key components of this analysis. In making its investment decisions, the Adviser uses a "bottom-up" approach focused on individual companies, rather than focusing on specific economic factors or specific industries. In order to select investments that meet the criteria described above, the Adviser uses independent, in-house research to analyze each company. As part of this selection process, the Adviser's analysts typically visit companies and conduct other research on the companies and their industries. Once the Adviser determines that a stock is selling at a significant discount and that the company has the additional qualities mentioned above, the Adviser may consider buying that stock for the Fund. The Adviser usually sells a stock when the price approaches its estimated worth. This means the Adviser sets specific "buy" and "sell" targets for each stock held by the Fund. The Adviser also monitors each holding and adjusts those price targets as warranted to reflect changes in a company's fundamentals. The Adviser believes that holding a relatively small number of stocks allows its "best ideas" to have a meaningful impact on the Fund's performance. Therefore, the Fund's portfolio typically holds thirty to sixty stocks rather than hundreds.
Risk, Heading	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk, Narrative	rr_RiskNarrativeTextBlock	As an investor in the Fund, you should have a long-term perspective and be able to tolerate potentially wide fluctuations in the value of your Fund shares. Your investment in the Fund is subject to risks, including the possibility that the value of the Fund's portfolio holdings may fluctuate in response to events specific to the companies in which the Fund invests, as well as economic, political or social events in the U.S. or abroad. As a result, when you redeem your Fund shares, they may be worth more or less than you paid for them. Although the Fund makes every effort to achieve its objective, it cannot guarantee it will attain that objective. The principal risks of investing in the Fund are: Market Risk. The Fund is subject to market risk-the risk that securities markets and individual securities will increase or decrease in value. Market risk applies to every market and every security. Security prices may fluctuate widely over short or extended periods in response to market or economic news and conditions, and securities markets also tend to move in cycles. If there is a general decline in the securities markets, it is possible your investment may lose value regardless of the individual results of the companies in which the Fund invests. The magnitude of up and down price or market fluctuations over time is sometimes referred to as "volatility," which, at times, can be significant. In addition, different asset classes and geographic markets may experience periods of significant correlation with each other. As a result of this correlation, the securities and markets in which the Fund invests may experience volatility due to market, economic, political or social events and conditions that may not readily appear to directly relate to such securities, the securities' issuer or the markets in which they trade. Common Stock Risk. Common stocks are subject to greater fluctuations in market value than other asset classes as a result of such factors as a company's business performance, investor perceptions, stock market trends and general economic conditions. The rights of common stockholders are subordinate to all other claims on a company's assets including debt holders and preferred stockholders; therefore, the Fund could lose money if a company in which it invests becomes financially distressed. Focused Portfolio Risk. The Fund's portfolio tends to be invested in a relatively small number of stocks. As a result, the appreciation or depreciation of any one security held by the Fund will have a greater impact on the Fund's net asset value than it would if the Fund invested in a larger number of securities. Although that strategy has the potential to generate attractive returns over time, it also increases the Fund's volatility. Small and Mid Cap Securities Risk. Investments in small and mid cap companies may be riskier than investments in larger, more established companies. The securities of smaller companies may trade less frequently and in smaller volumes, and as a result, may be less liquid than securities of larger companies. In addition, smaller companies may be more vulnerable to economic, market and industry changes. As a result, share price changes may be more sudden or erratic than the prices of other equity securities, especially over the short term. Because smaller companies may have limited product lines, markets or financial resources or may depend on a few key employees, they may be more susceptible to particular economic events or competitive factors than large capitalization companies. Value Style Risk. Investing in "value" stocks presents the risk that the stocks may never reach what the Adviser believes are their full market values, either because the market fails to recognize what the Adviser considers to be the companies' true business values or because the Adviser misjudged those values. In addition, value stocks may fall out of favor with investors and underperform growth stocks during given periods. Non-U.S. Securities Risk. Investments in securities issued by entities based outside the United States involve risks relating to political, social and economic developments abroad, as well as risks resulting from the differences between the regulations to which U.S. and non-U.S. issuers and markets are subject. These risks may result in the Fund experiencing rapid and extreme value changes due to currency controls; different accounting, auditing, financial reporting, and legal standards and practices; political and diplomatic changes and developments; expropriation; changes in tax policy; a lack of available public information regarding non-U.S. issuers; greater market volatility; a lack of sufficient market liquidity; differing securities market structures; higher transaction costs; and various administrative difficulties, such as delays in clearing and settling portfolio transactions or in receiving payment of dividends. These risks may be heightened in connection with investments in issuers located in developing and emerging countries, and in issuers in more developed countries that conduct substantial business in such developing and emerging countries. Fluctuations in the exchange rates between currencies may negatively affect an investment in non-U.S. securities. The Fund may hedge its exposure to foreign currencies. Although hedging may be used to protect the Fund from adverse currency movements, the use of such hedges may reduce or eliminate the potentially positive effect of currency revaluations on the Fund's total return, and there is no guarantee that the Fund's hedging strategy will be successful. Your investment in the Fund is not a deposit in a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You may lose money by investing in the Fund. The likelihood of loss may be greater if you invest for a shorter period of time.
Risk, Lose Money	rr_RiskLoseMoney	You may lose money by investing in the Fund.
Risk, Not Insured Depository Institution	rr_RiskNotInsuredDepositoryInstitution	Your investment in the Fund is not a deposit in a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance, Narrative	rr_PerformanceNarrativeTextBlock	The Fund's past performance (before and after taxes), as provided by the bar chart and performance table that follow, is not an indication of how the Fund will perform in the future. This information can help you evaluate the potential risk and reward of investing in the Fund by showing changes in the performance of the Fund's Class I Shares from year to year. The information illustrates the volatility of the Fund's historical returns and shows how the Fund's annual average returns compare with those of a broad measure of market performance. Updated performance information is available at oakmark.com or by calling 1-800-OAKMARK.
Performance, Information Illustrates Variability of Returns	rr_PerformanceInformationIllustratesVariabilityOfReturns	The information illustrates the volatility of the Fund's historical returns and shows how the Fund's annual average returns compare with those of a broad measure of market performance.
Performance, Availability Phone Number	rr_PerformanceAvailabilityPhone	1-800-OAKMARK
Performance, Availability Website Address	rr_PerformanceAvailabilityWebSiteAddress	oakmark.com
Performance, Past Does Not Indicate Future	rr_PerformancePastDoesNotIndicateFuture	The Fund's past performance (before and after taxes), as provided by the bar chart and performance table that follow, is not an indication of how the Fund will perform in the future.
Bar Chart, Heading	rr_BarChartHeading	Class I Shares Total Returns for Years Ended December 31 (%)
Bar Chart, Narrative	rr_BarChartNarrativeTextBlock	Since 2002, the highest and lowest quarterly returns for the Fund's Class I Shares were: • Highest quarterly return: 33.2%, during the quarter ended June 30, 2009 • Lowest quarterly return: -22.9%, during the quarter ended September 30, 2002
Performance Table, Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table, Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	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 who hold their shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts or individual retirement accounts.
Performance Table, One Class of after Tax Shown	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown only for Class I shares. After-tax returns for Class II shares will vary from returns shown for Class I.
Performance Table, Explanation after Tax Higher	rr_PerformanceTableExplanationAfterTaxHigher	In some cases, the after-tax returns may exceed the return before taxes due to an assumed tax benefit from any losses on a sale of Fund shares at the end of the measurement period.
Performance Table, Closing	rr_PerformanceTableClosingTextBlock	The Morgan Stanley Capital International (MSCI) World ex U.S. Index is an unmanaged index that includes countries throughout the world, in proportion to world stock market capitalization, but excludes U.S. companies. All returns reflect reinvested dividends. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of 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 who hold their shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts or individual retirement accounts. In some cases, the after-tax returns may exceed the return before taxes due to an assumed tax benefit from any losses on a sale of Fund shares at the end of the measurement period. After-tax returns are shown only for Class I shares. After-tax returns for Class II shares will vary from returns shown for Class I.
Average Annual Returns, Caption	rr_AverageAnnualReturnCaption	Average Annual Total Returns for Periods Ended December 31, 2011
Oakmark International Fund (Prospectus Summary) | Oakmark International Fund | MSCI World ex U.S. Index
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	MSCI World ex U.S. Index (does not reflect the deduction of fees, expenses or taxes)
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	(12.21%)
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	(4.09%)
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	5.14%
Oakmark International Fund (Prospectus Summary) | Oakmark International Fund | Class I
Risk Return [Abstract]	rr_RiskReturnAbstract
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	(2.00%)
Exchange fee	rr_ExchangeFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.90%
Distribution (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.16%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.06%
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	108
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	337
Expense Example, With Redemption, 5 Years	rr_ExpenseExampleYear05	585
Expense Example, With Redemption, 10 Years	rr_ExpenseExampleYear10	1,294
Annual Return 2002	rr_AnnualReturn2002	(8.46%)
Annual Return 2003	rr_AnnualReturn2003	38.04%
Annual Return 2004	rr_AnnualReturn2004	19.09%
Annual Return 2005	rr_AnnualReturn2005	14.12%
Annual Return 2006	rr_AnnualReturn2006	30.60%
Annual Return 2007	rr_AnnualReturn2007	(0.51%)
Annual Return 2008	rr_AnnualReturn2008	(41.06%)
Annual Return 2009	rr_AnnualReturn2009	56.30%
Annual Return 2010	rr_AnnualReturn2010	16.22%
Annual Return 2011	rr_AnnualReturn2011	(14.07%)
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest quarterly return:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	33.20%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest quarterly return:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2002
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(22.90%)
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	International Fund - Class I Return before taxes
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	(14.07%)
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	(1.75%)
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	7.46%
Oakmark International Fund (Prospectus Summary) | Oakmark International Fund | Class I | After Taxes on Distributions
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	International Fund - Class I Return after taxes on distributions
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	(14.06%)
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	(2.68%)
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	6.60%
Oakmark International Fund (Prospectus Summary) | Oakmark International Fund | Class I | After Taxes on Distributions and Sales
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	International Fund - Class I Return after taxes on distributions and sale of Fund shares
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	(8.91%)
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	(1.52%)
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	6.58%
Oakmark International Fund (Prospectus Summary) | Oakmark International Fund | Class II
Risk Return [Abstract]	rr_RiskReturnAbstract
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	(2.00%)
Exchange fee	rr_ExchangeFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.90%
Distribution (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.55%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.45%
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	148
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	459
Expense Example, With Redemption, 5 Years	rr_ExpenseExampleYear05	792
Expense Example, With Redemption, 10 Years	rr_ExpenseExampleYear10	1,735
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	International Fund - Class II Return before taxes
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	(14.38%)
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	(2.06%)
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	7.10%

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Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	Jan. 27, 2012
Oakmark Global Fund (Prospectus Summary) | Oakmark Global Fund
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	OAKMARK GLOBAL FUND
Investment Objective, Heading	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	Oakmark Global Fund seeks long-term capital appreciation.
Expense, Heading	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense, Narrative	rr_ExpenseNarrativeTextBlock	Below are the fees and expenses that you would pay if you buy and hold shares of the Fund.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses, Caption	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover, Heading	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover	rr_PortfolioTurnoverTextBlock	The Fund pays 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 29% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	29.00%
Expense Example, Heading	rr_ExpenseExampleHeading	Example.
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 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 remain the same.
Expense Example, By Year, Caption	rr_ExpenseExampleByYearCaption	Although your actual returns and costs may be higher or lower, based on these assumptions your expenses would be:
Investment Strategy, Heading	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGY
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	The Fund invests primarily in a diversified portfolio of common stocks of U.S. and non-U.S. companies. The Fund invests in the securities of companies located in at least three countries. Typically, the Fund invests between 25-75% of its total assets in securities of U.S. companies and between 25-75% of its total assets in securities of non-U.S. companies. There are no geographic limits on the Fund's non-U.S. investments, and the Fund may invest in securities of companies located in developed or emerging markets. The Fund may invest in the securities of large-, mid-, and small-capitalization companies. The Fund uses a value investment philosophy in selecting equity securities. This investment philosophy is based upon the belief that, over time, a company's stock price converges with the company's intrinsic or true business value. By "true business value," we mean an estimate of the price a knowledgeable buyer would pay to acquire the entire business. We believe that investing in securities priced significantly below their true business value presents the best opportunity to achieve the Fund's investment objective. The Fund's investment adviser, Harris Associates L.P. (the "Adviser"), uses this value philosophy to identify companies that it believes have discounted stock prices compared to the companies' true business values. In assessing such companies, the Adviser looks for the following characteristics, although not all of the companies selected will have these attributes: (1) free cash flows and intelligent investment of excess cash; (2) earnings that are growing and are reasonably predictable; and (3) high level of manager ownership. Key Tenets of the Oakmark Investment Philosophy: 1. Buy businesses that are trading at a significant discount to the Adviser's estimate of the company's intrinsic value. At the time the Adviser buys a company, the Adviser wants the company's stock to be inexpensive relative to what it believes the entire business is worth. 2. Invest with companies expected to grow shareholder value over time. Value investors can sometimes fall into the trap of buying a stock that is inexpensive for a reason-because the company just does not grow. The Adviser looks for good quality, growing businesses with positive free cash flow and intelligent investment of cash. 3. Invest with management teams that think and act as owners. The Adviser seeks out companies with management teams that understand the dynamics of per share value growth and are focused on achieving such growth. Stock ownership and incentives that align managements' interests with those of shareholders are key components of this analysis. In making its investment decisions, the Adviser uses a "bottom-up" approach focused on individual companies, rather than focusing on specific economic factors or specific industries. In order to select investments that meet the criteria described above, the Adviser uses independent, in-house research to analyze each company. As part of this selection process, the Adviser's analysts typically visit companies and conduct other research on the companies and their industries. Once the Adviser determines that a stock is selling at a significant discount and that the company has the additional qualities mentioned above, the Adviser may consider buying that stock for the Fund. The Adviser usually sells a stock when the price approaches its estimated worth. This means the Adviser sets specific "buy" and "sell" targets for each stock held by the Fund. The Adviser also monitors each holding and adjusts those price targets as warranted to reflect changes in a company's fundamentals. The Adviser believes that holding a relatively small number of stocks allows its "best ideas" to have a meaningful impact on the Fund's performance. Therefore, the Fund's portfolio typically holds thirty to sixty stocks rather than hundreds.
Risk, Heading	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk, Narrative	rr_RiskNarrativeTextBlock	As an investor in the Fund, you should have a long-term perspective and be able to tolerate potentially wide fluctuations in the value of your Fund shares. Your investment in the Fund is subject to risks, including the possibility that the value of the Fund's portfolio holdings may fluctuate in response to events specific to the companies in which the Fund invests, as well as economic, political or social events in the U.S. or abroad. As a result, when you redeem your Fund shares, they may be worth more or less than you paid for them. Although the Fund makes every effort to achieve its objective, it cannot guarantee it will attain that objective. The principal risks of investing in the Fund are: Market Risk. The Fund is subject to market risk-the risk that securities markets and individual securities will increase or decrease in value. Market risk applies to every market and every security. Security prices may fluctuate widely over short or extended periods in response to market or economic news and conditions, and securities markets also tend to move in cycles. If there is a general decline in the securities markets, it is possible your investment may lose value regardless of the individual results of the companies in which the Fund invests. The magnitude of up and down price or market fluctuations over time is sometimes referred to as "volatility," which, at times, can be significant. In addition, different asset classes and geographic markets may experience periods of significant correlation with each other. As a result of this correlation, the securities and markets in which the Fund invests may experience volatility due to market, economic, political or social events and conditions that may not readily appear to directly relate to such securities, the securities' issuer or the markets in which they trade. Common Stock Risk. Common stocks are subject to greater fluctuations in market value than other asset classes as a result of such factors as a company's business performance, investor perceptions, stock market trends and general economic conditions. The rights of common stockholders are subordinate to all other claims on a company's assets including debt holders and preferred stockholders; therefore, the Fund could lose money if a company in which it invests becomes financially distressed. Focused Portfolio Risk. The Fund's portfolio tends to be invested in a relatively small number of stocks. As a result, the appreciation or depreciation of any one security held by the Fund will have a greater impact on the Fund's net asset value than it would if the Fund invested in a larger number of securities. Although that strategy has the potential to generate attractive returns over time, it also increases the Fund's volatility. Small and Mid Cap Securities Risk. Investments in small and mid cap companies may be riskier than investments in larger, more established companies. The securities of smaller companies may trade less frequently and in smaller volumes, and as a result, may be less liquid than securities of larger companies. In addition, smaller companies may be more vulnerable to economic, market and industry changes. As a result, share price changes may be more sudden or erratic than the prices of other equity securities, especially over the short term. Because smaller companies may have limited product lines, markets or financial resources or may depend on a few key employees, they may be more susceptible to particular economic events or competitive factors than large capitalization companies. Value Style Risk. Investing in "value" stocks presents the risk that the stocks may never reach what the Adviser believes are their full market values, either because the market fails to recognize what the Adviser considers to be the companies' true business values or because the Adviser misjudged those values. In addition, value stocks may fall out of favor with investors and underperform growth stocks during given periods. Non-U.S. Securities Risk. Investments in securities issued by entities based outside the United States involve risks relating to political, social and economic developments abroad, as well as risks resulting from the differences between the regulations to which U.S. and non-U.S. issuers and markets are subject. These risks may result in the Fund experiencing rapid and extreme value changes due to currency controls; different accounting, auditing, financial reporting, and legal standards and practices; political and diplomatic changes and developments; expropriation; changes in tax policy; a lack of available public information regarding non-U.S. issuers; greater market volatility; a lack of sufficient market liquidity; differing securities market structures; higher transaction costs; and various administrative difficulties, such as delays in clearing and settling portfolio transactions or in receiving payment of dividends. These risks may be heightened in connection with investments in issuers located in developing and emerging countries, and in issuers in more developed countries that conduct substantial business in such developing and emerging countries. Fluctuations in the exchange rates between currencies may negatively affect an investment in non-U.S. securities. Investments in securities issued by entities domiciled in the United States also may be subject to many of these risks. The Fund may hedge its exposure to foreign currencies. Although hedging may be used to protect the Fund from adverse currency movements, the use of such hedges may reduce or eliminate the potentially positive effect of currency revaluations on the Fund's total return, and there is no guarantee that the Fund's hedging strategy will be successful. Your investment in the Fund is not a deposit in a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You may lose money by investing in the Fund. The likelihood of loss may be greater if you invest for a shorter period of time.
Risk, Lose Money	rr_RiskLoseMoney	You may lose money by investing in the Fund.
Risk, Not Insured Depository Institution	rr_RiskNotInsuredDepositoryInstitution	Your investment in the Fund is not a deposit in a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance, Narrative	rr_PerformanceNarrativeTextBlock	The Fund's past performance (before and after taxes), as provided by the bar chart and performance table that follow, is not an indication of how the Fund will perform in the future. This information can help you evaluate the potential risk and reward of investing in the Fund by showing changes in the performance of the Fund's Class I Shares from year to year. The information illustrates the volatility of the Fund's historical returns and shows how the Fund's average annual returns compare with those of a broad measure of market performance. Updated performance information is available at oakmark.com or by calling 1-800-OAKMARK.
Performance, Information Illustrates Variability of Returns	rr_PerformanceInformationIllustratesVariabilityOfReturns	The information illustrates the volatility of the Fund's historical returns and shows how the Fund's average annual returns compare with those of a broad measure of market performance.
Performance, Availability Phone Number	rr_PerformanceAvailabilityPhone	1-800-OAKMARK
Performance, Availability Website Address	rr_PerformanceAvailabilityWebSiteAddress	oakmark.com
Performance, Past Does Not Indicate Future	rr_PerformancePastDoesNotIndicateFuture	The Fund's past performance (before and after taxes), as provided by the bar chart and performance table that follow, is not an indication of how the Fund will perform in the future.
Bar Chart, Heading	rr_BarChartHeading	Class I Shares Total Returns for Years Ended December 31 (%)
Bar Chart, Narrative	rr_BarChartNarrativeTextBlock	Since 2002, the highest and lowest quarterly returns for the Fund's Class I Shares were: • Highest quarterly return: 33.5%, during the quarter ended June 30, 2003 • Lowest quarterly return: -24.1%, during the quarter ended December 31, 2008
Performance Table, Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table, Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	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 who hold their shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts or individual retirement accounts.
Performance Table, One Class of after Tax Shown	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown only for Class I shares. After-tax returns for Class II shares will vary from returns shown for Class I.
Performance Table, Explanation after Tax Higher	rr_PerformanceTableExplanationAfterTaxHigher	In some cases, the after-tax returns may exceed the return before taxes due to an assumed tax benefit from any losses on a sale of Fund shares at the end of the measurement period. After-tax returns are shown only for Class I shares.
Performance Table, Closing	rr_PerformanceTableClosingTextBlock	The Morgan Stanley Capital International (MSCI) World Index is an unmanaged index that includes countries throughout the world, in proportion to world stock market capitalization. All returns reflect reinvested dividends. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of 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 who hold their shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts or individual retirement accounts. In some cases, the after-tax returns may exceed the return before taxes due to an assumed tax benefit from any losses on a sale of Fund shares at the end of the measurement period. After-tax returns are shown only for Class I shares. After-tax returns for Class II shares will vary from returns shown for Class I.
Average Annual Returns, Caption	rr_AverageAnnualReturnCaption	Average Annual Total Returns for Periods Ended December 31, 2011
Oakmark Global Fund (Prospectus Summary) | Oakmark Global Fund | MSCI World Index
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	MSCI World Index (does not reflect the deduction of fees, expenses or taxes)
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	(5.54%)
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	(2.37%)
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	3.62%
Oakmark Global Fund (Prospectus Summary) | Oakmark Global Fund | Class I
Risk Return [Abstract]	rr_RiskReturnAbstract
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	(2.00%)
Exchange fee	rr_ExchangeFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	1.00%
Distribution (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.16%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.16%
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	118
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	368
Expense Example, With Redemption, 5 Years	rr_ExpenseExampleYear05	638
Expense Example, With Redemption, 10 Years	rr_ExpenseExampleYear10	1,409
Annual Return 2002	rr_AnnualReturn2002	(2.11%)
Annual Return 2003	rr_AnnualReturn2003	48.98%
Annual Return 2004	rr_AnnualReturn2004	15.63%
Annual Return 2005	rr_AnnualReturn2005	13.23%
Annual Return 2006	rr_AnnualReturn2006	24.18%
Annual Return 2007	rr_AnnualReturn2007	7.33%
Annual Return 2008	rr_AnnualReturn2008	(38.78%)
Annual Return 2009	rr_AnnualReturn2009	40.19%
Annual Return 2010	rr_AnnualReturn2010	15.74%
Annual Return 2011	rr_AnnualReturn2011	(11.65%)
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest quarterly return:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2003
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	33.50%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest quarterly return:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(24.10%)
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Global Fund - Class I Return before taxes
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	(11.65%)
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	(1.19%)
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	8.37%
Oakmark Global Fund (Prospectus Summary) | Oakmark Global Fund | Class I | After Taxes on Distributions
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Global Fund - Class I Return after taxes on distributions
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	(11.65%)
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	(1.66%)
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	7.80%
Oakmark Global Fund (Prospectus Summary) | Oakmark Global Fund | Class I | After Taxes on Distributions and Sales
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Global Fund - Class I Return after taxes on distributions and sale of Fund shares
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	(7.58%)
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	(0.96%)
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	7.48%
Oakmark Global Fund (Prospectus Summary) | Oakmark Global Fund | Class II
Risk Return [Abstract]	rr_RiskReturnAbstract
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	(2.00%)
Exchange fee	rr_ExchangeFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	1.00%
Distribution (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.55%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.55%
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	158
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	490
Expense Example, With Redemption, 5 Years	rr_ExpenseExampleYear05	845
Expense Example, With Redemption, 10 Years	rr_ExpenseExampleYear10	1,845
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Global Fund - Class II Return before taxes
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	(12.05%)
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	(1.56%)
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	7.98%

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Oakmark International Small Cap Fund (Prospectus Summary) | Oakmark International Small Cap Fund

OAKMARK INTERNATIONAL SMALL CAP FUND

INVESTMENT OBJECTIVE

Oakmark International Small Cap Fund seeks long-term capital appreciation.

FEES AND EXPENSES OF THE FUND

Below are the fees and expenses that you would pay if you buy and hold shares of
the Fund.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees Oakmark International Small Cap Fund	Class I	Class II
Maximum sales charge (load) imposed on purchases	none	none
Maximum deferred sales charge (load)	none	none
Redemption fee (as a percentage of amount redeemed on shares held for 90 days or less)	2.00%	2.00%
Exchange fee	none	none

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

Annual Fund Operating Expenses Oakmark International Small Cap Fund	Class I	Class II
Management fees	1.15%	1.15%
Distribution (12b-1) Fees	none	none
Other expenses	0.23%	0.57%
Total Annual Fund Operating Expenses	1.38%	1.72%

Example.

The Example is intended to help you compare the cost of investing in
the Fund with the cost of investing in other mutual funds. The Example assumes
that you invest $10,000 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
remain the same.

Although your actual returns and costs may be higher or lower, based on these assumptions your expenses would be:

Expense Example Oakmark International Small Cap Fund (USD $)	Class I	Class II
Expense Example, With Redemption, 1 Year	140	175
Expense Example, With Redemption, 3 Years	437	542
Expense Example, With Redemption, 5 Years	755	933
Expense Example, With Redemption, 10 Years	1,657	2,030

Portfolio Turnover

The Fund pays 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 46%
of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGY

The Fund invests primarily in a diversified portfolio of common stocks of
non-U.S. companies. Under normal market conditions, the Fund invests at least
80% of its net assets (plus any borrowings for investment purposes) in the
stocks of "small cap companies." A small cap company is one whose market
capitalization is less than $5 billion at the time of investment.

The Fund may invest in non-U.S. markets throughout the world, including emerging
markets. Ordinarily, the Fund will invest in the securities of at least five
countries outside the U.S. There are no geographic limits on the Fund's non-U.S.
investments.

The Fund uses a value investment philosophy in selecting equity securities. This
investment philosophy is based upon the belief that, over time, a company's
stock price converges with the company's intrinsic or true business value. By
"true business value," we mean an estimate of the price a knowledgeable buyer
would pay to acquire the entire business. We believe that investing in
securities priced significantly below their true business value presents the
best opportunity to achieve the Fund's investment objective.

The Fund's investment adviser, Harris Associates L.P. (the "Adviser"), uses this
value philosophy to identify companies that it believes have discounted stock
prices compared to the companies' true business values. In assessing such
companies, the Adviser looks for the following characteristics, although not all
of the companies selected will have these attributes: (1) free cash flows and
intelligent investment of excess cash; (2) earnings that are growing and are
reasonably predictable; and (3) high level of manager ownership.

Key Tenets of the Oakmark Investment Philosophy:

1. Buy businesses that are trading at a significant discount to the Adviser's
estimate of the company's intrinsic value. At the time the Adviser buys a
company, the Adviser wants the company's stock to be inexpensive relative to
what it believes the entire business is worth.

2. Invest with companies expected to grow shareholder value over time. Value
investors can sometimes fall into the trap of buying a stock that is inexpensive
for a reason-because the company just does not grow. The Adviser looks for good
quality, growing businesses with positive free cash flow and intelligent
investment of cash.

3. Invest with management teams that think and act as owners. The Adviser seeks
out companies with management teams that understand the dynamics of per share
value growth and are focused on achieving such growth. Stock ownership and
incentives that align managements' interests with those of shareholders are key
components of this analysis.

In making its investment decisions, the Adviser uses a "bottom-up" approach
focused on individual companies, rather than focusing on specific economic
factors or specific industries. In order to select investments that meet the
criteria described above, the Adviser uses independent, in-house research to
analyze each company. As part of this selection process, the Adviser's analysts
typically visit companies and conduct other research on the companies and their
industries.

Once the Adviser determines that a stock is selling at a significant discount
and that the company has the additional qualities mentioned above, the Adviser
may consider buying that stock for the Fund. The Adviser usually sells a stock
when the price approaches its estimated worth. This means the Adviser sets
specific "buy" and "sell" targets for each stock held by the Fund. The Adviser
also monitors each holding and adjusts those price targets as warranted to
reflect changes in a company's fundamentals.

The Adviser believes that holding a relatively small number of stocks allows its
"best ideas" to have a meaningful impact on the Fund's performance. Therefore,
the Fund's portfolio typically holds thirty to seventy stocks rather than
hundreds.

PRINCIPAL INVESTMENT RISKS

As an investor in the Fund, you should have a long-term perspective and be able
to tolerate potentially wide fluctuations in the value of your Fund shares. Your
investment in the Fund is subject to risks, including the possibility that the
value of the Fund's portfolio holdings may fluctuate in response to events
specific to the companies in which the Fund invests, as well as economic,
political or social events in the U.S. or abroad. As a result, when you redeem
your Fund shares, they may be worth more or less than you paid for them.

Although the Fund makes every effort to achieve its objective, it cannot
guarantee it will attain that objective. The principal risks of investing in the
Fund are:

Market Risk. The Fund is subject to market risk-the risk that securities markets
and individual securities will increase or decrease in value. Market risk
applies to every market and every security. Security prices may fluctuate widely
over short or extended periods in response to market or economic news and
conditions, and securities markets also tend to move in cycles. If there is a
general decline in the securities markets, it is possible your investment may
lose value regardless of the individual results of the companies in which the
Fund invests. The magnitude of up and down price or market fluctuations over
time is sometimes referred to as "volatility," which, at times, can be
significant. In addition, different asset classes and geographic markets may
experience periods of significant correlation with each other. As a result of
this correlation, the securities and markets in which the Fund invests may
experience volatility due to market, economic, political or social events and
conditions that may not readily appear to directly relate to such securities,
the securities' issuer or the markets in which they trade.

Common Stock Risk. Common stocks are subject to greater fluctuations in market
value than other asset classes as a result of such factors as a company's
business performance, investor perceptions, stock market trends and general
economic conditions. The rights of common stockholders are subordinate to all
other claims on a company's assets including debt holders and preferred
stockholders; therefore, the Fund could lose money if a company in which it
invests becomes financially distressed.

Focused Portfolio Risk. The Fund's portfolio tends to be invested in a
relatively small number of stocks. As a result, the appreciation or depreciation
of any one security held by the Fund will have a greater impact on the Fund's
net asset value than it would if the Fund invested in a larger number of
securities. Although that strategy has the potential to generate attractive
returns over time, it also increases the Fund's volatility.

Value Style Risk. Investing in "value" stocks presents the risk that the stocks
may never reach what the Adviser believes are their full market values, either
because the market fails to recognize what the Adviser considers to be the
companies' true business values or because the Adviser misjudged those values.
In addition, value stocks may fall out of favor with investors and underperform
growth stocks during given periods.

Non-U.S. Securities Risk. Investments in securities issued by entities based
outside the United States involve risks relating to political, social and
economic developments abroad, as well as risks resulting from the differences
between the regulations to which U.S. and non-U.S. issuers and markets are
subject. These risks may result in the Fund experiencing rapid and extreme value
changes due to currency controls; different accounting, auditing, financial
reporting, and legal standards and practices; political and diplomatic changes
and developments; expropriation; changes in tax policy; a lack of available
public information regarding non-U.S. issuers; greater market volatility; a lack
of sufficient market liquidity; differing securities market structures; higher
transaction costs; and various administrative difficulties, such as delays in
clearing and settling portfolio transactions or in receiving payment of
dividends. These risks may be heightened in connection with investments in
issuers located in developing and emerging countries, and in issuers in more
developed countries that conduct substantial business in such developing and
emerging countries. Fluctuations in the exchange rates between currencies may
negatively affect an investment in non-U.S. securities. The Fund may hedge its
exposure to foreign currencies. Although hedging may be used to protect the Fund
from adverse currency movements, the use of such hedges may reduce or eliminate
the potentially positive effect of currency revaluations on the Fund's total
return, and there is no guarantee that the Fund's hedging strategy will be
successful.

Small Cap Securities Risk. Investments in small cap companies may be riskier
than investments in larger, more established companies. The securities of
smaller companies may trade less frequently and in smaller volumes, and as a
result, may be less liquid than securities of larger companies. In addition,
smaller companies may be more vulnerable to economic, market and industry
changes. As a result, share price changes may be more sudden or erratic than the
prices of other equity securities, especially over the short term. Because
smaller companies may have limited product lines, markets or financial resources
or may depend on a few key employees, they may be more susceptible to particular
economic events or competitive factors than large capitalization companies.

Your investment in the Fund is not a deposit in a bank and is not insured or
guaranteed by the Federal Deposit Insurance Corporation or any other government
agency. You may lose money by investing in the Fund. The likelihood of loss may
be greater if you invest for a shorter period of time.

PERFORMANCE INFORMATION

The Fund's past performance (before and after taxes), as provided by the bar
chart and performance table that follow, is not an indication of how the Fund
will perform in the future. This information can help you evaluate the potential
risk and reward of investing in the Fund by showing changes in the performance
of the Fund's Class I Shares from year to year. The information illustrates the
volatility of the Fund's historical returns and shows how the Fund's annual
average returns compare with a broad measure of market performance. Updated
performance information is available at oakmark.com or by calling 1-800-OAKMARK.

Since 2002, the highest and lowest quarterly returns for the Fund's Class I Shares were:
• Highest quarterly return: 43.7%, during the quarter ended June 30, 2009
• Lowest quarterly return: -27.3%, during the  quarter ended December 31, 2008

Class I Shares Total Returns for Years Ended December 31 (%)

Average Annual Total Returns for Periods Ended December 31, 2011

Average Annual Total Returns Oakmark International Small Cap Fund	Average Annual Returns, Label	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Class I	International Small Cap Fund - Class I Return before taxes	(16.44%)	(3.28%)	9.95%
Class I After Taxes on Distributions	International Small Cap Fund - Class I Return after taxes on distributions	(16.34%)	(4.53%)	8.54%
Class I After Taxes on Distributions and Sales	International Small Cap Fund - Class I Return after taxes on distributions and sale of Fund shares	(10.55%)	(2.82%)	8.77%
Class II	International Small Cap Fund - Class II Return before taxes	(16.72%)	(3.52%)	9.74%
MSCI World ex U.S. Small Cap Index	MSCI World ex U.S. Small Cap Index	(12.21%)	(4.09%)	5.14%

The Morgan Stanley Capital International (MSCI) World ex U.S. Small Cap Index is
an unmanaged index that measures the equity market performance of small cap
companies in developed markets excluding the U.S. The Index is a free
float-adjusted market capitalization index.

After-tax returns are calculated using the historical highest individual federal
marginal income tax rates and do not reflect the impact of 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
who hold their shares through tax-deferred arrangements, such as 401(k) plans,
qualified plans, education savings accounts or individual retirement accounts.
In some cases, the after-tax returns may exceed the return before taxes due to
an assumed tax benefit from any losses on a sale of Fund shares at the end of
the measurement period. After-tax returns are shown only for Class I shares.
After-tax returns for Class II shares will vary from returns shown for Class I.

XML

Oakmark Global Select Fund (Prospectus Summary) | Oakmark Global Select Fund

OAKMARK GLOBAL SELECT FUND

INVESTMENT OBJECTIVE

Oakmark Global Select Fund seeks long-term capital appreciation.

FEES AND EXPENSES OF THE FUND

Below are the fees and expenses that you would pay if you buy and hold shares of
the Fund.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees Oakmark Global Select Fund	Class I	Class II
Maximum sales charge (load) imposed on purchases	none	none
Maximum deferred sales charge (load)	none	none
Redemption fee (as a percentage of amount redeemed on shares held for 90 days or less)	2.00%	2.00%
Exchange fee	none	none

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

Annual Fund Operating Expenses Oakmark Global Select Fund	Class I	Class II
Management fees	1.00%	1.00%
Distribution (12b-1) Fees	none	none
Other expenses	0.24%	0.49%
Total Annual Fund Operating Expenses	1.24%	1.49%

Example.

The Example is intended to help you compare the cost of investing in
the Fund with the cost of investing in other mutual funds. The example assumes
that you invest $10,000 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
remain the same.

Although your actual returns and costs may be higher or lower, based on these assumptions your expenses would be:

Expense Example Oakmark Global Select Fund (USD $)	Class I	Class II
Expense Example, With Redemption, 1 Year	126	152
Expense Example, With Redemption, 3 Years	393	471
Expense Example, With Redemption, 5 Years	681	813
Expense Example, With Redemption, 10 Years	1,500	1,779

Portfolio Turnover

The Fund pays 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 49%
of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGY

The Fund invests primarily in common stocks of U.S. and non-U.S. companies. The
Fund invests in the securities of companies located in at least three countries.
The Fund is non-diversified, which means that it may invest a greater portion of
its assets in a more limited number of issuers than a diversified fund. The Fund
could own as few as twelve securities, but generally will have approximately
twenty securities in its portfolio. Typically, the Fund will invest at least 40%
of its total assets in securities of non-U.S. companies (unless Harris
Associates L.P., the Fund's investment adviser (the "Adviser"), deems market
conditions and/or company valuations less favorable to non-U.S. companies, in
which case the Fund will invest at least 30% of its total assets in securities
of non-U.S. companies). There are no geographic limits on the Fund's non-U.S.
investments, and the Fund may invest in securities of companies located in
developed or emerging markets. The Fund may invest in the securities of large-,
mid-, and small-capitalization companies.

The Fund uses a value investment philosophy in selecting equity securities. This
investment philosophy is based upon the belief that, over time, a company's
stock price converges with the company's intrinsic or true business value. By
"true business value," we mean an estimate of the price a knowledgeable buyer
would pay to acquire the entire business. We believe that investing in
securities priced significantly below their true business value presents the
best opportunity to achieve the Fund's investment objective.

The Adviser uses this value philosophy to identify companies that it believes
have discounted stock prices compared to the companies' true business values. In
assessing such companies, the Adviser looks for the following characteristics,
although not all of the companies selected will have these attributes: (1) free
cash flows and intelligent investment of excess cash; (2) earnings that are
growing and are reasonably predictable; and (3) high level of manager ownership.

Key Tenets of the Oakmark Investment Philosophy:

1. Buy businesses that are trading at a significant discount to the Adviser's
estimate of the company's intrinsic value. At the time the Adviser buys a
company, the Adviser wants the company's stock to be inexpensive relative to
what it believes the entire business is worth.

2. Invest with companies expected to grow shareholder value over time. Value
investors can sometimes fall into the trap of buying a stock that is inexpensive
for a reason-because the company just does not grow. The Adviser looks for good
quality, growing businesses with positive free cash flow and intelligent
investment of cash.

3. Invest with management teams that think and act as owners. The Adviser seeks
out companies with management teams that understand the dynamics of per share
value growth and are focused on achieving such growth. Stock ownership and
incentives that align managements' interests with those of shareholders are key
components of this analysis.

In making its investment decisions, the Adviser uses a "bottom-up" approach
focused on individual companies, rather than focusing on specific economic
factors or specific industries. In order to select investments that meet the
criteria described above, the Adviser uses independent, in-house research to
analyze each company. As part of this selection process, the Adviser's analysts
typically visit companies and conduct other research on the companies and their
industries.

Once the Adviser determines that a stock is selling at a significant discount
and that the company has the additional qualities mentioned above, the Adviser
may consider buying that stock for the Fund. The Adviser usually sells a stock
when the price approaches its estimated worth. This means the Adviser sets
specific "buy" and "sell" targets for each stock held by the Fund. The Adviser
also monitors each holding and adjusts those price targets as warranted to
reflect changes in a company's fundamentals.

PRINCIPAL INVESTMENT RISKS

As an investor in the Fund, you should have a long-term perspective and be able
to tolerate potentially wide fluctuations in the value of your Fund shares. Your
investment in the Fund is subject to risks, including the possibility that the
value of the Fund's portfolio holdings may fluctuate in response to events
specific to the companies in which the Fund invests, as well as economic,
political or social events in the U.S. or abroad. As a result, when you redeem
your Fund shares, they may be worth more or less than you paid for them.

Although the Fund makes every effort to achieve its objective, it cannot
guarantee it will attain that objective. The principal risks of investing in the
Fund are:

Market Risk. The Fund is subject to market risk-the risk that securities markets
and individual securities will increase or decrease in value. Market risk
applies to every market and every security. Security prices may fluctuate widely
over short or extended periods in response to market or economic news and
conditions, and securities markets also tend to move in cycles. If there is a
general decline in the securities markets, it is possible your investment may
lose value regardless of the individual results of the companies in which the
Fund invests. The magnitude of up and down price or market fluctuations over
time is sometimes referred to as "volatility," which, at times, can be
significant. In addition, different asset classes and geographic markets may
experience periods of significant correlation with each other. As a result of
this correlation, the securities and markets in which the Fund invests may
experience volatility due to market, economic, political or social events and
conditions that may not readily appear to directly relate to such securities,
the securities' issuer or the markets in which they trade.

Common Stock Risk. Common stocks are subject to greater fluctuations in market
value than other asset classes as a result of such factors as a company's
business performance, investor perceptions, stock market trends and general
economic conditions. The rights of common stockholders are subordinate to all
other claims on a company's assets including debt holders and preferred
stockholders; therefore, the Fund could lose money if a company in which it
invests becomes financially distressed.

Small and Mid Cap Securities Risk. Investments in small and mid cap companies
may be riskier than investments in larger, more established companies. The
securities of smaller companies may trade less frequently and in smaller
volumes, and as a result, may be less liquid than securities of larger
companies. In addition, smaller companies may be more vulnerable to economic,
market and industry changes. As a result, share price changes may be more sudden
or erratic than the prices of other equity securities, especially over the short
term. Because smaller companies may have limited product lines, markets or
financial resources or may depend on a few key employees, they may be more
susceptible to particular economic events or competitive factors than large
capitalization companies.

Value Style Risk. Investing in "value" stocks presents the risk that the stocks
may never reach what the Adviser believes are their full market values, either
because the market fails to recognize what the Adviser considers to be the
companies' true business values or because the Adviser misjudged those values.
In addition, value stocks may fall out of favor with investors and underperform
growth stocks during given periods.

Non-U.S. Securities Risk. Investments in securities issued by entities based
outside the United States involve risks relating to political, social and
economic developments abroad, as well as risks resulting from the differences
between the regulations to which U.S. and non-U.S. issuers and markets are
subject. These risks may result in the Fund experiencing rapid and extreme value
changes due to currency controls; different accounting, auditing, financial
reporting, and legal standards and practices; political and diplomatic changes
and developments; expropriation; changes in tax policy; a lack of available
public information regarding non-U.S. issuers; greater market volatility; a lack
of sufficient market liquidity; differing securities market structures; higher
transaction costs; and various administrative difficulties, such as delays in
clearing and settling portfolio transactions or in receiving payment of
dividends. These risks may be heightened in connection with investments in
issuers located in developing and emerging countries, and in issuers in more
developed countries that conduct substantial business in such developing and
emerging countries. Fluctuations in the exchange rates between currencies may
negatively affect an investment in non-U.S. securities. Investments in
securities issued by entities domiciled in the United States also may be subject
to many of these risks. The Fund may hedge its exposure to foreign currencies.
Although hedging may be used to protect the Fund from adverse currency
movements, the use of such hedges may reduce or eliminate the potentially
positive effect of currency revaluations on the Fund's total return, and there
is no guarantee that the Fund's hedging strategy will be successful.

Non-Diversification Risk. A non-diversified fund may be subject to greater risk
than a diversified fund because changes in the financial condition or market
assessment of a single issuer may cause greater fluctuation in the value of a
non-diversified fund's shares. Lack of broad diversification also may cause a
non-diversified fund to be more susceptible to economic, political or regulatory
events than a diversified fund. A non-diversification strategy may increase the
Fund's volatility.

Your investment in the Fund is not a deposit in a bank and is not insured or
guaranteed by the Federal Deposit Insurance Corporation or any other government
agency. You may lose money by investing in the Fund. The likelihood of loss may
be greater if you invest for a shorter period of time.

PERFORMANCE INFORMATION

The Fund's past performance (before and after taxes), as provided by the bar
chart and performance table that follow, is not an indication of how the Fund
will perform in the future. This information can help you evaluate the potential
risk and reward of investing in the Fund by showing changes in the performance
of the Fund's Class I Shares from year to year. The information illustrates the
volatility of the Fund's historical returns and shows how the Fund's annual
average returns compare with those of a broad measure of market performance.
Updated performance information is available at oakmark.com or by calling
1-800-OAKMARK.

Since 2007, the highest and lowest quarterly returns for the Fund's Class I Shares were:
• Highest quarterly return: 26.6%, during the quarter ended June 30, 2009
• Lowest quarterly return: -16.3%, during the quarter ended December 31, 2008

Class I Shares Total Returns for Years Ended December 31 (%)

Average Annual Total Returns for Periods Ended December 31, 2011

Average Annual Total Returns Oakmark Global Select Fund	Average Annual Returns, Label	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, Since Inception	Average Annual Returns, Inception Date
Class I	Global Select Fund - Class I Return before taxes	(5.87%)	1.39%	2.81%	Oct. 02, 2006
Class I After Taxes on Distributions	Global Select Fund - Class I Return after taxes on distributions	(5.87%)	0.92%	2.35%	Oct. 02, 2006
Class I After Taxes on Distributions and Sales	Global Select Fund - Class I Return after taxes on distributions and sale of Fund shares	(3.82%)	0.97%	2.19%	Oct. 02, 2006
MSCI World Index	MSCI World Index (does not reflect the deduction of fees, expenses or taxes)	(5.54%)	(2.37%)	(0.78%)	Oct. 02, 2006

The Morgan Stanley Capital International (MSCI) World Index is an unmanaged
index that includes countries throughout the world, in proportion to world stock
market capitalization. All returns reflect reinvested dividends.

After-tax returns are calculated using the historical highest individual federal
marginal income tax rates and do not reflect the impact of 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
who hold their shares through tax-deferred arrangements, such as 401(k) plans,
qualified plans, education savings accounts or individual retirement accounts.
In some cases, the after-tax returns may exceed the return before taxes due to
an assumed tax benefit from any losses on a sale of Fund shares at the end of
the measurement period. After-tax returns are shown only for Class I shares.
After-tax returns for Class II shares will vary from returns shown for Class I.

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	Jan. 27, 2012
Oakmark Fund (Prospectus Summary) | Oakmark Fund
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	OAKMARK FUND
Investment Objective, Heading	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	Oakmark Fund seeks long-term capital appreciation.
Expense, Heading	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense, Narrative	rr_ExpenseNarrativeTextBlock	Below are the fees and expenses that you would pay if you buy and hold shares of the Fund.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses, Caption	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover, Heading	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover	rr_PortfolioTurnoverTextBlock	The Fund pays 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 18% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	18.00%
Expense Example, Heading	rr_ExpenseExampleHeading	Example.
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 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 remain the same.
Expense Example, By Year, Caption	rr_ExpenseExampleByYearCaption	Although your actual returns and costs may be higher or lower, based on these assumptions your expenses would be:
Investment Strategy, Heading	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGY
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	The Fund invests primarily in a diversified portfolio of common stocks of U.S. companies. The Fund may invest in the securities of large-, mid-, and small-capitalization companies. The Fund uses a value investment philosophy in selecting equity securities. This investment philosophy is based upon the belief that, over time, a company's stock price converges with the company's intrinsic or true business value. By "true business value," we mean an estimate of the price a knowledgeable buyer would pay to acquire the entire business. We believe that investing in securities priced significantly below their true business value presents the best opportunity to achieve the Fund's investment objective. The Fund's investment adviser, Harris Associates L.P. (the "Adviser"), uses this value philosophy to identify companies that it believes have discounted stock prices compared to the companies' true business values. In assessing such companies, the Adviser looks for the following characteristics, although not all of the companies selected will have these attributes: (1) free cash flows and intelligent investment of excess cash; (2) earnings that are growing and are reasonably predictable; and (3) high level of manager ownership. Key Tenets of the Oakmark Investment Philosophy: 1. Buy businesses that are trading at a significant discount to the Adviser's estimate of the company's intrinsic value. At the time the Adviser buys a company, the Adviser wants the company's stock to be inexpensive relative to what it believes the entire business is worth. 2. Invest with companies expected to grow shareholder value over time. Value investors can sometimes fall into the trap of buying a stock that is inexpensive for a reason-because the company just does not grow. The Adviser looks for good quality, growing businesses with positive free cash flow and intelligent investment of cash. 3. Invest with management teams that think and act as owners. The Adviser seeks out companies with management teams that understand the dynamics of per share value growth and are focused on achieving such growth. Stock ownership and incentives that align managements' interests with those of shareholders are key components of this analysis. In making its investment decisions, the Adviser uses a "bottom-up" approach focused on individual companies, rather than focusing on specific economic factors or specific industries. In order to select investments that meet the criteria described above, the Adviser uses independent, in-house research to analyze each company. As part of this selection process, the Adviser's analysts typically visit companies and conduct other research on the companies and their industries. Once the Adviser determines that a stock is selling at a significant discount and that the company has the additional qualities mentioned above, the Adviser may consider buying that stock for the Fund. The Adviser usually sells a stock when the price approaches its estimated worth. This means the Adviser sets specific "buy" and "sell" targets for each stock held by the Fund. The Adviser also monitors each holding and adjusts those price targets as warranted to reflect changes in a company's fundamentals. The Adviser believes that holding a relatively small number of stocks allows its "best ideas" to have a meaningful impact on the Fund's performance. Therefore, the Fund's portfolio typically holds thirty to sixty stocks rather than hundreds.
Risk, Heading	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk, Narrative	rr_RiskNarrativeTextBlock	As an investor in the Fund, you should have a long-term perspective and be able to tolerate potentially wide fluctuations in the value of your Fund shares. Your investment in the Fund is subject to risks, including the possibility that the value of the Fund's portfolio holdings may fluctuate in response to events specific to the companies in which the Fund invests, as well as economic, political or social events in the U.S. or abroad. As a result, when you redeem your Fund shares, they may be worth more or less than you paid for them. Although the Fund makes every effort to achieve its objective, it cannot guarantee it will attain that objective. The principal risks of investing in the Fund are: Market Risk. The Fund is subject to market risk-the risk that securities markets and individual securities will increase or decrease in value. Market risk applies to every market and every security. Security prices may fluctuate widely over short or extended periods in response to market or economic news and conditions, and securities markets also tend to move in cycles. If there is a general decline in the securities markets, it is possible your investment may lose value regardless of the individual results of the companies in which the Fund invests. The magnitude of up and down price or market fluctuations over time is sometimes referred to as "volatility," which, at times, can be significant. In addition, different asset classes and geographic markets may experience periods of significant correlation with each other. As a result of this correlation, the securities and markets in which the Fund invests may experience volatility due to market, economic, political or social events and conditions that may not readily appear to directly relate to such securities, the securities' issuer or the markets in which they trade. Common Stock Risk. Common stocks are subject to greater fluctuations in market value than other asset classes as a result of such factors as a company's business performance, investor perceptions, stock market trends and general economic conditions. The rights of common stockholders are subordinate to all other claims on a company's assets including debt holders and preferred stockholders; therefore, the Fund could lose money if a company in which it invests becomes financially distressed. Focused Portfolio Risk. The Fund's portfolio tends to be invested in a relatively small number of stocks. As a result, the appreciation or depreciation of any one security held by the Fund will have a greater impact on the Fund's net asset value than it would if the Fund invested in a larger number of securities. Although that strategy has the potential to generate attractive returns over time, it also increases the Fund's volatility. Small and Mid Cap Securities Risk. Investments in small and mid cap companies may be riskier than investments in larger, more established companies. The securities of smaller companies may trade less frequently and in smaller volumes, and as a result, may be less liquid than securities of larger companies. In addition, smaller companies may be more vulnerable to economic, market and industry changes. As a result, share price changes may be more sudden or erratic than the prices of other equity securities, especially over the short term. Because smaller companies may have limited product lines, markets or financial resources or may depend on a few key employees, they may be more susceptible to particular economic events or competitive factors than large capitalization companies. Value Style Risk. Investing in "value" stocks presents the risk that the stocks may never reach what the Adviser believes are their full market values, either because the market fails to recognize what the Adviser considers to be the companies' true business values or because the Adviser misjudged those values. In addition, value stocks may fall out of favor with investors and underperform growth stocks during given periods. Your investment in the Fund is not a deposit in a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You may lose money by investing in the Fund. The likelihood of loss may be greater if you invest for a shorter period of time.
Risk, Lose Money	rr_RiskLoseMoney	You may lose money by investing in the Fund.
Risk, Not Insured Depository Institution	rr_RiskNotInsuredDepositoryInstitution	Your investment in the Fund is not a deposit in a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance, Narrative	rr_PerformanceNarrativeTextBlock	The Fund's past performance (before and after taxes), as provided by the bar chart and performance table that follow, is not an indication of how the Fund will perform in the future. This information can help you evaluate the potential risk and reward of investing in the Fund by showing changes in the performance of the Fund's Class I Shares from year to year. The information illustrates the volatility of the Fund's historical returns and shows how the Fund's average annual returns compare with those of a broad measure of market performance. Updated performance information is available at oakmark.com or by calling 1-800-OAKMARK.
Performance, Information Illustrates Variability of Returns	rr_PerformanceInformationIllustratesVariabilityOfReturns	The information illustrates the volatility of the Fund's historical returns and shows how the Fund's average annual returns compare with those of a broad measure of market performance.
Performance, Availability Phone Number	rr_PerformanceAvailabilityPhone	1-800-OAKMARK
Performance, Availability Website Address	rr_PerformanceAvailabilityWebSiteAddress	oakmark.com
Performance, Past Does Not Indicate Future	rr_PerformancePastDoesNotIndicateFuture	The Fund's past performance (before and after taxes), as provided by the bar chart and performance table that follow, is not an indication of how the Fund will perform in the future.
Bar Chart, Heading	rr_BarChartHeading	Class I Shares Total Returns for Years Ended December 31 (%)
Bar Chart, Narrative	rr_BarChartNarrativeTextBlock	Since 2002, the highest and lowest quarterly returns for the Fund's Class I Shares were: • Highest quarterly return: 23.2%, during the quarter ended June 30, 2009 • Lowest quarterly return: -23.0%, during the quarter ended December 31, 2008
Performance Table, Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table, Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	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 who hold their shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts or individual retirement accounts.
Performance Table, One Class of after Tax Shown	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown only for Class I shares. After-tax returns for Class II shares will vary from returns shown for Class I.
Performance Table, Explanation after Tax Higher	rr_PerformanceTableExplanationAfterTaxHigher	In some cases, the after-tax returns may exceed the return before taxes due to an assumed tax benefit from any losses on a sale of Fund shares at the end of the measurement period.
Performance Table, Closing	rr_PerformanceTableClosingTextBlock	The S&P 500 Index is a widely quoted, unmanaged, market-weighted stock market index that includes 500 of the largest companies publicly traded in the U.S. All returns reflect reinvested dividends. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of 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 who hold their shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts or individual retirement accounts. In some cases, the after-tax returns may exceed the return before taxes due to an assumed tax benefit from any losses on a sale of Fund shares at the end of the measurement period. After-tax returns are shown only for Class I shares. After-tax returns for Class II shares will vary from returns shown for Class I.
Average Annual Returns, Caption	rr_AverageAnnualReturnCaption	Average Annual Total Returns for Periods Ended December 31, 2011
Oakmark Fund (Prospectus Summary) | Oakmark Fund | S&P 500
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	S&P 500 (does not reflect the deduction of fees, expenses or taxes)
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	2.11%
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	(0.25%)
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	2.92%
Oakmark Fund (Prospectus Summary) | Oakmark Fund | Class I
Risk Return [Abstract]	rr_RiskReturnAbstract
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_ExchangeFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.92%
Distribution (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.12%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.04%
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	106
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	331
Expense Example, With Redemption, 5 Years	rr_ExpenseExampleYear05	574
Expense Example, With Redemption, 10 Years	rr_ExpenseExampleYear10	1,271
Annual Return 2002	rr_AnnualReturn2002	(14.41%)
Annual Return 2003	rr_AnnualReturn2003	25.30%
Annual Return 2004	rr_AnnualReturn2004	11.73%
Annual Return 2005	rr_AnnualReturn2005	(1.31%)
Annual Return 2006	rr_AnnualReturn2006	18.26%
Annual Return 2007	rr_AnnualReturn2007	(3.64%)
Annual Return 2008	rr_AnnualReturn2008	(32.61%)
Annual Return 2009	rr_AnnualReturn2009	44.77%
Annual Return 2010	rr_AnnualReturn2010	12.18%
Annual Return 2011	rr_AnnualReturn2011	1.82%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest quarterly return:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	23.20%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest quarterly return:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(23.00%)
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Oakmark Fund - Class I Return before taxes
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	1.82%
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	1.44%
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	4.15%
Oakmark Fund (Prospectus Summary) | Oakmark Fund | Class I | After Taxes on Distributions
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Oakmark Fund - Class I Return after taxes on distributions
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	1.69%
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	0.94%
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	3.77%
Oakmark Fund (Prospectus Summary) | Oakmark Fund | Class I | After Taxes on Distributions and Sales
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Oakmark Fund - Class I Return after taxes on distributions and sale of Fund shares
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	1.35%
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	1.15%
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	3.55%
Oakmark Fund (Prospectus Summary) | Oakmark Fund | Class II
Risk Return [Abstract]	rr_RiskReturnAbstract
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_ExchangeFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.92%
Distribution (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.53%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.45%
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	148
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	459
Expense Example, With Redemption, 5 Years	rr_ExpenseExampleYear05	792
Expense Example, With Redemption, 10 Years	rr_ExpenseExampleYear10	1,735
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Oakmark Fund - Class II Return before taxes
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	1.45%
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	1.12%
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	3.83%

XML

Oakmark Fund (Prospectus Summary) | Oakmark Fund

OAKMARK FUND

INVESTMENT OBJECTIVE

Oakmark Fund seeks long-term capital appreciation.

FEES AND EXPENSES OF THE FUND

Below are the fees and expenses that you would pay if you buy and hold shares of
the Fund.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees Oakmark Fund	Class I	Class II
Maximum sales charge (load) imposed on purchases	none	none
Maximum deferred sales charge (load)	none	none
Redemption fee (as a percentage of amount redeemed on shares held for 90 days or less)	none	none
Exchange fee	none	none

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

Annual Fund Operating Expenses Oakmark Fund	Class I	Class II
Management fees	0.92%	0.92%
Distribution (12b-1) Fees	none	none
Other expenses	0.12%	0.53%
Total Annual Fund Operating Expenses	1.04%	1.45%

Example.

The Example is intended to help you compare the cost of investing in
the Fund with the cost of investing in other mutual funds. The Example assumes
that you invest $10,000 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
remain the same.

Although your actual returns and costs may be higher or lower, based on these assumptions your expenses would be:

Expense Example Oakmark Fund (USD $)	Class I	Class II
Expense Example, With Redemption, 1 Year	106	148
Expense Example, With Redemption, 3 Years	331	459
Expense Example, With Redemption, 5 Years	574	792
Expense Example, With Redemption, 10 Years	1,271	1,735

Portfolio Turnover

The Fund pays 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 18% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGY

The Fund invests primarily in a diversified portfolio of common stocks of U.S.
companies. The Fund may invest in the securities of large-, mid-, and
small-capitalization companies. The Fund uses a value investment philosophy in
selecting equity securities. This investment philosophy is based upon the belief
that, over time, a company's stock price converges with the company's intrinsic
or true business value. By "true business value," we mean an estimate of the
price a knowledgeable buyer would pay to acquire the entire business. We believe
that investing in securities priced significantly below their true business
value presents the best opportunity to achieve the Fund's investment objective.

The Fund's investment adviser, Harris Associates L.P. (the "Adviser"), uses this
value philosophy to identify companies that it believes have discounted stock
prices compared to the companies' true business values. In assessing such
companies, the Adviser looks for the following characteristics, although not all
of the companies selected will have these attributes: (1) free cash flows and
intelligent investment of excess cash; (2) earnings that are growing and are
reasonably predictable; and (3) high level of manager ownership.

Key Tenets of the Oakmark Investment Philosophy:

1. Buy businesses that are trading at a significant discount to the Adviser's
estimate of the company's intrinsic value. At the time the Adviser buys a
company, the Adviser wants the company's stock to be inexpensive relative to
what it believes the entire business is worth.

2. Invest with companies expected to grow shareholder value over time. Value
investors can sometimes fall into the trap of buying a stock that is inexpensive
for a reason-because the company just does not grow. The Adviser looks for good
quality, growing businesses with positive free cash flow and intelligent
investment of cash.

3. Invest with management teams that think and act as owners. The Adviser seeks
out companies with management teams that understand the dynamics of per share
value growth and are focused on achieving such growth. Stock ownership and
incentives that align managements' interests with those of shareholders are key
components of this analysis.

In making its investment decisions, the Adviser uses a "bottom-up" approach
focused on individual companies, rather than focusing on specific economic
factors or specific industries. In order to select investments that meet the
criteria described above, the Adviser uses independent, in-house research to
analyze each company. As part of this selection process, the Adviser's analysts
typically visit companies and conduct other research on the companies and their
industries.

Once the Adviser determines that a stock is selling at a significant discount
and that the company has the additional qualities mentioned above, the Adviser
may consider buying that stock for the Fund. The Adviser usually sells a stock
when the price approaches its estimated worth. This means the Adviser sets
specific "buy" and "sell" targets for each stock held by the Fund. The Adviser
also monitors each holding and adjusts those price targets as warranted to reflect
changes in a company's fundamentals.

The Adviser believes that holding a relatively small number of stocks allows its
"best ideas" to have a meaningful impact on the Fund's performance. Therefore,
the Fund's portfolio typically holds thirty to sixty stocks rather than
hundreds.

PRINCIPAL INVESTMENT RISKS

As an investor in the Fund, you should have a long-term perspective and be able
to tolerate potentially wide fluctuations in the value of your Fund shares. Your
investment in the Fund is subject to risks, including the possibility that the
value of the Fund's portfolio holdings may fluctuate in response to events
specific to the companies in which the Fund invests, as well as economic,
political or social events in the U.S. or abroad. As a result, when you redeem
your Fund shares, they may be worth more or less than you paid for them.

Although the Fund makes every effort to achieve its objective, it cannot
guarantee it will attain that objective. The principal risks of investing in the
Fund are:

Market Risk. The Fund is subject to market risk-the risk that securities markets
and individual securities will increase or decrease in value. Market risk
applies to every market and every security. Security prices may fluctuate widely
over short or extended periods in response to market or economic news and
conditions, and securities markets also tend to move in cycles. If there is a
general decline in the securities markets, it is possible your investment may
lose value regardless of the individual results of the companies in which the
Fund invests. The magnitude of up and down price or market fluctuations over
time is sometimes referred to as "volatility," which, at times, can be
significant. In addition, different asset classes and geographic markets may
experience periods of significant correlation with each other. As a result of
this correlation, the securities and markets in which the Fund invests may
experience volatility due to market, economic, political or social events and
conditions that may not readily appear to directly relate to such securities,
the securities' issuer or the markets in which they trade.

Common Stock Risk. Common stocks are subject to greater fluctuations in market
value than other asset classes as a result of such factors as a company's
business performance, investor perceptions, stock market trends and general
economic conditions. The rights of common stockholders are subordinate to all
other claims on a company's assets including debt holders and preferred
stockholders; therefore, the Fund could lose money if a company in which it
invests becomes financially distressed.

Focused Portfolio Risk. The Fund's portfolio tends to be invested in a
relatively small number of stocks. As a result, the appreciation or depreciation
of any one security held by the Fund will have a greater impact on the Fund's
net asset value than it would if the Fund invested in a larger number of
securities. Although that strategy has the potential to generate attractive
returns over time, it also increases the Fund's volatility.

Small and Mid Cap Securities Risk. Investments in small and mid cap companies
may be riskier than investments in larger, more established companies. The
securities of smaller companies may trade less frequently and in smaller
volumes, and as a result, may be less liquid than securities of larger
companies. In addition, smaller companies may be more vulnerable to economic,
market and industry changes. As a result, share price changes may be more sudden
or erratic than the prices of other equity securities, especially over the short
term. Because smaller companies may have limited product lines, markets or
financial resources or may depend on a few key employees, they may be more
susceptible to particular economic events or competitive factors than large
capitalization companies.

Value Style Risk. Investing in "value" stocks presents the risk that the stocks
may never reach what the Adviser believes are their full market values, either
because the market fails to recognize what the Adviser considers to be the
companies' true business values or because the Adviser misjudged those values.
In addition, value stocks may fall out of favor with investors and underperform
growth stocks during given periods.

Your investment in the Fund is not a deposit in a bank and is not insured or
guaranteed by the Federal Deposit Insurance Corporation or any other government
agency. You may lose money by investing in the Fund. The likelihood of loss may
be greater if you invest for a shorter period of time.

PERFORMANCE INFORMATION

The Fund's past performance (before and after taxes), as provided by the bar
chart and performance table that follow, is not an indication of how the Fund
will perform in the future. This information can help you evaluate the potential
risk and reward of investing in the Fund by showing changes in the performance
of the Fund's Class I Shares from year to year. The information illustrates the
volatility of the Fund's historical returns and shows how the Fund's average
annual returns compare with those of a broad measure of market performance.
Updated performance information is available at oakmark.com or by calling
1-800-OAKMARK.

Since 2002, the highest and lowest quarterly returns for the Fund's Class I Shares were:
• Highest quarterly return: 23.2%, during the quarter ended June 30, 2009
• Lowest quarterly return: -23.0%, during the quarter ended December 31, 2008

Class I Shares Total Returns for Years Ended December 31 (%)

Average Annual Total Returns for Periods Ended December 31, 2011

Average Annual Total Returns Oakmark Fund	Average Annual Returns, Label	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Class I	Oakmark Fund - Class I Return before taxes	1.82%	1.44%	4.15%
Class I After Taxes on Distributions	Oakmark Fund - Class I Return after taxes on distributions	1.69%	0.94%	3.77%
Class I After Taxes on Distributions and Sales	Oakmark Fund - Class I Return after taxes on distributions and sale of Fund shares	1.35%	1.15%	3.55%
Class II	Oakmark Fund - Class II Return before taxes	1.45%	1.12%	3.83%
S&P 500	S&P 500 (does not reflect the deduction of fees, expenses or taxes)	2.11%	(0.25%)	2.92%

The S&P 500 Index is a widely quoted, unmanaged, market-weighted stock market
index that includes 500 of the largest companies publicly traded in the U.S. All
returns reflect reinvested dividends.

After-tax returns are calculated using the historical highest individual federal
marginal income tax rates and do not reflect the impact of 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
who hold their shares through tax-deferred arrangements, such as 401(k) plans,
qualified plans, education savings accounts or individual retirement accounts.
In some cases, the after-tax returns may exceed the return before taxes due to
an assumed tax benefit from any losses on a sale of Fund shares at the end of
the measurement period. After-tax returns are shown only for Class I shares.
After-tax returns for Class II shares will vary from returns shown for Class I.

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	Jan. 27, 2012
Oakmark Equity and Income Fund (Prospectus Summary) | Oakmark Equity and Income Fund
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	OAKMARK EQUITY AND INCOME FUND
Investment Objective, Heading	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	Oakmark Equity and Income Fund seeks income and preservation and growth of capital.
Expense, Heading	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense, Narrative	rr_ExpenseNarrativeTextBlock	Below are the fees and expenses that you would pay if you buy and hold shares of the Fund.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses, Caption	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover, Heading	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover	rr_PortfolioTurnoverTextBlock	The Fund pays 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 47% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	47.00%
Expense Example, Heading	rr_ExpenseExampleHeading	Example.
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 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 remain the same.
Expense Example, By Year, Caption	rr_ExpenseExampleByYearCaption	Although your actual returns and costs may be higher or lower, based on these assumptions your expenses would be:
Investment Strategy, Heading	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGY
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	The Fund invests primarily in a diversified portfolio of U.S. equity and debt securities (although the Fund may invest up to 35% of its total assets in equity and debt securities of non-U.S. issuers). The Fund is intended to present a balanced investment program between growth and income by investing approximately 40-75% of its total assets in common stock, including securities convertible into common stock, and up to 60% of its assets in U.S. government securities and debt securities rated at time of purchase within the two highest grades assigned by Moody's Investors Service, Inc. or by Standard & Poor's Corporation Ratings Group, a division of The McGraw-Hill Companies. The Fund also may invest up to 20% of its assets in unrated or lower rated debt securities, sometimes called junk bonds. The types of equity securities in which the Fund may invest include common and preferred stocks and warrants or other similar rights and convertible securities. The types of debt securities in which the Fund may invest include debt securities of both governmental and corporate issuers. The Fund may invest in the securities of large-, mid-, and small-capitalization companies. The Fund uses a value investment philosophy in selecting equity securities. This investment philosophy is based upon the belief that, over time, a company's stock price converges with the company's intrinsic or true business value. By "true business value," we mean an estimate of the price a knowledgeable buyer would pay to acquire the entire business. We believe that investing in securities priced significantly below their true business value presents the best opportunity to achieve the Fund's investment objective. The Fund's investment adviser, Harris Associates L.P. (the "Adviser"), uses this value philosophy to identify companies that it believes have discounted stock prices compared to the companies' true business values. In assessing such companies, the Adviser looks for the following characteristics, although not all of the companies selected will have these attributes: (1) free cash flows and intelligent investment of excess cash; (2) earnings that are growing and are reasonably predictable; and (3) high level of manager ownership. Key Tenets of the Oakmark Investment Philosophy-Equity Portion of the Fund: 1. Buy businesses that are trading at a significant discount to the Adviser's estimate of the company's intrinsic value. At the time the Adviser buys a company, the Adviser wants the company's stock to be inexpensive relative to what it believes the entire business is worth. 2. Invest with companies expected to grow shareholder value over time. Value investors can sometimes fall into the trap of buying a stock that is inexpensive for a reason-because the company just does not grow. The Adviser looks for good quality, growing businesses with positive free cash flow and intelligent investment of cash. 3. Invest with management teams that think and act as owners. The Adviser seeks out companies with management teams that understand the dynamics of per share value growth and are focused on achieving such growth. Stock ownership and incentives that align managements' interests with those of shareholders are key components of this analysis. In making its investment decisions, the Adviser uses a "bottom-up" approach focused on individual companies, rather than focusing on specific economic factors or specific industries. In order to select investments that meet the criteria described above, the Adviser uses independent, in-house research to analyze each company. As part of this selection process, the Adviser's analysts typically visit companies and conduct other research on the companies and their industries. Once the Adviser determines that a stock is selling at a significant discount and that the company has the additional qualities mentioned above, the Adviser may consider buying that stock for the Fund. The Adviser usually sells a stock when the price approaches its estimated worth. This means the Adviser sets specific "buy" and "sell" targets for each stock held by the Fund. The Adviser also monitors each holding and adjusts those price targets as warranted to reflect changes in a company's fundamentals. The Adviser believes that holding a relatively small number of stocks allows its "best ideas" to have a meaningful impact on the Fund's performance. Therefore, the Fund's portfolio typically holds thirty to sixty stocks rather than hundreds.
Risk, Heading	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk, Narrative	rr_RiskNarrativeTextBlock	As an investor in the Fund, you should have a long-term perspective and be able to tolerate potentially wide fluctuations in the value of your Fund shares. Your investment in the Fund is subject to risks, including the possibility that the value of the Fund's portfolio holdings may fluctuate in response to events specific to the companies in which the Fund invests, as well as economic, political or social events in the U.S. or abroad. As a result, when you redeem your Fund shares, they may be worth more or less than you paid for them. Although the Fund makes every effort to achieve its objective, it cannot guarantee it will attain that objective. The principal risks of investing in the Fund are: Market Risk. The Fund is subject to market risk-the risk that securities markets and individual securities will increase or decrease in value. Market risk applies to every market and every security. Security prices may fluctuate widely over short or extended periods in response to market or economic news and conditions, and securities markets also tend to move in cycles. If there is a general decline in the securities markets, it is possible your investment may lose value regardless of the individual results of the companies in which the Fund invests. The magnitude of up and down price or market fluctuations over time is sometimes referred to as "volatility," which, at times, can be significant. In addition, different asset classes and geographic markets may experience periods of significant correlation with each other. As a result of this correlation, the securities and markets in which the Fund invests may experience volatility due to market, economic, political or social events and conditions that may not readily appear to directly relate to such securities, the securities' issuer or the markets in which they trade. Common Stock Risk. Common stocks are subject to greater fluctuations in market value than other asset classes as a result of such factors as a company's business performance, investor perceptions, stock market trends and general economic conditions. The rights of common stockholders are subordinate to all other claims on a company's assets including debt holders and preferred stockholders; therefore, the Fund could lose money if a company in which it invests becomes financially distressed. Focused Portfolio Risk. The Fund's portfolio tends to be invested in a relatively small number of stocks. As a result, the appreciation or depreciation of any one security held by the Fund will have a greater impact on the Fund's net asset value than it would if the Fund invested in a larger number of securities. Although that strategy has the potential to generate attractive returns over time, it also increases the Fund's volatility. Small and Mid Cap Securities Risk. Investments in small and mid cap companies may be riskier than investments in larger, more established companies. The securities of smaller companies may trade less frequently and in smaller volumes, and as a result, may be less liquid than securities of larger companies. In addition, smaller companies may be more vulnerable to economic, market and industry changes. As a result, share price changes may be more sudden or erratic than the prices of other equity securities, especially over the short term. Because smaller companies may have limited product lines, markets or financial resources or may depend on a few key employees, they may be more susceptible to particular economic events or competitive factors than large capitalization companies. Value Style Risk. Investing in "value" stocks presents the risk that the stocks may never reach what the Adviser believes are their full market values, either because the market fails to recognize what the Adviser considers to be the companies' true business values or because the Adviser misjudged those values. In addition, value stocks may fall out of favor with investors and underperform growth stocks during given periods. Debt Securities Risk. Debt securities are subject to credit risk, interest rate risk and liquidity risk. Credit risk is the risk the issuer or guarantor of a debt security will be unable or unwilling to make timely payments of interest or principal or to otherwise honor its obligations. Interest rate risk is the risk of losses due to changes in interest rates. In general, the prices of debt securities rise when interest rates fall, and the prices fall when interest rates rise. Liquidity risk is the risk a particular security may be difficult to purchase or sell and that the Fund may be unable to sell illiquid securities at an advantageous time or price. The Fund's investments in government-sponsored entity securities also exhibit these risks, although the degree of such risks may vary significantly among the different government-sponsored entity securities. Some securities issued or guaranteed by U.S. government agencies or instrumentalities are not backed by the full faith and credit of the U.S. and may only be supported by the right of the agency or instrumentality to borrow from the U.S. Treasury. There can be no assurance that the U.S. government will always provide financial support to those agencies or instrumentalities. Foreign sovereign debt instruments are subject to the risk that a governmental entity may delay or refuse to pay interest or repay principal on its sovereign debt. There is no legal process for collecting sovereign debt that a government does not pay, nor are there bankruptcy proceedings through which all or part of the sovereign debt that a government entity has not repaid may be collected. Inflation-Indexed Securities Risk. The principal value of an investment is not protected or otherwise guaranteed by virtue of the Fund's investments in inflation-indexed bonds. If the index measuring inflation falls, the principal value of inflation-indexed bonds will be adjusted downward, and consequently the interest payable on these securities (calculated with respect to a smaller principal amount) will be reduced. Repayment of the original bond principal upon maturity (as adjusted for inflation) is guaranteed in the case of U.S. Treasury inflation-indexed bonds. For bonds that do not provide a similar guarantee, the adjusted principal value of the bond repaid at maturity may be less than the original principal value. The value of inflation-indexed bonds is expected to change in response to changes in real interest rates. Real interest rates are tied to the relationship between nominal interest rates and the rate of inflation. If nominal interest rates increase at a faster rate than inflation, real interest rates may rise, leading to a decrease in value of inflation indexed bonds. Short-term increases in inflation may lead to a decline in value. Any increase in the principal amount of an inflation-indexed bond will be considered taxable ordinary income, even though investors do not receive their principal until maturity. Periodic adjustments for inflation to the principal amount of an inflation-indexed bond may give rise to original issue discount, which will be includable in the Fund's gross income. Due to original issue discount, the Fund may be required to make annual distributions to shareholders that exceed the cash received, which may cause the Fund to liquidate certain investments when it is not advantageous to do so. Also, if the principal value of an inflation-indexed bond is adjusted downward due to deflation, amounts previously distributed in the taxable year may be characterized in some circumstances as a return of capital. Non-U.S. Securities Risk. Investments in securities issued by entities based outside the United States involve risks relating to political, social and economic developments abroad, as well as risks resulting from the differences between the regulations to which U.S. and non-U.S. issuers and markets are subject. These risks may result in the Fund experiencing rapid and extreme value changes due to currency controls; different accounting, auditing, financial reporting, and legal standards and practices; political and diplomatic changes and developments; expropriation; changes in tax policy; a lack of available public information regarding non-U.S. issuers; greater market volatility; a lack of sufficient market liquidity; differing securities market structures; higher transaction costs; and various administrative difficulties, such as delays in clearing and settling portfolio transactions or in receiving payment of dividends. These risks may be heightened in connection with investments in issuers located in developing and emerging countries, and in issuers in more developed countries that conduct substantial business in such developing and emerging countries. Fluctuations in the exchange rates between currencies may negatively affect an investment in non-U.S. securities. Investments in securities issued by entities domiciled in the United States also may be subject to many of these risks. Your investment in the Fund is not a deposit in a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You may lose money by investing in the Fund. The likelihood of loss may be greater if you invest for a shorter period of time.
Risk, Lose Money	rr_RiskLoseMoney	You may lose money by investing in the Fund.
Risk, Not Insured Depository Institution	rr_RiskNotInsuredDepositoryInstitution	Your investment in the Fund is not a deposit in a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance, Narrative	rr_PerformanceNarrativeTextBlock	The Fund's past performance (before and after taxes), as provided by the bar chart and performance table that follow, is not an indication of how the Fund will perform in the future. This information can help you evaluate the potential risk and reward of investing in the Fund by showing changes in the performance of the Fund's Class I Shares from year to year. The information illustrates the volatility of the Fund's historical returns and shows how the Fund's annual average returns compare with those of a broad measure of market performance. Updated performance information is available at oakmark.com or by calling 1-800-OAKMARK.
Performance, Information Illustrates Variability of Returns	rr_PerformanceInformationIllustratesVariabilityOfReturns	The information illustrates the volatility of the Fund's historical returns and shows how the Fund's annual average returns compare with those of a broad measure of market performance.
Performance, Availability Phone Number	rr_PerformanceAvailabilityPhone	1-800-OAKMARK
Performance, Availability Website Address	rr_PerformanceAvailabilityWebSiteAddress	oakmark.com
Bar Chart, Heading	rr_BarChartHeading	Class I Shares Total Returns for Years Ended December 31 (%)
Bar Chart, Narrative	rr_BarChartNarrativeTextBlock	Since 2002, the highest and lowest quarterly returns for the Fund's Class I Shares were: • Highest quarterly return: 13.2%, during the quarter ended June 30, 2003 • Lowest quarterly return: -12.8%, during the quarter ended Septebmer 30, 2011
Performance Table, Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table, Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	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 who hold their shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts or individual retirement accounts.
Performance Table, One Class of after Tax Shown	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown only for Class I shares. After-tax returns for Class II shares will vary from returns shown for Class I.
Performance Table, Explanation after Tax Higher	rr_PerformanceTableExplanationAfterTaxHigher	In some cases, the after-tax returns may exceed the return before taxes due to an assumed tax benefit from any losses on a sale of Fund shares at the end of the measurement period.
Performance Table, Closing	rr_PerformanceTableClosingTextBlock	Lipper Balanced Fund Index is an index of thirty balanced funds. All returns reflect reinvested dividends. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of 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 who hold their shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts or individual retirement accounts. In some cases, the after-tax returns may exceed the return before taxes due to an assumed tax benefit from any losses on a sale of Fund shares at the end of the measurement period. After-tax returns are shown only for Class I shares. After-tax returns for Class II shares will vary from returns shown for Class I.
Average Annual Returns, Caption	rr_AverageAnnualReturnCaption	Average Annual Total Returns for Periods Ended December 31, 2011
Oakmark Equity and Income Fund (Prospectus Summary) | Oakmark Equity and Income Fund | Lipper Balanced Fund Index
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Lipper Balanced Fund Index (does not reflect the deduction of fees, expenses or taxes)
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	0.74%
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	1.80%
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	4.13%
Oakmark Equity and Income Fund (Prospectus Summary) | Oakmark Equity and Income Fund | Class I
Risk Return [Abstract]	rr_RiskReturnAbstract
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_ExchangeFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.67%
Distribution (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.10%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.77%
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	79
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	246
Expense Example, With Redemption, 5 Years	rr_ExpenseExampleYear05	428
Expense Example, With Redemption, 10 Years	rr_ExpenseExampleYear10	954
Annual Return 2002	rr_AnnualReturn2002	(2.14%)
Annual Return 2003	rr_AnnualReturn2003	23.21%
Annual Return 2004	rr_AnnualReturn2004	10.36%
Annual Return 2005	rr_AnnualReturn2005	8.60%
Annual Return 2006	rr_AnnualReturn2006	10.82%
Annual Return 2007	rr_AnnualReturn2007	11.97%
Annual Return 2008	rr_AnnualReturn2008	(16.18%)
Annual Return 2009	rr_AnnualReturn2009	19.84%
Annual Return 2010	rr_AnnualReturn2010	9.50%
Annual Return 2011	rr_AnnualReturn2011	0.64%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest quarterly return:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2003
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	13.20%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest quarterly return:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2011
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(12.80%)
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Equity and Income Fund - Class I Return before taxes
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	0.64%
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	4.39%
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	7.10%
Oakmark Equity and Income Fund (Prospectus Summary) | Oakmark Equity and Income Fund | Class I | After Taxes on Distributions
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Equity and Income Fund - Class I Return after taxes on distributions
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	0.15%
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	3.77%
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	6.48%
Oakmark Equity and Income Fund (Prospectus Summary) | Oakmark Equity and Income Fund | Class I | After Taxes on Distributions and Sales
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Equity and Income Fund - Class I Return after taxes on distributions and sale of Fund shares
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	0.99%
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	3.63%
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	6.06%
Oakmark Equity and Income Fund (Prospectus Summary) | Oakmark Equity and Income Fund | Class II
Risk Return [Abstract]	rr_RiskReturnAbstract
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_ExchangeFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.67%
Distribution (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.42%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.09%
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	111
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	347
Expense Example, With Redemption, 5 Years	rr_ExpenseExampleYear05	601
Expense Example, With Redemption, 10 Years	rr_ExpenseExampleYear10	1,329
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Equity and Income Fund - Class II Return before taxes
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	0.27%
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	4.04%
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	6.78%

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	Jan. 27, 2012
Oakmark Global Select Fund (Prospectus Summary) | Oakmark Global Select Fund
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	OAKMARK GLOBAL SELECT FUND
Investment Objective, Heading	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	Oakmark Global Select Fund seeks long-term capital appreciation.
Expense, Heading	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense, Narrative	rr_ExpenseNarrativeTextBlock	Below are the fees and expenses that you would pay if you buy and hold shares of the Fund.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses, Caption	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover, Heading	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover	rr_PortfolioTurnoverTextBlock	The Fund pays 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 49% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	49.00%
Expense Example, Heading	rr_ExpenseExampleHeading	Example.
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 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 remain the same.
Expense Example, By Year, Caption	rr_ExpenseExampleByYearCaption	Although your actual returns and costs may be higher or lower, based on these assumptions your expenses would be:
Investment Strategy, Heading	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGY
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	The Fund invests primarily in common stocks of U.S. and non-U.S. companies. The Fund invests in the securities of companies located in at least three countries. The Fund is non-diversified, which means that it may invest a greater portion of its assets in a more limited number of issuers than a diversified fund. The Fund could own as few as twelve securities, but generally will have approximately twenty securities in its portfolio. Typically, the Fund will invest at least 40% of its total assets in securities of non-U.S. companies (unless Harris Associates L.P., the Fund's investment adviser (the "Adviser"), deems market conditions and/or company valuations less favorable to non-U.S. companies, in which case the Fund will invest at least 30% of its total assets in securities of non-U.S. companies). There are no geographic limits on the Fund's non-U.S. investments, and the Fund may invest in securities of companies located in developed or emerging markets. The Fund may invest in the securities of large-, mid-, and small-capitalization companies. The Fund uses a value investment philosophy in selecting equity securities. This investment philosophy is based upon the belief that, over time, a company's stock price converges with the company's intrinsic or true business value. By "true business value," we mean an estimate of the price a knowledgeable buyer would pay to acquire the entire business. We believe that investing in securities priced significantly below their true business value presents the best opportunity to achieve the Fund's investment objective. The Adviser uses this value philosophy to identify companies that it believes have discounted stock prices compared to the companies' true business values. In assessing such companies, the Adviser looks for the following characteristics, although not all of the companies selected will have these attributes: (1) free cash flows and intelligent investment of excess cash; (2) earnings that are growing and are reasonably predictable; and (3) high level of manager ownership. Key Tenets of the Oakmark Investment Philosophy: 1. Buy businesses that are trading at a significant discount to the Adviser's estimate of the company's intrinsic value. At the time the Adviser buys a company, the Adviser wants the company's stock to be inexpensive relative to what it believes the entire business is worth. 2. Invest with companies expected to grow shareholder value over time. Value investors can sometimes fall into the trap of buying a stock that is inexpensive for a reason-because the company just does not grow. The Adviser looks for good quality, growing businesses with positive free cash flow and intelligent investment of cash. 3. Invest with management teams that think and act as owners. The Adviser seeks out companies with management teams that understand the dynamics of per share value growth and are focused on achieving such growth. Stock ownership and incentives that align managements' interests with those of shareholders are key components of this analysis. In making its investment decisions, the Adviser uses a "bottom-up" approach focused on individual companies, rather than focusing on specific economic factors or specific industries. In order to select investments that meet the criteria described above, the Adviser uses independent, in-house research to analyze each company. As part of this selection process, the Adviser's analysts typically visit companies and conduct other research on the companies and their industries. Once the Adviser determines that a stock is selling at a significant discount and that the company has the additional qualities mentioned above, the Adviser may consider buying that stock for the Fund. The Adviser usually sells a stock when the price approaches its estimated worth. This means the Adviser sets specific "buy" and "sell" targets for each stock held by the Fund. The Adviser also monitors each holding and adjusts those price targets as warranted to reflect changes in a company's fundamentals.
Risk, Heading	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk, Narrative	rr_RiskNarrativeTextBlock	As an investor in the Fund, you should have a long-term perspective and be able to tolerate potentially wide fluctuations in the value of your Fund shares. Your investment in the Fund is subject to risks, including the possibility that the value of the Fund's portfolio holdings may fluctuate in response to events specific to the companies in which the Fund invests, as well as economic, political or social events in the U.S. or abroad. As a result, when you redeem your Fund shares, they may be worth more or less than you paid for them. Although the Fund makes every effort to achieve its objective, it cannot guarantee it will attain that objective. The principal risks of investing in the Fund are: Market Risk. The Fund is subject to market risk-the risk that securities markets and individual securities will increase or decrease in value. Market risk applies to every market and every security. Security prices may fluctuate widely over short or extended periods in response to market or economic news and conditions, and securities markets also tend to move in cycles. If there is a general decline in the securities markets, it is possible your investment may lose value regardless of the individual results of the companies in which the Fund invests. The magnitude of up and down price or market fluctuations over time is sometimes referred to as "volatility," which, at times, can be significant. In addition, different asset classes and geographic markets may experience periods of significant correlation with each other. As a result of this correlation, the securities and markets in which the Fund invests may experience volatility due to market, economic, political or social events and conditions that may not readily appear to directly relate to such securities, the securities' issuer or the markets in which they trade. Common Stock Risk. Common stocks are subject to greater fluctuations in market value than other asset classes as a result of such factors as a company's business performance, investor perceptions, stock market trends and general economic conditions. The rights of common stockholders are subordinate to all other claims on a company's assets including debt holders and preferred stockholders; therefore, the Fund could lose money if a company in which it invests becomes financially distressed. Small and Mid Cap Securities Risk. Investments in small and mid cap companies may be riskier than investments in larger, more established companies. The securities of smaller companies may trade less frequently and in smaller volumes, and as a result, may be less liquid than securities of larger companies. In addition, smaller companies may be more vulnerable to economic, market and industry changes. As a result, share price changes may be more sudden or erratic than the prices of other equity securities, especially over the short term. Because smaller companies may have limited product lines, markets or financial resources or may depend on a few key employees, they may be more susceptible to particular economic events or competitive factors than large capitalization companies. Value Style Risk. Investing in "value" stocks presents the risk that the stocks may never reach what the Adviser believes are their full market values, either because the market fails to recognize what the Adviser considers to be the companies' true business values or because the Adviser misjudged those values. In addition, value stocks may fall out of favor with investors and underperform growth stocks during given periods. Non-U.S. Securities Risk. Investments in securities issued by entities based outside the United States involve risks relating to political, social and economic developments abroad, as well as risks resulting from the differences between the regulations to which U.S. and non-U.S. issuers and markets are subject. These risks may result in the Fund experiencing rapid and extreme value changes due to currency controls; different accounting, auditing, financial reporting, and legal standards and practices; political and diplomatic changes and developments; expropriation; changes in tax policy; a lack of available public information regarding non-U.S. issuers; greater market volatility; a lack of sufficient market liquidity; differing securities market structures; higher transaction costs; and various administrative difficulties, such as delays in clearing and settling portfolio transactions or in receiving payment of dividends. These risks may be heightened in connection with investments in issuers located in developing and emerging countries, and in issuers in more developed countries that conduct substantial business in such developing and emerging countries. Fluctuations in the exchange rates between currencies may negatively affect an investment in non-U.S. securities. Investments in securities issued by entities domiciled in the United States also may be subject to many of these risks. The Fund may hedge its exposure to foreign currencies. Although hedging may be used to protect the Fund from adverse currency movements, the use of such hedges may reduce or eliminate the potentially positive effect of currency revaluations on the Fund's total return, and there is no guarantee that the Fund's hedging strategy will be successful. Non-Diversification Risk. A non-diversified fund may be subject to greater risk than a diversified fund because changes in the financial condition or market assessment of a single issuer may cause greater fluctuation in the value of a non-diversified fund's shares. Lack of broad diversification also may cause a non-diversified fund to be more susceptible to economic, political or regulatory events than a diversified fund. A non-diversification strategy may increase the Fund's volatility. Your investment in the Fund is not a deposit in a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You may lose money by investing in the Fund. The likelihood of loss may be greater if you invest for a shorter period of time.
Risk, Lose Money	rr_RiskLoseMoney	You may lose money by investing in the Fund.
Risk, Nondiversified Status	rr_RiskNondiversifiedStatus	A non-diversified fund may be subject to greater risk than a diversified fund because changes in the financial condition or market assessment of a single issuer may cause greater fluctuation in the value of a non-diversified fund's shares. Lack of broad diversification also may cause a non-diversified fund to be more susceptible to economic, political or regulatory events than a diversified fund. A non-diversification strategy may increase the Fund's volatility.
Risk, Not Insured Depository Institution	rr_RiskNotInsuredDepositoryInstitution	Your investment in the Fund is not a deposit in a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance, Narrative	rr_PerformanceNarrativeTextBlock	The Fund's past performance (before and after taxes), as provided by the bar chart and performance table that follow, is not an indication of how the Fund will perform in the future. This information can help you evaluate the potential risk and reward of investing in the Fund by showing changes in the performance of the Fund's Class I Shares from year to year. The information illustrates the volatility of the Fund's historical returns and shows how the Fund's annual average returns compare with those of a broad measure of market performance. Updated performance information is available at oakmark.com or by calling 1-800-OAKMARK.
Performance, Information Illustrates Variability of Returns	rr_PerformanceInformationIllustratesVariabilityOfReturns	The information illustrates the volatility of the Fund's historical returns and shows how the Fund's annual average returns compare with those of a broad measure of market performance.
Performance, Availability Phone Number	rr_PerformanceAvailabilityPhone	1-800-OAKMARK
Performance, Availability Website Address	rr_PerformanceAvailabilityWebSiteAddress	oakmark.com
Performance, Past Does Not Indicate Future	rr_PerformancePastDoesNotIndicateFuture	The Fund's past performance (before and after taxes), as provided by the bar chart and performance table that follow, is not an indication of how the Fund will perform in the future.
Bar Chart, Heading	rr_BarChartHeading	Class I Shares Total Returns for Years Ended December 31 (%)
Bar Chart, Narrative	rr_BarChartNarrativeTextBlock	Since 2007, the highest and lowest quarterly returns for the Fund's Class I Shares were: • Highest quarterly return: 26.6%, during the quarter ended June 30, 2009 • Lowest quarterly return: -16.3%, during the quarter ended December 31, 2008
Performance Table, Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table, Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	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 who hold their shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts or individual retirement accounts.
Performance Table, One Class of after Tax Shown	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown only for Class I shares. After-tax returns for Class II shares will vary from returns shown for Class I.
Performance Table, Explanation after Tax Higher	rr_PerformanceTableExplanationAfterTaxHigher	In some cases, the after-tax returns may exceed the return before taxes due to an assumed tax benefit from any losses on a sale of Fund shares at the end of the measurement period.
Performance Table, Closing	rr_PerformanceTableClosingTextBlock	The Morgan Stanley Capital International (MSCI) World Index is an unmanaged index that includes countries throughout the world, in proportion to world stock market capitalization. All returns reflect reinvested dividends. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of 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 who hold their shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts or individual retirement accounts. In some cases, the after-tax returns may exceed the return before taxes due to an assumed tax benefit from any losses on a sale of Fund shares at the end of the measurement period. After-tax returns are shown only for Class I shares. After-tax returns for Class II shares will vary from returns shown for Class I.
Average Annual Returns, Caption	rr_AverageAnnualReturnCaption	Average Annual Total Returns for Periods Ended December 31, 2011
Oakmark Global Select Fund (Prospectus Summary) | Oakmark Global Select Fund | MSCI World Index
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	MSCI World Index (does not reflect the deduction of fees, expenses or taxes)
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	(5.54%)
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	(2.37%)
Average Annual Returns, Since Inception	rr_AverageAnnualReturnSinceInception	(0.78%)
Average Annual Returns, Inception Date	rr_AverageAnnualReturnInceptionDate	Oct. 02, 2006
Oakmark Global Select Fund (Prospectus Summary) | Oakmark Global Select Fund | Class I
Risk Return [Abstract]	rr_RiskReturnAbstract
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	(2.00%)
Exchange fee	rr_ExchangeFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	1.00%
Distribution (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.24%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.24%
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	126
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	393
Expense Example, With Redemption, 5 Years	rr_ExpenseExampleYear05	681
Expense Example, With Redemption, 10 Years	rr_ExpenseExampleYear10	1,500
Annual Return 2007	rr_AnnualReturn2007	(1.16%)
Annual Return 2008	rr_AnnualReturn2008	(32.49%)
Annual Return 2009	rr_AnnualReturn2009	53.58%
Annual Return 2010	rr_AnnualReturn2010	11.06%
Annual Return 2011	rr_AnnualReturn2011	(5.87%)
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest quarterly return:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	26.60%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest quarterly return:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(16.30%)
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Global Select Fund - Class I Return before taxes
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	(5.87%)
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	1.39%
Average Annual Returns, Since Inception	rr_AverageAnnualReturnSinceInception	2.81%
Average Annual Returns, Inception Date	rr_AverageAnnualReturnInceptionDate	Oct. 02, 2006
Oakmark Global Select Fund (Prospectus Summary) | Oakmark Global Select Fund | Class I | After Taxes on Distributions
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Global Select Fund - Class I Return after taxes on distributions
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	(5.87%)
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	0.92%
Average Annual Returns, Since Inception	rr_AverageAnnualReturnSinceInception	2.35%
Average Annual Returns, Inception Date	rr_AverageAnnualReturnInceptionDate	Oct. 02, 2006
Oakmark Global Select Fund (Prospectus Summary) | Oakmark Global Select Fund | Class I | After Taxes on Distributions and Sales
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Global Select Fund - Class I Return after taxes on distributions and sale of Fund shares
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	(3.82%)
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	0.97%
Average Annual Returns, Since Inception	rr_AverageAnnualReturnSinceInception	2.19%
Average Annual Returns, Inception Date	rr_AverageAnnualReturnInceptionDate	Oct. 02, 2006
Oakmark Global Select Fund (Prospectus Summary) | Oakmark Global Select Fund | Class II
Risk Return [Abstract]	rr_RiskReturnAbstract
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	(2.00%)
Exchange fee	rr_ExchangeFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	1.00%
Distribution (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.49%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.49%
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	152
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	471
Expense Example, With Redemption, 5 Years	rr_ExpenseExampleYear05	813
Expense Example, With Redemption, 10 Years	rr_ExpenseExampleYear10	1,779

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
Document Type	dei_DocumentType	485BPOS
Document Period End Date	dei_DocumentPeriodEndDate	Sep. 30, 2011
Registrant Name	dei_EntityRegistrantName	HARRIS ASSOCIATES INVESTMENT TRUST
Central Index Key	dei_EntityCentralIndexKey	0000872323
Amendment Flag	dei_AmendmentFlag	false
Document Creation Date	dei_DocumentCreationDate	Jan. 27, 2012
Document Effective Date	dei_DocumentEffectiveDate	Jan. 27, 2012
Oakmark Fund (Prospectus Summary) | Oakmark Fund | Class I
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	OAKMX
Oakmark Fund (Prospectus Summary) | Oakmark Fund | Class II
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	OARMX
Oakmark Select Fund (Prospectus Summary) | Oakmark Select Fund | Class I
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	OAKLX
Oakmark Select Fund (Prospectus Summary) | Oakmark Select Fund | Class II
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	OARLX
Oakmark Equity and Income Fund (Prospectus Summary) | Oakmark Equity and Income Fund | Class I
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	OAKBX
Oakmark Equity and Income Fund (Prospectus Summary) | Oakmark Equity and Income Fund | Class II
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	OARBX
Oakmark Global Fund (Prospectus Summary) | Oakmark Global Fund | Class I
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	OAKGX
Oakmark Global Fund (Prospectus Summary) | Oakmark Global Fund | Class II
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	OARGX
Oakmark Global Select Fund (Prospectus Summary) | Oakmark Global Select Fund | Class I
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	OAKWX
Oakmark Global Select Fund (Prospectus Summary) | Oakmark Global Select Fund | Class II
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	OARWX
Oakmark International Fund (Prospectus Summary) | Oakmark International Fund | Class I
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	OAKIX
Oakmark International Fund (Prospectus Summary) | Oakmark International Fund | Class II
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	OARIX
Oakmark International Small Cap Fund (Prospectus Summary) | Oakmark International Small Cap Fund | Class I
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	OAKEX
Oakmark International Small Cap Fund (Prospectus Summary) | Oakmark International Small Cap Fund | Class II
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	OAREX

XML

Oakmark Global Fund (Prospectus Summary) | Oakmark Global Fund

OAKMARK GLOBAL FUND

INVESTMENT OBJECTIVE

Oakmark Global Fund seeks long-term capital appreciation.

FEES AND EXPENSES OF THE FUND

Below are the fees and expenses that you would pay if you buy and hold shares of
the Fund.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees Oakmark Global Fund	Class I	Class II
Maximum sales charge (load) imposed on purchases	none	none
Maximum deferred sales charge (load)	none	none
Redemption fee (as a percentage of amount redeemed on shares held for 90 days or less)	2.00%	2.00%
Exchange fee	none	none

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

Annual Fund Operating Expenses Oakmark Global Fund	Class I	Class II
Management fees	1.00%	1.00%
Distribution (12b-1) Fees	none	none
Other expenses	0.16%	0.55%
Total Annual Fund Operating Expenses	1.16%	1.55%

Example.

The Example is intended to help you compare the cost of investing in
the Fund with the cost of investing in other mutual funds. The Example assumes
that you invest $10,000 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
remain the same.

Although your actual returns and costs may be higher or lower, based on these assumptions your expenses would be:

Expense Example Oakmark Global Fund (USD $)	Class I	Class II
Expense Example, With Redemption, 1 Year	118	158
Expense Example, With Redemption, 3 Years	368	490
Expense Example, With Redemption, 5 Years	638	845
Expense Example, With Redemption, 10 Years	1,409	1,845

Portfolio Turnover

The Fund pays 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 29%
of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGY

The Fund invests primarily in a diversified portfolio of common stocks of U.S.
and non-U.S. companies. The Fund invests in the securities of companies located
in at least three countries. Typically, the Fund invests between 25-75% of its
total assets in securities of U.S. companies and between 25-75% of its total
assets in securities of non-U.S. companies. There are no geographic limits on
the Fund's non-U.S. investments, and the Fund may invest in securities of
companies located in developed or emerging markets. The Fund may invest in the
securities of large-, mid-, and small-capitalization companies.

The Fund uses a value investment philosophy in selecting equity securities. This
investment philosophy is based upon the belief that, over time, a company's
stock price converges with the company's intrinsic or true business value. By
"true business value," we mean an estimate of the price a knowledgeable buyer
would pay to acquire the entire business. We believe that investing in
securities priced significantly below their true business value presents the
best opportunity to achieve the Fund's investment objective.

The Fund's investment adviser, Harris Associates L.P. (the "Adviser"), uses this
value philosophy to identify companies that it believes have discounted stock
prices compared to the companies' true business values. In assessing such
companies, the Adviser looks for the following characteristics, although not all
of the companies selected will have these attributes: (1) free cash flows and
intelligent investment of excess cash; (2) earnings that are growing and are
reasonably predictable; and (3) high level of manager ownership.

Key Tenets of the Oakmark Investment Philosophy:

1. Buy businesses that are trading at a significant discount to the Adviser's
estimate of the company's intrinsic value. At the time the Adviser buys a
company, the Adviser wants the company's stock to be inexpensive relative to
what it believes the entire business is worth.

2. Invest with companies expected to grow shareholder value over time. Value
investors can sometimes fall into the trap of buying a stock that is inexpensive
for a reason-because the company just does not grow. The Adviser looks for good
quality, growing businesses with positive free cash flow and intelligent
investment of cash.

3. Invest with management teams that think and act as owners. The Adviser seeks
out companies with management teams that understand the dynamics of per share
value growth and are focused on achieving such growth. Stock ownership and
incentives that align managements' interests with those of shareholders are key
components of this analysis.

In making its investment decisions, the Adviser uses a "bottom-up" approach
focused on individual companies, rather than focusing on specific economic
factors or specific industries. In order to select investments that meet the
criteria described above, the Adviser uses independent, in-house research to
analyze each company. As part of this selection process, the Adviser's analysts
typically visit companies and conduct other research on the companies and their
industries.

Once the Adviser determines that a stock is selling at a significant discount
and that the company has the additional qualities mentioned above, the Adviser
may consider buying that stock for the Fund. The Adviser usually sells a stock
when the price approaches its estimated worth. This means the Adviser sets
specific "buy" and "sell" targets for each stock held by the Fund. The Adviser
also monitors each holding and adjusts those price targets as warranted to
reflect changes in a company's fundamentals.

The Adviser believes that holding a relatively small number of stocks allows its
"best ideas" to have a meaningful impact on the Fund's performance. Therefore,
the Fund's portfolio typically holds thirty to sixty stocks rather than
hundreds.

PRINCIPAL INVESTMENT RISKS

As an investor in the Fund, you should have a long-term perspective and be able
to tolerate potentially wide fluctuations in the value of your Fund shares. Your
investment in the Fund is subject to risks, including the possibility that the
value of the Fund's portfolio holdings may fluctuate in response to events
specific to the companies in which the Fund invests, as well as economic,
political or social events in the U.S. or abroad. As a result, when you redeem
your Fund shares, they may be worth more or less than you paid for them.

Although the Fund makes every effort to achieve its objective, it cannot
guarantee it will attain that objective. The principal risks of investing in the
Fund are:

Market Risk. The Fund is subject to market risk-the risk that securities markets
and individual securities will increase or decrease in value. Market risk
applies to every market and every security. Security prices may fluctuate widely
over short or extended periods in response to market or economic news and
conditions, and securities markets also tend to move in cycles. If there is a
general decline in the securities markets, it is possible your investment may
lose value regardless of the individual results of the companies in which the
Fund invests. The magnitude of up and down price or market fluctuations over
time is sometimes referred to as "volatility," which, at times, can be
significant. In addition, different asset classes and geographic markets may
experience periods of significant correlation with each other. As a result of
this correlation, the securities and markets in which the Fund invests may
experience volatility due to market, economic, political or social events and
conditions that may not readily appear to directly relate to such securities,
the securities' issuer or the markets in which they trade.

Common Stock Risk. Common stocks are subject to greater fluctuations in market
value than other asset classes as a result of such factors as a company's
business performance, investor perceptions, stock market trends and general
economic conditions. The rights of common stockholders are subordinate to all
other claims on a company's assets including debt holders and preferred
stockholders; therefore, the Fund could lose money if a company in which it
invests becomes financially distressed.

Focused Portfolio Risk. The Fund's portfolio tends to be invested in a
relatively small number of stocks. As a result, the appreciation or depreciation
of any one security held by the Fund will have a greater impact on the Fund's
net asset value than it would if the Fund invested in a larger number of
securities. Although that strategy has the potential to generate attractive
returns over time, it also increases the Fund's volatility.

Small and Mid Cap Securities Risk. Investments in small and mid cap companies
may be riskier than investments in larger, more established companies. The
securities of smaller companies may trade less frequently and in smaller
volumes, and as a result, may be less liquid than securities of larger
companies. In addition, smaller companies may be more vulnerable to economic,
market and industry changes. As a result, share price changes may be more sudden
or erratic than the prices of other equity securities, especially over the short
term. Because smaller companies may have limited product lines, markets or
financial resources or may depend on a few key employees, they may be more
susceptible to particular economic events or competitive factors than large
capitalization companies.

Value Style Risk. Investing in "value" stocks presents the risk that the stocks
may never reach what the Adviser believes are their full market values, either
because the market fails to recognize what the Adviser considers to be the
companies' true business values or because the Adviser misjudged those values.
In addition, value stocks may fall out of favor with investors and underperform
growth stocks during given periods.

Non-U.S. Securities Risk. Investments in securities issued by entities based
outside the United States involve risks relating to political, social and
economic developments abroad, as well as risks resulting from the differences
between the regulations to which U.S. and non-U.S. issuers and markets are
subject. These risks may result in the Fund experiencing rapid and extreme value
changes due to currency controls; different accounting, auditing, financial
reporting, and legal standards and practices; political and diplomatic changes
and developments; expropriation; changes in tax policy; a lack of available
public information regarding non-U.S. issuers; greater market volatility; a lack
of sufficient market liquidity; differing securities market structures; higher
transaction costs; and various administrative difficulties, such as delays in
clearing and settling portfolio transactions or in receiving payment of
dividends. These risks may be heightened in connection with investments in
issuers located in developing and emerging countries, and in issuers in more
developed countries that conduct substantial business in such developing and
emerging countries. Fluctuations in the exchange rates between currencies may
negatively affect an investment in non-U.S. securities. Investments in
securities issued by entities domiciled in the United States also may be subject
to many of these risks. The Fund may hedge its exposure to foreign currencies.
Although hedging may be used to protect the Fund from adverse currency
movements, the use of such hedges may reduce or eliminate the potentially
positive effect of currency revaluations on the Fund's total return, and there
is no guarantee that the Fund's hedging strategy will be successful.

Your investment in the Fund is not a deposit in a bank and is not insured or
guaranteed by the Federal Deposit Insurance Corporation or any other government
agency. You may lose money by investing in the Fund. The likelihood of loss may
be greater if you invest for a shorter period of time.

PERFORMANCE INFORMATION

The Fund's past performance (before and after taxes), as provided by the bar
chart and performance table that follow, is not an indication of how the Fund
will perform in the future. This information can help you evaluate the potential
risk and reward of investing in the Fund by showing changes in the performance
of the Fund's Class I Shares from year to year. The information illustrates the
volatility of the Fund's historical returns and shows how the Fund's average
annual returns compare with those of a broad measure of market performance.
Updated performance information is available at oakmark.com or by calling
1-800-OAKMARK.

Since 2002, the highest and lowest quarterly returns for the Fund's Class I Shares were:
• Highest quarterly return: 33.5%, during the quarter ended June 30, 2003
• Lowest quarterly return: -24.1%, during the quarter ended December 31, 2008

Class I Shares Total Returns for Years Ended December 31 (%)

Average Annual Total Returns for Periods Ended December 31, 2011

Average Annual Total Returns Oakmark Global Fund	Average Annual Returns, Label	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Class I	Global Fund - Class I Return before taxes	(11.65%)	(1.19%)	8.37%
Class I After Taxes on Distributions	Global Fund - Class I Return after taxes on distributions	(11.65%)	(1.66%)	7.80%
Class I After Taxes on Distributions and Sales	Global Fund - Class I Return after taxes on distributions and sale of Fund shares	(7.58%)	(0.96%)	7.48%
Class II	Global Fund - Class II Return before taxes	(12.05%)	(1.56%)	7.98%
MSCI World Index	MSCI World Index (does not reflect the deduction of fees, expenses or taxes)	(5.54%)	(2.37%)	3.62%

The Morgan Stanley Capital International (MSCI) World Index is an unmanaged
index that includes countries throughout the world, in proportion to world stock
market capitalization. All returns reflect reinvested dividends.

After-tax returns are calculated using the historical highest individual federal
marginal income tax rates and do not reflect the impact of 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 who hold
their shares through tax-deferred arrangements, such as 401(k) plans, qualified
plans, education savings accounts or individual retirement accounts. In some
cases, the after-tax returns may exceed the return before taxes due to an
assumed tax benefit from any losses on a sale of Fund shares at the end of the
measurement period. After-tax returns are shown only for Class I shares.
After-tax returns for Class II shares will vary from returns shown for Class I.

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	Jan. 27, 2012
Oakmark Select Fund (Prospectus Summary) | Oakmark Select Fund
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	OAKMARK SELECT FUND
Investment Objective, Heading	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	Oakmark Select Fund seeks long-term capital appreciation.
Expense, Heading	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense, Narrative	rr_ExpenseNarrativeTextBlock	Below are the fees and expenses that you would pay if you buy and hold shares of the Fund.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses, Caption	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover, Heading	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover	rr_PortfolioTurnoverTextBlock	The Fund pays 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 16% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	16.00%
Expense Example, Heading	rr_ExpenseExampleHeading	Example.
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 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 remain the same.
Expense Example, By Year, Caption	rr_ExpenseExampleByYearCaption	Although your actual returns and costs may be higher or lower, based on these assumptions your expenses would be:
Investment Strategy, Heading	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGY
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	The Fund invests primarily in common stocks of U.S. companies. The Fund is non-diversified, which means that it may invest a greater portion of its assets in a more limited number of issuers than a diversified fund. The Fund could own as few as twelve securities, but generally will have approximately twenty securities in its portfolio. The Fund may invest in the securities of large-, mid-, and small-capitalization companies. The Fund uses a value investment philosophy in selecting equity securities. This investment philosophy is based upon the belief that, over time, a company's stock price converges with the company's intrinsic or true business value. By "true business value," we mean an estimate of the price a knowledgeable buyer would pay to acquire the entire business. We believe that investing in securities priced significantly below their true business value presents the best opportunity to achieve the Fund's investment objective. The Fund's investment adviser, Harris Associates L.P. (the "Adviser"), uses this value philosophy to identify companies that it believes have discounted stock prices compared to the companies' true business values. In assessing such companies, the Adviser looks for the following characteristics, although not all of the companies selected will have these attributes: (1) free cash flows and intelligent investment of excess cash; (2) earnings that are growing and are reasonably predictable; and (3) high level of manager ownership. Key Tenets of the Oakmark Investment Philosophy: 1. Buy businesses that are trading at a significant discount to the Adviser's estimate of the company's intrinsic value. At the time the Adviser buys a company, the Adviser wants the company's stock to be inexpensive relative to what it believes the entire business is worth. 2. Invest with companies expected to grow shareholder value over time. Value investors can sometimes fall into the trap of buying a stock that is inexpensive for a reason-because the company just does not grow. The Adviser looks for good quality, growing businesses with positive free cash flow and intelligent investment of cash. 3. Invest with management teams that think and act as owners. The Adviser seeks out companies with management teams that understand the dynamics of per share value growth and are focused on achieving such growth. Stock ownership and incentives that align managements' interests with those of shareholders are key components of this analysis. In making its investment decisions, the Adviser uses a "bottom-up" approach focused on individual companies, rather than focusing on specific economic factors or specific industries. In order to select investments that meet the criteria described above, the Adviser uses independent, in-house research to analyze each company. As part of this selection process, the Adviser's analysts typically visit companies and conduct other research on the companies and their industries. Once the Adviser determines that a stock is selling at a significant discount and that the company has the additional qualities mentioned above, the Adviser may consider buying that stock for the Fund. The Adviser usually sells a stock when the price approaches its estimated worth. This means the Adviser sets specific "buy" and "sell" targets for each stock held by the Fund. The Adviser also monitors each holding and adjusts those price targets as warranted to reflect changes in a company's fundamentals.
Risk, Heading	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk, Narrative	rr_RiskNarrativeTextBlock	As an investor in the Fund, you should have a long-term perspective and be able to tolerate potentially wide fluctuations in the value of your Fund shares. Your investment in the Fund is subject to risks, including the possibility that the value of the Fund's portfolio holdings may fluctuate in response to events specific to the companies in which the Fund invests, as well as economic, political or social events in the U.S. or abroad. As a result, when you redeem your Fund shares, they may be worth more or less than you paid for them. Although the Fund makes every effort to achieve its objective, it cannot guarantee it will attain that objective. The principal risks of investing in the Fund are: Market Risk. The Fund is subject to market risk-the risk that securities markets and individual securities will increase or decrease in value. Market risk applies to every market and every security. Security prices may fluctuate widely over short or extended periods in response to market or economic news and conditions, and securities markets also tend to move in cycles. If there is a general decline in the securities markets, it is possible your investment may lose value regardless of the individual results of the companies in which the Fund invests. The magnitude of up and down price or market fluctuations over time is sometimes referred to as "volatility," which, at times, can be significant. In addition, different asset classes and geographic markets may experience periods of significant correlation with each other. As a result of this correlation, the securities and markets in which the Fund invests may experience volatility due to market, economic, political or social events and conditions that may not readily appear to directly relate to such securities, the securities' issuer or the markets in which they trade. Common Stock Risk. Common stocks are subject to greater fluctuations in market value than other asset classes as a result of such factors as a company's business performance, investor perceptions, stock market trends and general economic conditions. The rights of common stockholders are subordinate to all other claims on a company's assets including debt holders and preferred stockholders; therefore, the Fund could lose money if a company in which it invests becomes financially distressed. Small and Mid Cap Securities Risk. Investments in small and mid cap companies may be riskier than investments in larger, more established companies. The securities of smaller companies may trade less frequently and in smaller volumes, and as a result, may be less liquid than securities of larger companies. In addition, smaller companies may be more vulnerable to economic, market and industry changes. As a result, share price changes may be more sudden or erratic than the prices of other equity securities, especially over the short term. Because smaller companies may have limited product lines, markets or financial resources or may depend on a few key employees, they may be more susceptible to particular economic events or competitive factors than large capitalization companies. Value Style Risk. Investing in "value" stocks presents the risk that the stocks may never reach what the Adviser believes are their full market values, either because the market fails to recognize what the Adviser considers to be the companies' true business values or because the Adviser misjudged those values. In addition, value stocks may fall out of favor with investors and underperform growth stocks during given periods. Non-Diversification Risk. A non-diversified fund may be subject to greater risk than a diversified fund because changes in the financial condition or market assessment of a single issuer may cause greater fluctuation in the value of a non-diversified fund's shares. Lack of broad diversification also may cause a non-diversified fund to be more susceptible to economic, political or regulatory events than a diversified fund. A non-diversification strategy may increase the Fund's volatility. Your investment in the Fund is not a deposit in a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You may lose money by investing in the Fund. The likelihood of loss may be greater if you invest for a shorter period of time.
Risk, Lose Money	rr_RiskLoseMoney	You may lose money by investing in the Fund.
Risk, Nondiversified Status	rr_RiskNondiversifiedStatus	A non-diversified fund may be subject to greater risk than a diversified fund because changes in the financial condition or market assessment of a single issuer may cause greater fluctuation in the value of a non-diversified fund's shares. Lack of broad diversification also may cause a non-diversified fund to be more susceptible to economic, political or regulatory events than a diversified fund. A non-diversification strategy may increase the Fund's volatility.
Risk, Not Insured Depository Institution	rr_RiskNotInsuredDepositoryInstitution	Your investment in the Fund is not a deposit in a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance, Narrative	rr_PerformanceNarrativeTextBlock	The Fund's past performance (before and after taxes), as provided by the bar chart and performance table that follow, is not an indication of how the Fund will perform in the future. This information can help you evaluate the potential risk and reward of investing in the Fund by showing changes in the performance of the Fund's Class I Shares from year to year. The information illustrates the volatility of the Fund's historical returns and shows how the Fund's annual average returns compare with those of a broad measure of market performance. Updated performance information is available at oakmark.com or by calling 1-800-OAKMARK.
Performance, Information Illustrates Variability of Returns	rr_PerformanceInformationIllustratesVariabilityOfReturns	The information illustrates the volatility of the Fund's historical returns and shows how the Fund's annual average returns compare with those of a broad measure of market performance.
Performance, Availability Phone Number	rr_PerformanceAvailabilityPhone	1-800-OAKMARK
Performance, Availability Website Address	rr_PerformanceAvailabilityWebSiteAddress	oakmark.com
Performance, Past Does Not Indicate Future	rr_PerformancePastDoesNotIndicateFuture	The Fund's past performance (before and after taxes), as provided by the bar chart and performance table that follow, is not an indication of how the Fund will perform in the future.
Bar Chart, Heading	rr_BarChartHeading	Class I Shares Total Returns for Years Ended December 31 (%)
Bar Chart, Narrative	rr_BarChartNarrativeTextBlock	Since 2002, the highest and lowest quarterly returns for the Fund's Class I Shares were: • Highest quarterly return: 25.7%, during the quarter ended June 30, 2009 • Lowest quarterly return: -20.2%, during the quarter ended December 31, 2008
Performance Table, Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table, Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	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 who hold their shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts or individual retirement accounts.
Performance Table, One Class of after Tax Shown	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown only for Class I shares. After-tax returns for Class II shares will vary from returns shown for Class I.
Performance Table, Explanation after Tax Higher	rr_PerformanceTableExplanationAfterTaxHigher	In some cases, the after-tax returns may exceed the return before taxes due to an assumed tax benefit from any losses on a sale of Fund shares at the end of the measurement period.
Performance Table, Closing	rr_PerformanceTableClosingTextBlock	The S&P 500 Index is a widely quoted, unmanaged, market-weighted stock market index that includes 500 of the largest companies publicly traded in the U.S. All returns reflect reinvested dividends. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of 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 who hold their shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts or individual retirement accounts. In some cases, the after-tax returns may exceed the return before taxes due to an assumed tax benefit from any losses on a sale of Fund shares at the end of the measurement period. After-tax returns are shown only for Class I shares. After-tax returns for Class II shares will vary from returns shown for Class I.
Average Annual Returns, Caption	rr_AverageAnnualReturnCaption	Average Annual Total Returns for Periods Ended December 31, 2011
Oakmark Select Fund (Prospectus Summary) | Oakmark Select Fund | S&P 500
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	S&P 500 (does not reflect the deduction of fees, expenses or taxes)
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	2.11%
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	(0.25%)
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	2.92%
Oakmark Select Fund (Prospectus Summary) | Oakmark Select Fund | Class I
Risk Return [Abstract]	rr_RiskReturnAbstract
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_ExchangeFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.94%
Distribution (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.13%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.07%
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	109
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	340
Expense Example, With Redemption, 5 Years	rr_ExpenseExampleYear05	590
Expense Example, With Redemption, 10 Years	rr_ExpenseExampleYear10	1,306
Annual Return 2002	rr_AnnualReturn2002	(12.47%)
Annual Return 2003	rr_AnnualReturn2003	29.00%
Annual Return 2004	rr_AnnualReturn2004	9.73%
Annual Return 2005	rr_AnnualReturn2005	4.84%
Annual Return 2006	rr_AnnualReturn2006	13.60%
Annual Return 2007	rr_AnnualReturn2007	(14.04%)
Annual Return 2008	rr_AnnualReturn2008	(36.22%)
Annual Return 2009	rr_AnnualReturn2009	52.46%
Annual Return 2010	rr_AnnualReturn2010	13.24%
Annual Return 2011	rr_AnnualReturn2011	2.15%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest quarterly return:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	25.70%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest quarterly return:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(20.20%)
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Select Fund - Class I Return before taxes
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	2.15%
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	(0.67%)
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	3.62%
Oakmark Select Fund (Prospectus Summary) | Oakmark Select Fund | Class I | After Taxes on Distributions
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Select Fund - Class I Return after taxes on distributions
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	2.12%
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	(1.09%)
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	3.12%
Oakmark Select Fund (Prospectus Summary) | Oakmark Select Fund | Class I | After Taxes on Distributions and Sales
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Select Fund - Class I Return after taxes on distributions and sale of Fund shares
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	1.44%
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	(0.61%)
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	3.11%
Oakmark Select Fund (Prospectus Summary) | Oakmark Select Fund | Class II
Risk Return [Abstract]	rr_RiskReturnAbstract
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_ExchangeFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.94%
Distribution (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.44%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.38%
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	140
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	437
Expense Example, With Redemption, 5 Years	rr_ExpenseExampleYear05	755
Expense Example, With Redemption, 10 Years	rr_ExpenseExampleYear10	1,657
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Select Fund - Class II Return before taxes
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	1.82%
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	(0.92%)
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	3.34%

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Oakmark Equity and Income Fund (Prospectus Summary) | Oakmark Equity and Income Fund

OAKMARK EQUITY AND INCOME FUND

INVESTMENT OBJECTIVE

Oakmark Equity and Income Fund seeks income and preservation and growth of
capital.

FEES AND EXPENSES OF THE FUND

Below are the fees and expenses that you would pay if you buy and hold shares of
the Fund.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees Oakmark Equity and Income Fund	Class I	Class II
Maximum sales charge (load) imposed on purchases	none	none
Maximum deferred sales charge (load)	none	none
Redemption fee (as a percentage of amount redeemed on shares held for 90 days or less)	none	none
Exchange fee	none	none

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

Annual Fund Operating Expenses Oakmark Equity and Income Fund	Class I	Class II
Management fees	0.67%	0.67%
Distribution (12b-1) Fees	none	none
Other expenses	0.10%	0.42%
Total Annual Fund Operating Expenses	0.77%	1.09%

Example.

The Example is intended to help you compare the cost of investing in
the Fund with the cost of investing in other mutual funds. The Example assumes
that you invest $10,000 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
remain the same.

Although your actual returns and costs may be higher or lower, based on these assumptions your expenses would be:

Expense Example Oakmark Equity and Income Fund (USD $)	Class I	Class II
Expense Example, With Redemption, 1 Year	79	111
Expense Example, With Redemption, 3 Years	246	347
Expense Example, With Redemption, 5 Years	428	601
Expense Example, With Redemption, 10 Years	954	1,329

Portfolio Turnover

The Fund pays 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 47%
of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGY

The Fund invests primarily in a diversified portfolio of U.S. equity and debt
securities (although the Fund may invest up to 35% of its total assets in equity
and debt securities of non-U.S. issuers). The Fund is intended to present a
balanced investment program between growth and income by investing approximately
40-75% of its total assets in common stock, including securities convertible
into common stock, and up to 60% of its assets in U.S. government securities and
debt securities rated at time of purchase within the two highest grades assigned
by Moody's Investors Service, Inc. or by Standard & Poor's Corporation Ratings
Group, a division of The McGraw-Hill Companies. The Fund also may invest up to
20% of its assets in unrated or lower rated debt securities, sometimes called
junk bonds. The types of equity securities in which the Fund may invest include
common and preferred stocks and warrants or other similar rights and convertible
securities. The types of debt securities in which the Fund may invest include
debt securities of both governmental and corporate issuers. The Fund may invest
in the securities of large-, mid-, and small-capitalization companies.

The Fund uses a value investment philosophy in selecting equity securities. This
investment philosophy is based upon the belief that, over time, a company's
stock price converges with the company's intrinsic or true business value. By
"true business value," we mean an estimate of the price a knowledgeable buyer
would pay to acquire the entire business. We believe that investing in
securities priced significantly below their true business value presents the
best opportunity to achieve the Fund's investment objective.

The Fund's investment adviser, Harris Associates L.P. (the "Adviser"), uses this
value philosophy to identify companies that it believes have discounted stock
prices compared to the companies' true business values. In assessing such
companies, the Adviser looks for the following characteristics, although not all
of the companies selected will have these attributes: (1) free cash flows and
intelligent investment of excess cash; (2) earnings that are growing and are
reasonably predictable; and (3) high level of manager ownership.

Key Tenets of the Oakmark Investment Philosophy-Equity Portion of the Fund:

1. Buy businesses that are trading at a significant discount to the Adviser's
estimate of the company's intrinsic value. At the time the Adviser buys a
company, the Adviser wants the company's stock to be inexpensive relative to
what it believes the entire business is worth.

2. Invest with companies expected to grow shareholder value over time. Value
investors can sometimes fall into the trap of buying a stock that is inexpensive
for a reason-because the company just does not grow. The Adviser looks for good
quality, growing businesses with positive free cash flow and intelligent
investment of cash.

3. Invest with management teams that think and act as owners. The Adviser seeks
out companies with management teams that understand the dynamics of per share
value growth and are focused on achieving such growth. Stock ownership and
incentives that align managements' interests with those of shareholders are key
components of this analysis.

In making its investment decisions, the Adviser uses a "bottom-up" approach
focused on individual companies, rather than focusing on specific economic
factors or specific industries. In order to select investments that meet the
criteria described above, the Adviser uses independent, in-house research to
analyze each company. As part of this selection process, the Adviser's analysts
typically visit companies and conduct other research on the companies and their
industries.

Once the Adviser determines that a stock is selling at a significant discount
and that the company has the additional qualities mentioned above, the Adviser
may consider buying that stock for the Fund. The Adviser usually sells a stock
when the price approaches its estimated worth. This means the Adviser sets
specific "buy" and "sell" targets for each stock held by the Fund. The Adviser
also monitors each holding and adjusts those price targets as warranted to
reflect changes in a company's fundamentals.

The Adviser believes that holding a relatively small number of stocks allows its
"best ideas" to have a meaningful impact on the Fund's performance. Therefore,
the Fund's portfolio typically holds thirty to sixty stocks rather than
hundreds.

PRINCIPAL INVESTMENT RISKS

As an investor in the Fund, you should have a long-term perspective and be able
to tolerate potentially wide fluctuations in the value of your Fund shares. Your
investment in the Fund is subject to risks, including the possibility that the
value of the Fund's portfolio holdings may fluctuate in response to events
specific to the companies in which the Fund invests, as well as economic,
political or social events in the U.S. or abroad. As a result, when you redeem
your Fund shares, they may be worth more or less than you paid for them.

Although the Fund makes every effort to achieve its objective, it cannot
guarantee it will attain that objective. The principal risks of investing in the
Fund are:

Market Risk. The Fund is subject to market risk-the risk that securities markets
and individual securities will increase or decrease in value. Market risk
applies to every market and every security. Security prices may fluctuate widely
over short or extended periods in response to market or economic news and conditions,
and securities markets also tend to move in cycles. If there is a general decline
in the securities markets, it is possible your investment may lose value regardless
of the individual results of the companies in which the Fund invests. The
magnitude of up and down price or market fluctuations over time is sometimes
referred to as "volatility," which, at times, can be significant. In addition,
different asset classes and geographic markets may experience periods of
significant correlation with each other. As a result of this correlation, the
securities and markets in which the Fund invests may experience volatility due
to market, economic, political or social events and conditions that may not
readily appear to directly relate to such securities, the securities' issuer or
the markets in which they trade.

Common Stock Risk. Common stocks are subject to greater fluctuations in market
value than other asset classes as a result of such factors as a company's
business performance, investor perceptions, stock market trends and general
economic conditions. The rights of common stockholders are subordinate to all
other claims on a company's assets including debt holders and preferred
stockholders; therefore, the Fund could lose money if a company in which it
invests becomes financially distressed.

Focused Portfolio Risk. The Fund's portfolio tends to be invested in a
relatively small number of stocks. As a result, the appreciation or depreciation
of any one security held by the Fund will have a greater impact on the Fund's
net asset value than it would if the Fund invested in a larger number of
securities. Although that strategy has the potential to generate attractive
returns over time, it also increases the Fund's volatility.

Small and Mid Cap Securities Risk. Investments in small and mid cap companies
may be riskier than investments in larger, more established companies. The
securities of smaller companies may trade less frequently and in smaller
volumes, and as a result, may be less liquid than securities of larger
companies. In addition, smaller companies may be more vulnerable to economic,
market and industry changes. As a result, share price changes may be more sudden
or erratic than the prices of other equity securities, especially over the short
term. Because smaller companies may have limited product lines, markets or
financial resources or may depend on a few key employees, they may be more
susceptible to particular economic events or competitive factors than large
capitalization companies.

Value Style Risk. Investing in "value" stocks presents the risk that the stocks
may never reach what the Adviser believes are their full market values, either
because the market fails to recognize what the Adviser considers to be the
companies' true business values or because the Adviser misjudged those values.
In addition, value stocks may fall out of favor with investors and underperform
growth stocks during given periods.

Debt Securities Risk. Debt securities are subject to credit risk, interest rate
risk and liquidity risk. Credit risk is the risk the issuer or guarantor of a
debt security will be unable or unwilling to make timely payments of interest or
principal or to otherwise honor its obligations. Interest rate risk is the risk
of losses due to changes in interest rates. In general, the prices of debt
securities rise when interest rates fall, and the prices fall when interest
rates rise. Liquidity risk is the risk a particular security may be difficult to
purchase or sell and that the Fund may be unable to sell illiquid securities
at an advantageous time or price. The Fund's investments in
government-sponsored entity securities also exhibit these risks, although the
degree of such risks may vary significantly among the different
government-sponsored entity securities. Some securities issued or guaranteed by
U.S. government agencies or instrumentalities are not backed by the full faith
and credit of the U.S. and may only be supported by the right of the agency or
instrumentality to borrow from the U.S. Treasury. There can be no assurance that
the U.S. government will always provide financial support to those agencies or
instrumentalities. Foreign sovereign debt instruments are subject to the risk
that a governmental entity may delay or refuse to pay interest or repay
principal on its sovereign debt. There is no legal process for collecting
sovereign debt that a government does not pay, nor are there bankruptcy
proceedings through which all or part of the sovereign debt that a government
entity has not repaid may be collected.

Inflation-Indexed Securities Risk. The principal value of an investment is not
protected or otherwise guaranteed by virtue of the Fund's investments in
inflation-indexed bonds. If the index measuring inflation falls, the principal
value of inflation-indexed bonds will be adjusted downward, and consequently the
interest payable on these securities (calculated with respect to a smaller
principal amount) will be reduced.

Repayment of the original bond principal upon maturity (as adjusted for
inflation) is guaranteed in the case of U.S. Treasury inflation-indexed bonds.
For bonds that do not provide a similar guarantee, the adjusted principal value
of the bond repaid at maturity may be less than the original principal value.

The value of inflation-indexed bonds is expected to change in response to
changes in real interest rates. Real interest rates are tied to the relationship
between nominal interest rates and the rate of inflation. If nominal interest
rates increase at a faster rate than inflation, real interest rates may rise,
leading to a decrease in value of inflation indexed bonds. Short-term increases
in inflation may lead to a decline in value. Any increase in the principal
amount of an inflation-indexed bond will be considered taxable ordinary income,
even though investors do not receive their principal until maturity.

Periodic adjustments for inflation to the principal amount of an
inflation-indexed bond may give rise to original issue discount, which will be
includable in the Fund's gross income. Due to original issue discount, the Fund
may be required to make annual distributions to shareholders that exceed the
cash received, which may cause the Fund to liquidate certain investments when it
is not advantageous to do so. Also, if the principal value of an
inflation-indexed bond is adjusted downward due to deflation, amounts previously
distributed in the taxable year may be characterized in some circumstances as a
return of capital.

Non-U.S. Securities Risk. Investments in securities issued by entities based
outside the United States involve risks relating to political, social and
economic developments abroad, as well as risks resulting from the differences
between the regulations to which U.S. and non-U.S. issuers and markets are
subject. These risks may result in the Fund experiencing rapid and extreme value
changes due to currency controls; different accounting, auditing, financial
reporting, and legal standards and practices; political and diplomatic changes
and developments; expropriation; changes in tax policy; a lack of available
public information regarding non-U.S. issuers; greater market volatility; a lack of
sufficient market liquidity; differing securities market structures; higher
transaction costs; and various administrative difficulties, such as delays in
clearing and settling portfolio transactions or in receiving payment of dividends.
These risks may be heightened in connection with investments in issuers located
in developing and emerging countries, and in issuers in more developed countries
that conduct substantial business in such developing and emerging countries.
Fluctuations in the exchange rates between currencies may negatively affect an
investment in non-U.S. securities. Investments in securities issued by entities
domiciled in the United States also may be subject to many of these risks.

Your investment in the Fund is not a deposit in a bank and is not insured or
guaranteed by the Federal Deposit Insurance Corporation or any other government
agency. You may lose money by investing in the Fund. The likelihood of loss may
be greater if you invest for a shorter period of time.

PERFORMANCE INFORMATION

The Fund's past performance (before and after taxes), as provided by the bar
chart and performance table that follow, is not an indication of how the Fund
will perform in the future. This information can help you evaluate the potential
risk and reward of investing in the Fund by showing changes in the performance
of the Fund's Class I Shares from year to year. The information illustrates the
volatility of the Fund's historical returns and shows how the Fund's annual
average returns compare with those of a broad measure of market performance.
Updated performance information is available at oakmark.com or by calling
1-800-OAKMARK.

Since 2002, the highest and lowest quarterly returns for the Fund's Class I Shares were:
• Highest quarterly return: 13.2%, during the quarter ended June 30, 2003
• Lowest quarterly return: -12.8%, during the quarter ended Septebmer 30, 2011

Class I Shares Total Returns for Years Ended December 31 (%)

Average Annual Total Returns for Periods Ended December 31, 2011

Average Annual Total Returns Oakmark Equity and Income Fund	Average Annual Returns, Label	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
Class I	Equity and Income Fund - Class I Return before taxes	0.64%	4.39%	7.10%
Class I After Taxes on Distributions	Equity and Income Fund - Class I Return after taxes on distributions	0.15%	3.77%	6.48%
Class I After Taxes on Distributions and Sales	Equity and Income Fund - Class I Return after taxes on distributions and sale of Fund shares	0.99%	3.63%	6.06%
Class II	Equity and Income Fund - Class II Return before taxes	0.27%	4.04%	6.78%
Lipper Balanced Fund Index	Lipper Balanced Fund Index (does not reflect the deduction of fees, expenses or taxes)	0.74%	1.80%	4.13%

Lipper Balanced Fund Index is an index of thirty balanced funds. All returns
reflect reinvested dividends.

After-tax returns are calculated using the historical highest individual federal
marginal income tax rates and do not reflect the impact of 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
who hold their shares through tax-deferred arrangements, such as 401(k) plans,
qualified plans, education savings accounts or individual retirement accounts.
In some cases, the after-tax returns may exceed the return before taxes due to
an assumed tax benefit from any losses on a sale of Fund shares at the end of
the measurement period. After-tax returns are shown only for Class I shares.
After-tax returns for Class II shares will vary from returns shown for Class I.