2.4.0.8000309 - Disclosure - Risk/Return Detail Data {Elements} - NORTHERN CALIFORNIA TAX-EXEMPT FUNDtruetruefalse1false falsefalseDuration_01Aug2012_31Jul2013http://www.sec.gov/CIK0000916620duration2012-08-01T00:00:002013-07-31T00:00:001true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:2false 3dei_EntityRegistrantNamedei_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00NORTHERN FUNDSfalsefalsefalsexbrli:normalizedStringItemTypenormalizedstringThe exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation 12B -Number 240 -Section 12b -Subsection 1 false0Registrant Name3false 3rr_ProspectusDaterr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002013-07-31falsefalsetruexbrli:dateItemTypedateThe date of the prospectus.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 1 -Subsection a -Paragraph 3 false0Prospectus Date4false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2false truefalseDuration_01Aug2012_31Jul2013S000001251_Memberhttp://www.sec.gov/CIK0000916620duration2012-08-01T00:00:002013-07-31T00:00:00falsefalseNORTHERN CALIFORNIA TAX-EXEMPT FUNDdei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldinf_S000001251Memberdei_LegalEntityAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0nanafalse0NORTHERN CALIFORNIA TAX-EXEMPT FUND5true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:6false 3rr_RiskReturnHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<a name="tx553153_4"></a>CALIFORNIA TAX-EXEMPT FUND falsefalsefalsexbrli:stringItemTypestringRisk/Return Summary Investment Objectives/Goals Include the following information, in plain English under rule 421(d) under the Securities Act, in the order and subject matter indicatedReference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 2 false0Risk/Return [Heading]7false 3rr_ObjectiveHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00INVESTMENT OBJECTIVE falsefalsefalsexbrli:stringItemTypestringInvestment Objectives/Goals. Disclose the Fund's investment objectives or goals. A Fund also may identify its type or category (e.g., that it is a Money Market Fund or a balanced fund).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 2 -Subsection a false0Objective [Heading]8false 3rr_ObjectivePrimaryTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00The Fund seeks to provide high current income exempt from regular federal income tax and California state personal income tax.falsefalsefalsenonnum:textBlockItemTypenaInvestment Objectives/Goals. Disclose the Fund's investment objectives or goals. A Fund also may identify its type or category (e.g., that it is a Money Market Fund or a balanced fund).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 2 -Subsection a false0Objective, Primary [Text Block]9false 3rr_ExpenseHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00FEES AND EXPENSES OF THE FUND falsefalsefalsexbrli:stringItemTypestringRisk/Return Summary Fee Table Includes the following information, in plain English under rule 421(d) under the Securities Act, after Item 2 Fees and expenses of the Fund This table describes the fees and expenses that you may pay if you buy and hold shared of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $[_____] in [name of fund family] funds. Shareholder Fees (fees paid directly from your investment) Example This 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 in the Fund for the time periods indicated and then you redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return per year and that the Fund's operating expenses remained the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be You would pay the following expenses if you did not redeem your shares The Example does not reflect sales charges (loads) on reinvested dividends [and other distributions]. If these sales charges (loads) were included, your costs would be higher. 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 may indicate higher transaction costs. 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 __% of the average value of its whole portfolio. Instructions. A.3.instructions.6 New Funds. For purposes of this Item, a "New Fund" is a Fund that does not include in Form N-1A financial statements reporting operating results or that includes financial statements for the Fund's initial fiscal year reporting operating results for a period of 6 months or less. The following Instructions apply to New Funds.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 1 -Subparagraph d false0Expense [Heading]10false 3rr_ExpenseNarrativeTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.falsefalsefalsenonnum:textBlockItemTypenaThis table describes the fees and expenses that you may pay if you buy and hold shared of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $[_____] in [name of fund family] funds. Include the narrative explanations in the order indicated. A Fund may modify the narrative explanations if the explanation contains comparable information to that shown. The narrative explanation regarding sales charge discounts is only required by a Fund that offers such discounts and should specify the minimum level of investment required to qualify for a discount. Modify the narrative explanation to state that Fund shares are sold on a national securities exchange at the end of the time periods indicated, and that brokerage commissions for buying and selling Fund shares through a broker are not reflected.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 1 -Subparagraph b false0Expense Narrative [Text Block]11false 3rr_ShareholderFeesCaptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Shareholder Fees (fees paid directly from your investment)falsefalsefalsexbrli:stringItemTypestringShareholder Fees (fees paid directly from your investment).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection table -Paragraph 1 false0Shareholder Fees Caption [Text]12false 3rr_OperatingExpensesCaptionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)falsefalsefalsexbrli:stringItemTypestringAnnual Fund Operating Expenses (ongoing expenses that you pay each year as a percentage of the value of your investment)Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection table -Paragraph 1 -Subparagraph 7 false0Operating Expenses Caption [Text]13false 3rr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00July 31, 2014falsefalsefalsexbrli:stringItemTypestringThis element represents the date of expected termination of any expense reimbursement or fee waiver arrangements that reduce any Fund operating expenses (SEC Form N-1A 2006-09-14 A.3.table.1.11 Total Annual Fund Operating Expenses A.3.instructions.3.e).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 3 -Subparagraph e false0Fee Waiver or Reimbursement over Assets, Date of Termination14false 3rr_PortfolioTurnoverHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00PORTFOLIO TURNOVER.falsefalsefalsexbrli:stringItemTypestringDisclose the portfolio turnover rate provided in response to Item 14(a) for the most recent fiscal year (or for such shorter period as the Fund has been in operation). Disclose the period for which the information is provided if less than a full fiscal year. A Fund that is a Money Market Fund may omit the portfolio turnover information required by this Item.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 5 false0Portfolio Turnover [Heading]15false 3rr_PortfolioTurnoverTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00The 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 portfolio operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 145.22% of the average value of its portfolio.falsefalsefalsenonnum:textBlockItemTypenaDisclose the portfolio turnover rate provided in response to Item 14(a) for the most recent fiscal year (or for such shorter period as the Fund has been in operation). Disclose the period for which the information is provided if less than a full fiscal year. A Fund that is a Money Market Fund may omit the portfolio turnover information required by this Item.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection example -Paragraph 3 false0Portfolio Turnover [Text Block]16false 3rr_PortfolioTurnoverRaterr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse1.45221.4522falsefalsefalsexbrli:pureItemTypepureThis element represents the rate of portfolio turnover presented as a percentage (SEC Form N-1A 2006-09-14 A.3.example.3 Portfolio Turnover A.3.instructions.5 Portfolio Turnover).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection example -Paragraph 3 false0Portfolio Turnover, Rate17false 3rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFeesrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00The Total Annual Fund Operating Expenses and Total Annual Fund Operating Expenses After Expense Reimbursement will not correlate to the Fund's ratios of average net assets to (1) expenses before reimbursements and credits and (2) expenses net of reimbursements and credits, respectively, included in the Fund's Financial Highlights in the Fund's complete Prospectus, which do not reflect indirect expenses, such as Acquired Fund Fees and Expenses.falsefalsefalsexbrli:stringItemTypestringThe Fund may clarify in a footnote to the fee table that the total annual fund operating expenses under Item 3 do not correlate to the ratio of expenses to average net assets given in response to Item 8, which reflects the operating expenses of the Fund and does not include Acquired Fund fees and expenses.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 3 -Subparagraph f -Clause vii false0Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]18false 3rr_ExpenseExampleHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00EXAMPLE falsefalsefalsexbrli:stringItemTypestringHeading for Expense Example.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 4 false0Expense Example [Heading]19false 3rr_ExpenseExampleNarrativeTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00The following 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 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:falsefalsefalsenonnum:textBlockItemTypenaThe Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection example -Paragraph 1 -Subparagraph 1 false0Expense Example Narrative [Text Block]20false 3rr_StrategyHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00PRINCIPAL INVESTMENT STRATEGIES falsefalsefalsexbrli:stringItemTypestringPrincipal investment strategies of the Fund. Summarize how the Fund intends to achieve its investment objectives by identifying the Fund's principal investment strategies (including the type or types of securities in which the Fund invests or will invest principally) and any policy to concentrate in securities of issuers in a particular industry or group of industries.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection a false0Strategy [Heading]21false 3rr_StrategyNarrativeTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00In seeking high current income exempt from regular federal income tax and California state personal income tax, the Fund will invest in municipal instruments. A municipal instrument is a fixed-income obligation issued by a state, territory and possession of the United States (including the District of Columbia) and the political subdivisions, agencies and instrumentalities thereof. Interest income received by holders of municipal instruments is often exempt from the federal income tax and from the income tax of the state in which they are issued, although municipal instruments issued for certain purposes may not be tax-exempt. The municipal instruments in which the Fund invests may include:<ul type="square"><li style="margin-left:-20px">General obligation bonds secured by the issuer's full faith, credit and taxing power;</li></ul><ul type="square"><li style="margin-left:-20px">Revenue obligation bonds payable from the revenues derived from a particular facility or class of facilities;</li></ul><ul type="square"><li style="margin-left:-20px">Industrial development bonds;</li></ul><ul type="square"><li style="margin-left:-20px">Moral obligation bonds;</li></ul><ul type="square"><li style="margin-left:-20px">Tax-exempt derivative instruments;</li></ul><ul type="square"><li style="margin-left:-20px">Stand-by commitments; and</li></ul><ul type="square"><li style="margin-left:-20px">Municipal instruments backed by letters of credit, insurance or other forms of credit enhancement issued by domestic or foreign banks, insurance companies and other financial institutions.</li></ul>The Fund primarily invests in investment grade debt obligations (i.e., obligations rated within the top four rating categories by a Nationally Recognized Statistical Rating Organization ("NRSRO") or of comparable quality as determined by the Fund's investment adviser). However, it may invest to a limited extent in obligations that are rated below-investment grade (commonly referred to as "junk bonds"). Except in extraordinary circumstances, at least 80% of the Fund's net assets will be invested in debt instruments that pay interest that is exempt from regular federal income tax. Alternative Minimum Tax ("AMT") obligations (also known as "private activity bonds"), which pay interest that may be treated as an item of tax preference to shareholders under the federal AMT, will not be deemed to be eligible debt instruments for the purposes of determining whether the Fund meets this policy. For shareholders subject to AMT, a limited portion of the Fund's dividends may be subject to federal tax. In addition, under normal circumstances, at least 80% of the Fund's net assets will be invested in instruments that pay income that is exempt from California state personal income tax ("California municipal instruments"). These may include certain securities of issuers located outside the State of California. During temporary defensive periods, all or any portion of the Fund's assets may be held uninvested or invested in AMT obligations and taxable instruments. The Fund may not achieve its investment objective when this temporary defensive strategy is used. In buying and selling securities for the Fund, the Fund's investment adviser uses a relative value approach. This approach involves an analysis of general economic and market conditions. It also involves the use of models that analyze and compare expected returns and assumed risks. Under the relative value approach, the Fund's investment adviser will emphasize particular securities and types of securities (such as general obligation bonds and revenue obligation bonds) that the team believes will provide a favorable return in light of these risks. The Fund's dollar-weighted average maturity, under normal circumstances, will range between ten and thirty years. The Fund is "non-diversified" under the Investment Company Act of 1940, as amended (the "1940 Act"), and may invest more of its assets in fewer issuers than "diversified" mutual funds. In seeking to achieve its investment objective, the Fund may make significant investments in structured securities and also may invest, to a lesser extent, in futures contracts, options and swaps, all of which are considered to be derivative instruments, for both hedging and non-hedging purposes.falsefalsefalsenonnum:textBlockItemTypenaPrincipal investment strategies of the Fund. Summarize how the Fund intends to achieve its investment objectives by identifying the Fund's principal investment strategies (including the type or types of securities in which the Fund invests or will invest principally) and any policy to concentrate in securities of issuers in a particular industry or group of industries.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection a false0Strategy Narrative [Text Block]22false 3rr_RiskHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00PRINCIPAL RISKS falsefalsefalsexbrli:stringItemTypestringNarrative Risk Disclosure.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 1 false0Risk [Heading]23false 3rr_RiskNarrativeTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00MARKET RISK is the risk that the market values of fixed-income securities owned by the Funds may decline, at times sharply and unpredictably. MANAGEMENT RISK is the risk that a strategy used by the Fund's investment adviser may fail to produce the intended results. LIQUIDITY RISK is the risk that certain portfolio securities may be less liquid than others, which may make them difficult or impossible to sell at the time and the price that the Fund would like, adversely affecting the value of the Fund's investments and its returns. INTEREST RATE/MATURITY RISK is the risk that the value of the Fund's assets will decline because of rising interest rates. This risk is generally lower for funds that have shorter-weighted maturities, such as money market funds and short-term bond funds. The magnitude of this decline will often be greater for longer-term fixed-income securities than shorter-term fixed-income securities. STRUCTURED SECURITIES RISK is the risk that loss may result from the Fund's investments in structured securities. Structured securities may be more volatile, less liquid and more difficult to price accurately than less complex securities due to their derivative nature. As a result, investments in structured securities may adversely affect the Fund's net asset value. In some cases it is possible that the Fund may suffer a total loss on its investment in a structured security. PREPAYMENT (OR CALL) RISK is the risk that prepayment of the underlying mortgages or other collateral of some fixed-income securities may result in a decreased rate of return and a decline in value of those securities. DEBT EXTENSION RISK is the risk that an issuer will exercise its right to pay principal on an obligation held by the Fund (such as a mortgage-backed security) later than expected. This may happen during a period of rising interest rates. Under these circumstances, the value of the obligation will decrease and the Fund will suffer from the inability to invest in higher yielding securities. CREDIT (OR DEFAULT) RISK is the risk that the inability or unwillingness of an issuer or guarantor of a fixed-income security, or a counterparty to a repurchase or other transaction, to meet its payment or other financial obligations will adversely affect the value of the Fund's investments and its returns. Changes in the credit rating of a debt security held by the Fund could have a similar effect. PROJECT/INDUSTRIAL DEVELOPMENT BOND RISK is the risk that the Fund may be more sensitive to an adverse economic, business or political development if it invests more than 25% of its assets in municipal instruments, the interest upon which is paid solely from revenues of similar projects, or in industrial development bonds. TAX RISK is the risk that future legislative or administrative changes or court decisions may materially affect the value of municipal instruments or the ability of the Fund to pay tax-exempt dividends. PORTFOLIO TURNOVER RISK is the risk that high portfolio turnover is likely to lead to increased Fund expenses that may result in lower investment returns. High portfolio turnover also is likely to result in higher short-term capital gains taxable to shareholders. For the last fiscal year, the annual portfolio turnover rate of the Fund exceeded 100%. MUNICIPAL MARKET VOLATILITY RISK is the risk that the Fund may be adversely affected by the volatile municipal market. The municipal market can be significantly affected by adverse tax, legislative, or political changes and the financial condition of the issuers of municipal securities. NON-DIVERSIFICATION RISK is the risk that the Fund may be more susceptible to adverse financial, economic or other developments affecting any single issuer, and more susceptible to greater losses because of these developments, than if it were diversified. CALIFORNIA-SPECIFIC RISK is the risk that the Fund will be more exposed to risks associated with the negative aspects of California's economy, political system and government financing structures than a fund that invests more widely. Unfavorable developments in any economic sector may have a substantial impact on the overall California municipal market. Provisions of the California Constitution and State statutes that limit the taxing and spending authority of California governmental entities may impair the ability of California issuers to pay principal and/or interest on their obligations. While California's economy is broad, it does have major concentrations in high technology, aerospace and defense-related manufacturing, trade, entertainment, real estate and financial services, and may be sensitive to economic problems affecting those industries. Future California political and economic developments, constitutional amendments, legislative measures, executive orders, administrative regulations, litigation and voter initiatives could have an adverse effect on the debt obligations of California issuers. As of June 2013, California's general obligation bonds had one of the lowest credit ratings assigned to state obligation bonds in the country. As with any mutual fund, it is possible to lose money on an investment in the Fund. An investment in the Fund is not a deposit of any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation, any other government agency, or The Northern Trust Company, its affiliates, subsidiaries or any other bank.falsefalsefalsenonnum:textBlockItemTypenaNarrative Risk Disclosure. A Fund may, in responding to this Item, describe the types of investors for whom the Fund is intended or the types of investment goals that may be consistent with an investment in the Fund.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 1 -Subparagraph i -Clause instruction false0Risk Narrative [Text Block]24false 3rr_RiskLoseMoneyrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00As with any mutual fund, it is possible to lose money on an investment in the Fund. falsefalsefalsexbrli:stringItemTypestringSummarize the principal risks of investing in the Fund, including the risks to which the Fund's portfolio as a whole is subject and the circumstances reasonably likely to affect adversely the Fund's net asset value, yield, and total return. Unless the Fund is a Money Market Fund, disclose that loss of money is a risk of investing in the Fund. A Fund may, in responding to this Item, describe the types of investors for whom the Fund is intended or the types of investment goals that may be consistent with an investment in the Fund.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 1 -Subparagraph i false0Risk Lose Money [Text]25false 3rr_RiskNondiversifiedStatusrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00NON-DIVERSIFICATION RISK is the risk that the Fund may be more susceptible to adverse financial, economic or other developments affecting any single issuer, and more susceptible to greater losses because of these developments, than if it were diversified.falsefalsefalsexbrli:stringItemTypestringIf applicable, state that the Fund is non-diversified, describe the effect of non-diversification (e.g., disclose that, compared with other funds, the Fund may invest a greater percentage of its assets in a particular issuer), and summarize the risks of investing in a non-diversified fund.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 1 -Subparagraph iv false0Risk Nondiversified Status [Text]26false 3rr_RiskNotInsuredDepositoryInstitutionrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00An investment in the Fund is not a deposit of any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation, any other government agency, or The Northern Trust Company, its affiliates, subsidiaries or any other bank. falsefalsefalsexbrli:stringItemTypestringIf the Fund is advised by or sold through an insured depository institution, state that An investment in the Fund is not a deposit of the bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. A Money Market Fund that is advised by or sold through an insured depository institution should combine the disclosure required by Items 2(c)(1)(ii) and (iii) in a single statement.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 1 -Subparagraph iii false0Risk Not Insured Depository Institution [Text]27false 3rr_BarChartAndPerformanceTableHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00FUND PERFORMANCE falsefalsefalsexbrli:stringItemTypestringRisk/Return Bar Chart and Table.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 false0Bar Chart and Performance Table [Heading]28false 3rr_PerformanceNarrativeTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00The bar chart and table that follow provide an indication of the risks of investing in the Fund by showing (A) changes in the performance of the Fund from year to year, and (B) how the average annual total returns of the Fund compare to those of a broad-based securities market index. The Fund's past performance, before and after taxes, is not necessarily an indication of how the Fund will perform in the future. Updated performance information for the Fund is available and may be obtained on the Fund's Web site at www.northernfunds.com or by calling 800-595-9111.falsefalsefalsenonnum:textBlockItemTypenaRisk/Return Bar Chart and Table.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 false0Performance Narrative [Text Block]29false 3rr_PerformanceInformationIllustratesVariabilityOfReturnsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00The bar chart and table that follow provide an indication of the risks of investing in the Fund by showing (A) changes in the performance of the Fund from year to year, and (B) how the average annual total returns of the Fund compare to those of a broad-based securities market index.falsefalsefalsexbrli:stringItemTypestringInclude the bar chart and table required by paragraphs (b)(2)(ii) and (iii) of this section. Provide a brief explanation of how the information illustrates the variability of the Fund's returns (e.g., by stating that the information provides some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual returns for 1, 5, and 10 years compare with those of a broad measure of market performance). Provide a statement to the effect that the Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph i false0Performance Information Illustrates Variability of Returns [Text]30false 3rr_PerformanceAvailabilityPhonerr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00800-595-9111falsefalsefalsexbrli:stringItemTypestringIf applicable, include a statement explaining that updated performance information is available and providing a Web site address and/or toll-free (or collect) telephone number where the updated information may be obtained.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph i false0Performance Availability Phone [Text]31false 3rr_PerformanceAvailabilityWebSiteAddressrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00www.northernfunds.comfalsefalsefalsexbrli:stringItemTypestringIf applicable, include a statement explaining that updated performance information is available and providing a Website address and/or toll-free (or collect) telephone number where the updated information may be obtained.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph i false0Performance Availability Website Address [Text]32false 3rr_PerformancePastDoesNotIndicateFuturerr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00The Fund's past performance, before and after taxes, is not necessarily an indication of how the Fund will perform in the future.falsefalsefalsexbrli:stringItemTypestringInclude the bar chart and table required by paragraphs (b)(2)(ii) and (iii) of this section. Provide a brief explanation of how the information illustrates the variability of the Fund's returns (e.g., by stating that the information provides some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual returns for 1, 5, and 10 years compare with those of a broad measure of market performance). Provide a statement to the effect that the Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph i false0Performance Past Does Not Indicate Future [Text]33false 3rr_BarChartHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00CALENDAR YEAR TOTAL RETURN* falsefalsefalsexbrli:stringItemTypestringRisk/Return Bar Chart and Table.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 false0Bar Chart [Heading]34false 3rr_BarChartClosingTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00* Year to date total return for the six months ended June 30, 2013 is (4.08)%. For the periods shown in the bar chart above, the highest quarterly return was 9.39% in the third quarter of 2009, and the lowest quarterly return was (6.44)% in the fourth quarter of 2010.falsefalsefalsenonnum:textBlockItemTypenaIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph ii false0Bar Chart Closing [Text Block]35false 3rr_PerformanceTableHeadingrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00AVERAGE ANNUAL TOTAL RETURN (For the periods ended December 31, 2012)falsefalsefalsexbrli:stringItemTypestringThis item represents Average Anuual Total Returns. If a Multiple Class Fund offers a Class in the prospectus that converts into another Class after a stated period, compute average annual total returns in the table by using the returns of the other Class for the period after conversion.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph instructions -Clause 3 -Exhibit c false0Performance Table Heading36false 3rr_PerformanceTableUsesHighestFederalRaterr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00After-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.falsefalsefalsexbrli:stringItemTypestringProvide a brief explanation that 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.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph iii false0Performance Table Uses Highest Federal Rate37false 3rr_PerformanceTableNotRelevantToTaxDeferredrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Actual 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 or individual retirement accounts.falsefalsefalsexbrli:stringItemTypestringProvide a brief explanation that the actual after-tax returns depend on an investor's tax situation and may differ from those shown, and after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph iv -Clause B false0Performance Table Not Relevant to Tax Deferred38false 3rr_PerformanceTableNarrativeTextBlockrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00After-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 or individual retirement accounts.falsefalsefalsenonnum:textBlockItemTypenaIf the Fund has annual returns for at least one calendar year, provide a table showing the Fund's (A) average annual total return; (B) average annual total return (after taxes on distributions); and (C) average annual total return (after taxes on distributions and redemption). A Money Market Fund should show only the returns described in clause (A) of the preceding sentence. All returns should be shown for 1-, 5-, and 10- calendar year periods ending on the date of the most recently completed calendar year (or for the life of the Fund, if shorter), but only for periods subsequent to the effective date of the Fund's registration statement. The table also should show the returns of an appropriate broad-based securities market index as defined in Instruction 5 to Item 22(b)(7) for the same periods. A Fund that has been in existence for more than 10 years also may include returns for the life of the Fund. A Money Market Fund may provide the Fund's 7-day yield ending on the date of the most recent calendar year or disclose a toll-free (or collect) telephone number that investors can use to obtain the Fund's current 7-day yield. For a Fund (other than a Money Market Fund or a Fund described in General Instruction C.3.(d)(iii)), provide the information in the following table with the specified captions AVERAGE ANNUAL TOTAL RETURNS (For the periods ended December 31, _____). For a Fund that provides annual total returns for only one calendar year or for a Fund that does not include the bar chart because it does not have annual returns for a full calendar year, modify, as appropriate, the narrative explanation required by paragraph (c)(2)(i) (e.g., by stating that the information gives some indication of the risks of an investment in the Fund by comparing the Fund's performance with a broad measure of market performance).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph iv false0Performance Table Narrative39false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse3false USDtruefalse$Duration_01Aug2012_31Jul2013S000001251_MemberC000003397_Memberhttp://www.sec.gov/CIK0000916620duration2012-08-01T00:00:002013-07-31T00:00:00falsefalseNORTHERN CALIFORNIA TAX-EXEMPT FUNDdei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldinf_S000001251Memberdei_LegalEntityAxisexplicitMemberfalsefalseNORTHERN CALIFORNIA TAX-EXEMPT FUNDrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldinf_C000003397Memberrr_ProspectusShareClassAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$nanafalse0NORTHERN CALIFORNIA TAX-EXEMPT FUND | NORTHERN CALIFORNIA TAX-EXEMPT FUND40true 2rr_RiskReturnAbstractrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Risk/Return:41false 3rr_ShareholderFeeOtherrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsetrue00USD$falsetruefalserr:NonNegativeMonetaryTypemonetaryOther ExpensesReference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection table -Paragraph 1 -Subparagraph 10 false2Shareholder Fees (fees paid directly from your investment)42false 3rr_ManagementFeesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue0.00550.0055falsefalsefalserr:NonNegativePure4TypepureManagement Fees include investment advisory fees (including any fees based on the Fund's performance), any other management fees payable to the investment adviser or its affiliates, and administrative fees payable to the investment adviser or its affiliates that are not included as "Other Expenses."Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 3 -Subparagraph a false0Management Fees43false 3rr_OtherExpensesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue0.00420.0042falsefalsefalserr:NonNegativePure4Typepure"Other Expenses" include all expenses not otherwise disclosed in the table that are deducted from the Fund's assets or charged to all shareholder accounts. The amount of expenses deducted from the Fund's assets are the amounts shown as expenses in the Fund's statement of operations (including increases resulting from complying with paragraph 2(g) of rule 6-07 of Regulation S-X [17 CFR 210.6-07]). "Other Expenses" do not include extraordinary expenses as determined under generally accepted accounting principles (see Accounting Principles Board Opinion No. 30). If extraordinary expenses were incurred that materially affected the Fund's "Other Expenses," disclose in a footnote to the table what "Other Expenses" would have been had the extraordinary expenses been included.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 3 -Subparagraph c -Clause i false0Other Expenses44false 3rr_Component1OtherExpensesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue0.00150.0015falsefalsefalserr:NonNegativePure4TypepureThe Fund may subdivide this caption into no more than three subcaptions that identify the largest expense or expenses comprising "Other Expenses," but must include a total of all "Other Expenses." Alternatively, the Fund may include the components of "Other Expenses" in a parenthetical to the caption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 3 -Subparagraph c -Clause iii false0Administration Fees45false 3rr_Component2OtherExpensesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue0.0010.001falsefalsefalserr:NonNegativePure4TypepureThe Fund may subdivide this caption into no more than three subcaptions that identify the largest expense or expenses comprising "Other Expenses," but must include a total of all "Other Expenses." Alternatively, the Fund may include the components of "Other Expenses" in a parenthetical to the caption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection table -Paragraph 1 -Subparagraph 10 false0Transfer Agency Fees46false 3rr_Component3OtherExpensesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue0.00170.0017falsefalsefalserr:NonNegativePure4TypepureThe Fund may subdivide this caption into no more than three subcaptions that identify the largest expense or expenses comprising "Other Expenses," but must include a total of all "Other Expenses." Alternatively, the Fund may include the components of "Other Expenses" in a parenthetical to the caption.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 3 -Subparagraph c -Clause iii false0Other Operating Expenses47false 3rr_AcquiredFundFeesAndExpensesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue0.00010.0001falsefalsefalserr:NonNegativePure4TypepureTotal Annual Fund Operating Expenses.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection table -Paragraph 1 -Subparagraph 11 false0Acquired Fund Fees and Expenses48false 3rr_ExpensesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue0.00980.0098[1]falsefalsefalserr:NonNegativePure4TypepureTotal Annual Fund Operating Expenses. If the Fund is a Feeder Fund, reflect the aggregate expenses of the Feeder Fund and the Master Fund in a single fee table using the captions provided. In a footnote to the fee table, state that the table and Example reflect the expenses of both the Feeder and Master Funds. If the prospectus offers more than one Class of a Multiple Class Fund or more than one Feeder Fund that invests in the same Master Fund, provide a separate response for each Class or Feeder Fund. Base the percentages of "Annual Fund Operating Expenses" on amounts incurred during the Fund's most recent fiscal year, but include in expenses amounts that would have been incurred absent expense reimbursement or fee waiver arrangements. If the Fund has changed its fiscal year and, as a result, the most recent fiscal year is less than three months, use the fiscal year prior to the most recent fiscal year as the basis for determining "Annual Fund Operating Expenses."Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 3 -Subparagraph d false0Total Annual Fund Operating Expenses49false 3rr_FeeWaiverOrReimbursementOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue-0.0052-0.0052[2]falsefalsefalserr:NonPositivePure4TypepureTotal Annual Fund Operating Expenses. If there were expense reimbursement or fee waiver arrangements that reduced any Fund operating expenses and will continue to reduce them for no less than one year from the effective date of the Fund's registration statement, a Fund may add two captions to the table one caption showing the amount of the expense reimbursement or fee waiver, and a second caption showing the Fund's net expenses after subtracting the fee reimbursement or expense waiver from the total fund operating expenses. The Fund should place these additional captions directly below the "Total Annual Fund Operating Expenses" caption of the table and should use appropriate descriptive captions, such as "Fee Waiver [and/or Expense Reimbursement]" and "Total Annual Fund Operating Expenses After Fee Waiver [and/or Expense Reimbursement]," respectively. If the Fund provides this disclosure, also disclose the period for which the expense reimbursement or fee waiver arrangement is expected to continue, and briefly describe who can terminate the arrangement and under what circumstances.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection table -Paragraph 1 -Subparagraph 11 false0Expense Reimbursement50false 3rr_NetExpensesOverAssetsrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruetrue0.00460.0046[1]falsefalsefalserr:NonNegativePure4TypepureTotal Annual Fund Operating Expenses.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection table -Paragraph 1 -Subparagraph 11 false0Total Annual Fund Operating Expenses After Expense Reimbursement51false 3rr_ExpenseExampleYear01rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsetrue4747USD$falsefalsefalserr:NonNegativeMonetaryTypemonetaryThe Example assumes that you invest $10,000 in the Fund for the time periods indicated and then you redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return per year and that the Fund's operating expenses remained the same. Although your actual costs may be higher or lower.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection instructions -Paragraph 4 false21 Year52false 3rr_ExpenseExampleYear03rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsetrue260260USD$falsefalsefalserr:NonNegativeMonetaryTypemonetaryThe Example assumes that you invest $10,000 in the Fund for the time periods indicated and then you redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return per year and that the Fund's operating expenses remained the same. Although your actual costs may be higher or lower.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection example -Paragraph 1 -Subparagraph 2 false23 Years53false 3rr_ExpenseExampleYear05rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsetrue491491USD$falsefalsefalserr:NonNegativeMonetaryTypemonetaryThe Example assumes that you invest $10,000 in the Fund for the time periods indicated and then you redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return per year and that the Fund's operating expenses remained the same. Although your actual costs may be higher or lower.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection example -Paragraph 1 -Subparagraph 2 false25 Years54false 3rr_ExpenseExampleYear10rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsetrue11541154USD$falsetruefalserr:NonNegativeMonetaryTypemonetaryThe Example assumes that you invest $10,000 in the Fund for the time periods indicated and then you redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return per year and that the Fund's operating expenses remained the same. Although your actual costs may be higher or lower.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Subsection example -Paragraph 1 -Subparagraph 2 false210 Years55false 3rr_AnnualReturn2003rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruefalse0.0490.049falsefalsefalsexbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph instructions -Clause 3 -Exhibit a false0200356false 3rr_AnnualReturn2004rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruefalse0.04160.0416falsefalsefalsexbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph instructions -Clause 3 -Exhibit a false0200457false 3rr_AnnualReturn2005rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruefalse0.03830.0383falsefalsefalsexbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph ii false0200558false 3rr_AnnualReturn2006rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruefalse0.0380.038falsefalsefalsexbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph ii false0200659false 3rr_AnnualReturn2007rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruefalse0.02760.0276falsefalsefalsexbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph instructions -Clause 3 -Exhibit a false0200760false 3rr_AnnualReturn2008rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruefalse-0.0326-0.0326falsefalsefalsexbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph ii false0200861false 3rr_AnnualReturn2009rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruefalse0.12350.1235falsefalsefalsexbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph instructions -Clause 3 -Exhibit a false0200962false 3rr_AnnualReturn2010rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruefalse0.01740.0174falsefalsefalsexbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph ii false0201063false 3rr_AnnualReturn2011rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruefalse0.15150.1515falsefalsefalsexbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph instructions -Clause 3 -Exhibit a false0201164false 3rr_AnnualReturn2012rr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truetruefalse0.09580.0958falsefalsefalsexbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph ii false0201265false 3rr_YearToDateReturnLabelrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Year to date total returnfalsefalsefalsexbrli:stringItemTypestringIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph ii false0Year to Date Return, Label66false 3rr_BarChartYearToDateReturnDaterr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002013-06-30falsefalsetruexbrli:dateItemTypedateIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph ii false0Bar Chart, Year to Date Return, Date67false 3rr_BarChartYearToDateReturnrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse-0.0408-0.0408falsefalsefalsexbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph ii false0Bar Chart, Year to Date Return68false 3rr_HighestQuarterlyReturnLabelrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00highest quarterly returnfalsefalsefalsexbrli:stringItemTypestringIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph ii false0Highest Quarterly Return, Label69false 3rr_BarChartHighestQuarterlyReturnDaterr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002009-09-30falsefalsetruexbrli:dateItemTypedateIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph ii false0Highest Quarterly Return, Date70false 3rr_BarChartHighestQuarterlyReturnrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.09390.0939falsefalsefalsexbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph ii false0Highest Quarterly Return71false 3rr_LowestQuarterlyReturnLabelrr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00lowest quarterly returnfalsefalsefalsexbrli:stringItemTypestringIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph ii false0Lowest Quarterly Return, Label72false 3rr_BarChartLowestQuarterlyReturnDaterr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002010-12-31falsefalsetruexbrli:dateItemTypedateIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. 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If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. 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3rr_AverageAnnualReturnInceptionDaterr_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsetruefalse001997-04-08falsefalsetruexbrli:dateItemTypedateReturn Before Taxes.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection b -Paragraph 2 -Subparagraph instructions -Clause 4 false0Inception Date79false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse4false truefalseDuration_01Aug2012_31Jul2013AfterTaxesOnDistributions_MemberS000001251_MemberC000003397_Memberhttp://www.sec.gov/CIK0000916620duration2012-08-01T00:00:002013-07-31T00:00:00falsefalseNORTHERN CALIFORNIA TAX-EXEMPT FUNDdei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldinf_S000001251Memberdei_LegalEntityAxisexplicitMemberfalsefalseReturn after taxes on 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