Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	NORTHERN FUNDS
Prospectus Date	rr_ProspectusDate	Oct. 02, 2012
CORE BOND FUND
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	CORE BOND FUND
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Fund seeks to maximize total return (capital appreciation and income) consistent with reasonable risk.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	November 30, 2013
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	PORTFOLIO TURNOVER.
Portfolio Turnover [Text Block]	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 portfolio operating expenses or in the Example, affect the Fund’s performance. During its most recent fiscal year, the Predecessor Core Bond Fund’s turnover rate was 851.07% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	851.07%
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]	rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees	The Total Annual Fund Operating Expenses and Total Annual Fund Operating Expenses After Expense Reimbursement will not correlate to the Northern Institutional Core Bond Portfolio’s (the “Predecessor Core Bond Fund”) ratios of expenses to (1) expenses before waivers, reimbursements and credits and (2) expenses net of waivers, reimbursements and credits, respectively, included in the Financial Highlights in the Fund’s complete Prospectus, which do not reflect indirect expenses, such as Acquired Fund Fees and Expenses.
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The 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:
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund will seek capital appreciation and current income in its attempt to maximize total return. In doing so, the Fund will invest, under normal circumstances, at least 80% of its net assets in bonds and other fixed-income securities. These may include: Obligations of the U.S. government or its agencies, instrumentalities or sponsored enterprises, including obligations issued by private issuers that are guaranteed as to principal and interest by the U.S. government, its agencies or instrumentalities; Obligations of state, local and foreign governments; Obligations of domestic and foreign banks and corporations; Zero coupon bonds, debentures, preferred stock and convertible securities; Mortgage and other asset-backed securities; Stripped securities evidencing ownership of future interest or principal payments on debt obligations; and Repurchase agreements relating to the above instruments. The Fund invests primarily in the investment grade debt obligations of domestic issuers. Investment grade debt obligations are obligations rated within the top four rating categories by a Nationally Recognized Statistical Rating Organization (“NRSRO”) or determined by the Investment Adviser to be of comparable quality. The Fund also may invest to a limited extent in U.S. dollar denominated investment grade obligations of foreign issuers. In buying and selling securities for the Fund, the investment management team 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 investment management team will emphasize particular securities and types of securities (such as treasury, agency, asset-backed, mortgage-related and corporate securities) that the team believes will provide a favorable total return in light of these risks. The Fund’s dollar-weighted average maturity, under normal circumstances, will range between three and fifteen years. The investment management team may engage in active trading, and will not consider portfolio turnover a limiting factor in making decisions for the Fund.
Risk [Heading]	rr_RiskHeading	PRINCIPAL RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	MARKET RISK is the risk that the market values of fixed-income securities owned by the Fund may decline, at times sharply and unpredictably. MANAGEMENT RISK is the risk that a strategy used by the investment management team 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. PREPAYMENT (OR CALL) RISK is the risk that prepayment of the underlying mortgage 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. FOREIGN SECURITIES RISK is the risk that investing in foreign (non-U.S.) securities may result in the Fund experiencing more rapid and extreme changes in value than a fund that invests exclusively in securities of U.S. companies, due to less liquid markets, and adverse economic, political, diplomatic, financial, and regulatory factors. Foreign governments also may impose limits on investment and repatriation and impose taxes. Any of these events could cause the value of the Fund’s investments to decline. 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 Predecessor Core Bond Fund exceeded 100%. 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.
Risk Lose Money [Text]	rr_RiskLoseMoney	As with any mutual fund, it is possible to lose money on an investment in the Fund.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	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.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	FUND PERFORMANCE
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table that follow provide an indication of the risks of investing in the Fund. It is currently contemplated that before the Fund commences operations, substantially all of the assets of the Predecessor Core Bond Fund, another portfolio advised by the Investment Adviser, will be transferred to the Fund in a tax-free reorganization (the “Reorganization”), which is expected to occur on or about November 16, 2012. The Predecessor Core Bond Fund was managed with the same investment objective, strategies and policies as will be followed by the Fund. As a result of the Reorganization, the performance and accounting history of the Predecessor Core Bond Fund prior to the date of the Reorganization will be assumed by the Fund. The performance information set forth in the bar chart and table below is that of the Class A Shares of the Predecessor Core Bond Fund, which commenced operations on March 29, 2001. The Predecessor Core Bond 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.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table that follow provide an indication of the risks of investing in the Fund.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	800-595-9111
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.northernfunds.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Predecessor Core Bond Fund’s past performance, before and after taxes, is not necessarily an indication of how the Fund will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	CALENDAR YEAR TOTAL RETURN (CLASS A)*
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	* For the periods shown in the bar chart above, the highest quarterly return was 4.33% in the third quarter of 2002, and the lowest quarterly return was (2.61)% in the second quarter of 2004.
Performance Table Heading	rr_PerformanceTableHeading	AVERAGE ANNUAL TOTAL RETURNS (For the periods ended December 31, 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 or individual retirement accounts.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	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 or individual retirement accounts.
CORE BOND FUND | CORE BOND FUND
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees (fees paid directly from your investment)	rr_ShareholderFeeOther	none
Management Fees	rr_ManagementFeesOverAssets	0.40%
Other Expenses	rr_OtherExpensesOverAssets	0.42%
Administration Fees	rr_Component1OtherExpensesOverAssets	0.15%
Transfer Agency Fees	rr_Component2OtherExpensesOverAssets	0.10%
Other Operating Expenses	rr_Component3OtherExpensesOverAssets	0.17%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.83%	[1]
Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.42%)	[2]
Total Annual Fund Operating Expenses After Expense Reimbursement	rr_NetExpensesOverAssets	0.41%	[1]
1 Year	rr_ExpenseExampleYear01	42
3 Years	rr_ExpenseExampleYear03	223
5 Years	rr_ExpenseExampleYear05	419
10 Years	rr_ExpenseExampleYear10	986
2002	rr_AnnualReturn2002	8.37%
2003	rr_AnnualReturn2003	4.05%
2004	rr_AnnualReturn2004	4.17%
2005	rr_AnnualReturn2005	2.23%
2006	rr_AnnualReturn2006	4.23%
2007	rr_AnnualReturn2007	4.88%
2008	rr_AnnualReturn2008	4.03%
2009	rr_AnnualReturn2009	9.42%
2010	rr_AnnualReturn2010	6.58%
2011	rr_AnnualReturn2011	7.91%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	highest quarterly return
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2002
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	4.33%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	lowest quarterly return
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Jun. 30, 2004
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(2.61%)
1-Year	rr_AverageAnnualReturnYear01	7.91%
5-Year	rr_AverageAnnualReturnYear05	6.55%
10-Year	rr_AverageAnnualReturnYear10	5.56%
Since Inception	rr_AverageAnnualReturnSinceInception	5.54%
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 29, 2001
CORE BOND FUND | Return after taxes on distributions | CORE BOND FUND
Risk/Return:	rr_RiskReturnAbstract
1-Year	rr_AverageAnnualReturnYear01	5.85%
5-Year	rr_AverageAnnualReturnYear05	4.80%
10-Year	rr_AverageAnnualReturnYear10	3.86%
Since Inception	rr_AverageAnnualReturnSinceInception	3.73%
CORE BOND FUND | Return after taxes on distributions and sale of Fund shares | CORE BOND FUND
Risk/Return:	rr_RiskReturnAbstract
1-Year	rr_AverageAnnualReturnYear01	5.24%
5-Year	rr_AverageAnnualReturnYear05	4.59%
10-Year	rr_AverageAnnualReturnYear10	3.76%
Since Inception	rr_AverageAnnualReturnSinceInception	3.66%
CORE BOND FUND | Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)
Risk/Return:	rr_RiskReturnAbstract
1-Year	rr_AverageAnnualReturnYear01	7.84%
5-Year	rr_AverageAnnualReturnYear05	6.50%
10-Year	rr_AverageAnnualReturnYear10	5.78%
Since Inception	rr_AverageAnnualReturnSinceInception	5.86%

[1] The Total Annual Fund Operating Expenses and Total Annual Fund Operating Expenses After Expense Reimbursement will not correlate to the Northern Institutional Core Bond Portfolio's (the "Predecessor Core Bond Fund") ratios of expenses to (1) expenses before waivers, reimbursements and credits and (2) expenses net of waivers, reimbursements and credits, respectively, included in the Financial Highlights in the Fund's complete Prospectus, which do not reflect indirect expenses, such as Acquired Fund Fees and Expenses.

[2] Northern Trust Investments, Inc. (the "Investment Adviser") has contractually agreed to reimburse certain expenses of the Fund (excluding acquired fund fees and expenses; a portion of the compensation paid to each Trustee who is not an officer, director or employee of Northern Trust Corporation or its subsidiaries; expenses related to third-party consultants engaged by the Board of Trustees of the Fund; membership dues paid to the Investment Company Institute and Mutual Fund Directors Forum; extraordinary expenses; and interest, if any) to the extent the "Total Annual Fund Operating Expenses After Expense Reimbursement" exceed 0.40%. This contractual limitation may not be terminated before November 30, 2013 without the approval of the Fund's Board of Trustees.