Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

ELFUN TAX EXEMPT INCOME FUND

Prospectus Date

rr_ProspectusDate

Apr. 30, 2015

ELFUN TAX EXEMPT INCOME FUND

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Elfun Tax-Exempt Income Fund

Objective [Heading]

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Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

As high a level of current interest income exempt from federal income taxation as is available from a concentration of investments in municipal bonds consistent with prudent investment management and the preservation of capital.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses of the Fund

Expense Narrative [Text Block]

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The following 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).

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 the Annual Fund Operating Expenses or in the Expense Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 34% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

34.00%

Expense Example [Heading]

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Expense Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The example below 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 units at the end of those periods or continue to hold them. 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 seeks to achieve its investment objective by investing primarily in investment-grade municipal obligations. Under normal circumstances, the portfolio manager manages the Fund so that at least 80% of the Fund's income is exempt from both regular federal income taxes and the federal alternative minimum tax.

The portfolio manager seeks to identify debt securities with characteristics such as:

• attractive yields and prices

• the potential for income generation

• the potential for capital appreciation

• reasonable credit quality

The portfolio manager may consider selling a security when one of these characteristics no longer applies, or when valuation becomes excessive and more attractive alternatives are identified.

The Fund generally will have an effective duration of 75% to 125% of the duration of the Barclays Municipal Bond Index. As of December 31, 2014, the effective duration of the Barclays Municipal Bond Index was 6.32 years. Portfolio duration is one measure of risk, as noted under “Interest Rate Risk” below.

The Fund also may invest to a lesser extent in tax-free or taxable money market instruments and may hold cash.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

The principal risks of investing in the Fund are:

Municipal Obligations Risk is the risk of investing in municipal securities, and includes interest rate risk and the credit risk of the issuers of municipal securities. The municipal securities market is volatile and may be significantly affected by adverse tax, legislative or political changes. The value of municipal securities can also be adversely affected by changes in the financial condition of one or more individual municipal issuers or insurers of municipal issuers, and by uncertainties and public perceptions concerning these and other factors. In recent periods, a number of municipal issuers in the United States have defaulted on obligations and commenced insolvency proceedings, and financial difficulties of municipal issuers may continue or get worse.

Securities Market Risk is the risk that the value of securities owned by the Fund may go up or down, sometimes rapidly or unpredictably, due to factors affecting particular companies or the securities markets generally. A general downturn in the securities markets may cause multiple asset classes to decline in value simultaneously, although equity securities generally have greater price volatility than fixed income securities. Negative conditions and price declines may occur unexpectedly and dramatically. In addition, the Fund could be forced to sell portfolio securities at an inopportune time in order to meet unusually large or frequent redemption requests in times of overall market turmoil or declining prices for the securities.

Interest Rate Risk is the risk that fixed income securities will decline in value because of changes in interest rates. Bond prices generally rise when interest rates decline and generally decline when interest rates rise. In recent periods, governmental financial regulators, including the U.S. Federal Reserve, have taken steps to maintain historically low interest rates. It is possible there will be less governmental action in the future to maintain low interest rates or that governmental action will be less effective in maintaining low interest rates. Changes in market conditions and government action may have adverse effects on investments, volatility, and liquidity in debt markets and any negative impact on fixed income securities could be swift and significant, potentially increasing Fund redemptions and negatively impacting the Fund’s performance.

Credit Risk is the risk that the issuer or guarantor of a fixed income security, or the counterparty of a derivatives contract or repurchase agreement, is unable or unwilling (or is perceived to be unable or unwilling) to make timely payment of principal and/or interest, or to otherwise honor its obligations.

Valuation Risk is the risk that the portfolio securities that have been valued using techniques other than market quotations may have valuations that are different from those produced using other methodologies, and that such securities may be sold at discounts to the values established by the Fund.

It is possible to lose money on an investment in the Fund, and this risk of loss may be heightened if you hold shares of the Fund for a shorter period.

Risk Lose Money [Text]

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It is possible to lose money on an investment in the Fund, and this risk of loss may be heightened if you hold shares of the Fund for a shorter period.

Bar Chart and Performance Table [Heading]

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Performance

Performance Narrative [Text Block]

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The bar chart and the Average Annual Total Returns table below provide 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 compare with the returns of a broad-based securities market index. Past performance assumes the reinvestment of all dividend income and capital gains distributions. The Fund’s past performance, before and after taxes, is not necessarily an indication of how the Fund will perform in the future. For updated performance information, please visit the Fund’s website at www.geam.com or call 1-800-242-0134.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart and the Average Annual Total Returns table below provide 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 compare with the returns of a broad-based securities market index.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

1-800-242-0134

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.geam.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The 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]

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Calendar Year Total Returns (%)

Bar Chart Closing [Text Block]

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Highest/Lowest quarterly results during this time period were:

Highest                                                                            6.63%                                          (quarter ended September 30, 2009)
Lowest                                                                           -4.57%                                          (quarter ended December 31, 2010)

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns (%)
(for the periods ended December 31, 2014)

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

After-tax returns shown are not relevant to investors who hold their Fund units through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Narrative

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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 Fund units through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

ELFUN TAX EXEMPT INCOME FUND | Elfun Tax Exempt Income Fund

Risk/Return:

rr_RiskReturnAbstract

Shareholder Fees (fees paid directly from your investment)

rr_ShareholderFeeOther

Management Expenses

rr_ManagementFeesOverAssets

0.17%

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

Other Expenses

rr_OtherExpensesOverAssets

0.04%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

0.21%

1 Year

rr_ExpenseExampleYear01

22

3 Years

rr_ExpenseExampleYear03

68

5 Years

rr_ExpenseExampleYear05

118

10 Years

rr_ExpenseExampleYear10

268

1 Year

rr_ExpenseExampleNoRedemptionYear01

22

3 Years

rr_ExpenseExampleNoRedemptionYear03

68

5 Years

rr_ExpenseExampleNoRedemptionYear05

118

10 Years

rr_ExpenseExampleNoRedemptionYear10

268

2005

rr_AnnualReturn2005

3.64%

2006

rr_AnnualReturn2006

4.83%

2007

rr_AnnualReturn2007

2.96%

2008

rr_AnnualReturn2008

(2.51%)

2009

rr_AnnualReturn2009

13.64%

2010

rr_AnnualReturn2010

1.86%

2011

rr_AnnualReturn2011

10.57%

2012

rr_AnnualReturn2012

7.45%

2013

rr_AnnualReturn2013

(4.06%)

2014

rr_AnnualReturn2014

9.85%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

6.63%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2010

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(4.57%)

1 Year

rr_AverageAnnualReturnYear01

9.85%

5 Years

rr_AverageAnnualReturnYear05

4.98%

10 Years

rr_AverageAnnualReturnYear10

4.68%

ELFUN TAX EXEMPT INCOME FUND | Return After Taxes on Distributions | Elfun Tax Exempt Income Fund

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

9.85%

5 Years

rr_AverageAnnualReturnYear05

4.39%

10 Years

rr_AverageAnnualReturnYear10

4.35%

ELFUN TAX EXEMPT INCOME FUND | Return After Taxes on Distributions and Sale of Fund Units | Elfun Tax Exempt Income Fund

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

7.42%

5 Years

rr_AverageAnnualReturnYear05

4.27%

10 Years

rr_AverageAnnualReturnYear10

4.32%

ELFUN TAX EXEMPT INCOME FUND | Barclays Municipal Bond Index (does not reflect fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

9.05%

5 Years

rr_AverageAnnualReturnYear05

5.16%

10 Years

rr_AverageAnnualReturnYear10

4.74%