Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	COLUMBIA FUNDS SERIES TRUST I
Prospectus Date	rr_ProspectusDate	Dec. 01, 2013
CMG Ultra Short Term Bond Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Summary of the Fund
Objective [Heading]	rr_ObjectiveHeading	Investment Objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	CMG Ultra Short Term Bond Fund (the Fund) seeks a high level of current income consistent with the maintenance of liquidity and the preservation of capital.
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, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund may pay transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 67% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	67.00%
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 illustrates the hypothetical expenses that you would incur over the time periods indicated, and assumes that: you invest $10,000 in the Fund for the periods indicated, your investment has a 5% return each year, and the Fund’s total annual operating expenses remain the same as shown in the Annual Fund Operating Expenses table above. Since the waivers and/or reimbursements shown in the Annual Fund Operating Expenses table above expire as indicated in the preceding table, they are only reflected in the 1 year example and the first year of the other examples. Although your actual costs may be higher or lower, based on the assumptions listed above, your costs would be:
Strategy [Heading]	rr_StrategyHeading	Principal Investment Strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Under normal circumstances, the Fund invests at least 80% of its net assets (including the amount of any borrowings for investment purposes) in a diversified portfolio of domestic debt securities of investment grade quality. Debt securities may be issued by governments, companies or special purpose entities and may include notes, bonds, debentures and commercial paper. Debt securities may also include bank loans, as well as assignments, participations and other interests in bank loans. The Fund may invest in mortgage- and other asset-backed securities. The Fund also may participate in mortgage dollar rolls, which are a type of derivative, up to the Fund’s then current position in mortgage-backed securities. The Fund may invest in floating rate debt securities, which have interest rates that adjust or “float” periodically. The Fund may invest up to 20% of total assets in dollar-denominated foreign debt securities. Under normal circumstances, the Fund’s dollar weighted average effective maturity will be two years or less, and its duration will be one year or less.
Risk [Heading]	rr_RiskHeading	Principal Risks
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	An investment in the Fund involves risk, including those described below. There is no assurance that the Fund will achieve its investment objective and you may lose money. The value of the Fund’s holdings may decline, and the Fund’s net asset value (NAV) and Fund share price may go down. Active Management Risk. Due to its active management, the Fund could underperform its benchmark index and/or other funds with similar investment objectives. The Fund may fail to achieve its investment objective and you may lose money. Changing Distribution Level Risk. The amount of the distributions paid by the Fund will vary and generally depends on the amount of interest income and/or dividends received by the Fund on the securities it holds. The Fund may not be able to pay distributions or may have to reduce its distribution level if the interest income and/or dividends the Fund receives from its investments decline. Counterparty Risk. Counterparty risk is the risk that a counterparty to a financial instrument held by the Fund or by a special purpose or structured vehicle invested in by the Fund may become insolvent or otherwise fail to perform its obligations. As a result, the Fund may obtain no or limited recovery of its investment, and any recovery may be significantly delayed. Credit Risk. Credit risk is the risk that loans or other securities in the Fund’s portfolio may or will decline in price or fail to pay interest or repay principal when due because the borrower of the loan or the issuer of the security may or will default or otherwise become unable or unwilling, or is perceived to be unable or unwilling, to honor its financial obligations (such as making payments to the Fund), including as a result of bankruptcy. Bankruptcies may cause a delay to the Fund in acting on the collateral securing a loan, which may adversely affect the Fund. Further, there is risk that a court could take action adverse to the holders of a loan. A default or expected default of a loan could also make it difficult for the Fund to sell the loan at a price approximating the value previously placed on it. Lower quality or unrated loans or securities held by the Fund may present increased credit risk. In order to enforce its rights in the event of a default, bankruptcy or similar situation, the Fund may be required to retain legal or similar counsel. This may increase the Fund’s operating expenses and adversely affect net asset value. Loans that have a lower priority for repayment in an issuer’s capital structure may involve a higher degree of overall risk than more senior loans of the same borrower. Derivatives Risk. Losses involving derivative instruments may be substantial, because a relatively small movement in the price of an underlying security, instrument, commodity, currency or index may result in a substantial loss for the Fund. In addition to the potential for increased losses, the use of derivative instruments may lead to increased volatility within the Fund. Derivatives will typically increase the Fund’s exposure to principal risks to which it is otherwise exposed, and may expose the Fund to additional risks, including correlation risk, counterparty risk, hedging risk, leverage risk and liquidity risk. Derivatives Risk/Dollar Rolls Risk. Dollar rolls are transactions in which the Fund sells securities to a counterparty and simultaneously agrees to purchase those or similar securities in the future at a predetermined price. Dollar rolls involve the risk that the market value of the securities the Fund is obligated to repurchase may decline below the repurchase price, or that the counterparty may default on its obligations. These transactions may also increase the Fund's portfolio turnover rate. If the Fund reinvests the proceeds of the security sold, the Fund will also be subject to the risk that the investments purchased with such proceeds will decline in value (a form of leverage risk). Foreign Securities Risk. Investments in foreign securities involve certain risks not associated with investments in securities of U.S. companies. Foreign securities subject the Fund to the risks associated with investing in the particular country, including the political, regulatory, economic, social, diplomatic and other conditions or events occurring in the country or region, as well as risks associated with less developed custody and settlement practices. Foreign securities may be more volatile and less liquid than investments in securities of U.S. companies. The performance of the Fund may be negatively impacted by foreign currency strength or weakness relative to the U.S. dollar, particularly if the Fund invests a significant percentage of its assets in foreign securities or other assets denominated in currencies other than the U.S. dollar. Impairment of Collateral Risk. The value of collateral, if any, securing a loan can decline, and may be insufficient to meet the borrower’s obligations or difficult or costly to liquidate. In addition, the Fund’s access to collateral may be limited by bankruptcy or other insolvency laws. Further, certain floating rate and other loans may not be fully collateralized and may decline in value. Interest Rate Risk. Interest rate risk is the risk of losses attributable to changes in interest rates. In general, if prevailing interest rates rise, the values of debt securities will tend to fall, and if interest rates fall, the values of debt securities will tend to rise. Changes in the value of a debt security usually will not affect the amount of income the Fund receives from it but may affect the value of the Fund's shares. In general, the longer the maturity or duration of a debt security, the greater its sensitivity to changes in interest rates. Interest rate declines also may increase prepayments of debt obligations, which, in turn, would increase prepayment risk. As interest rates rise or spreads widen, the likelihood of prepayment decreases. Securities with floating interest rates are typically less sensitive to interest rate changes, but may decline in value if their interest rates do not rise as much as interest rates in general. Because rates on certain floating rate loans and other debt securities reset only periodically, changes in prevailing interest rates (and particularly sudden and significant changes) can be expected to cause fluctuations in the Fund’s net asset value. Issuer Risk. An issuer in which the Fund invests may perform poorly, and the value of its securities may therefore decline, which would negatively affect the Fund’s performance. Poor performance may be caused by poor management decisions, competitive pressures, breakthroughs in technology, reliance on suppliers, labor problems or shortages, corporate restructurings, fraudulent disclosures, natural disasters or other events, conditions or factors. Liquidity Risk. Liquidity risk is the risk associated with a lack of marketability of investments which may make it difficult to sell the investment at a desirable time or price. The Fund may have to lower the selling price, sell other investments, or forego another, more appealing investment opportunity. Judgment plays a larger role in valuing these investments as compared to valuing more liquid investments. Market Risk. Market risk refers to the possibility that the market values of securities or other investments that the Fund holds will fall, sometimes rapidly or unpredictably, or fail to rise. An investment in the Fund could lose money over short or even long periods. Mortgage- and Other Asset-Backed Securities Risk. The value of any mortgage-backed and other asset-backed securities held by the Fund may be affected by, among other things, changes or perceived changes in: interest rates, factors concerning the interests in and structure of the issuer or the originator of the mortgages or other assets, the creditworthiness of the entities that provide any supporting letters of credit, surety bonds or other credit enhancements, or the market's assessment of the quality of underlying assets. Payment of principal and interest on some mortgage-backed securities (but not the market value of the securities themselves) may be guaranteed by the full faith and credit of the U.S. Government or by its agencies, authorities, enterprises or instrumentalities, which are not insured or guaranteed by the U.S. Government. Mortgage-backed securities issued by non-governmental issuers (such as commercial banks, savings and loan institutions, private mortgage insurance companies, mortgage bankers and other secondary market issuers) may entail greater risk than obligations guaranteed by the U.S. Government. Mortgage-backed securities are subject to prepayment risk, which is the possibility that the underlying mortgage may be refinanced or prepaid prior to maturity during periods of declining or low interest rates, causing the Fund to have to reinvest the money received in securities that have lower yields. Rising or high interest rates tend to extend the duration of mortgage-backed securities, making their prices more volatile and more sensitive to changes in interest rates. Prepayment and Extension Risk. Prepayment and extension risk is the risk that a loan, bond or other security or investment might be called or otherwise converted, prepaid or redeemed before maturity, and the portfolio managers may not be able to invest the proceeds in other investments providing as high a level of income, resulting in a reduced yield to the Fund. As interest rates decrease or spreads narrow, the likelihood of prepayment increases. The portfolio managers may be unable to capitalize on securities with higher interest rates or wider spreads because the Fund’s investments are locked in at a lower rate for a longer period of time. Redemption Risk. The Fund may need to sell portfolio securities to meet redemption requests. The Fund could experience a loss when selling portfolio securities to meet redemption requests if there is (i) significant redemption activity by shareholders, including, for example, when a single investor or few large investors make a significant redemption of Fund shares, (ii) a disruption in the normal operation of the markets in which the Fund buys and sells portfolio securities or (iii) the inability of the Fund to sell portfolio securities because such securities are illiquid. In such events, the Fund could be forced to sell portfolio securities at unfavorable prices in an effort to generate sufficient cash to pay redeeming shareholders. The Fund may suspend redemptions or the payment of redemption proceeds when permitted by applicable regulations. Reinvestment Risk. Reinvestment risk is the risk that the Fund will not be able to reinvest income or principal at the same return it is currently earning. Rule 144A Securities Risk. The Fund may invest significantly in Rule 144A securities that are determined to be liquid in accordance with procedures adopted by the Fund’s Board. However, an insufficient number of qualified institutional buyers interested in purchasing Rule 144A securities at a particular time could affect adversely the marketability of such securities and the Fund might be unable to dispose of such securities promptly or at reasonable prices. Accordingly, even if determined to be liquid, the Fund’s holdings of Rule 144A securities may increase the level of Fund illiquidity if eligible buyers become uninterested in buying them at a particular time. Further, Rule 144A companies can require recipients of the information (such as the Fund) to agree contractually to keep the information confidential, which could also adversely affect the Fund’s ability to dispose of the security. U.S. Government Obligations Risk. While U.S. Treasury obligations are backed by the “full faith and credit” of the U.S. Government, such securities are nonetheless subject to credit risk (i.e., the risk that the U.S. Government may be, or be perceived to be, unable or unwilling to honor its financial obligations, such as making payments). Securities issued or guaranteed by federal agencies or authorities and U.S. Government-sponsored instrumentalities or enterprises may or may not be backed by the full faith and credit of the U.S. Government.
Risk Lose Money [Text]	rr_RiskLoseMoney	There is no assurance that the Fund will achieve its investment objective and you may lose money.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance Information
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following bar chart and table show you how the Fund has performed in the past, and can help you understand the risks of investing in the Fund. The bar chart shows how the Fund’s performance has varied for each full calendar year shown. The table below the bar chart compares the Fund’s returns for the periods shown with benchmark performance. The after-tax returns shown in the table below are calculated using the highest historical individual U.S. federal marginal income tax rates and do not reflect the impact of state, local or foreign taxes. Your actual after-tax returns will depend on your personal tax situation and may differ from those shown in the table. In addition, the after-tax returns shown in the table do not apply to shares held in tax-deferred accounts such as 401(k) plans or Individual Retirement Accounts (IRAs). The Fund commenced operations on November 23, 2009. The returns shown for all periods prior to November 23, 2009 are the returns of shares of CMG Ultra Short Term Bond Fund, the predecessor to the Fund and a series of Columbia Funds Institutional Trust. The Fund’s past performance (before and after taxes) is no guarantee of how the Fund will perform in the future. Updated performance information can be obtained by calling toll-free 800.345.6611 or visiting columbiamanagement.com.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following bar chart and table show you how the Fund has performed in the past, and can help you understand the risks of investing in the Fund. The bar chart shows how the Fund's performance has varied for each full calendar year shown. The table below the bar chart compares the Fund’s returns for the periods shown with benchmark performance.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	800.345.6611
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	columbiamanagement.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) is no guarantee of how the Fund will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Year by Year Total Return (%) as of December 31 Each Year
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best and Worst Quarterly Returns During the Period Shown in the Bar Chart Best                            3rd Quarter 2006                            1.59% Worst                          3rd Quarter 2008                          -1.06%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns After Applicable Sales Charges (for periods ended December 31, 2012)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	The after-tax returns shown in the table below are calculated using the highest historical individual U.S. federal marginal income tax rates and do not reflect the impact of state, local or foreign taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	In addition, the after-tax returns shown in the table do not apply to shares held in tax-deferred accounts such as 401(k) plans or Individual Retirement Accounts (IRAs).
CMG Ultra Short Term Bond Fund | CMG Ultra Short Term Bond Fund
Risk/Return:	rr_RiskReturnAbstract
Maximum sales charge (load) imposed on purchases (as a % of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum deferred sales charge (load) imposed on redemptions (as a % of the lower of the original purchase price or current net asset value)	rr_MaximumDeferredSalesChargeOverOther	none
Management fees	rr_ManagementFeesOverAssets	0.25%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.01%
Total annual Fund operating expenses	rr_ExpensesOverAssets	0.26%
Less: Fee waivers and/or expense reimbursements	rr_FeeWaiverOrReimbursementOverAssets	(0.01%)	[1]
Total annual Fund operating expenses after fee waivers and/or expense reimbursements	rr_NetExpensesOverAssets	0.25%
1 year	rr_ExpenseExampleYear01	$ 26
3 years	rr_ExpenseExampleYear03	83
5 years	rr_ExpenseExampleYear05	145
10 years	rr_ExpenseExampleYear10	330
1 year	rr_ExpenseExampleNoRedemptionYear01	26
3 years	rr_ExpenseExampleNoRedemptionYear03	83
5 years	rr_ExpenseExampleNoRedemptionYear05	145
10 years	rr_ExpenseExampleNoRedemptionYear10	$ 330
2005	rr_AnnualReturn2005	2.34%	[2]
2006	rr_AnnualReturn2006	4.67%	[2]
2007	rr_AnnualReturn2007	2.62%	[2]
2008	rr_AnnualReturn2008	0.32%	[2]
2009	rr_AnnualReturn2009	4.18%	[2]
2010	rr_AnnualReturn2010	1.60%	[2]
2011	rr_AnnualReturn2011	0.78%	[2]
2012	rr_AnnualReturn2012	1.38%	[2]
Year to Date Return, Label	rr_YearToDateReturnLabel	Year to Date return
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	0.24%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2006
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	1.59%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(1.06%)
1 Year	rr_AverageAnnualReturnYear01	1.38%
5 Years	rr_AverageAnnualReturnYear05	1.64%
Life of Fund	rr_AverageAnnualReturnSinceInception	2.11%
Share Class Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 08, 2004
CMG Ultra Short Term Bond Fund | returns after taxes on distributions | CMG Ultra Short Term Bond Fund
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	1.06%
5 Years	rr_AverageAnnualReturnYear05	0.76%
Life of Fund	rr_AverageAnnualReturnSinceInception	0.96%
Share Class Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 08, 2004
CMG Ultra Short Term Bond Fund | returns after taxes on distributions and sale of Fund shares | CMG Ultra Short Term Bond Fund
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.90%
5 Years	rr_AverageAnnualReturnYear05	0.89%
Life of Fund	rr_AverageAnnualReturnSinceInception	1.13%
Share Class Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 08, 2004
CMG Ultra Short Term Bond Fund | Barclays U.S. Short-Term Government/Corporate Index (reflects no deductions for fees, expenses or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.36%
5 Years	rr_AverageAnnualReturnYear05	1.30%
Life of Fund	rr_AverageAnnualReturnSinceInception	2.40%	[3]

[1] Columbia Management Investment Advisers, LLC and certain of its affiliates have contractually agreed to waive fees and/or to reimburse expenses (excluding transaction costs and certain other investment related expenses, interest, taxes, acquired fund fees and expenses, and extraordinary expenses) until November 30, 2014, unless sooner terminated at the sole discretion of the Fund's Board of Trustees. Under this agreement, the Fund's net operating expenses, subject to applicable exclusions, will not exceed the annual rate of 0.25%.

[2] Year to Date return as of September 30, 2013: 0.24%

[3] As of August 9, 2004.