Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	SCHWAB INVESTMENTS
Prospectus Date	rr_ProspectusDate	Aug. 10, 2020
Schwab High Yield Municipal Bond Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Schwab® High Yield Municipal Bond Fund
Objective [Heading]	rr_ObjectiveHeading	Investment Objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The fund seeks to generate interest income that is not subject to federal income tax.
Expense [Heading]	rr_ExpenseHeading	Fund Fees and Expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses you may pay if you buy and hold shares of the fund. This table does not reflect any brokerage fees or commissions you may incur when buying or selling fund shares.
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 % 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 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 example, affect the fund’s performance. The fund is the successor to the investment performance of the Wasmer Schroeder High Yield Municipal Fund (Predecessor Fund) as a result of the reorganization of the Predecessor Fund into the fund on August 10, 2020. During the most recent fiscal year ended on February 29, 2020, the Predecessor Fund’s portfolio turnover rate was 27% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	27.00%
Other Expenses, New Fund, Based on Estimates [Text]	rr_OtherExpensesNewFundBasedOnEstimates	“Other expenses” are based on estimated amounts for the current fiscal year.
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	Expenses on a $10,000 Investment
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the fund with the cost of investing in other 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 time periods. The example also assumes that your investment has a 5% return each year and that the fund’s operating expenses remain the same. The figures are based on total annual fund operating expenses after any expense reduction. The example does not reflect any brokerage fees or commissions you may incur when buying or selling fund shares. Your actual costs may be higher or lower.
Strategy [Heading]	rr_StrategyHeading	Principal Investment Strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Under normal market conditions, the fund invests at least 80% of its net assets (plus any borrowings for investment purposes) in municipal securities that pay interest not subject to regular federal income tax. Some of these investments in municipal securities may pay interest that is not exempt from the federal alternative minimum tax (AMT). Municipal securities may include debt obligations of U.S. states, territories, counties, cities, political subdivisions, government agencies and instrumentalities. The fund also invests in non-governmental municipal issuers, including, but not limited to, healthcare organizations, corporate issuers of municipal debt, and various project finance bond issues. The fund primarily invests in general obligation and revenue obligation securities, including fixed and variable rate securities, municipal notes and private placements, auction-rate securities, variable rate demand notes, lease-backed obligations and certificates of participation. The fund may from time to time invest temporarily up to 20% of its net assets in taxable securities of at least comparable quality to the municipal securities in which the Fund invests. The fund may also invest up to 25% of its net assets in municipal securities that are subject to the AMT. The fund has no policy limiting its investments in municipal securities whose issuers are located in the same state or territory. However, the fund currently intends to invest no more than 25% of the fund’s net assets in issuers located in the same state. The fund may hold up to 15% of its net assets in illiquid or thinly traded securities, which may include securities that are subject to resale restrictions such as those issued pursuant to Rule 144A of the Securities Act of 1933, as amended. The fund may invest in securities that do not produce immediate cash income, such as zero coupon securities and securities that are in payment default. The fund invests at least 60% of its net assets in investment grade municipal securities, as determined by a nationally recognized rating organization (NRSRO) (e.g., Baa3 or higher by Moody’s Investors Service, Inc. (“Moody’s”) or if unrated, determined to be of comparable quality by the investment adviser. The fund may also invest in municipal securities that are less-than-investment grade, as determined by an NRSRO (e.g., Ba1 or lower by Moody’s) or by the investment adviser. In choosing securities, the fund’s investment adviser seeks to maximize current income within the limits of the fund’s credit and average maturity standards. The investment adviser’s credit research department analyzes and monitors the securities that the fund owns or is considering buying. Under normal market conditions, the fund anticipates investing substantially in municipal bonds with remaining maturities of 5- to 30-years. The fund does not target a specific level of portfolio turnover as purchases and sales are made if the investment adviser determines the transactions will be advantageous to the fund. The fund may also invest in derivative instruments, principally futures contracts. The fund typically uses futures as a substitute for taking a position in the underlying asset or as a part of a strategy designed to reduce exposure to other risks. During unusual market conditions, the fund may invest entirely in taxable securities as a temporary defensive measure. When the fund engages in such activities, the fund would not be pursuing its investment strategy and, as a result, it may not achieve its investment objective.
Risk [Heading]	rr_RiskHeading	Principal Risks
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The fund is subject to risks, any of which could cause an investor to lose money. The fund’s principal risks include: Market Risk. Financial markets rise and fall in response to a variety of factors, sometimes rapidly and unpredictably. Markets may be impacted by economic, political, regulatory and other conditions, including economic sanctions and other government actions. In addition, the occurrence of global events, such as war, terrorism, environmental disasters, natural disasters and epidemics, may also negatively affect the financial markets. As with any investment whose performance is tied to these markets, the value of an investment in the fund will fluctuate, which means that an investor could lose money over short or long periods. Management Risk. As an actively managed mutual fund, the fund is subject to the risk that its investment adviser will select investments or allocate assets in a manner that could cause the fund to underperform or otherwise not meet its investment objective. The fund’s investment adviser applies its own investment techniques and risk analyses in making investment decisions for the fund, but there can be no guarantee that they will produce the desired results. Investment Style Risk. The fund is not designed to offer substantial capital appreciation. In exchange for its goal of capital preservation, the fund may offer lower long-term performance than stock investments or certain other types of bond investments. Some of the fund’s investments may have greater risks than investments in some taxable bonds. Interest Rate Risk. Interest rates rise and fall over time. As with any investment whose yield reflects current interest rates, the fund’s yield will change over time. During periods when interest rates are low, the fund’s yield (and total return) also may be low. Changes in interest rates also may affect the fund’s share price: a rise in interest rates generally causes the fund’s share price to fall. The longer the fund’s portfolio duration, the more sensitive to interest rate movements its share price is likely to be. Also, a change in a central bank’s monetary policy or economic conditions, among other things, may result in a change in interest rates, which could have sudden and unpredictable effects on the markets and significantly impact the value of fixed-income securities in which the fund invests. Credit Risk. A decline in the credit quality of an issuer, guarantor or liquidity provider of a portfolio investment or a counterparty could cause the fund to lose money or underperform. The fund could lose money if, due to a decline in credit quality, the issuer, guarantor or liquidity provider of a portfolio investment or a counterparty fails to make, or is perceived as being unable or unwilling to make, timely principal or interest payments or otherwise honor its obligations. Liquidity Risk. The fund may be unable to sell certain securities, such as illiquid securities, readily at a favorable time or price, or the fund may have to sell them at a loss. High-Yield Risk. High-yield securities and unrated securities of similar credit quality (junk bonds) are subject to greater levels of credit and liquidity risks, and may be more volatile than higher-rated securities. High-yield securities are considered predominately speculative with respect to the issuer’s continuing ability to make principal and interest payments. Prepayment and Extension Risk. Certain fixed-income securities are subject to the risk that the securities may be paid off earlier or later than expected, especially during periods of falling or rising interest rates, respectively. Prepayments of obligations could cause the fund to forgo future interest income on the portion of the security’s principal repaid early and force the fund to reinvest that money at the lower prevailing interest rates. Extensions of obligations could cause the fund to exhibit additional volatility and hold securities paying lower-than-market rates of interest. Either case could hurt the fund’s performance. Municipal Securities Risk. The fund primarily invests in municipal securities whose interest, in the opinion of the issuers’ counsel, is exempt from federal income tax. Neither the investment adviser nor the fund guarantees that this opinion is correct, and there is no assurance that the Internal Revenue Service (IRS) will agree with such counsel’s opinion. If certain types of investments the fund buys as tax-exempt are later ruled to be taxable, a portion of the fund’s income could be taxable. To the extent that the fund invests in municipal securities from a given state or geographic region, its share price and performance could be affected by local, state and regional factors, including erosion of the tax base and changes in the economic climate. In addition, many municipal securities are issued to finance specific projects (especially those relating to education, health care, transportation and utilities) and conditions in those sectors can affect the overall municipal market. National governmental actions, such as the elimination of tax-exempt status or the reduction of financial support to municipalities, also could affect performance. Municipalities continue to experience difficulties in the current economic and political environment. Derivatives Risk. The fund’s use of derivative instruments involves risks different from, or possibly greater than, the risks associated with investing directly in securities and other traditional investments. The fund’s use of derivatives could reduce the fund’s performance, increase the fund’s volatility, and cause the fund to lose more than the initial amount invested. In addition, investments in derivatives may involve leverage, which means a small percentage of assets invested in derivatives can have a disproportionately large impact on the fund. Distressed or Defaulted Securities Risk. Investments in defaulted securities and obligations of distressed issuers, including securities that are, or may be, involved in reorganizations or other financial restructurings, either out of court or in bankruptcy, involve substantial risks in addition to the risks of investing in high-yield debt securities. The fund’s share price may decline if the reorganization or restructuring is not completed as anticipated. The fund will generally not receive interest payments on the distressed securities and may incur costs to protect its investment. Repayment of defaulted securities and obligations of distressed issuers is subject to significant uncertainties. The fund could lose its entire investment in such securities. Rule 144A Securities Risk. The market for Rule 144A securities typically is less active than the market for publicly-traded securities. Rule 144A securities carry the risk that the liquidity of these securities may become impaired, making it more difficult for the fund to sell these bonds. Zero Coupon Securities Risk. While interest payments are not made on such securities, holders of such securities are deemed to have received income annually, notwithstanding that cash may not be received currently. Some of these securities may be subject to substantially greater price fluctuations during periods of changing market interest rates than are comparable securities that pay interest currently. Longer term zero coupon bonds are more exposed to interest rate risk than shorter term zero coupon bonds. Taxable Investments Risk. The fund may invest a portion of its assets in securities that generate income that is not exempt from federal income tax and in securities whose interest is subject to the AMT. These investments could generate taxable income for shareholders. For more information on the risks of investing in the fund, please see the “Fund Details” section in the prospectus.
Risk Lose Money [Text]	rr_RiskLoseMoney	The fund is subject to risks, any of which could cause an investor to lose money.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart below shows how the fund’s investment results have varied from year to year, and the following table shows how the fund’s average annual total returns for various periods compared to that of two indices. This information provides some indication of the risks of investing in the fund. All figures assume distributions were reinvested. Keep in mind that future performance (both before and after taxes) may differ from past performance. For current performance information, please see  www.schwabfunds.com/schwabfunds_prospectus. The performance data provided below is that of the Predecessor Fund. The Fund has an investment objective, strategies and policies that are substantially similar to those of the Predecessor Fund.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart below shows how the fund’s investment results have varied from year to year, and the following table shows how the fund’s average annual total returns for various periods compared to that of two indices.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.schwabfunds.com/schwabfunds_prospectus
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Keep in mind that future performance (both before and after taxes) may differ from past performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns (%) as of 12/31
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter: 3.50% Q2 2016 Worst Quarter: (4.40%) Q4 2016 Year-to-date performance (before taxes) as of 3/31/2020: (7.28%)
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns as of 12/31/19
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	The after-tax figures reflect the highest individual federal income tax rates in effect during the period and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Your actual after-tax returns depend on your individual tax situation. In addition, after-tax returns are not relevant if you hold your fund shares through a tax-deferred arrangement, such as a 401(k) plan, an individual retirement account (IRA) or other tax-advantaged account.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The after-tax figures reflect the highest individual federal income tax rates in effect during the period and do not reflect the impact of state and local taxes. Your actual after-tax returns depend on your individual tax situation. In addition, after-tax returns are not relevant if you hold your fund shares through a tax-deferred arrangement, such as a 401(k) plan, an individual retirement account (IRA) or other tax-advantaged account.
Schwab High Yield Municipal Bond Fund | Schwab High Yield Municipal Bond Fund
Risk/Return:	rr_RiskReturnAbstract
Redemption fee (as a % of the amount sold or exchanged within 60 days of purchase)	rr_RedemptionFeeOverRedemption	1.00%
Management fees	rr_ManagementFeesOverAssets	0.50%
Distribution (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.23%	[1]
Total annual fund operating expenses	rr_ExpensesOverAssets	0.73%
Less expense reduction	rr_FeeWaiverOrReimbursementOverAssets	(0.13%)
Total annual fund operating expenses after expense reduction	rr_NetExpensesOverAssets	0.60%	[2]
1 Year	rr_ExpenseExampleYear01	$ 61
3 Years	rr_ExpenseExampleYear03	192
5 Years	rr_ExpenseExampleYear05	335
10 Years	rr_ExpenseExampleYear10	$ 750
2015	rr_AnnualReturn2015	4.24%
2016	rr_AnnualReturn2016	1.56%
2017	rr_AnnualReturn2017	8.26%
2018	rr_AnnualReturn2018	1.10%
2019	rr_AnnualReturn2019	9.14%
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-date performance (before taxes)
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2020
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	(7.28%)
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2016
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	3.50%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2016
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(4.40%)
Label	rr_AverageAnnualReturnLabel	Before taxes
1 Year	rr_AverageAnnualReturnYear01	9.14%
5 Years	rr_AverageAnnualReturnYear05	4.81%
Since Inception	rr_AverageAnnualReturnSinceInception	6.28%	[3]
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 31, 2014
Schwab High Yield Municipal Bond Fund | After taxes on distributions | Schwab High Yield Municipal Bond Fund
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	After taxes on distributions
1 Year	rr_AverageAnnualReturnYear01	8.89%
5 Years	rr_AverageAnnualReturnYear05	4.56%
Since Inception	rr_AverageAnnualReturnSinceInception	5.99%	[3]
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 31, 2014
Schwab High Yield Municipal Bond Fund | After taxes on distributions and sale of shares | Schwab High Yield Municipal Bond Fund
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	After taxes on distributions and sale of shares
1 Year	rr_AverageAnnualReturnYear01	7.09%
5 Years	rr_AverageAnnualReturnYear05	4.46%
Since Inception	rr_AverageAnnualReturnSinceInception	5.65%	[3]
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 31, 2014
Schwab High Yield Municipal Bond Fund | Comparative Index (reflects no deduction for expeses or taxes) Bloomberg Barclays Municipal High Yield Index
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Comparative Index (reflects no deduction for expeses or taxes) Bloomberg Barclays Municipal High Yield Index
1 Year	rr_AverageAnnualReturnYear01	10.68%
5 Years	rr_AverageAnnualReturnYear05	5.93%
Since Inception	rr_AverageAnnualReturnSinceInception	6.46%	[3]
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 31, 2014
Schwab High Yield Municipal Bond Fund | Comparative Index (reflects no deduction for expeses or taxes) Bloomberg Barclays Municipal Bond Index
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Comparative Index (reflects no deduction for expeses or taxes) Bloomberg Barclays Municipal Bond Index
1 Year	rr_AverageAnnualReturnYear01	7.54%
5 Years	rr_AverageAnnualReturnYear05	3.53%
Since Inception	rr_AverageAnnualReturnSinceInception	4.03%	[3]
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 31, 2014

[1] “Other expenses” are based on estimated amounts for the current fiscal year.

[2] The investment adviser and its affiliates have agreed to limit the total annual fund operating expenses (excluding interest, taxes and certain non-routine expenses) of the fund to 0.60% for so long as the investment adviser serves as the adviser to the fund. This agreement may only be amended or terminated with the approval of the fund’s Board of Trustees.

[3] Inception of the Predecessor Fund.