Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	SCHWAB INVESTMENTS
Prospectus Date	rr_ProspectusDate	Feb. 28, 2020
Schwab 1000 Index Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Schwab 1000 Index® Fund
Objective [Heading]	rr_ObjectiveHeading	Investment Objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The fund's goal is to match the total return of the Schwab 1000 Index®.
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. During the most recent fiscal year, the fund's portfolio turnover rate was 5% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	5.00%
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 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	To pursue its goal, the fund generally invests in stocks that are included in the Schwab 1000 Index. It is the fund's policy that under normal circumstances it will invest at least 80% of its net assets (including, for this purpose, any borrowings for investment purposes) in these stocks; typically, the actual percentage is considerably higher. The fund will notify its shareholders at least 60 days before changing this policy. The fund generally will seek to replicate the performance of the index by giving the same weight to a given stock as the index does. However, when the investment adviser believes it is in the best interest of the fund, such as to avoid purchasing odd-lots (i.e., purchasing less than the usual number of shares traded for a security), for tax considerations, or to address liquidity considerations with respect to a stock, the investment adviser may cause the fund's weighting of a stock to be more or less than the index's weighting of the stock. The fund may sell securities that are represented in the index in anticipation of their removal from the index, or buy securities that are not yet represented in the index in anticipation of their addition to the index. The Schwab 1000 Index is a float-adjusted market capitalization weighted index that includes the 1,000 largest stocks of publicly traded companies in the United States, with size being determined by market capitalization (total market value of all shares outstanding). The index is designed to be a measure of the performance of large- and mid-cap U.S. stocks. The fund may invest in derivatives, principally futures contracts, and lend its securities to minimize the gap in performance that naturally exists between any index fund and its corresponding index. This gap occurs mainly because, unlike the index, the fund incurs expenses and must keep a small portion of its assets in cash for business operations. By using futures, the fund potentially can offset a portion of the gap attributable to its cash holdings. In addition, any income realized through securities lending may help reduce the portion of the gap attributable to expenses. The fund may concentrate its investments in an industry or group of industries to the extent that the index the fund is designed to track is also so concentrated.
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. 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. Equity Risk. The prices of equity securities rise and fall daily. These price movements may result from factors affecting individual companies, industries or the securities market as a whole. In addition, equity markets tend to move in cycles, which may cause stock prices to fall over short or extended periods of time. Investment Style Risk. The fund is an index fund. Therefore, the fund follows the securities included in the index during upturns as well as downturns. Because of its indexing strategy, the fund does not take steps to reduce market exposure or to lessen the effects of a declining market. In addition, because of the fund’s expenses, the fund’s performance may be below that of the index. Tracking Error Risk. As an index fund, the fund seeks to track the performance of the index, although it may not be successful in doing so. The divergence between the performance of the fund and the index, positive or negative, is called “tracking error.” Tracking error can be caused by many factors and it may be significant. Market Capitalization Risk. Securities issued by companies of different market capitalizations tend to go in and out of favor based on market and economic conditions. During a period when securities of a particular market capitalization fall behind other types of investments, the fund’s performance could be impacted. Large-Cap Company Risk. Large-cap companies are generally more mature and the securities issued by these companies may not be able to reach the same levels of growth as the securities issued by small- or mid-cap companies. Mid-Cap Company Risk. Mid-cap companies may be more vulnerable to adverse business or economic events than larger, more established companies and the value of securities issued by these companies may move sharply. Concentration Risk. To the extent that the fund’s or the index’s portfolio is concentrated in the securities of issuers in a particular market, industry, group of industries, sector or asset class, the fund may be adversely affected by the performance of those securities, may be subject to increased price volatility and may be more vulnerable to adverse economic, market, political or regulatory occurrences affecting that market, industry, group of industries, sector or asset class. 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 could 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. 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. Securities Lending Risk. Securities lending involves the risk of loss of rights in, or delay in recovery of, the loaned securities if the borrower fails to return the security loaned or becomes insolvent. 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.
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: 13.97% Q1 2019 Worst Quarter: (14.68%) Q3 2011
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 1000 Index Fund | Schwab 1000 Index Fund
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees (fees paid directly from your investment)	rr_ShareholderFeeOther	none
Management fees	rr_ManagementFeesOverAssets	0.05%
Other expenses	rr_OtherExpensesOverAssets	none
Total annual fund operating expenses	rr_ExpensesOverAssets	0.05%
1 Year	rr_ExpenseExampleYear01	$ 5
3 Years	rr_ExpenseExampleYear03	16
5 Years	rr_ExpenseExampleYear05	28
10 Years	rr_ExpenseExampleYear10	$ 64
2010	rr_AnnualReturn2010	15.96%
2011	rr_AnnualReturn2011	1.27%
2012	rr_AnnualReturn2012	15.77%
2013	rr_AnnualReturn2013	32.67%
2014	rr_AnnualReturn2014	12.75%
2015	rr_AnnualReturn2015	0.76%
2016	rr_AnnualReturn2016	11.53%
2017	rr_AnnualReturn2017	21.68%
2018	rr_AnnualReturn2018	(4.91%)
2019	rr_AnnualReturn2019	31.41%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Mar. 31, 2019
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	13.97%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2011
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(14.68%)
Label	rr_AverageAnnualReturnLabel	Before taxes
1 Year	rr_AverageAnnualReturnYear01	31.41%
5 Years	rr_AverageAnnualReturnYear05	11.31%
10 Years	rr_AverageAnnualReturnYear10	13.26%
Schwab 1000 Index Fund | After taxes on distributions | Schwab 1000 Index Fund
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	After taxes on distributions
1 Year	rr_AverageAnnualReturnYear01	30.47%
5 Years	rr_AverageAnnualReturnYear05	10.11%
10 Years	rr_AverageAnnualReturnYear10	12.15%
Schwab 1000 Index Fund | After taxes on distributions and sale of shares | Schwab 1000 Index Fund
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	After taxes on distributions and sale of shares
1 Year	rr_AverageAnnualReturnYear01	19.22%
5 Years	rr_AverageAnnualReturnYear05	8.75%
10 Years	rr_AverageAnnualReturnYear10	10.84%
Schwab 1000 Index Fund | Comparative Indices (reflect no deduction for expenses or taxes) Schwab 1000 Index
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Comparative Indices (reflect no deduction for expenses or taxes) Schwab 1000 Index
1 Year	rr_AverageAnnualReturnYear01	31.45%
5 Years	rr_AverageAnnualReturnYear05	11.45%
10 Years	rr_AverageAnnualReturnYear10	13.50%
Schwab 1000 Index Fund | Comparative Indices (reflect no deduction for expenses or taxes) Russell 1000® Index
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Comparative Indices (reflect no deduction for expenses or taxes) Russell 1000® Index
1 Year	rr_AverageAnnualReturnYear01	31.43%
5 Years	rr_AverageAnnualReturnYear05	11.48%
10 Years	rr_AverageAnnualReturnYear10	13.54%