Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	AIM INVESTMENT SECURITIES FUNDS (INVESCO INVESTMENT SECURITIES FUNDS)
Prospectus Date	rr_ProspectusDate	Jun. 28, 2016
Class AX, BX and CX | Invesco Government Money Market Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Fund Summary
Objective [Heading]	rr_ObjectiveHeading	Investment Objective(s)
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Fund's investment objective is to provide current income consistent with preservation of capital and liquidity.
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)
Expenses Restated to Reflect Current [Text]	rr_ExpensesRestatedToReflectCurrent	"Management Fees" have been restated to reflect current fees. "Other Expenses" have been restated to reflect current fees.
Expense Example [Heading]	rr_ExpenseExampleHeading	Example.
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 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:
Expense Example, No Redemption Narrative [Text Block]	rr_ExpenseExampleNoRedemptionNarrativeTextBlock	You would pay the following expenses if you did not redeem your shares:
Strategy [Heading]	rr_StrategyHeading	Principal Investment Strategies of the Fund
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund invests at least 99.5% of its total assets in cash, Government Securities, and repurchase agreements collateralized by cash or Government Securities. In addition, at least 80% of the Fund's net assets (plus any borrowings for investment purposes) will be invested, under normal circumstances, in Government Securities and/or repurchase agreements that are collateralized by Government Securities. Government Security generally means any security issued or guaranteed as to principal or interest by the U.S. Government or certain of its agencies or instrumentalities; or any certificate of deposit for any of the foregoing. The Fund will limit investments to those securities that are Eligible Securities as defined by applicable regulations at the time of purchase. The Fund is a Government Money Market Fund, as defined by Rule 2a-7 under the Investment Company Act of 1940, as amended (Rule 2a-7), that seeks to maintain a stable price of $1.00 per share by using the amortized cost method to value portfolio securities and rounding the share value to the nearest cent. The Fund invests in conformity with SEC rules and regulation requirements for money market funds for the quality, maturity, diversification and liquidity of investments. The Fund invests only in U.S. dollar-denominated securities maturing within 397 calendar days of the date of purchase, with certain exceptions permitted by applicable regulations. The Fund maintains a dollar-weighted average portfolio maturity of no more than 60 calendar days, and a dollar-weighted average portfolio maturity as determined without exceptions regarding certain interest rate adjustments under Rule 2a-7 of no more than 120 calendar days. Each investment must be determined to present minimal credit risks by Invesco Advisers, Inc. (Invesco or the Adviser) pursuant to guidelines approved by the Fund's Board of Trustees (the Board), and must be an Eligible Security. In selecting securities for the Fund's portfolio, the portfolio managers focus on securities that offer safety, liquidity, and a competitive yield. The Adviser conducts a credit analysis of each potential issuer prior to the purchase of its securities. The portfolio managers normally hold portfolio securities to maturity, but may sell a particular security when they deem it advisable, such as when market or credit factors materially change.
Risk [Heading]	rr_RiskHeading	Principal Risks of Investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	You could lose money by investing in the Fund. Although the Fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. An investment in the Fund is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. The risks associated with an investment in the Fund can increase during times of significant market volatility. The principal risks of investing in the Fund are: Debt Securities Risk. The prices of debt securities held by the Fund will be affected by changes in interest rates, the creditworthiness of the issuer and other factors. An increase in prevailing interest rates typically causes the value of existing debt securities to fall and often has a greater impact on longer-duration debt securities and higher quality debt securities. Falling interest rates will cause the Fund to reinvest the proceeds of debt securities that have been repaid by the issuer at lower interest rates. Falling interest rates may also reduce the Fund's distributable income because interest payments on floating rate debt instruments held by the Fund will decline. The Fund could lose money on investments in debt securities if the issuer or borrower fails to meet its obligations to make interest payments and/or to repay principal in a timely manner. Changes in an issuer's financial strength, the market's perception of such strength or in the credit rating of the issuer or the security may affect the value of debt securities. The Adviser's credit analysis may fail to anticipate such changes, which could result in buying a debt security at an inopportune time or failing to sell a debt security in advance of a price decline or other credit event. Management Risk. The Fund is actively managed and depends heavily on the Adviser's judgment about markets, interest rates or the attractiveness, relative values, liquidity, or potential appreciation of particular investments made for the Fund's portfolio. The Fund could experience losses if these judgments prove to be incorrect. Additionally, legislative, regulatory, or tax developments may adversely affect management of the Fund and, therefore, the ability of the Fund to achieve its investment objective. Market Risk. The market values of the Fund's investments, and therefore the value of the Fund's shares, will go up and down, sometimes rapidly or unpredictably. Market risk may affect a single issuer, industry or section of the economy, or it may affect the market as a whole. Individual stock prices tend to go up and down more dramatically than those of certain other types of investments, such as bonds. During a general downturn in the financial markets, multiple asset classes may decline in value. When markets perform well, there can be no assurance that specific investments held by the Fund will rise in value. Money Market Fund Risk. Although the Fund seeks to preserve the value of your investment at $1.00 per share, you may lose money by investing in the Fund. The share price of money market funds can fall below the $1.00 share price. The Fund's sponsor has no legal obligation to provide financial support to the Fund and you should not rely on or expect that the sponsor will enter into support agreements or take other actions to provide financial support to the Fund or to maintain the Fund's $1.00 share price at any time. The credit quality of the Fund's holdings can change rapidly in certain markets, and the default of a single holding could have an adverse impact on the Fund's share price. The Fund's share price can also be negatively affected during periods of high redemption pressures, illiquid markets and/or significant market volatility. Furthermore, amendments to money market fund regulations could impact a money market fund's operations and possibly negatively impact its return. Repurchase Agreement Risk. If the seller of a repurchase agreement defaults or otherwise does not fulfill its obligations, the Fund may incur delays and losses arising from selling the underlying securities, enforcing its rights, or declining collateral value. U.S. Government Obligations Risk. Obligations of U.S. Government agencies and authorities receive varying levels of support and may not be backed by the full faith and credit of the U.S. Government, which could affect the Fund's ability to recover should they default. No assurance can be given that the U.S. Government will provide financial support to its agencies and authorities if it is not obligated by law to do so. Yield Risk. The Fund's yield will vary as the short-term securities in its portfolio mature or are sold and the proceeds are reinvested in other securities. When interest rates are very low, the Fund's expenses could absorb all or a portion of the Fund's income and yield. Additionally, inflation may outpace and diminish investment returns over time.
Risk Lose Money [Text]	rr_RiskLoseMoney	You could lose money by investing in the Fund.
Risk Money Market Fund [Text]	rr_RiskMoneyMarketFund	Money Market Fund Risk. Although the Fund seeks to preserve the value of your investment at $1.00 per share, you may lose money by investing in the Fund. The share price of money market funds can fall below the $1.00 share price. The Fund's sponsor has no legal obligation to provide financial support to the Fund and you should not rely on or expect that the sponsor will enter into support agreements or take other actions to provide financial support to the Fund or to maintain the Fund's $1.00 share price at any time. The credit quality of the Fund's holdings can change rapidly in certain markets, and the default of a single holding could have an adverse impact on the Fund's share price. The Fund's share price can also be negatively affected during periods of high redemption pressures, illiquid markets and/or significant market volatility. Furthermore, amendments to money market fund regulations could impact a money market fund's operations and possibly negatively impact its return.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance Information
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and performance table provide an indication of the risks of investing in the Fund. The bar chart shows changes in the performance of the Fund from year to year as of December 31. The Fund's past performance is not necessarily an indication of its future performance. Effective June 28, 2016, the Fund changed its investment strategy from a prime money market strategy to a strategy that classified the Fund as a “government money market fund,” as defined by Rule 2a-7 under the Investment Company Act of 1940 (1940 Act), and simultaneously changed its name to Invesco Government Money Market Fund. Performance shown prior to that date reflects the Fund's former prime money market strategy, which permitted investments in certain types of securities that as a government money market fund, the Fund is no longer permitted to hold. Consequently, the performance information below would have been different if the current investment limitations had been in effect during the period prior to the Fund's conversion to a government money market fund. Updated performance information is available on the Fund's website at www.invesco.com/us.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and performance table provide an indication of the risks of investing in the Fund. The bar chart shows changes in the performance of the Fund from year to year as of December 31.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.invesco.com/us
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund's past performance is not necessarily an indication of its future performance.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Class AX shares year-to-date (ended March 31, 2016): 0.00% Best Quarter (ended December 31, 2014 and December 31, 2015): 0.05% Worst Quarter (ended March 31, 2014, June 30, 2014, September 30, 2014, March 31, 2015, June 30, 2015 and September 30, 2015): 0.00%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (for the periods ended December 31, 2015)
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Class AX shares' seven day yield on December 31, 2015, was 0.01%. For the current seven day yield, call (800) 959-4246.
Money Market Seven Day Yield Phone	rr_MoneyMarketSevenDayYieldPhone	(800) 959-4246
Money Market Seven Day Yield	rr_MoneyMarketSevenDayYield	0.01%
Class AX, BX and CX | Invesco Government Money Market Fund | Class AX
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as a percentage of original purchase price or redemption proceeds, whichever is less)	rr_MaximumDeferredSalesChargeOverOther	none	[1]
Management Fees	rr_ManagementFeesOverAssets	0.15%	[2]
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.15%
Other Expenses	rr_OtherExpensesOverAssets	0.34%	[3]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.64%
Expenses Deferred Charges [Text Block]	rr_ExpensesDeferredChargesTextBlock	A contingent deferred sales charge may apply in some cases. See "Shareholder Account Information-Contingent Deferred Sales Charges (CDSCs)."
1 Year	rr_ExpenseExampleYear01	$ 65
3 Years	rr_ExpenseExampleYear03	205
5 Years	rr_ExpenseExampleYear05	357
10 Years	rr_ExpenseExampleYear10	798
1 Year	rr_ExpenseExampleNoRedemptionYear01	65
3 Years	rr_ExpenseExampleNoRedemptionYear03	205
5 Years	rr_ExpenseExampleNoRedemptionYear05	357
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 798
2011	rr_AnnualReturn2011	0.03%
2012	rr_AnnualReturn2012	0.03%
2013	rr_AnnualReturn2013	0.07%
2014	rr_AnnualReturn2014	0.06%
2015	rr_AnnualReturn2015	0.06%
Year to Date Return, Label	rr_YearToDateReturnLabel	Class AX shares year-to-date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	none
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Dec. 31, 2015
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	0.05%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2015
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	none
1 Year	rr_AverageAnnualReturnYear01	0.06%	[4]
5 Years	rr_AverageAnnualReturnYear05	0.05%	[4]
10 Years	rr_AverageAnnualReturnYear10	1.09%	[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 07, 2010	[4]
Class AX, BX and CX | Invesco Government Money Market Fund | Class BX
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as a percentage of original purchase price or redemption proceeds, whichever is less)	rr_MaximumDeferredSalesChargeOverOther	5.00%
Management Fees	rr_ManagementFeesOverAssets	0.15%	[2]
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.90%
Other Expenses	rr_OtherExpensesOverAssets	0.34%	[3]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.39%
1 Year	rr_ExpenseExampleYear01	$ 642
3 Years	rr_ExpenseExampleYear03	740
5 Years	rr_ExpenseExampleYear05	961
10 Years	rr_ExpenseExampleYear10	1,463
1 Year	rr_ExpenseExampleNoRedemptionYear01	142
3 Years	rr_ExpenseExampleNoRedemptionYear03	440
5 Years	rr_ExpenseExampleNoRedemptionYear05	761
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,463
1 Year	rr_AverageAnnualReturnYear01	(4.94%)	[5]
5 Years	rr_AverageAnnualReturnYear05	(0.35%)	[5]
10 Years	rr_AverageAnnualReturnYear10	0.75%	[5]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 07, 2010	[5]
Class AX, BX and CX | Invesco Government Money Market Fund | Class CX
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as a percentage of original purchase price or redemption proceeds, whichever is less)	rr_MaximumDeferredSalesChargeOverOther	1.00%
Management Fees	rr_ManagementFeesOverAssets	0.15%	[2]
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.90%
Other Expenses	rr_OtherExpensesOverAssets	0.34%	[3]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.39%
1 Year	rr_ExpenseExampleYear01	$ 242
3 Years	rr_ExpenseExampleYear03	440
5 Years	rr_ExpenseExampleYear05	761
10 Years	rr_ExpenseExampleYear10	1,669
1 Year	rr_ExpenseExampleNoRedemptionYear01	142
3 Years	rr_ExpenseExampleNoRedemptionYear03	440
5 Years	rr_ExpenseExampleNoRedemptionYear05	761
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,669
1 Year	rr_AverageAnnualReturnYear01	(0.94%)	[5]
5 Years	rr_AverageAnnualReturnYear05	0.05%	[5]
10 Years	rr_AverageAnnualReturnYear10	0.75%	[5]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 07, 2010	[5]

[1] A contingent deferred sales charge may apply in some cases. See "Shareholder Account Information-Contingent Deferred Sales Charges (CDSCs)."

[2] "Management Fees" have been restated to reflect current fees.

[3] "Other Expenses" have been restated to reflect current fees.

[4] Class AX shares' performance shown prior to the inception date is that of the Fund's Invesco Cash Reserve Shares and includes the 12b-1 fees applicable to Invesco Cash Reserve Shares. The inception date of the Fund's Invesco Cash Reserve Shares is October 16, 1993.

[5] Class BX and Class CX shares' performance shown prior to the inception date is that of the Fund's Invesco Cash Reserve Shares restated to reflect the higher the 12b-1 fees applicable to Invesco Cash Reserve Shares. The inception date of the Fund's Invesco Cash Reserve Shares is October 16, 1993.