| Label | Element | Value | ||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Prospectus [Line Items] | rr_ProspectusLineItems | |||||||||||||||||||
| Document Type | dei_DocumentType | 485BPOS | ||||||||||||||||||
| Document Period End Date | dei_DocumentPeriodEndDate | Dec. 31, 2023 | ||||||||||||||||||
| Entity Registrant Name | dei_EntityRegistrantName | Putnam Asset Allocation Funds | ||||||||||||||||||
| Entity Central Index Key | dei_EntityCentralIndexKey | 0000914209 | ||||||||||||||||||
| Entity Inv Company Type | dei_EntityInvCompanyType | N-1A | ||||||||||||||||||
| Amendment Flag | dei_AmendmentFlag | false | ||||||||||||||||||
| Putnam Multi-Asset Income Fund | ||||||||||||||||||||
| Prospectus [Line Items] | rr_ProspectusLineItems | |||||||||||||||||||
| Risk/Return [Heading] | rr_RiskReturnHeading | Fund summary | ||||||||||||||||||
| Objective [Heading] | rr_ObjectiveHeading | Goal | ||||||||||||||||||
| Objective, Primary [Text Block] | rr_ObjectivePrimaryTextBlock | Putnam Multi-Asset Income Fund seeks total return consistent with conservation of capital. Within the fund’s total return orientation, the fund seeks to provide current income, along with long-term capital appreciation. |
||||||||||||||||||
| Expense [Heading] | rr_ExpenseHeading | Fees and expenses | ||||||||||||||||||
| Expense Narrative [Text Block] | rr_ExpenseNarrativeTextBlock | The following tables describe the fees and expenses you may pay if you buy, hold and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Putnam funds. More information about these and other discounts is available from your financial professional and in How do I buy fund shares? beginning on page 21 of the fund’s prospectus, in the Appendix to the fund’s prospectus, and in How to buy shares beginning on page II-1 of the fund’s statement of additional information (“SAI”). |
||||||||||||||||||
| 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 you pay each year as a percentage of the value of your investment) | ||||||||||||||||||
| Fee Waiver or Reimbursement over Assets, Date of Termination | rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination | December 30, 2025 | ||||||||||||||||||
| Portfolio Turnover [Heading] | rr_PortfolioTurnoverHeading | Portfolio turnover | ||||||||||||||||||
| Portfolio Turnover [Text Block] | rr_PortfolioTurnoverTextBlock | The fund pays transaction-related costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher turnover rate may indicate higher transaction costs and may result in higher taxes when the fund’s shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or the above example, affect fund performance. The fund’s turnover rate in the most recent fiscal year was 143%. |
||||||||||||||||||
| Portfolio Turnover, Rate | rr_PortfolioTurnoverRate | 143.00% | ||||||||||||||||||
| Expense Breakpoint Discounts [Text] | rr_ExpenseBreakpointDiscounts | You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Putnam funds. | ||||||||||||||||||
| Expense Breakpoint, Minimum Investment Required [Amount] | rr_ExpenseBreakpointMinimumInvestmentRequiredAmount | $ 50,000 | ||||||||||||||||||
| Expense Example [Heading] | rr_ExpenseExampleHeading | Example | ||||||||||||||||||
| Expense Example Narrative [Text Block] | rr_ExpenseExampleNarrativeTextBlock | The following hypothetical example is intended to help you compare the cost of investing in the fund with the cost of investing in other funds. It assumes that you invest $10,000 in the fund for the time periods indicated and then, except as indicated, redeem all your shares at the end of those periods. It assumes a 5% return on your investment each year and that the fund’s operating expenses remain the same. Only the first year of each period in the example takes into account the expense reimbursement described above. Your actual costs may be higher or lower. |
||||||||||||||||||
| Strategy [Heading] | rr_StrategyHeading | Investments, risks, and performance | ||||||||||||||||||
| Strategy Narrative [Text Block] | rr_StrategyNarrativeTextBlock | Investments We invest mainly in fixed-income investments, including U.S. and foreign (including emerging market) government obligations, corporate obligations and securitized debt instruments (such as mortgage-backed investments) of any credit quality. We
also invest, to a lesser extent, in equity securities (growth or value stocks or both) of U.S. and foreign (including emerging market) companies of any size. The fund has a strategic, or typical, allocation between equity and fixed income investments. Using qualitative analysis and quantitative models and techniques, we adjust portfolio allocations from time to time within a certain range to try to optimize the fund’s performance consistent with its goal. The strategic allocation and the range of allowable allocation for the fund is shown below:
We may consider, among other factors, a company’s valuation, financial strength, growth potential, competitive position in its industry, projected future earnings, cash flows and dividends when deciding whether to buy or sell equity investments. We may also consider, among other factors, credit, interest rate and prepayment risks, as well as general market conditions, when deciding whether to buy or sell fixed-income investments. We typically use derivatives to a significant extent, such as futures, options, certain foreign currency transactions, warrants and interest rate and total return swap contracts, for both hedging and non-hedging purposes. We may also use derivatives and debt instruments with terms determined by reference to a particular commodity or to all or portions of a commodities index. |
||||||||||||||||||
| Risk [Heading] | rr_RiskHeading | Risks | ||||||||||||||||||
| Risk [Text Block] | rr_RiskTextBlock | It is important to understand that you can lose money by investing in the fund. Our allocation of assets among asset classes may hurt performance, and our efforts to diversify risk through the use of leverage and allocation decisions may not be successful. If the quantitative models or data that are used in managing the fund prove to be incorrect or incomplete, investment decisions made in reliance on the models or data may not produce the desired results and the fund may realize losses. The value of investments in the fund’s portfolio may fall or fail to rise over extended periods of time for a variety of reasons, including general economic, political or financial market conditions, investor sentiment and market perceptions, government actions, geopolitical events or changes, and factors related to a specific issuer, asset class, geography, industry or sector. These and other factors may lead to increased volatility and reduced liquidity in the fund’s portfolio holdings, may negatively impact the fund’s performance, and may exacerbate other risks to which the fund is subject. Growth stocks may be more susceptible to earnings disappointments, and value stocks may fail to rebound. These risks are generally greater for small and midsize companies. In addition, small and midsize companies, at times, may not perform as well as stocks of larger companies or the stock market in general, and may be out of favor with investors for varying periods of time.
Bond investments are subject to interest rate risk, which is the risk that the value of the fund’s bond investments is likely to fall if interest rates rise. Bond investments also are subject to credit risk, which is the risk that the issuers of the bond may default on payment of interest or principal. Interest rate risk is generally greater for longer-term bonds, and credit risk is generally greater for below-investment grade bonds (sometimes referred to as “junk bonds”), which can be more sensitive to changes in markets, credit conditions, and interest rates and may be considered speculative. Bond investments may be more susceptible to downgrades or defaults during economic downturns or other periods of economic stress. Mortgage-backed investments, unlike traditional debt investments, are also subject to prepayment risk, which means that they may increase in value less than other bonds when interest rates decline and decline in value more than other bonds when interest rates rise. We may have to invest the proceeds from prepaid investments, including mortgage- and asset-backed investments, in other investments with less attractive terms and yields. The value of international investments traded in foreign currencies may be adversely impacted by fluctuations in exchange rates. International investments, particularly investments in emerging markets, may carry risks associated with potentially less stable economies or governments (such as the risk of seizure by a foreign government, the imposition of currency or other restrictions, or high levels of inflation), and may be or become illiquid. Our use of derivatives may increase the risk of investing in the fund by increasing investment exposure (which may be considered leverage and magnify or otherwise increase investment losses to the fund) or, in the case of many over-the-counter instruments, because of the potential inability to terminate or sell derivatives positions and the potential failure of the other party to the instrument to meet its obligations. The risk of a party failing to meet its obligations may increase if the fund has significant exposure to that counterparty. The value of derivatives may move in unexpected ways due to unanticipated market movements, the use of leverage, imperfect correlation between the derivative instrument and the reference asset, or other factors, especially in unusual market conditions, and volatility in the value of derivatives could adversely impact the fund’s returns, obligations and exposures. Derivatives are also subject to other risks, including liquidity risk (e.g., liquidity demands arising from the requirement to make payments to a derivative counterparty), operational risk (e.g., settlement issues or system failures) and legal risk (e.g., insufficient legal documentation or contract enforceability issues). The fund expects to engage in frequent trading. Funds with high turnover may be more likely to realize capital gains that must be distributed to shareholders as taxable income and may incur higher transaction costs than funds with relatively lower turnover, which may detract from performance. Certain accounts or affiliates of the Investment Manager, including other funds advised by the Investment Manager or third parties, may from time to time own (beneficially or of record) or control a substantial amount of the fund’s shares, including through seed capital arrangements. Such shareholders may at times
be considered to control the fund. Dispositions of a large number of shares by these shareholders may adversely affect the fund’s liquidity and net assets. These redemptions may also force the fund to sell securities, which may increase the fund’s brokerage costs. The fund may be an investment option for mutual funds that are managed by Franklin Resources, Inc. (“Franklin Templeton”) and its affiliates as “funds of funds.” Additionally, other investors from time to time may make substantial investments in the fund. Such shareholders may at times be considered to control the fund. Dispositions of a large number of shares by these shareholders may adversely affect the fund’s liquidity and net assets. These redemptions may also force the fund to sell securities, which may increase the fund’s brokerage costs. There is no guarantee that the investment techniques, analyses, or judgments that we apply in making investment decisions for the fund will produce the intended outcome or that the investments we select for the fund will perform as well as other securities that were not selected for the fund. We, or the fund’s other service providers, may experience disruptions or operating errors that could negatively impact the fund. The fund may not achieve its goal, and it is not intended to be a complete investment program. 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 | ||||||||||||||||||
| Performance Narrative [Text Block] | rr_PerformanceNarrativeTextBlock | The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time. The bar chart does not reflect the impact of sales charges. If it did, performance would be lower. Please remember that past performance is not necessarily an indication of future results. Monthly performance figures for the fund are available at www.franklintempleton.com. |
||||||||||||||||||
| Performance Information Illustrates Variability of Returns [Text] | rr_PerformanceInformationIllustratesVariabilityOfReturns | The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time. | ||||||||||||||||||
| Performance Availability Website Address [Text] | rr_PerformanceAvailabilityWebSiteAddress | www.franklintempleton.com | ||||||||||||||||||
| Performance Past Does Not Indicate Future [Text] | rr_PerformancePastDoesNotIndicateFuture | Please remember that past performance is not necessarily an indication of future results. | ||||||||||||||||||
| Bar Chart [Heading] | rr_BarChartHeading | Annual total returns for class P shares before sales charges | ||||||||||||||||||
| Bar Chart Does Not Reflect Sales Loads [Text] | rr_BarChartDoesNotReflectSalesLoads | The bar chart does not reflect the impact of sales charges. | ||||||||||||||||||
| Year to Date Return, Label | rr_YearToDateReturnLabel | Year-to-date performance through | ||||||||||||||||||
| Bar Chart, Year to Date Return, Date | rr_BarChartYearToDateReturnDate | Sep. 30, 2024 | ||||||||||||||||||
| Bar Chart, Year to Date Return | rr_BarChartYearToDateReturn | 10.95% | ||||||||||||||||||
| Highest Quarterly Return, Label | rr_HighestQuarterlyReturnLabel | Best calendar quarter | ||||||||||||||||||
| Highest Quarterly Return, Date | rr_BarChartHighestQuarterlyReturnDate | Dec. 31, 2023 | ||||||||||||||||||
| Highest Quarterly Return | rr_BarChartHighestQuarterlyReturn | 8.37% | ||||||||||||||||||
| Lowest Quarterly Return, Label | rr_LowestQuarterlyReturnLabel | Worst calendar quarter | ||||||||||||||||||
| Lowest Quarterly Return, Date | rr_BarChartLowestQuarterlyReturnDate | Jun. 30, 2022 | ||||||||||||||||||
| Lowest Quarterly Return | rr_BarChartLowestQuarterlyReturn | (8.14%) | ||||||||||||||||||
| Performance Table Heading | rr_PerformanceTableHeading | Average annual total returns after sales charges (for periods ended 12/31/23) | ||||||||||||||||||
| Performance Table Uses Highest Federal Rate | rr_PerformanceTableUsesHighestFederalRate | After-tax returns reflect the historical highest individual federal marginal income tax rates and do not reflect state and local taxes | ||||||||||||||||||
| Performance Table Not Relevant to Tax Deferred | rr_PerformanceTableNotRelevantToTaxDeferred | Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. | ||||||||||||||||||
| Performance Table One Class of after Tax Shown [Text] | rr_PerformanceTableOneClassOfAfterTaxShown | After-tax returns are shown for class A shares only and will vary for other classes. | ||||||||||||||||||
| Performance Table Closing [Text Block] | rr_PerformanceTableClosingTextBlock |
|
||||||||||||||||||
| Putnam Multi-Asset Income Fund | Bloomberg U.S. Aggregate Index (no deduction for fees, expenses or taxes) | ||||||||||||||||||||
| Prospectus [Line Items] | rr_ProspectusLineItems | |||||||||||||||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 5.53% | [1] | |||||||||||||||||
| Since Inception | rr_AverageAnnualReturnSinceInception | (0.72%) | [1] | |||||||||||||||||
| Inception Date | rr_AverageAnnualReturnInceptionDate | Dec. 31, 2019 | ||||||||||||||||||
| Putnam Multi-Asset Income Fund | Putnam Multi-Asset Income Blended Benchmark (no deduction for fees, expenses or taxes) | ||||||||||||||||||||
| Prospectus [Line Items] | rr_ProspectusLineItems | |||||||||||||||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 12.01% | [1],[2] | |||||||||||||||||
| Since Inception | rr_AverageAnnualReturnSinceInception | 3.17% | [1],[2] | |||||||||||||||||
| Inception Date | rr_AverageAnnualReturnInceptionDate | Dec. 31, 2019 | ||||||||||||||||||
| Putnam Multi-Asset Income Fund | Class A Shares | ||||||||||||||||||||
| Prospectus [Line Items] | rr_ProspectusLineItems | |||||||||||||||||||
| Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) | rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice | 4.00% | ||||||||||||||||||
| Maximum Deferred Sales Charge (as a percentage) | rr_MaximumDeferredSalesChargeOverOther | 1.00% | [3] | |||||||||||||||||
| Management Fees (as a percentage of Assets) | rr_ManagementFeesOverAssets | 0.46% | ||||||||||||||||||
| Distribution and Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | 0.25% | ||||||||||||||||||
| Other Expenses (as a percentage of Assets): | rr_OtherExpensesOverAssets | 0.38% | [4] | |||||||||||||||||
| Expenses (as a percentage of Assets) | rr_ExpensesOverAssets | 1.09% | ||||||||||||||||||
| Fee Waiver or Reimbursement | rr_FeeWaiverOrReimbursementOverAssets | (0.26%) | [4],[5] | |||||||||||||||||
| Net Expenses (as a percentage of Assets) | rr_NetExpensesOverAssets | 0.83% | ||||||||||||||||||
| Expense Example, with Redemption, 1 Year | rr_ExpenseExampleYear01 | $ 481 | ||||||||||||||||||
| Expense Example, with Redemption, 3 Years | rr_ExpenseExampleYear03 | 708 | ||||||||||||||||||
| Expense Example, with Redemption, 5 Years | rr_ExpenseExampleYear05 | 953 | ||||||||||||||||||
| Expense Example, with Redemption, 10 Years | rr_ExpenseExampleYear10 | $ 1,653 | ||||||||||||||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 6.33% | [6] | |||||||||||||||||
| Since Inception | rr_AverageAnnualReturnSinceInception | 0.68% | [6] | |||||||||||||||||
| Inception Date | rr_AverageAnnualReturnInceptionDate | Dec. 31, 2019 | ||||||||||||||||||
| Putnam Multi-Asset Income Fund | Class C Shares | ||||||||||||||||||||
| Prospectus [Line Items] | rr_ProspectusLineItems | |||||||||||||||||||
| Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) | rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice | none | ||||||||||||||||||
| Maximum Deferred Sales Charge (as a percentage) | rr_MaximumDeferredSalesChargeOverOther | 1.00% | [7] | |||||||||||||||||
| Management Fees (as a percentage of Assets) | rr_ManagementFeesOverAssets | 0.46% | ||||||||||||||||||
| Distribution and Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | 1.00% | ||||||||||||||||||
| Other Expenses (as a percentage of Assets): | rr_OtherExpensesOverAssets | 0.38% | [4] | |||||||||||||||||
| Expenses (as a percentage of Assets) | rr_ExpensesOverAssets | 1.84% | ||||||||||||||||||
| Fee Waiver or Reimbursement | rr_FeeWaiverOrReimbursementOverAssets | (0.26%) | [4],[5] | |||||||||||||||||
| Net Expenses (as a percentage of Assets) | rr_NetExpensesOverAssets | 1.58% | ||||||||||||||||||
| Expense Example, with Redemption, 1 Year | rr_ExpenseExampleYear01 | $ 261 | ||||||||||||||||||
| Expense Example, with Redemption, 3 Years | rr_ExpenseExampleYear03 | 553 | ||||||||||||||||||
| Expense Example, with Redemption, 5 Years | rr_ExpenseExampleYear05 | 971 | ||||||||||||||||||
| Expense Example, with Redemption, 10 Years | rr_ExpenseExampleYear10 | 1,940 | ||||||||||||||||||
| Expense Example, No Redemption, 1 Year | rr_ExpenseExampleNoRedemptionYear01 | 161 | ||||||||||||||||||
| Expense Example, No Redemption, 3 Years | rr_ExpenseExampleNoRedemptionYear03 | 553 | ||||||||||||||||||
| Expense Example, No Redemption, 5 Years | rr_ExpenseExampleNoRedemptionYear05 | 971 | ||||||||||||||||||
| Expense Example, No Redemption, 10 Years | rr_ExpenseExampleNoRedemptionYear10 | $ 1,940 | ||||||||||||||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 8.91% | [8] | |||||||||||||||||
| Since Inception | rr_AverageAnnualReturnSinceInception | 0.93% | [8] | |||||||||||||||||
| Inception Date | rr_AverageAnnualReturnInceptionDate | Dec. 31, 2019 | ||||||||||||||||||
| Putnam Multi-Asset Income Fund | Class P Shares | ||||||||||||||||||||
| Prospectus [Line Items] | rr_ProspectusLineItems | |||||||||||||||||||
| Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) | rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice | none | ||||||||||||||||||
| Maximum Deferred Sales Charge (as a percentage) | rr_MaximumDeferredSalesChargeOverOther | none | ||||||||||||||||||
| Management Fees (as a percentage of Assets) | rr_ManagementFeesOverAssets | 0.46% | ||||||||||||||||||
| Distribution and Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | none | ||||||||||||||||||
| Other Expenses (as a percentage of Assets): | rr_OtherExpensesOverAssets | 0.21% | [4] | |||||||||||||||||
| Expenses (as a percentage of Assets) | rr_ExpensesOverAssets | 0.67% | ||||||||||||||||||
| Fee Waiver or Reimbursement | rr_FeeWaiverOrReimbursementOverAssets | (0.26%) | [4],[5] | |||||||||||||||||
| Net Expenses (as a percentage of Assets) | rr_NetExpensesOverAssets | 0.41% | ||||||||||||||||||
| Expense Example, with Redemption, 1 Year | rr_ExpenseExampleYear01 | $ 42 | ||||||||||||||||||
| Expense Example, with Redemption, 3 Years | rr_ExpenseExampleYear03 | 188 | ||||||||||||||||||
| Expense Example, with Redemption, 5 Years | rr_ExpenseExampleYear05 | 347 | ||||||||||||||||||
| Expense Example, with Redemption, 10 Years | rr_ExpenseExampleYear10 | $ 810 | ||||||||||||||||||
| Annual Return 2020 | rr_AnnualReturn2020 | 8.46% | ||||||||||||||||||
| Annual Return 2021 | rr_AnnualReturn2021 | 6.25% | ||||||||||||||||||
| Annual Return 2022 | rr_AnnualReturn2022 | (12.36%) | ||||||||||||||||||
| Annual Return 2023 | rr_AnnualReturn2023 | 11.40% | ||||||||||||||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 11.40% | ||||||||||||||||||
| Since Inception | rr_AverageAnnualReturnSinceInception | 2.99% | ||||||||||||||||||
| Inception Date | rr_AverageAnnualReturnInceptionDate | Dec. 31, 2019 | ||||||||||||||||||
| Putnam Multi-Asset Income Fund | Class P Shares | After Taxes on Distributions | ||||||||||||||||||||
| Prospectus [Line Items] | rr_ProspectusLineItems | |||||||||||||||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 10.14% | ||||||||||||||||||
| Since Inception | rr_AverageAnnualReturnSinceInception | 2.01% | ||||||||||||||||||
| Inception Date | rr_AverageAnnualReturnInceptionDate | Dec. 31, 2019 | ||||||||||||||||||
| Putnam Multi-Asset Income Fund | Class P Shares | After Taxes on Distributions and Sales | ||||||||||||||||||||
| Prospectus [Line Items] | rr_ProspectusLineItems | |||||||||||||||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 6.70% | ||||||||||||||||||
| Since Inception | rr_AverageAnnualReturnSinceInception | 1.93% | ||||||||||||||||||
| Inception Date | rr_AverageAnnualReturnInceptionDate | Dec. 31, 2019 | ||||||||||||||||||
| Putnam Multi-Asset Income Fund | Class R Shares | ||||||||||||||||||||
| Prospectus [Line Items] | rr_ProspectusLineItems | |||||||||||||||||||
| Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) | rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice | none | ||||||||||||||||||
| Maximum Deferred Sales Charge (as a percentage) | rr_MaximumDeferredSalesChargeOverOther | none | ||||||||||||||||||
| Management Fees (as a percentage of Assets) | rr_ManagementFeesOverAssets | 0.46% | ||||||||||||||||||
| Distribution and Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | 0.50% | ||||||||||||||||||
| Other Expenses (as a percentage of Assets): | rr_OtherExpensesOverAssets | 0.38% | [4] | |||||||||||||||||
| Expenses (as a percentage of Assets) | rr_ExpensesOverAssets | 1.34% | ||||||||||||||||||
| Fee Waiver or Reimbursement | rr_FeeWaiverOrReimbursementOverAssets | (0.26%) | [4],[5] | |||||||||||||||||
| Net Expenses (as a percentage of Assets) | rr_NetExpensesOverAssets | 1.08% | ||||||||||||||||||
| Expense Example, with Redemption, 1 Year | rr_ExpenseExampleYear01 | $ 110 | ||||||||||||||||||
| Expense Example, with Redemption, 3 Years | rr_ExpenseExampleYear03 | 399 | ||||||||||||||||||
| Expense Example, with Redemption, 5 Years | rr_ExpenseExampleYear05 | 709 | ||||||||||||||||||
| Expense Example, with Redemption, 10 Years | rr_ExpenseExampleYear10 | $ 1,590 | ||||||||||||||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 10.39% | [8] | |||||||||||||||||
| Since Inception | rr_AverageAnnualReturnSinceInception | 1.45% | [8] | |||||||||||||||||
| Inception Date | rr_AverageAnnualReturnInceptionDate | Dec. 31, 2019 | ||||||||||||||||||
| Putnam Multi-Asset Income Fund | Class R5 Shares | ||||||||||||||||||||
| Prospectus [Line Items] | rr_ProspectusLineItems | |||||||||||||||||||
| Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) | rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice | none | ||||||||||||||||||
| Maximum Deferred Sales Charge (as a percentage) | rr_MaximumDeferredSalesChargeOverOther | none | ||||||||||||||||||
| Management Fees (as a percentage of Assets) | rr_ManagementFeesOverAssets | 0.46% | ||||||||||||||||||
| Distribution and Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | none | ||||||||||||||||||
| Other Expenses (as a percentage of Assets): | rr_OtherExpensesOverAssets | 0.35% | [4] | |||||||||||||||||
| Expenses (as a percentage of Assets) | rr_ExpensesOverAssets | 0.81% | ||||||||||||||||||
| Fee Waiver or Reimbursement | rr_FeeWaiverOrReimbursementOverAssets | (0.26%) | [4],[5] | |||||||||||||||||
| Net Expenses (as a percentage of Assets) | rr_NetExpensesOverAssets | 0.55% | ||||||||||||||||||
| Expense Example, with Redemption, 1 Year | rr_ExpenseExampleYear01 | $ 56 | ||||||||||||||||||
| Expense Example, with Redemption, 3 Years | rr_ExpenseExampleYear03 | 233 | ||||||||||||||||||
| Expense Example, with Redemption, 5 Years | rr_ExpenseExampleYear05 | 424 | ||||||||||||||||||
| Expense Example, with Redemption, 10 Years | rr_ExpenseExampleYear10 | $ 977 | ||||||||||||||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 11.01% | [9] | |||||||||||||||||
| Since Inception | rr_AverageAnnualReturnSinceInception | 1.94% | [9] | |||||||||||||||||
| Inception Date | rr_AverageAnnualReturnInceptionDate | Dec. 31, 2019 | ||||||||||||||||||
| Putnam Multi-Asset Income Fund | Class R6 Shares | ||||||||||||||||||||
| Prospectus [Line Items] | rr_ProspectusLineItems | |||||||||||||||||||
| Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) | rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice | none | ||||||||||||||||||
| Maximum Deferred Sales Charge (as a percentage) | rr_MaximumDeferredSalesChargeOverOther | none | ||||||||||||||||||
| Management Fees (as a percentage of Assets) | rr_ManagementFeesOverAssets | 0.46% | ||||||||||||||||||
| Distribution and Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | none | ||||||||||||||||||
| Other Expenses (as a percentage of Assets): | rr_OtherExpensesOverAssets | 0.25% | [4] | |||||||||||||||||
| Expenses (as a percentage of Assets) | rr_ExpensesOverAssets | 0.71% | ||||||||||||||||||
| Fee Waiver or Reimbursement | rr_FeeWaiverOrReimbursementOverAssets | (0.26%) | [4],[5] | |||||||||||||||||
| Net Expenses (as a percentage of Assets) | rr_NetExpensesOverAssets | 0.45% | ||||||||||||||||||
| Expense Example, with Redemption, 1 Year | rr_ExpenseExampleYear01 | $ 46 | ||||||||||||||||||
| Expense Example, with Redemption, 3 Years | rr_ExpenseExampleYear03 | 201 | ||||||||||||||||||
| Expense Example, with Redemption, 5 Years | rr_ExpenseExampleYear05 | 369 | ||||||||||||||||||
| Expense Example, with Redemption, 10 Years | rr_ExpenseExampleYear10 | $ 858 | ||||||||||||||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 11.12% | [9] | |||||||||||||||||
| Since Inception | rr_AverageAnnualReturnSinceInception | 2.05% | [9] | |||||||||||||||||
| Inception Date | rr_AverageAnnualReturnInceptionDate | Dec. 31, 2019 | ||||||||||||||||||
| Putnam Multi-Asset Income Fund | Class Y Shares | ||||||||||||||||||||
| Prospectus [Line Items] | rr_ProspectusLineItems | |||||||||||||||||||
| Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) | rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice | none | ||||||||||||||||||
| Maximum Deferred Sales Charge (as a percentage) | rr_MaximumDeferredSalesChargeOverOther | none | ||||||||||||||||||
| Management Fees (as a percentage of Assets) | rr_ManagementFeesOverAssets | 0.46% | ||||||||||||||||||
| Distribution and Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | none | ||||||||||||||||||
| Other Expenses (as a percentage of Assets): | rr_OtherExpensesOverAssets | 0.38% | [4] | |||||||||||||||||
| Expenses (as a percentage of Assets) | rr_ExpensesOverAssets | 0.84% | ||||||||||||||||||
| Fee Waiver or Reimbursement | rr_FeeWaiverOrReimbursementOverAssets | (0.26%) | [4],[5] | |||||||||||||||||
| Net Expenses (as a percentage of Assets) | rr_NetExpensesOverAssets | 0.58% | ||||||||||||||||||
| Expense Example, with Redemption, 1 Year | rr_ExpenseExampleYear01 | $ 59 | ||||||||||||||||||
| Expense Example, with Redemption, 3 Years | rr_ExpenseExampleYear03 | 242 | ||||||||||||||||||
| Expense Example, with Redemption, 5 Years | rr_ExpenseExampleYear05 | 440 | ||||||||||||||||||
| Expense Example, with Redemption, 10 Years | rr_ExpenseExampleYear10 | $ 1,013 | ||||||||||||||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 11.00% | [9] | |||||||||||||||||
| Since Inception | rr_AverageAnnualReturnSinceInception | 1.97% | [9] | |||||||||||||||||
| Inception Date | rr_AverageAnnualReturnInceptionDate | Dec. 31, 2019 | ||||||||||||||||||
| Putnam Multi-Asset Income Fund | Risk Lose Money [Member] | ||||||||||||||||||||
| Prospectus [Line Items] | rr_ProspectusLineItems | |||||||||||||||||||
| Risk [Text Block] | rr_RiskTextBlock | It is important to understand that you can lose money by investing in the fund. | ||||||||||||||||||
| Putnam Multi-Asset Income Fund | Risk Not Insured Depository Institution [Member] | ||||||||||||||||||||
| Prospectus [Line Items] | rr_ProspectusLineItems | |||||||||||||||||||
| Risk [Text Block] | rr_RiskTextBlock | An investment in the fund is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. | ||||||||||||||||||
| ||||||||||||||||||||