Label	Element	Value
Risk Return Abstract	rr_RiskReturnAbstract
Document Type	dei_DocumentType	485BPOS
Document Period End Date	dei_DocumentPeriodEndDate	Dec. 31, 2017
Registrant Name	dei_EntityRegistrantName	PUTNAM FUNDS TRUST
Central Index Key	dei_EntityCentralIndexKey	0001005942
Amendment Flag	dei_AmendmentFlag	false
Trading Symbol	dei_TradingSymbol	PFT
Document Creation Date	dei_DocumentCreationDate	Oct. 26, 2018
Document Effective Date	dei_DocumentEffectiveDate	Oct. 30, 2018
Prospectus Date	rr_ProspectusDate	Oct. 30, 2018
Putnam International Value Fund
Risk Return Abstract	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	<b>Fund Summary</b>
Objective [Heading]	rr_ObjectiveHeading	<b>Goal</b>
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Putnam International Value Fund seeks capital growth.
Objective, Secondary [Text Block]	rr_ObjectiveSecondaryTextBlock	Current income is a secondary objective.
Expense [Heading]	rr_ExpenseHeading	<b>Fees and expenses</b>
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The following table describes the fees and expenses you may pay if you buy and hold shares of the fund. 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 advisor and in How do I buy fund shares? beginning on page 14 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	<b>Shareholder fees </b><i>(fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	<b>Annual fund operating expenses </b><i><br />(expenses you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	<b>Portfolio turnover</b>
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 15%.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	15.00%
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. More information about these and other discounts is available from your financial advisor and in <i>How do I buy fund shares?</i> beginning on page 14 of the fund’s prospectus, in the Appendix to the fund’s prospectus, and in <i>How to buy shares</i> beginning on page II-1 of the fund’s statement of additional information (SAI).
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	$ 50,000
Expenses Restated to Reflect Current [Text]	rr_ExpensesRestatedToReflectCurrent	Restated to reflect current fees.
Expense Example [Heading]	rr_ExpenseExampleHeading	<b>Example</b>
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. Your actual costs may be higher or lower.
Strategy [Heading]	rr_StrategyHeading	<b>Investments, risks, and performance</b><br /> <br /> <b>Investments</b>
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	We invest mainly in common stocks of large and midsize companies outside the United States, with a focus on value stocks. Value stocks are those that we believe are currently undervalued by the market. If we are correct and other investors ultimately recognize the value of the company, the price of its stock may rise. We invest mainly in developed countries, but may invest in emerging markets. 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 investments. We may also use derivatives, such as futures, options, certain foreign currency transactions, warrants and swap contracts, for both hedging and non-hedging purposes.
Risk [Heading]	rr_RiskHeading	<b>Risks</b>
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	It is important to understand that you can lose money by investing in the fund. The value of stocks in the fund’s portfolio may fall or fail to rise over extended periods of time for a variety of reasons, including general financial market conditions, changing market perceptions, changes in government intervention in the financial markets, and factors related to a specific issuer, industry or sector. These and other factors may lead to increased volatility and reduced liquidity in the fund’s portfolio holdings. Value stocks may fail to rebound, and the market may not favor value-style investing. These risks are generally greater for small and midsize companies. From time to time, the fund may invest a significant portion of its assets in companies in one or more related industries or sectors, which would make the fund more vulnerable to adverse developments affecting those industries or sectors. 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 or deflation), and may be or become illiquid. Investments focused in a single region may be affected by common economic forces and other factors. In addition, events in any one country within the region may impact the other countries or the region as a whole. Because the fund currently, and may in the future, invests significantly in European companies, the fund is particularly susceptible to economic, political, regulatory or other events or conditions affecting issuers in Europe. European financial markets have in recent years experienced increased volatility due to concerns with some countries’ high levels of sovereign debt, budget deficits, and unemployment. Our use of derivatives may increase the risks of investing in the fund by increasing investment exposure (which may be considered leverage) 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 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.
Risk Lose Money [Text]	rr_RiskLoseMoney	It is important to understand that you can lose money by investing in the fund.
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	<b>Performance</b>
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 putnam.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	putnam.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	<b>Annual total returns for class A shares before sales charges</b>
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The bar chart does not reflect the impact of sales charges. If it did, performance would be lower.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Year-to-date performance through 9/30/18    −4.83% Best calendar quarter Q2 2009   24.11% Worst calendar quarter Q4 2008     –23.19%
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-date performance through
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2018
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	(4.83%)
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best calendar quarter
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	24.11%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst calendar quarter
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(23.19%)
Performance Table Heading	rr_PerformanceTableHeading	<b>Average annual total returns after sales charges </b><i>(for periods ended 12/31/17)</i>
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	After-tax returns reflect the historical highest individual federal marginal income tax rates and do not reflect state and local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns are shown for class A shares only and will vary for other classes. These after-tax returns do not apply if you hold your fund shares through a 401(k) plan, an IRA, or another tax-advantaged arrangement. Class B share performance reflects conversion to class A shares after eight years.
Putnam International Value Fund | Class A
Risk Return Abstract	rr_RiskReturnAbstract
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	5.75%
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOther	1.00%	[1]
Management fees	rr_ManagementFeesOverAssets	0.71%	[2]
Distribution and service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other expenses	rr_OtherExpensesOverAssets	0.42%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.38%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	$ 707
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	987
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	1,287
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	$ 2,137
Annual Return 2008	rr_AnnualReturn2008	(46.05%)
Annual Return 2009	rr_AnnualReturn2009	25.96%
Annual Return 2010	rr_AnnualReturn2010	7.29%
Annual Return 2011	rr_AnnualReturn2011	(13.53%)
Annual Return 2012	rr_AnnualReturn2012	21.49%
Annual Return 2013	rr_AnnualReturn2013	22.04%
Annual Return 2014	rr_AnnualReturn2014	(9.83%)
Annual Return 2015	rr_AnnualReturn2015	(1.84%)
Annual Return 2016	rr_AnnualReturn2016	0.92%
Annual Return 2017	rr_AnnualReturn2017	24.08%
1 Year	rr_AverageAnnualReturnYear01	16.95%
5 Years	rr_AverageAnnualReturnYear05	4.97%
10 Years	rr_AverageAnnualReturnYear10	(0.24%)
Putnam International Value Fund | Class B
Risk Return Abstract	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 lower)	rr_MaximumDeferredSalesChargeOverOther	5.00%	[3]
Management fees	rr_ManagementFeesOverAssets	0.71%	[2]
Distribution and service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other expenses	rr_OtherExpensesOverAssets	0.42%
Total annual fund operating expenses	rr_ExpensesOverAssets	2.13%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	$ 716
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	967
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	1,344
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	2,271
Expense Example, No Redemption, 1 Year	rr_ExpenseExampleNoRedemptionYear01	216
Expense Example, No Redemption, 3 Years	rr_ExpenseExampleNoRedemptionYear03	667
Expense Example, No Redemption, 5 Years	rr_ExpenseExampleNoRedemptionYear05	1,144
Expense Example, No Redemption, 10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 2,271
1 Year	rr_AverageAnnualReturnYear01	18.16%
5 Years	rr_AverageAnnualReturnYear05	5.12%
10 Years	rr_AverageAnnualReturnYear10	(0.24%)
Putnam International Value Fund | Class C
Risk Return Abstract	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 lower)	rr_MaximumDeferredSalesChargeOverOther	1.00%	[4]
Management fees	rr_ManagementFeesOverAssets	0.71%	[2]
Distribution and service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other expenses	rr_OtherExpensesOverAssets	0.42%
Total annual fund operating expenses	rr_ExpensesOverAssets	2.13%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	$ 316
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	667
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	1,144
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	2,462
Expense Example, No Redemption, 1 Year	rr_ExpenseExampleNoRedemptionYear01	216
Expense Example, No Redemption, 3 Years	rr_ExpenseExampleNoRedemptionYear03	667
Expense Example, No Redemption, 5 Years	rr_ExpenseExampleNoRedemptionYear05	1,144
Expense Example, No Redemption, 10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 2,462
1 Year	rr_AverageAnnualReturnYear01	22.05%
5 Years	rr_AverageAnnualReturnYear05	5.43%
10 Years	rr_AverageAnnualReturnYear10	(0.40%)
Putnam International Value Fund | Class M
Risk Return Abstract	rr_RiskReturnAbstract
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	3.50%
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOther	none
Management fees	rr_ManagementFeesOverAssets	0.71%	[2]
Distribution and service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.75%
Other expenses	rr_OtherExpensesOverAssets	0.42%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.88%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	$ 534
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	920
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	1,331
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	$ 2,474
1 Year	rr_AverageAnnualReturnYear01	19.13%
5 Years	rr_AverageAnnualReturnYear05	4.93%
10 Years	rr_AverageAnnualReturnYear10	(0.51%)
Putnam International Value Fund | Class R
Risk Return Abstract	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 lower)	rr_MaximumDeferredSalesChargeOverOther	none
Management fees	rr_ManagementFeesOverAssets	0.71%	[2]
Distribution and service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.50%
Other expenses	rr_OtherExpensesOverAssets	0.42%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.63%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	$ 166
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	514
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	887
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	$ 1,933
1 Year	rr_AverageAnnualReturnYear01	23.79%
5 Years	rr_AverageAnnualReturnYear05	5.97%
10 Years	rr_AverageAnnualReturnYear10	0.11%
Putnam International Value Fund | Class R6
Risk Return Abstract	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 lower)	rr_MaximumDeferredSalesChargeOverOther	none
Management fees	rr_ManagementFeesOverAssets	0.71%	[2]
Other expenses	rr_OtherExpensesOverAssets	0.22%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.93%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	$ 95
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	296
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	515
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	$ 1,143
1 Year	rr_AverageAnnualReturnYear01	24.67%	[5]
5 Years	rr_AverageAnnualReturnYear05	6.65%	[5]
10 Years	rr_AverageAnnualReturnYear10	0.67%	[5]
Putnam International Value Fund | Class Y
Risk Return Abstract	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 lower)	rr_MaximumDeferredSalesChargeOverOther	none
Management fees	rr_ManagementFeesOverAssets	0.71%	[2]
Other expenses	rr_OtherExpensesOverAssets	0.42%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.13%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	$ 115
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	359
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	622
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	$ 1,375
1 Year	rr_AverageAnnualReturnYear01	24.43%
5 Years	rr_AverageAnnualReturnYear05	6.50%
10 Years	rr_AverageAnnualReturnYear10	0.60%
Putnam International Value Fund | after taxes on distributions | Class A
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	16.93%
5 Years	rr_AverageAnnualReturnYear05	4.82%
10 Years	rr_AverageAnnualReturnYear10	(0.33%)
Putnam International Value Fund | after taxes on distributions and sale of fund shares | Class A
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	10.13%
5 Years	rr_AverageAnnualReturnYear05	4.05%
10 Years	rr_AverageAnnualReturnYear10	0.03%
Putnam International Value Fund | MSCI EAFE Value Index (ND) (no deduction for fees, expenses or taxes, other than withholding taxes on reinvested dividends)
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	21.44%
5 Years	rr_AverageAnnualReturnYear05	6.95%
10 Years	rr_AverageAnnualReturnYear10	1.15%
Putnam Small Cap Growth Fund
Risk Return Abstract	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	<b>Fund Summary</b>
Objective [Heading]	rr_ObjectiveHeading	<b>Goal</b>
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Putnam Small Cap Growth Fund seeks capital appreciation.
Expense [Heading]	rr_ExpenseHeading	<b>Fees and expenses</b>
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The following table describes the fees and expenses you may pay if you buy and hold shares of the fund. 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 advisor and in How do I buy fund shares? beginning on page 12 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	<b>Shareholder fees </b><i>(fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	<b>Annual fund operating expenses </b><i><br />(expenses you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	<b>Portfolio turnover</b>
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 68%.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	68.00%
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. More information about these and other discounts is available from your financial advisor and in <i>How do I buy fund shares?</i> beginning on page 12 of the fund’s prospectus, in the Appendix to the fund’s prospectus, and in <i>How to buy shares</i> beginning on page II-1 of the fund’s statement of additional information (SAI).
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	$ 50,000
Expense Example [Heading]	rr_ExpenseExampleHeading	<b>Example</b>
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. Your actual costs may be higher or lower.
Strategy [Heading]	rr_StrategyHeading	<b>Investments, risks, and performance</b><br /> <br /> <b>Investments</b>
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	We invest mainly in common stocks of small U.S. companies, with a focus on growth stocks. Growth stocks are issued by companies whose earnings are expected to grow faster than those of similar firms, and whose business growth and other characteristics may lead to an increase in stock price. Under normal circumstances, we invest at least 80% of the fund’s net assets in companies of a size similar to those in the Russell 2000 Growth Index. This policy may be changed only after 60 days’ notice to shareholders. As of August 31, 2018, the index was composed of companies having market capitalizations of between approximately $32.78 million and $8.31 billion. 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 investments.
Risk [Heading]	rr_RiskHeading	<b>Risks</b>
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	It is important to understand that you can lose money by investing in the fund. The value of stocks in the fund’s portfolio may fall or fail to rise over extended periods of time for a variety of reasons, including general financial market conditions, changing market perceptions, changes in government intervention in the financial markets, and factors related to a specific issuer, industry or sector. These and other factors may lead to increased volatility and reduced liquidity in the fund’s portfolio holdings. Growth stocks may be more susceptible to earnings disappointments, and the market may not favor growth-style investing. These risks are generally greater for small and midsize companies. From time to time, the fund may invest a significant portion of its assets in companies in one or more related industries or sectors, which would make the fund more vulnerable to adverse developments affecting those industries or sectors. 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
Risk Lose Money [Text]	rr_RiskLoseMoney	It is important to understand that you can lose money by investing in the fund.
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	<b>Performance</b>
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 putnam.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	putnam.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	<b>Annual total returns for class A shares before sales charges</b>
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The bar chart does not reflect the impact of sales charges. If it did, performance would be lower.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Year-to-date performance through 9/30/18    22.92% Best calendar quarter Q3 2009   18.09% Worst calendar quarter Q4 2008     –27.21%
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-date performance through
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2018
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	22.92%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best calendar quarter
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	18.09%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst calendar quarter
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(27.21%)
Performance Table Heading	rr_PerformanceTableHeading	<b>Average annual total returns after sales charges </b><i>(for periods ended 12/31/17)</i>
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	After-tax returns reflect the historical highest individual federal marginal income tax rates and do not reflect state and local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns are shown for class A shares only and will vary for other classes. These after-tax returns do not apply if you hold your fund shares through a 401(k) plan, an IRA, or another tax-advantaged arrangement. Class B share performance reflects conversion to class A shares after eight years.
Putnam Small Cap Growth Fund | Class A
Risk Return Abstract	rr_RiskReturnAbstract
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	5.75%
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOther	1.00%	[1]
Management fees	rr_ManagementFeesOverAssets	0.57%	[6]
Distribution and service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other expenses	rr_OtherExpensesOverAssets	0.38%	[7]
Total annual fund operating expenses	rr_ExpensesOverAssets	1.20%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	$ 690
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	934
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	1,197
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	$ 1,946
Annual Return 2008	rr_AnnualReturn2008	(43.16%)
Annual Return 2009	rr_AnnualReturn2009	26.30%
Annual Return 2010	rr_AnnualReturn2010	28.12%
Annual Return 2011	rr_AnnualReturn2011	(3.87%)
Annual Return 2012	rr_AnnualReturn2012	14.29%
Annual Return 2013	rr_AnnualReturn2013	47.55%
Annual Return 2014	rr_AnnualReturn2014	1.99%
Annual Return 2015	rr_AnnualReturn2015	(2.82%)
Annual Return 2016	rr_AnnualReturn2016	8.50%
Annual Return 2017	rr_AnnualReturn2017	20.19%
1 Year	rr_AverageAnnualReturnYear01	13.28%
5 Years	rr_AverageAnnualReturnYear05	12.44%
10 Years	rr_AverageAnnualReturnYear10	6.15%
Putnam Small Cap Growth Fund | Class B
Risk Return Abstract	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 lower)	rr_MaximumDeferredSalesChargeOverOther	5.00%	[3]
Management fees	rr_ManagementFeesOverAssets	0.57%	[6]
Distribution and service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other expenses	rr_OtherExpensesOverAssets	0.38%	[7]
Total annual fund operating expenses	rr_ExpensesOverAssets	1.95%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	$ 698
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	912
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	1,252
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	2,080
Expense Example, No Redemption, 1 Year	rr_ExpenseExampleNoRedemptionYear01	198
Expense Example, No Redemption, 3 Years	rr_ExpenseExampleNoRedemptionYear03	612
Expense Example, No Redemption, 5 Years	rr_ExpenseExampleNoRedemptionYear05	1,052
Expense Example, No Redemption, 10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 2,080
1 Year	rr_AverageAnnualReturnYear01	14.29%
5 Years	rr_AverageAnnualReturnYear05	12.69%
10 Years	rr_AverageAnnualReturnYear10	6.17%
Putnam Small Cap Growth Fund | Class C
Risk Return Abstract	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 lower)	rr_MaximumDeferredSalesChargeOverOther	1.00%	[4]
Management fees	rr_ManagementFeesOverAssets	0.57%	[6]
Distribution and service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other expenses	rr_OtherExpensesOverAssets	0.38%	[7]
Total annual fund operating expenses	rr_ExpensesOverAssets	1.95%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	$ 298
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	612
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	1,052
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	2,275
Expense Example, No Redemption, 1 Year	rr_ExpenseExampleNoRedemptionYear01	198
Expense Example, No Redemption, 3 Years	rr_ExpenseExampleNoRedemptionYear03	612
Expense Example, No Redemption, 5 Years	rr_ExpenseExampleNoRedemptionYear05	1,052
Expense Example, No Redemption, 10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 2,275
1 Year	rr_AverageAnnualReturnYear01	18.29%
5 Years	rr_AverageAnnualReturnYear05	12.93%
10 Years	rr_AverageAnnualReturnYear10	5.98%
Putnam Small Cap Growth Fund | Class M
Risk Return Abstract	rr_RiskReturnAbstract
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	3.50%
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOther	none
Management fees	rr_ManagementFeesOverAssets	0.57%	[6]
Distribution and service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.75%
Other expenses	rr_OtherExpensesOverAssets	0.38%	[7]
Total annual fund operating expenses	rr_ExpensesOverAssets	1.70%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	$ 517
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	867
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	1,241
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	$ 2,288
1 Year	rr_AverageAnnualReturnYear01	15.40%
5 Years	rr_AverageAnnualReturnYear05	12.41%
10 Years	rr_AverageAnnualReturnYear10	5.87%
Putnam Small Cap Growth Fund | Class R
Risk Return Abstract	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 lower)	rr_MaximumDeferredSalesChargeOverOther	none
Management fees	rr_ManagementFeesOverAssets	0.57%	[6]
Distribution and service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.50%
Other expenses	rr_OtherExpensesOverAssets	0.38%	[7]
Total annual fund operating expenses	rr_ExpensesOverAssets	1.45%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	$ 148
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	459
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	792
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	$ 1,735
1 Year	rr_AverageAnnualReturnYear01	19.89%
5 Years	rr_AverageAnnualReturnYear05	13.50%
10 Years	rr_AverageAnnualReturnYear10	6.52%
Putnam Small Cap Growth Fund | Class R6
Risk Return Abstract	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 lower)	rr_MaximumDeferredSalesChargeOverOther	none
Management fees	rr_ManagementFeesOverAssets	0.57%	[6]
Other expenses	rr_OtherExpensesOverAssets	0.20%	[7]
Total annual fund operating expenses	rr_ExpensesOverAssets	0.77%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	$ 79
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	246
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	428
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	$ 954
1 Year	rr_AverageAnnualReturnYear01	20.72%	[8]
5 Years	rr_AverageAnnualReturnYear05	14.17%	[8]
10 Years	rr_AverageAnnualReturnYear10	7.09%	[8]
Putnam Small Cap Growth Fund | Class Y
Risk Return Abstract	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 lower)	rr_MaximumDeferredSalesChargeOverOther	none
Management fees	rr_ManagementFeesOverAssets	0.57%	[6]
Other expenses	rr_OtherExpensesOverAssets	0.38%	[7]
Total annual fund operating expenses	rr_ExpensesOverAssets	0.95%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	$ 97
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	303
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	525
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	$ 1,166
1 Year	rr_AverageAnnualReturnYear01	20.51%
5 Years	rr_AverageAnnualReturnYear05	14.08%
10 Years	rr_AverageAnnualReturnYear10	7.05%
Putnam Small Cap Growth Fund | after taxes on distributions | Class A
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	13.28%
5 Years	rr_AverageAnnualReturnYear05	12.44%
10 Years	rr_AverageAnnualReturnYear10	6.14%
Putnam Small Cap Growth Fund | after taxes on distributions and sale of fund shares | Class A
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	7.52%
5 Years	rr_AverageAnnualReturnYear05	9.96%
10 Years	rr_AverageAnnualReturnYear10	4.95%
Putnam Small Cap Growth Fund | Russell 2000 Growth Index (no deduction for fees, expenses or taxes)
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	22.17%	[9]
5 Years	rr_AverageAnnualReturnYear05	15.21%	[9]
10 Years	rr_AverageAnnualReturnYear10	9.19%	[9]

[1] Applies only to certain redemptions of shares bought with no initial sales charge.

[2] Management fees reflect a performance adjustment. The fund's base management fee is subject to adjustment, up or down, based on the fund's performance relative to the performance of the MSCI EAFE Value Index (ND). For the most recent fiscal year, the fund's base management fee prior to any performance adjustment was 0.693%.

[3] This charge is phased out over six years.

[4] This charge is eliminated after one year.

[5] Performance for class R6 shares prior to its inception (12/2/13) is derived from the historical performance of class Y shares and has not been adjusted for the lower investor servicing fees applicable to class R6 shares; had it, returns would have been higher.

[6] Management fees reflect a performance adjustment. The fund's base management fee is subject to adjustment, up or down, based on the fund's performance relative to the performance of the Russell 2000 Growth Index. For the most recent fiscal year, the fund's base management fee prior to any performance adjustment was 0.623%.

[7] Restated to reflect current fees.

[8] Performance for class R6 shares prior to its inception (6/29/15) is derived from the historical performance of class Y shares and has not been adjusted for the lower investor servicing fees applicable to class R6 shares; had it, returns would have been higher.

[9] Frank Russell Company is the source and owner of the trademarks, service marks and copyrights related to the Russell Indexes. Russell(R) is a trademark of Frank Russell Company.