Label	Element	Value
Prospectus [Line Items]	rr_ProspectusLineItems
Document Type	dei_DocumentType	485BPOS
Document Period End Date	dei_DocumentPeriodEndDate	Dec. 31, 2018
Entity Registrant Name	dei_EntityRegistrantName	PUTNAM FUNDS TRUST
Entity Central Index Key	dei_EntityCentralIndexKey	0001005942
Amendment Flag	dei_AmendmentFlag	false
Entity Inv Company Type	dei_EntityInvCompanyType	N-1A
Trading Symbol	dei_TradingSymbol	PFT
Document Creation Date	dei_DocumentCreationDate	Oct. 25, 2019
Document Effective Date	dei_DocumentEffectiveDate	Oct. 30, 2019
Prospectus Date	rr_ProspectusDate	Oct. 30, 2019
Putnam International Value 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 International Value Fund seeks capital growth.
Objective, Secondary [Text Block]	rr_ObjectiveSecondaryTextBlock	Current income is a secondary objective.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
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	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)
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 10%.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	10.00%
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 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).
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. 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 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	Risks
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	It is important to understand that you can lose money by investing in the fund. 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, geography, 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), 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 invests, and may in the future invest, significantly in European companies, the fund is particularly susceptible to economic, political, regulatory and 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	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 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	Annual total returns for class A 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. If it did, performance would be lower.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Year-to-date performance through 9/30/19  10.22% Best calendar quarter Q2 2009   24.11% Worst calendar quarter Q3 2011 −22.13%
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-date performance
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2019
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	10.22%
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	Sep. 30, 2011
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(22.13%)
Performance Table Heading	rr_PerformanceTableHeading	Average annual total returns after sales charges (for periods ended 12/31/18)
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 | MSCI EAFE Value Index (ND) (no deduction for fees, expenses or taxes other than withholding taxes on reinvested dividends)
Prospectus [Line Items]	rr_ProspectusLineItems
1 Year	rr_AverageAnnualReturnYear01	(14.78%)
5 Years	rr_AverageAnnualReturnYear05	(0.61%)
10 Years	rr_AverageAnnualReturnYear10	5.50%
Putnam International Value Fund | Class A
Prospectus [Line Items]	rr_ProspectusLineItems
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	0.63%	[2]
Distribution and service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other expenses	rr_OtherExpensesOverAssets	0.45%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.33%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	$ 703
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	972
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	1,262
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	$ 2,084
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%
Annual Return 2018	rr_AnnualReturn2018	(17.96%)
Label	rr_AverageAnnualReturnLabel	before taxes
1 Year	rr_AverageAnnualReturnYear01	(22.68%)
5 Years	rr_AverageAnnualReturnYear05	(3.04%)
10 Years	rr_AverageAnnualReturnYear10	4.03%
Putnam International Value Fund | Class A | after taxes on distributions
Prospectus [Line Items]	rr_ProspectusLineItems
1 Year	rr_AverageAnnualReturnYear01	(23.17%)
5 Years	rr_AverageAnnualReturnYear05	(3.29%)
10 Years	rr_AverageAnnualReturnYear10	3.81%
Putnam International Value Fund | Class A | after taxes on distributions and sale of fund shares
Prospectus [Line Items]	rr_ProspectusLineItems
1 Year	rr_AverageAnnualReturnYear01	(12.60%)
5 Years	rr_AverageAnnualReturnYear05	(2.05%)
10 Years	rr_AverageAnnualReturnYear10	3.45%
Putnam International Value Fund | Class B
Prospectus [Line Items]	rr_ProspectusLineItems
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	0.63%	[2]
Distribution and service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other expenses	rr_OtherExpensesOverAssets	0.45%
Total annual fund operating expenses	rr_ExpensesOverAssets	2.08%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	$ 711
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	952
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	1,319
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	2,219
Expense Example, No Redemption, 1 Year	rr_ExpenseExampleNoRedemptionYear01	211
Expense Example, No Redemption, 3 Years	rr_ExpenseExampleNoRedemptionYear03	652
Expense Example, No Redemption, 5 Years	rr_ExpenseExampleNoRedemptionYear05	1,119
Expense Example, No Redemption, 10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 2,219
Label	rr_AverageAnnualReturnLabel	before taxes
1 Year	rr_AverageAnnualReturnYear01	(22.53%)
5 Years	rr_AverageAnnualReturnYear05	(2.99%)
10 Years	rr_AverageAnnualReturnYear10	4.01%
Putnam International Value Fund | Class C
Prospectus [Line Items]	rr_ProspectusLineItems
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	0.63%	[2]
Distribution and service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other expenses	rr_OtherExpensesOverAssets	0.45%
Total annual fund operating expenses	rr_ExpensesOverAssets	2.08%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	$ 311
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	652
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	1,119
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	2,410
Expense Example, No Redemption, 1 Year	rr_ExpenseExampleNoRedemptionYear01	211
Expense Example, No Redemption, 3 Years	rr_ExpenseExampleNoRedemptionYear03	652
Expense Example, No Redemption, 5 Years	rr_ExpenseExampleNoRedemptionYear05	1,119
Expense Example, No Redemption, 10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 2,410
Label	rr_AverageAnnualReturnLabel	before taxes
1 Year	rr_AverageAnnualReturnYear01	(19.28%)
5 Years	rr_AverageAnnualReturnYear05	(2.61%)
10 Years	rr_AverageAnnualReturnYear10	3.86%
Putnam International Value Fund | Class M
Prospectus [Line Items]	rr_ProspectusLineItems
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	0.63%	[2]
Distribution and service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.75%
Other expenses	rr_OtherExpensesOverAssets	0.45%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.83%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	$ 529
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	905
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	1,306
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	$ 2,423
Label	rr_AverageAnnualReturnLabel	before taxes
1 Year	rr_AverageAnnualReturnYear01	(21.17%)
5 Years	rr_AverageAnnualReturnYear05	(3.08%)
10 Years	rr_AverageAnnualReturnYear10	3.75%
Putnam International Value Fund | Class R
Prospectus [Line Items]	rr_ProspectusLineItems
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	0.63%	[2]
Distribution and service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.50%
Other expenses	rr_OtherExpensesOverAssets	0.45%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.58%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	$ 161
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	499
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	860
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	$ 1,878
Label	rr_AverageAnnualReturnLabel	before taxes
1 Year	rr_AverageAnnualReturnYear01	(18.17%)
5 Years	rr_AverageAnnualReturnYear05	(2.14%)
10 Years	rr_AverageAnnualReturnYear10	4.38%
Putnam International Value Fund | Class R6
Prospectus [Line Items]	rr_ProspectusLineItems
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	0.63%	[2]
Other expenses	rr_OtherExpensesOverAssets	0.25%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.88%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	$ 90
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	280
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	487
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	$ 1,084
Label	rr_AverageAnnualReturnLabel	before taxes
1 Year	rr_AverageAnnualReturnYear01	(17.61%)	[5]
5 Years	rr_AverageAnnualReturnYear05	(1.48%)	[5]
10 Years	rr_AverageAnnualReturnYear10	5.00%	[5]
Putnam International Value Fund | Class Y
Prospectus [Line Items]	rr_ProspectusLineItems
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	0.63%	[2]
Other expenses	rr_OtherExpensesOverAssets	0.45%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.08%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	$ 110
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	343
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	595
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	$ 1,317
Label	rr_AverageAnnualReturnLabel	before taxes
1 Year	rr_AverageAnnualReturnYear01	(17.70%)
5 Years	rr_AverageAnnualReturnYear05	(1.63%)
10 Years	rr_AverageAnnualReturnYear10	4.92%
Putnam Small Cap Growth 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 Small Cap Growth Fund seeks capital appreciation.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
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 13 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)
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 37%.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	37.00%
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 How do I buy fund shares? beginning on page 13 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).
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. 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 common stocks of small U.S. companies, with a focus on growth stocks. Growth stocks are stocks of 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, 2019, the index was composed of companies having market capitalizations of between approximately $27.3 million and $8.9 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	Risks
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	It is important to understand that you can lose money by investing in the fund. 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, geography, 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	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 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	Annual total returns for class A 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. If it did, performance would be lower.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Year-to-date performance through 9/30/19  27.34% Best calendar quarter Q3 2009   18.09% Worst calendar quarter Q3 2011 −24.96%
Year to Date Return, Label	rr_YearToDateReturnLabel	Year-to-date performance
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2019
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	27.34%
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	Sep. 30, 2011
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(24.96%)
Performance Table Heading	rr_PerformanceTableHeading	Average annual total returns after sales charges (for periods ended 12/31/18)
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. Class C share performance reflects conversion to class A shares after 10 years.
Putnam Small Cap Growth Fund | Russell 2000 Growth Index (no deduction for fees, expenses or taxes)
Prospectus [Line Items]	rr_ProspectusLineItems
1 Year	rr_AverageAnnualReturnYear01	(9.31%)	[6]
5 Years	rr_AverageAnnualReturnYear05	5.13%	[6]
10 Years	rr_AverageAnnualReturnYear10	13.52%	[6]
Putnam Small Cap Growth Fund | Class A
Prospectus [Line Items]	rr_ProspectusLineItems
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	0.65%	[7]
Distribution and service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other expenses	rr_OtherExpensesOverAssets	0.30%	[8]
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 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%
Annual Return 2018	rr_AnnualReturn2018	(2.49%)
Label	rr_AverageAnnualReturnLabel	before taxes
1 Year	rr_AverageAnnualReturnYear01	(8.10%)
5 Years	rr_AverageAnnualReturnYear05	3.50%
10 Years	rr_AverageAnnualReturnYear10	12.04%
Putnam Small Cap Growth Fund | Class A | after taxes on distributions
Prospectus [Line Items]	rr_ProspectusLineItems
1 Year	rr_AverageAnnualReturnYear01	(8.43%)
5 Years	rr_AverageAnnualReturnYear05	3.43%
10 Years	rr_AverageAnnualReturnYear10	11.99%
Putnam Small Cap Growth Fund | Class A | after taxes on distributions and sale of fund shares
Prospectus [Line Items]	rr_ProspectusLineItems
1 Year	rr_AverageAnnualReturnYear01	(4.46%)
5 Years	rr_AverageAnnualReturnYear05	2.72%
10 Years	rr_AverageAnnualReturnYear10	10.09%
Putnam Small Cap Growth Fund | Class B
Prospectus [Line Items]	rr_ProspectusLineItems
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	0.65%	[7]
Distribution and service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other expenses	rr_OtherExpensesOverAssets	0.30%	[8]
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
Label	rr_AverageAnnualReturnLabel	before taxes
1 Year	rr_AverageAnnualReturnYear01	(7.97%)
5 Years	rr_AverageAnnualReturnYear05	3.61%
10 Years	rr_AverageAnnualReturnYear10	12.07%
Putnam Small Cap Growth Fund | Class C
Prospectus [Line Items]	rr_ProspectusLineItems
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	0.65%	[7]
Distribution and service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other expenses	rr_OtherExpensesOverAssets	0.30%	[8]
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
Label	rr_AverageAnnualReturnLabel	before taxes
1 Year	rr_AverageAnnualReturnYear01	(4.18%)
5 Years	rr_AverageAnnualReturnYear05	3.95%
10 Years	rr_AverageAnnualReturnYear10	11.86%
Putnam Small Cap Growth Fund | Class M
Prospectus [Line Items]	rr_ProspectusLineItems
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	0.65%	[7]
Distribution and service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.75%
Other expenses	rr_OtherExpensesOverAssets	0.30%	[8]
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
Label	rr_AverageAnnualReturnLabel	before taxes
1 Year	rr_AverageAnnualReturnYear01	(6.36%)
5 Years	rr_AverageAnnualReturnYear05	3.47%
10 Years	rr_AverageAnnualReturnYear10	11.75%
Putnam Small Cap Growth Fund | Class R
Prospectus [Line Items]	rr_ProspectusLineItems
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	0.65%	[7]
Distribution and service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.50%
Other expenses	rr_OtherExpensesOverAssets	0.30%	[8]
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
Label	rr_AverageAnnualReturnLabel	before taxes
1 Year	rr_AverageAnnualReturnYear01	(2.72%)
5 Years	rr_AverageAnnualReturnYear05	4.48%
10 Years	rr_AverageAnnualReturnYear10	12.43%
Putnam Small Cap Growth Fund | Class R6
Prospectus [Line Items]	rr_ProspectusLineItems
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	0.65%	[7]
Other expenses	rr_OtherExpensesOverAssets	0.14%	[8]
Total annual fund operating expenses	rr_ExpensesOverAssets	0.79%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	$ 81
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	252
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	439
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	$ 978
Label	rr_AverageAnnualReturnLabel	before taxes	[9]
1 Year	rr_AverageAnnualReturnYear01	(2.07%)	[9]
5 Years	rr_AverageAnnualReturnYear05	5.12%	[9]
10 Years	rr_AverageAnnualReturnYear10	13.05%	[9]
Putnam Small Cap Growth Fund | Class Y
Prospectus [Line Items]	rr_ProspectusLineItems
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	0.65%	[7]
Other expenses	rr_OtherExpensesOverAssets	0.30%	[8]
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
Label	rr_AverageAnnualReturnLabel	before taxes
1 Year	rr_AverageAnnualReturnYear01	(2.26%)
5 Years	rr_AverageAnnualReturnYear05	5.00%
10 Years	rr_AverageAnnualReturnYear10	12.99%

[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 0.690%.

[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 their 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] 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.

[7] Management fees are subject to 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%.

[8] Restated to reflect current fees.

[9] Performance for class R6 shares prior to their 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.