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 U S GOVERNMENT INCOME TRUST
Central Index Key	dei_EntityCentralIndexKey	0000732337
Amendment Flag	dei_AmendmentFlag	false
Trading Symbol	dei_TradingSymbol	PGSIX
Document Creation Date	dei_DocumentCreationDate	Feb. 01, 2018
Document Effective Date	dei_DocumentEffectiveDate	Jan. 30, 2018
Prospectus Date	rr_ProspectusDate	Jan. 30, 2018
Putnam US Government Income Trust
Risk Return Abstract	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Fund Summary
Objective [Heading]	rr_ObjectiveHeading	Goal
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Putnam U.S. Government Income Trust seeks as high a level of current income as Putnam Investment Management, LLC believes is consistent with preservation of capital.
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 $100,000 in class A shares or $50,000 in class M shares of 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 11 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 1452%.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	1452.00%
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 $100,000 in class A shares or $50,000 in class M shares of 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 11 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 Investments
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	We invest mainly in bonds and securitized debt instruments (such as mortgage-backed investments) that are obligations of the U.S. government, its agencies and instrumentalities, and accordingly are backed by the full faith and credit of the United States (e.g., U.S. Treasury bonds and Ginnie Mae mortgage-backed bonds) or by only the credit of a federal agency or government-sponsored entity (e.g., Fannie Mae and Freddie Mac mortgage-backed bonds) and that have short-to-long term maturities. Under normal circumstances, we invest at least 80% of the fund’s net assets in U.S. government securities. We may invest up to 20% of the fund’s net assets in mortgage-backed and other asset-backed securities of private (non-governmental) issuers and securities issued by money market funds, in each case rated AAA or its equivalent at the time of purchase by a nationally recognized securities rating agency or, if unrated, that we determine to be of comparable quality. This policy may be changed only after 60 days’ notice to shareholders. We may consider, among other factors, credit, interest rate and prepayment risks, as well as general market conditions, when deciding whether to buy or sell investments. We typically use to a significant extent derivatives, such as futures, options 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 bonds 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 (including perceptions about the risk of default and expectations about monetary policy or interest rates), changes in government intervention in the financial markets, and factors related to a specific issuer or industry. These and other factors may lead to increased volatility and reduced liquidity in the fund’s portfolio holdings. The risks associated with bond investments include interest rate risk, which means the value of the fund’s investments is likely to fall if interest rates rise. Bond investments are also subject to credit risk, which is the risk that the issuer of a bond may default on payment of interest or principal. Credit risk is generally greater for debt not backed by the full faith and credit of the U.S. government, and interest rate risk is generally greater for longer-term bonds. 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-backed investments, in other investments with less attractive terms and yields. Our use of derivatives may increase these risks 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	Best calendar quarter Q1 2009   8.00% Worst calendar quarter Q3 2008  −3.50%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best calendar quarter
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Mar. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	8.00%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst calendar quarter
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(3.50%)
Performance Table Heading	rr_PerformanceTableHeading	Average annual total returns after sales charges (for periods ending 12/31/17)
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 US Government Income Trust | Class A
Risk Return Abstract	rr_RiskReturnAbstract
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	4.00%
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	0.40%
Distribution and Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other expenses	rr_OtherExpensesOverAssets	0.24%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.89%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	$ 487
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	672
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	873
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	$ 1,452
Annual Return 2008	rr_AnnualReturn2008	(4.92%)
Annual Return 2009	rr_AnnualReturn2009	28.60%
Annual Return 2010	rr_AnnualReturn2010	5.36%
Annual Return 2011	rr_AnnualReturn2011	4.73%
Annual Return 2012	rr_AnnualReturn2012	3.31%
Annual Return 2013	rr_AnnualReturn2013	(0.48%)
Annual Return 2014	rr_AnnualReturn2014	5.49%
Annual Return 2015	rr_AnnualReturn2015	(0.26%)
Annual Return 2016	rr_AnnualReturn2016	0.63%
Annual Return 2017	rr_AnnualReturn2017	0.82%
1 Year	rr_AverageAnnualReturnYear01	(3.21%)
5 Years	rr_AverageAnnualReturnYear05	0.39%
10 Years	rr_AverageAnnualReturnYear10	3.58%
Putnam US Government Income Trust | 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%	[2]
Management fees	rr_ManagementFeesOverAssets	0.40%
Distribution and Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.98%	[3]
Other expenses	rr_OtherExpensesOverAssets	0.24%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.62%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	$ 665
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	811
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	1,081
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	1,727
Expense Example, No Redemption, 1 Year	rr_ExpenseExampleNoRedemptionYear01	165
Expense Example, No Redemption, 3 Years	rr_ExpenseExampleNoRedemptionYear03	511
Expense Example, No Redemption, 5 Years	rr_ExpenseExampleNoRedemptionYear05	881
Expense Example, No Redemption, 10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,727
1 Year	rr_AverageAnnualReturnYear01	(4.74%)
5 Years	rr_AverageAnnualReturnYear05	0.11%
10 Years	rr_AverageAnnualReturnYear10	3.41%
Putnam US Government Income Trust | 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	0.40%
Distribution and Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other expenses	rr_OtherExpensesOverAssets	0.24%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.64%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	$ 267
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	517
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	892
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	1,944
Expense Example, No Redemption, 1 Year	rr_ExpenseExampleNoRedemptionYear01	167
Expense Example, No Redemption, 3 Years	rr_ExpenseExampleNoRedemptionYear03	517
Expense Example, No Redemption, 5 Years	rr_ExpenseExampleNoRedemptionYear05	892
Expense Example, No Redemption, 10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,944
1 Year	rr_AverageAnnualReturnYear01	(0.84%)
5 Years	rr_AverageAnnualReturnYear05	0.46%
10 Years	rr_AverageAnnualReturnYear10	3.18%
Putnam US Government Income Trust | Class M
Risk Return Abstract	rr_RiskReturnAbstract
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	3.25%
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	0.40%
Distribution and Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.49%	[3]
Other expenses	rr_OtherExpensesOverAssets	0.24%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.13%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	$ 436
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	672
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	927
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	$ 1,655
1 Year	rr_AverageAnnualReturnYear01	(2.72%)
5 Years	rr_AverageAnnualReturnYear05	0.31%
10 Years	rr_AverageAnnualReturnYear10	3.43%
Putnam US Government Income Trust | 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	0.40%
Distribution and Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.50%
Other expenses	rr_OtherExpensesOverAssets	0.24%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.14%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	$ 116
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	362
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	628
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	$ 1,386
1 Year	rr_AverageAnnualReturnYear01	0.63%
5 Years	rr_AverageAnnualReturnYear05	0.97%
10 Years	rr_AverageAnnualReturnYear10	3.67%
Putnam US Government Income Trust | Class T
Risk Return Abstract	rr_RiskReturnAbstract
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	2.50%
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	0.40%
Distribution and Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other expenses	rr_OtherExpensesOverAssets	0.24%	[5]
Total annual fund operating expenses	rr_ExpensesOverAssets	0.89%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	$ 339
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	527
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	731
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	$ 1,319
1 Year	rr_AverageAnnualReturnYear01	(1.70%)	[6]
5 Years	rr_AverageAnnualReturnYear05	0.71%	[6]
10 Years	rr_AverageAnnualReturnYear10	3.74%	[6]
Putnam US Government Income Trust | 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	0.40%
Other expenses	rr_OtherExpensesOverAssets	0.24%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.64%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	$ 65
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	205
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	357
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	$ 798
1 Year	rr_AverageAnnualReturnYear01	1.11%
5 Years	rr_AverageAnnualReturnYear05	1.47%
10 Years	rr_AverageAnnualReturnYear10	4.23%
Putnam US Government Income Trust | after taxes on distributions | Class A
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(4.49%)
5 Years	rr_AverageAnnualReturnYear05	(0.63%)
10 Years	rr_AverageAnnualReturnYear10	1.98%
Putnam US Government Income Trust | after taxes on distributions and sale of fund shares | Class A
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(1.82%)
5 Years	rr_AverageAnnualReturnYear05	(0.16%)
10 Years	rr_AverageAnnualReturnYear10	2.19%
Putnam US Government Income Trust | Bloomberg Barclays GNMA Index (no deduction for fees, expenses or taxes)
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	1.86%
5 Years	rr_AverageAnnualReturnYear05	1.70%
10 Years	rr_AverageAnnualReturnYear10	3.84%

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

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

[3] Represents a blended rate.

[4] This charge is eliminated after one year.

[5] Other expenses are based on expenses of class A shares for the fund's last fiscal year.

[6] Class T shares were not outstanding during the periods shown. Performance shown for class T shares is derived from the historical performance of class A shares, adjusted for the lower initial sales charge currently applicable to class T shares.