485BPOS

1933 Act File No.	33-54445
1940 Act File No.	811-7193

Form N-1A

SECURITIES AND EXCHANGE COMMISSION

Washington, DC 20549

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933
	Pre-Effective Amendment No.
	Post-Effective Amendment No.	93
and/or
REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT OF 1940
	Amendment No.	94

FEDERATED INSTITUTIONAL TRUST

(Exact Name of Registrant as Specified in Charter)

Federated Investors Funds

4000 Ericsson Drive

Warrendale, PA 15086-7561

(Address of Principal Executive Offices)

(412) 288-1900

(Registrant’s Telephone Number, including Area Code)

Peter J. Germain, Esquire

Federated Investors Tower

Pittsburgh, Pennsylvania 15222-3779

(Name and Address of Agent for Service)

It is proposed that this filing will become effective (check appropriate box):
X	immediately upon filing pursuant to paragraph (b)
	on                                    pursuant to paragraph (b)
	60 days after filing pursuant to paragraph (a)(1)
	on	pursuant to paragraph (a)(1)
	75 days after filing pursuant to paragraph (a)(2)
	on	pursuant to paragraph (a)(2) of Rule 485
If appropriate, check the following box:
	This post-effective amendment designates a new effective date for a previously filed post-effective amendment.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933 and the Investment Company Act of 1940, the Registrant, FEDERATED INSTITUTIONAL TRUST, certifies that it meets all of the requirements for effectiveness of this Amendment to its Registration Statement pursuant to Rule 485(b) under the Securities Act of 1933 and has duly caused this Amendment to its Registration Statement to be signed on its behalf by the undersigned, duly authorized, in the City of Pittsburgh and Commonwealth of Pennsylvania, on the 11th day of October, 2018.

FEDERATED INSTITUTIONAL TRUST

BY: /s/ George F. Magera

George F. Magera, Assistant Secretary

Pursuant to the requirements of the Securities Act of 1933, this Amendment to its Registration Statement has been signed below by the following person in the capacity and on the date indicated:

NAME	TITLE	DATE
BY: /s/ George F. Magera George F. Magera, Assistant Secretary	Attorney In Fact For the Persons Listed Below	October 11, 2018
J. Christopher Donahue*	President and Trustee (Principal Executive Officer)
John B. Fisher*	Trustee
Lori A. Hensler*	Treasurer (Principal Financial Officer/Principal Accounting Officer)
John T. Collins*	Trustee
G. Thomas Hough*	Trustee
Maureen E. Lally-Green*	Trustee
Charles F. Mansfield, Jr.*	Trustee
Thomas O’Neill*	Trustee
P. Jerome Richey*	Trustee
John S. Walsh*	Trustee
*By Power of Attorney

Federated Government Ultra Short Fund (the “Fund”)

Class A Shares, Institutional Shares, Services Shares, Class R6 Shares

Portfolio of Federated Institutional Trust

Post-Effective Amendment No. 93

This Post-Effective Amendment is filed for the sole purpose of submitting the XBRL Interactive Data File exhibits for the Risk/Return Summary of the above-named Fund filed as part of Post-Effective Amendment No. 92 on September 25, 2018.  The exhibits filed herewith do not constitute the complete publicly filed disclosure for the Fund, and should be used in conjunction with the complete prospectus for the Fund.

Exhibit List for Interactive Data File Submissions.

EX-101.INS	INSTANCE
EX-101.SCH	SCHEMA
EX-101.CAL	CALCULATION LINKBASE
EX-101.DEF	DEFINITION LINKBASE
EX-101.LAB	LABEL LINKBASE
EX-101.PRE	PRESENTATION LINKBASE

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Document Type	dei_DocumentType	485BPOS
Document Period End Date	dei_DocumentPeriodEndDate	Jul. 31, 2018
Registrant Name	dei_EntityRegistrantName	FEDERATED INSTITUTIONAL TRUST
Central Index Key	dei_EntityCentralIndexKey	0000925723
Amendment Flag	dei_AmendmentFlag	false
Document Creation Date	dei_DocumentCreationDate	Sep. 25, 2018
Document Effective Date	dei_DocumentEffectiveDate	Sep. 27, 2018
Prospectus Date	rr_ProspectusDate	Sep. 30, 2018

XML

Federated Government Ultrashort Duration Fund

<b>Federated Government Ultrashort Duration Fund (the "Fund")</b>

<b>RISK/RETURN SUMMARY: INVESTMENT OBJECTIVE </b>

The Fund's investment objective is current income.

<b>RISK/RETURN SUMMARY: FEES AND EXPENSES </b>

This table describes the fees and expenses that you may pay if you buy and hold Class A Shares (A), Institutional Shares (IS), Service Shares (SS) or Class R6 Shares (R6) of the Fund. You may qualify for certain sales charge discounts, if you and your family invest, or agree to invest in the future, at least $50,000 in certain classes of Federated funds. More information about these and other discounts is available from your financial professional, in the “What Do Shares Cost?” section of the Prospectus on page 10 and in “Appendix B” to this Prospectus. If you purchase the Fund's IS, SS or R6 Shares through a broker acting as an agent on behalf of its customers, you may be required to pay a commission to such broker; such commissions, if any are not reflected in the Example below.

<b>Shareholder Fees (fees paid directly from your investment) </b>

Shareholder Fees - Federated Government Ultrashort Duration Fund	A	IS	SS	R6
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	2.00%	none	none	none
Maximum Deferred Sales Charge (Load) (as a percentage of original purchase price or redemption proceeds, as applicable)	none	none	none	none
Maximum Sales Charge (Load) Imposed on Reinvested Dividends (and other Distributions) (as a percentage of offering price)	none	none	none	none
Redemption Fee (as a percentage of amount redeemed, if applicable)	none	none	none	none
Exchange Fee	none	none	none	none

<b>Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment) </b>

Annual Fund Operating Expenses - Federated Government Ultrashort Duration Fund		A	IS	SS		R6
Management Fee		0.30%	0.30%	0.30%		0.30%
Distribution (12b-1) Fee		0.25%	none	none	[1]	none
Other Expenses		0.44%	0.18%	0.44%		0.13%
Total Annual Fund Operating Expenses		0.99%	0.48%	0.74%		0.43%
Fee Waivers and/or Expense Reimbursements	[2]	(0.28%)	(0.22%)	(0.38%)		(0.19%)
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements		0.71%	0.26%	0.36%		0.24%

<b>Example </b>

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 for the time periods indicated and then redeem all of your Shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that operating expenses are as shown in the table above and remain the same. Although your actual costs and returns may be higher or lower, based on these assumptions your costs would be:

Expense Example - Federated Government Ultrashort Duration Fund - USD ($)	1 Year	3 Years	5 Years	10 Years
A	299	509	736	1,389
IS	49	154	269	604
SS	76	237	411	918
R6	44	138	241	542

<b>Portfolio Turnover </b>

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund Shares are held in a taxable account. These costs, which are not reflected in Annual Fund Operating Expenses or in the Example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 18% of the average value of its portfolio.

<b>RISK/RETURN SUMMARY: INVESTMENTS, RISKS AND PERFORMANCE <br/><br/>What are the Fund's Main Investment Strategies? </b>

The Fund's overall strategy is to invest in a portfolio of U.S. government securities and U.S. government agency securities (including mortgage-backed securities issued or guaranteed by U.S. government-sponsored enterprises (GSEs)) with an overall dollar-weighted average duration of one year or less. Duration measures the price sensitivity of a fixed-income security to changes in interest rates. Within the one-year duration constraint, the Adviser will seek to increase the Fund's current income by lengthening or shortening portfolio duration based on its interest rate outlook.

The Fund implements this strategy by dividing its portfolio into two major components. Although the Fund is not a money market fund and its share price will fluctuate, the Fund invests one component in U.S. government securities (including repurchase agreements collateralized by U.S. government securities and U.S. government agency securities) that are eligible for purchase by money market funds. The Fund invests the other component in mortgage-backed securities issued or guaranteed by GSEs. The Fund uses mortgage-backed securities to increase the income provided by the portfolio and to extend the portfolio to the targeted duration. Within each component of the portfolio, the Adviser makes decisions of which securities to buy and sell based on the relative yield and risks of available securities with comparable durations. The Fund evaluates its investment strategy by comparing the performance and composition of the Fund's portfolio against the performance and composition of an index composed of U.S. Treasury bills with maturities of six months.

The Fund intends to qualify as a permissible investment for national banks, federal credit unions and savings associations under current applicable federal laws and regulations. Accordingly, the Fund will limit its investments to securities that are eligible for direct investment by such institutions. However, the Fund does not limit its investments to “Type 1 Securities” under the federal banking laws and regulations; and accordingly, a national bank is not permitted under these laws and regulations to invest more than 10% of its capital and surplus in the Fund. In addition, certain of the Fund's investment transactions and techniques may be subject to the general lending limits imposed on national banks. Such national banks and federal credit unions and savings associations should consult their legal counsel regarding federal laws and regulations applicable to their investment in the Fund.

Certain of the government securities in which the Fund invests are not backed by the full faith and credit of the U.S. government, such as those issued by the Federal Home Loan Mortgage Corporation (“Freddie Mac”), the Federal National Mortgage Association (“Fannie Mae”) and the Federal Home Loan Bank System. These entities are, however, supported through federal subsidies, loans or other benefits. The Fund may also invest in government securities that are supported by the full faith and credit of the U.S. government, such as those issued by the Government National Mortgage Association (“Ginnie Mae”). Finally, the Fund may invest in a few government securities that have no explicit financial support, but which are regarded as having implied support because the federal government sponsors their activities.

The Fund will invest its assets so that at least 80% of its net assets (plus any borrowings for investment purposes) are invested in government investments. The Fund will notify shareholders at least 60 days in advance of any change in its investment policy that would enable the Fund to invest, under normal circumstances, less than 80% of its net assets (plus any borrowings for investment purposes) in government investments.

<b>What are the Main Risks of Investing in the Fund? </b>

All mutual funds take investment risks. Therefore, it is possible to lose money by investing in the Fund. The primary factors that may reduce the Fund's returns include:

• Interest Rate Risk. Prices of fixed-income securities generally fall when interest rates rise. The longer the duration of a fixed-income security, the more susceptible it is to interest-rate risk. Recent and potential future changes in monetary policy made by central banks and/or their governments are likely to affect the level of interest rates.

• Credit Risk. It is possible that interest or principal on securities will not be paid when due. Such non-payment or default may reduce the value of the Fund's portfolio holdings, its share price and its performance.

• Counterparty Risk. Counterparty risk includes the possibility that a party to a transaction involving the Fund will fail to meet its obligations. This could cause the Fund to lose money or to lose the benefit of the transaction or prevent the Fund from selling or buying other securities to implement its investment strategy.

• Prepayment and Extension Risk. When homeowners prepay their mortgages in response to lower interest rates, the Fund will be required to reinvest the proceeds at the lower interest rates available. Also, when interest rates fall, the price of mortgage-backed securities may not rise to as great an extent as that of other fixed-income securities. When interest rates rise, homeowners are less likely to prepay their mortgages. A decreased rate of prepayments lengthens the expected maturity of a mortgage-backed security, and the price of mortgage-backed securities may decrease more than the price of other fixed income securities when interest rates rise.

• MBS Risk. A rise in interest rates may cause the value of MBS held by the Fund to decline. Certain MBS issued by GSEs are not backed by the full faith and credit of the U.S. government. The Fund's investments in collateralized mortgage obligations (CMOs) may entail greater market, prepayment and liquidity risks than other MBS.

• Risk Related to the Economy. The value of the Fund's portfolio may decline in tandem with a drop in the overall value of the markets in which the Fund invests and/or other markets. Economic, political and financial conditions, or industry or economic trends and developments, may, from time to time, and for varying periods of time, cause the Fund to experience volatility, illiquidity, shareholder redemptions, or other potentially adverse effects.

• Technology Risk. The Adviser uses various technologies in managing the Fund, consistent with its investment objective and strategy described in this Prospectus. For example, proprietary and third-party data and systems are utilized to support decision making for the Fund. Data imprecision, software or other technology malfunctions, programming inaccuracies and similar circumstances may impair the performance of these systems, which may negatively affect Fund performance.

The Shares offered by this Prospectus are not deposits or obligations of any bank, are not endorsed or guaranteed by any bank and are not insured or guaranteed by the U.S. government, the Federal Deposit Insurance Corporation, the Federal Reserve Board or any other government agency.

<b>PERFORMANCE: BAR CHART AND TABLE </b><br/><br/><b>Risk/Return Bar Chart </b>

The bar chart and performance table below reflect historical performance data for the Fund and are intended to help you analyze the Fund's investment risks in light of its historical returns. The bar chart shows the variability of the Fund's IS class total returns on a calendar year-by-year basis. The Average Annual Total Return table shows returns for each class averaged over the stated periods, and includes comparative performance information. The Fund's performance will fluctuate, and past performance (before and after taxes) is not necessarily an indication of future results. Updated performance information for the Fund is available under the “Products” section at FederatedInvestors.com or by calling 1-800-341-7400.

Federated Government Ultrashort Duration Fund - IS Class

The Fund's IS class total return for the six-month period from January 1, 2018 to June 30, 2018, was 0.89%.

Within the periods shown in the bar chart, the Fund's IS class highest quarterly return was 0.78% (quarter ended June 30, 2008). Its lowest quarterly return was (0.22)% (quarter ended December 31, 2015).

<b>Average Annual Total Return Table </b>

The Fund's Class R6 Shares commenced operations on March 29, 2016. For the periods prior to the commencement of operations of Class R6 Shares, the R6 class performance information shown below is for the Fund's IS class. The performance of the Fund's IS class has not been adjusted to reflect the expenses applicable to the R6 class since the R6 class has a lower expense ratio than the expense ratio of the IS class. The performance of the IS class has been adjusted to remove any voluntary waiver of Fund expenses related to the IS class that may have occurred during the periods prior to the commencement of operations of the R6 class.

In addition to Return Before Taxes, Return After Taxes is shown for the Fund's IS class to illustrate the effect of federal taxes on Fund returns. After-tax returns are shown only for IS class, and after-tax returns for the A, SS and R6 classes will differ from those shown for the IS class. Actual after-tax returns depend on each investor's personal tax situation, and are likely to differ from those shown. After-tax returns are calculated using a standard set of assumptions. The stated returns assume the highest historical federal income and capital gains tax rates. These after-tax returns do not reflect the effect of any applicable state and local taxes. After-tax returns are not relevant to investors holding shares through tax-deferred programs, such as a 401(k) plan, an Individual Retirement Account or other tax-advantaged investment plans.

(For the Period Ended December 31, 2017)

Average Annual Total Returns - Federated Government Ultrashort Duration Fund		1 Year	5 Years	10 Years
A		(1.30%)	(0.47%)	0.14%
IS		1.06%	0.37%	0.78%
IS | Return After Taxes on Distributions		0.64%	0.18%	0.48%
IS | Return After Taxes on Distributions and Sale of Fund Shares		0.60%	0.20%	0.49%
SS		1.06%	0.27%	0.69%
R6		1.08%	0.19%	0.56%
ICE BofAML US 6-Month Treasury Bill Index (reflects no deduction for fees, expenses or taxes)	[1]	0.95%	0.43%	0.71%

[1] The Fund has adopted a Distribution (12b-1) Plan for its SS class pursuant to which the SS class of the Fund may incur or charge a Distribution (12b-1) fee of up to a maximum amount of 0.05%. No such fee is currently incurred or charged by the SS class of the Fund. The SS class of the Fund will not incur or charge such a Distribution (12b-1) fee until such time as approved by the Fund's Board of Trustees (the "Trustees").

[2] The Adviser and certain of its affiliates on their own initiative have agreed to waive certain amounts of their respective fees and/or reimburse expenses. Total annual fund operating expenses (excluding acquired fund fees and expenses, interest expense, extraordinary expenses and proxy-related expenses paid by the Fund, if any) paid by the Fund's A, IS, SS and R6 classes (after the voluntary waivers and/or reimbursements) will not exceed 0.71%, 0.26%, 0.36% and 0.24% (the "Fee Limit"), respectively, up to but not including the later of (the "Termination Date"): (a) October 1, 2019; or (b) the date of the Fund's next effective Prospectus. While the Adviser and its affiliates currently do not anticipate terminating or increasing these arrangements prior to the Termination Date, these arrangements may only be terminated or the Fee Limit increased prior to the Termination Date with the agreement of the Trustees.

[1] ICE BofAML US 6-Month Treasury Bill Index is comprised of a single issue purchased at the beginning of the month and held for a full month. At the end of the month that issue is sold and rolled into a newly selected issue. The issue selected at each month-end rebalancing is the outstanding Treasury Bill that matures closest to, but not beyond, six months from the rebalancing date. To qualify for selection, an issue must have settled on or before the month-end rebalancing date. Effective October 22, 2017, the index name changed from "BofA Merrill Lynch US 6-Month Treasury Bill Index" to "ICE BofAML US 6-Month Treasury Bill Index."

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	FEDERATED INSTITUTIONAL TRUST
Prospectus Date	rr_ProspectusDate	Sep. 30, 2018
Federated Government Ultrashort Duration Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	<b>Federated Government Ultrashort Duration Fund (the "Fund")</b>
Objective [Heading]	rr_ObjectiveHeading	<b>RISK/RETURN SUMMARY: INVESTMENT OBJECTIVE </b>
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Fund's investment objective is current income.
Expense [Heading]	rr_ExpenseHeading	<b>RISK/RETURN SUMMARY: FEES AND EXPENSES </b>
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Class A Shares (A), Institutional Shares (IS), Service Shares (SS) or Class R6 Shares (R6) of the Fund. You may qualify for certain sales charge discounts, if you and your family invest, or agree to invest in the future, at least $50,000 in certain classes of Federated funds. More information about these and other discounts is available from your financial professional, in the “What Do Shares Cost?” section of the Prospectus on page 10 and in “Appendix B” to this Prospectus. If you purchase the Fund's IS, SS or R6 Shares through a broker acting as an agent on behalf of its customers, you may be required to pay a commission to such broker; such commissions, if any are not reflected in the Example below.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	<b>Shareholder Fees (fees paid directly from your investment) </b>
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	<b>Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment) </b>
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	October 1, 2019
Fee Waiver Or Reimbursement Over Assets, Later Of Termination Or Next Effective Prospectus	finst_FeeWaiverOrReimbursementOverAssetsLaterOfTerminationOrNextEffectiveProspectus	up to but not including the later of (the "Termination Date"): (a) October 1, 2019; or (b) the date of the Fund's next effective Prospectus.
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	<b>Portfolio Turnover </b>
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund Shares are held in a taxable account. These costs, which are not reflected in Annual Fund Operating Expenses or in the Example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 18% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	18.00%
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	You may qualify for certain sales charge discounts, if you and your family invest, or agree to invest in the future, at least $50,000 in certain classes of Federated funds.
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	$ 50,000
Expense Exchange Traded Fund Commissions [Text]	rr_ExpenseExchangeTradedFundCommissions	If you purchase the Fund's IS, SS or R6 Shares through a broker acting as an agent on behalf of its customers, you may be required to pay a commission to such broker; such commissions, if any are not reflected in the Example below.
Expense Example [Heading]	rr_ExpenseExampleHeading	<b>Example </b>
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 for the time periods indicated and then redeem all of your Shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that operating expenses are as shown in the table above and remain the same. Although your actual costs and returns may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	<b>RISK/RETURN SUMMARY: INVESTMENTS, RISKS AND PERFORMANCE <br/><br/>What are the Fund's Main Investment Strategies? </b>
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund's overall strategy is to invest in a portfolio of U.S. government securities and U.S. government agency securities (including mortgage-backed securities issued or guaranteed by U.S. government-sponsored enterprises (GSEs)) with an overall dollar-weighted average duration of one year or less. Duration measures the price sensitivity of a fixed-income security to changes in interest rates. Within the one-year duration constraint, the Adviser will seek to increase the Fund's current income by lengthening or shortening portfolio duration based on its interest rate outlook. The Fund implements this strategy by dividing its portfolio into two major components. Although the Fund is not a money market fund and its share price will fluctuate, the Fund invests one component in U.S. government securities (including repurchase agreements collateralized by U.S. government securities and U.S. government agency securities) that are eligible for purchase by money market funds. The Fund invests the other component in mortgage-backed securities issued or guaranteed by GSEs. The Fund uses mortgage-backed securities to increase the income provided by the portfolio and to extend the portfolio to the targeted duration. Within each component of the portfolio, the Adviser makes decisions of which securities to buy and sell based on the relative yield and risks of available securities with comparable durations. The Fund evaluates its investment strategy by comparing the performance and composition of the Fund's portfolio against the performance and composition of an index composed of U.S. Treasury bills with maturities of six months. The Fund intends to qualify as a permissible investment for national banks, federal credit unions and savings associations under current applicable federal laws and regulations. Accordingly, the Fund will limit its investments to securities that are eligible for direct investment by such institutions. However, the Fund does not limit its investments to “Type 1 Securities” under the federal banking laws and regulations; and accordingly, a national bank is not permitted under these laws and regulations to invest more than 10% of its capital and surplus in the Fund. In addition, certain of the Fund's investment transactions and techniques may be subject to the general lending limits imposed on national banks. Such national banks and federal credit unions and savings associations should consult their legal counsel regarding federal laws and regulations applicable to their investment in the Fund. Certain of the government securities in which the Fund invests are not backed by the full faith and credit of the U.S. government, such as those issued by the Federal Home Loan Mortgage Corporation (“Freddie Mac”), the Federal National Mortgage Association (“Fannie Mae”) and the Federal Home Loan Bank System. These entities are, however, supported through federal subsidies, loans or other benefits. The Fund may also invest in government securities that are supported by the full faith and credit of the U.S. government, such as those issued by the Government National Mortgage Association (“Ginnie Mae”). Finally, the Fund may invest in a few government securities that have no explicit financial support, but which are regarded as having implied support because the federal government sponsors their activities. The Fund will invest its assets so that at least 80% of its net assets (plus any borrowings for investment purposes) are invested in government investments. The Fund will notify shareholders at least 60 days in advance of any change in its investment policy that would enable the Fund to invest, under normal circumstances, less than 80% of its net assets (plus any borrowings for investment purposes) in government investments.
Risk [Heading]	rr_RiskHeading	<b>What are the Main Risks of Investing in the Fund? </b>
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	All mutual funds take investment risks. Therefore, it is possible to lose money by investing in the Fund. The primary factors that may reduce the Fund's returns include: Interest Rate Risk. Prices of fixed-income securities generally fall when interest rates rise. The longer the duration of a fixed-income security, the more susceptible it is to interest-rate risk. Recent and potential future changes in monetary policy made by central banks and/or their governments are likely to affect the level of interest rates. Credit Risk. It is possible that interest or principal on securities will not be paid when due. Such non-payment or default may reduce the value of the Fund's portfolio holdings, its share price and its performance. Counterparty Risk. Counterparty risk includes the possibility that a party to a transaction involving the Fund will fail to meet its obligations. This could cause the Fund to lose money or to lose the benefit of the transaction or prevent the Fund from selling or buying other securities to implement its investment strategy. Prepayment and Extension Risk. When homeowners prepay their mortgages in response to lower interest rates, the Fund will be required to reinvest the proceeds at the lower interest rates available. Also, when interest rates fall, the price of mortgage-backed securities may not rise to as great an extent as that of other fixed-income securities. When interest rates rise, homeowners are less likely to prepay their mortgages. A decreased rate of prepayments lengthens the expected maturity of a mortgage-backed security, and the price of mortgage-backed securities may decrease more than the price of other fixed income securities when interest rates rise. MBS Risk. A rise in interest rates may cause the value of MBS held by the Fund to decline. Certain MBS issued by GSEs are not backed by the full faith and credit of the U.S. government. The Fund's investments in collateralized mortgage obligations (CMOs) may entail greater market, prepayment and liquidity risks than other MBS. Risk Related to the Economy. The value of the Fund's portfolio may decline in tandem with a drop in the overall value of the markets in which the Fund invests and/or other markets. Economic, political and financial conditions, or industry or economic trends and developments, may, from time to time, and for varying periods of time, cause the Fund to experience volatility, illiquidity, shareholder redemptions, or other potentially adverse effects. Technology Risk. The Adviser uses various technologies in managing the Fund, consistent with its investment objective and strategy described in this Prospectus. For example, proprietary and third-party data and systems are utilized to support decision making for the Fund. Data imprecision, software or other technology malfunctions, programming inaccuracies and similar circumstances may impair the performance of these systems, which may negatively affect Fund performance. The Shares offered by this Prospectus are not deposits or obligations of any bank, are not endorsed or guaranteed by any bank and are not insured or guaranteed by the U.S. government, the Federal Deposit Insurance Corporation, the Federal Reserve Board or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	All mutual funds take investment risks. Therefore, it is possible to lose money by investing in the Fund.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	The Shares offered by this Prospectus are not deposits or obligations of any bank, are not endorsed or guaranteed by any bank and are not insured or guaranteed by the U.S. government, the Federal Deposit Insurance Corporation, the Federal Reserve Board or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	<b>PERFORMANCE: BAR CHART AND TABLE </b><br/><br/><b>Risk/Return Bar Chart </b>
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and performance table below reflect historical performance data for the Fund and are intended to help you analyze the Fund's investment risks in light of its historical returns. The bar chart shows the variability of the Fund's IS class total returns on a calendar year-by-year basis. The Average Annual Total Return table shows returns for each class averaged over the stated periods, and includes comparative performance information. The Fund's performance will fluctuate, and past performance (before and after taxes) is not necessarily an indication of future results. Updated performance information for the Fund is available under the “Products” section at FederatedInvestors.com or by calling 1-800-341-7400.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and performance table below reflect historical performance data for the Fund and are intended to help you analyze the Fund's investment risks in light of its historical returns. The bar chart shows the variability of the Fund's IS class total returns on a calendar year-by-year basis.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-800-341-7400
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	FederatedInvestors.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund's performance will fluctuate, and past performance (before and after taxes) is not necessarily an indication of future results.
Bar Chart [Heading]	rr_BarChartHeading	Federated Government Ultrashort Duration Fund - IS Class
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	The Fund's IS class total return for the six-month period from January 1, 2018 to June 30, 2018, was 0.89%. Within the periods shown in the bar chart, the Fund's IS class highest quarterly return was 0.78% (quarter ended June 30, 2008). Its lowest quarterly return was (0.22)% (quarter ended December 31, 2015).
Performance Table Heading	rr_PerformanceTableHeading	<b>Average Annual Total Return Table </b>
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using a standard set of assumptions. The stated returns assume the highest historical <b>federal </b> income and capital gains tax rates. These after-tax returns do <b>not</b> reflect the effect of any applicable <b>state</b> and <b>local</b> taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	After-tax returns are not relevant to investors holding shares through tax-deferred programs, such as a 401(k) plan, an Individual Retirement Account or other tax-advantaged investment plans.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown only for IS class, and after-tax returns for the A, SS and R6 classes will differ from those shown for the IS class.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The Fund's Class R6 Shares commenced operations on March 29, 2016. For the periods prior to the commencement of operations of Class R6 Shares, the R6 class performance information shown below is for the Fund's IS class. The performance of the Fund's IS class has not been adjusted to reflect the expenses applicable to the R6 class since the R6 class has a lower expense ratio than the expense ratio of the IS class. The performance of the IS class has been adjusted to remove any voluntary waiver of Fund expenses related to the IS class that may have occurred during the periods prior to the commencement of operations of the R6 class. In addition to Return Before Taxes, Return After Taxes is shown for the Fund's IS class to illustrate the effect of federal taxes on Fund returns. After-tax returns are shown only for IS class, and after-tax returns for the A, SS and R6 classes will differ from those shown for the IS class. Actual after-tax returns depend on each investor's personal tax situation, and are likely to differ from those shown. After-tax returns are calculated using a standard set of assumptions. The stated returns assume the highest historical federal income and capital gains tax rates. These after-tax returns do not reflect the effect of any applicable state and local taxes. After-tax returns are not relevant to investors holding shares through tax-deferred programs, such as a 401(k) plan, an Individual Retirement Account or other tax-advantaged investment plans. (For the Period Ended December 31, 2017)
Federated Government Ultrashort Duration Fund | A
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	2.00%
Maximum Deferred Sales Charge (Load) (as a percentage of original purchase price or redemption proceeds, as applicable)	rr_MaximumDeferredSalesChargeOverOther	none
Maximum Sales Charge (Load) Imposed on Reinvested Dividends (and other Distributions) (as a percentage of offering price)	rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther	none
Redemption Fee (as a percentage of amount redeemed, if applicable)	rr_RedemptionFeeOverRedemption	none
Exchange Fee	rr_ExchangeFeeOverRedemption	none
Management Fee	rr_ManagementFeesOverAssets	0.30%
Distribution (12b-1) Fee	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.44%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.99%
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets	(0.28%)	[1]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	0.71%
1 Year	rr_ExpenseExampleYear01	$ 299
3 Years	rr_ExpenseExampleYear03	509
5 Years	rr_ExpenseExampleYear05	736
10 Years	rr_ExpenseExampleYear10	$ 1,389
1 Year	rr_AverageAnnualReturnYear01	(1.30%)
5 Years	rr_AverageAnnualReturnYear05	(0.47%)
10 Years	rr_AverageAnnualReturnYear10	0.14%
Federated Government Ultrashort Duration Fund | IS
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as a percentage of original purchase price or redemption proceeds, as applicable)	rr_MaximumDeferredSalesChargeOverOther	none
Maximum Sales Charge (Load) Imposed on Reinvested Dividends (and other Distributions) (as a percentage of offering price)	rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther	none
Redemption Fee (as a percentage of amount redeemed, if applicable)	rr_RedemptionFeeOverRedemption	none
Exchange Fee	rr_ExchangeFeeOverRedemption	none
Management Fee	rr_ManagementFeesOverAssets	0.30%
Distribution (12b-1) Fee	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.18%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.48%
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets	(0.22%)	[1]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	0.26%
1 Year	rr_ExpenseExampleYear01	$ 49
3 Years	rr_ExpenseExampleYear03	154
5 Years	rr_ExpenseExampleYear05	269
10 Years	rr_ExpenseExampleYear10	$ 604
2008	rr_AnnualReturn2008	2.50%
2009	rr_AnnualReturn2009	1.73%
2010	rr_AnnualReturn2010	0.73%
2011	rr_AnnualReturn2011	0.36%
2012	rr_AnnualReturn2012	0.68%
2013	rr_AnnualReturn2013	0.09%
2014	rr_AnnualReturn2014	0.26%
2015	rr_AnnualReturn2015	0.07%
2016	rr_AnnualReturn2016	0.40%
2017	rr_AnnualReturn2017	1.06%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund's IS class total return for the six-month period
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Jun. 30, 2018
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	0.89%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	highest quarterly return
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2008
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	0.78%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	lowest quarterly return
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2015
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(0.22%)
1 Year	rr_AverageAnnualReturnYear01	1.06%
5 Years	rr_AverageAnnualReturnYear05	0.37%
10 Years	rr_AverageAnnualReturnYear10	0.78%
Federated Government Ultrashort Duration Fund | SS
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as a percentage of original purchase price or redemption proceeds, as applicable)	rr_MaximumDeferredSalesChargeOverOther	none
Maximum Sales Charge (Load) Imposed on Reinvested Dividends (and other Distributions) (as a percentage of offering price)	rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther	none
Redemption Fee (as a percentage of amount redeemed, if applicable)	rr_RedemptionFeeOverRedemption	none
Exchange Fee	rr_ExchangeFeeOverRedemption	none
Management Fee	rr_ManagementFeesOverAssets	0.30%
Distribution (12b-1) Fee	rr_DistributionAndService12b1FeesOverAssets	none	[2]
Other Expenses	rr_OtherExpensesOverAssets	0.44%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.74%
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets	(0.38%)	[1]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	0.36%
1 Year	rr_ExpenseExampleYear01	$ 76
3 Years	rr_ExpenseExampleYear03	237
5 Years	rr_ExpenseExampleYear05	411
10 Years	rr_ExpenseExampleYear10	$ 918
1 Year	rr_AverageAnnualReturnYear01	1.06%
5 Years	rr_AverageAnnualReturnYear05	0.27%
10 Years	rr_AverageAnnualReturnYear10	0.69%
Federated Government Ultrashort Duration Fund | R6
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as a percentage of original purchase price or redemption proceeds, as applicable)	rr_MaximumDeferredSalesChargeOverOther	none
Maximum Sales Charge (Load) Imposed on Reinvested Dividends (and other Distributions) (as a percentage of offering price)	rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther	none
Redemption Fee (as a percentage of amount redeemed, if applicable)	rr_RedemptionFeeOverRedemption	none
Exchange Fee	rr_ExchangeFeeOverRedemption	none
Management Fee	rr_ManagementFeesOverAssets	0.30%
Distribution (12b-1) Fee	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.13%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.43%
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets	(0.19%)	[1]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	0.24%
1 Year	rr_ExpenseExampleYear01	$ 44
3 Years	rr_ExpenseExampleYear03	138
5 Years	rr_ExpenseExampleYear05	241
10 Years	rr_ExpenseExampleYear10	$ 542
1 Year	rr_AverageAnnualReturnYear01	1.08%
5 Years	rr_AverageAnnualReturnYear05	0.19%
10 Years	rr_AverageAnnualReturnYear10	0.56%
Federated Government Ultrashort Duration Fund | Return After Taxes on Distributions | IS
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.64%
5 Years	rr_AverageAnnualReturnYear05	0.18%
10 Years	rr_AverageAnnualReturnYear10	0.48%
Federated Government Ultrashort Duration Fund | Return After Taxes on Distributions and Sale of Fund Shares | IS
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.60%
5 Years	rr_AverageAnnualReturnYear05	0.20%
10 Years	rr_AverageAnnualReturnYear10	0.49%
Federated Government Ultrashort Duration Fund | ICE BofAML US 6-Month Treasury Bill Index (reflects no deduction for fees, expenses or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.95%	[3]
5 Years	rr_AverageAnnualReturnYear05	0.43%	[3]
10 Years	rr_AverageAnnualReturnYear10	0.71%	[3]

[1] The Adviser and certain of its affiliates on their own initiative have agreed to waive certain amounts of their respective fees and/or reimburse expenses. Total annual fund operating expenses (excluding acquired fund fees and expenses, interest expense, extraordinary expenses and proxy-related expenses paid by the Fund, if any) paid by the Fund's A, IS, SS and R6 classes (after the voluntary waivers and/or reimbursements) will not exceed 0.71%, 0.26%, 0.36% and 0.24% (the "Fee Limit"), respectively, up to but not including the later of (the "Termination Date"): (a) October 1, 2019; or (b) the date of the Fund's next effective Prospectus. While the Adviser and its affiliates currently do not anticipate terminating or increasing these arrangements prior to the Termination Date, these arrangements may only be terminated or the Fee Limit increased prior to the Termination Date with the agreement of the Trustees.

[2] The Fund has adopted a Distribution (12b-1) Plan for its SS class pursuant to which the SS class of the Fund may incur or charge a Distribution (12b-1) fee of up to a maximum amount of 0.05%. No such fee is currently incurred or charged by the SS class of the Fund. The SS class of the Fund will not incur or charge such a Distribution (12b-1) fee until such time as approved by the Fund's Board of Trustees (the "Trustees").

[3] ICE BofAML US 6-Month Treasury Bill Index is comprised of a single issue purchased at the beginning of the month and held for a full month. At the end of the month that issue is sold and rolled into a newly selected issue. The issue selected at each month-end rebalancing is the outstanding Treasury Bill that matures closest to, but not beyond, six months from the rebalancing date. To qualify for selection, an issue must have settled on or before the month-end rebalancing date. Effective October 22, 2017, the index name changed from "BofA Merrill Lynch US 6-Month Treasury Bill Index" to "ICE BofAML US 6-Month Treasury Bill Index."

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	FEDERATED INSTITUTIONAL TRUST
Prospectus Date	rr_ProspectusDate	Sep. 30, 2018
Document Creation Date	dei_DocumentCreationDate	Sep. 25, 2018