485BPOS

As filed with the Securities and Exchange Commission on December 4, 2017

File Nos. 333-126384

811-21781

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-1A

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933	☒
Pre-Effective Amendment No.	☐
Post-Effective Amendment No. 29	☒
and/or
REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT OF 1940	☒
Amendment No. 31	☒

(Check appropriate box or boxes)

PIONEER SERIES TRUST IV

(Exact Name of Registrant as Specified in Charter)

60 State Street, Boston, Massachusetts 02109

(Address of Principal Executive Offices) (Zip Code)

Registrant’s Telephone Number, including Area Code: (617) 742-7825

Terrence J. Cullen, Amundi Pioneer Asset Management, Inc.

60 State Street, Boston, Massachusetts 02109

(Name and Address of Agent for Service)

It is proposed that this filing will become effective (check appropriate box):

☒ immediately upon filing pursuant to paragraph (b)

☐ on [date] pursuant to paragraph (b)

☐ 60 days after filing pursuant to paragraph (a)(1)

☐ on [date] pursuant to paragraph (a)(1)

☐ 75 days after filing pursuant to paragraph (a)(2)

☐ on [date] 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, as amended, and the Investment Company Act of 1940, as amended, the Trust certifies that it meets all of the requirements for effectiveness of this Registration Statement pursuant to Rule 485(b) of the Securities Act of 1933. The Trust has duly caused this Post-Effective Amendment No. 29 to its Registration Statement to be signed on its behalf by the undersigned, duly authorized, in the City of Boston, and the Commonwealth of Massachusetts, on the 4th day of December, 2017.

PIONEER SERIES TRUST IV
By:	/s/ Lisa M. Jones
	Lisa M. Jones
	President

Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed below by the following persons in the capacities indicated below on December 4, 2017:

	Signature	Title
/s/ Lisa M. Jones Lisa M. Jones		President (Principal Executive Officer) and Trustee
Mark E. Bradley* Mark E. Bradley		Treasurer (Principal Financial and Accounting Officer)
David R. Bock* David R. Bock		Trustee
Benjamin M. Friedman* Benjamin M. Friedman		Trustee
Margaret B. W. Graham* Margaret B. W. Graham		Trustee
Lorraine H. Monchak* Lorraine H. Monchak		Trustee
Thomas J. Perna* Thomas J. Perna		Chairman of the Board and Trustee
Marguerite A. Piret* Marguerite A. Piret		Trustee
Fred J. Ricciardi* Fred J. Ricciardi		Trustee
Kenneth J. Taubes* Kenneth J. Taubes		Trustee
*By:	/s/ Lisa M. Jones
	Lisa M. Jones	Dated: December 4, 2017
	Attorney-in-fact

EXHIBIT INDEX

Exhibit No.	Description
EX-101.INS	XBRL Instance Document
EX-101.SCH	XBRL Taxonomy Extension Schema Document
EX-101.CAL	XBRL Taxonomy Extension Calculation Linkbase
EX-101.DEF	XBRL Taxonomy Extension Definition Linkbase
EX-101.LAB	XBRL Taxonomy Extension Labels Linkbase
EX-101.PRE	XBRL Taxonomy Extension Presentation Linkbase

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Document Type	dei_DocumentType	485BPOS
Document Period End Date	dei_DocumentPeriodEndDate	Jul. 31, 2017
Registrant Name	dei_EntityRegistrantName	Pioneer Series Trust IV
Central Index Key	dei_EntityCentralIndexKey	0001331854
Amendment Flag	dei_AmendmentFlag	false
Document Creation Date	dei_DocumentCreationDate	Nov. 27, 2017
Document Effective Date	dei_DocumentEffectiveDate	Dec. 01, 2017
Prospectus Date	rr_ProspectusDate	Dec. 01, 2017

XML

Pioneer Classic Balanced Fund

PIONEER CLASSIC BALANCED FUND

INVESTMENT OBJECTIVES

Capital growth and current income.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

You may qualify for sales charge discounts if you or your family invest, or agree to invest in the future, at least $100,000 in Class A shares of the Pioneer funds. More information about these and other discounts is available from your investment professional and in the "Sales charges" section of the prospectus beginning on page 60, the "Intermediary defined sales charge waiver policies" section of the prospectus beginning on page 100, and the "Sales charges" section of the statement of additional information beginning on page 67.

SHAREOWNER FEES
(fees paid directly from your investment)

Shareholder Fees - Pioneer Classic Balanced Fund	CLASS A		CLASS C	CLASS K	CLASS R	CLASS Y
Maximum sales charge (load) when you buy shares (as a percentage of offering price)	4.50%		none	none	none	none
Maximum deferred sales charge (load) (as a percentage of offering price or the amount you receive when you sell shares, whichever is less)	none	[1]	1.00%	none	none	none

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a
percentage of the value of your investment)

Annual Fund Operating Expenses - Pioneer Classic Balanced Fund		CLASS A	CLASS C	CLASS K	CLASS R	CLASS Y
Management Fees		0.65%	0.65%	0.65%	0.65%	0.65%
Distribution and Service (12b-1) Fees		0.25%	1.00%	none	0.50%	none
Other Expenses		0.29%	0.26%	0.20%	0.41%	0.30%
Acquired Fund Fees and Expenses	[1]	0.13%	0.13%	0.13%	0.13%	0.13%
Total Annual Fund Operating Expenses Plus Acquired Fund Fees and Expenses	[1]	1.32%	2.04%	0.98%	1.69%	1.08%
Less: Fee Waiver and Expense Reimbursement	[2]	(0.03%)	none	none	(0.26%)	none
Net Expenses Plus Acquired Fund Fees and Expenses	[2]	1.29%	2.04%	0.98%	1.43%	1.08%

EXAMPLE

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 in the fund for the time periods shown and then, except as indicated, redeem all of your shares at the end of those periods. It also assumes that (a) your investment has a 5% return each year and (b) the fund's total annual operating expenses remain the same except for year one (which considers the effect of the expense limitation). Although your actual costs may be higher or lower, based on these assumptions your costs would be:

IF YOU REDEEM YOUR SHARES
NUMBER OF YEARS YOU OWN YOUR SHARES

Expense Example - Pioneer Classic Balanced Fund - USD ($)	1	3	5	10
Class A	575	847	1,138	1,966
Class C	307	640	1,098	2,369
Class K	100	312	542	1,201
Class R	146	507	893	1,976
Class Y	110	343	595	1,317

IF YOU DO NOT REDEEM YOUR SHARES
NUMBER OF YEARS YOU OWN YOUR SHARES

Expense Example, No Redemption - Pioneer Classic Balanced Fund - USD ($)	1	3	5	10
Class A	575	847	1,138	1,966
Class C	207	640	1,098	2,369
Class K	100	312	542	1,201
Class R	146	507	893	1,976
Class Y	110	343	595	1,317

PORTFOLIO TURNOVER

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 51% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The fund's investment adviser allocates the fund's assets between equity and debt securities based on its assessment of current business, economic and market conditions. Normally, equity and debt securities each represent 35% to 65% of the fund's net assets. Equity securities in which the fund invests include common stocks and securities with common stock characteristics, such as equity interests in real estate investment trusts (REITs), funds that invest primarily in equity securities, and preferred stocks. Debt securities in which the fund invests include instruments and obligations of U.S. and non-U.S. corporate and other non-governmental entities, those of U.S. and non-U.S. governmental entities, mortgage-related or mortgage-backed securities (including "sub-prime" mortgages), asset-backed securities, municipal securities, floating rate loans, debt convertible to equity securities, subordinated debt securities, event-linked bonds and other insurance-linked securities, funds that invest primarily in debt securities, short-term debt securities, cash and cash equivalents.

The fund may invest in debt securities with a broad range of maturities and maintains an average portfolio maturity which varies based upon the judgment of the fund's investment adviser. Debt securities in which the fund invests may have fixed or variable principal payments and all types of interest rate payment and reset terms, including fixed rate, adjustable rate, floating rate, inverse floating rate, zero coupon, contingent, deferred, payment in kind and auction rate features. The fund's investments may include instruments that allow for balloon payments or negative amortization payments.

The fund may invest up to 20% of its net assets in securities that are below investment grade (also known as "junk bonds"), including convertible debt. The fund may invest up to 20% of its net assets in real estate investment trusts (REITs).

The fund may invest up to 25% of its total assets in equity and debt securities of non-U.S. issuers. The fund will not invest more than 5% of its total assets in the securities of emerging markets issuers.

The fund may, but is not required to, use derivatives, such as credit default swaps. The fund may use derivatives for a variety of purposes, including: in an attempt to hedge against adverse changes in the market price of securities, interest rates or currency exchange rates; as a substitute for purchasing or selling securities; to attempt to increase the fund's return as a non-hedging strategy that may be considered speculative; to manage portfolio characteristics; and as a cash flow management technique. The fund may choose not to make use of derivatives for a variety of reasons, and any use may be limited by applicable law and regulations. The fund may also hold cash or other short-term investments.

In selecting equity securities to buy and sell, the fund's investment adviser uses a value approach to select the fund's investments. Using this investment style, the adviser seeks securities selling at reasonable prices or substantial discounts to their underlying values and then holds these securities until the market values reflect their intrinsic values.

In selecting debt securities to buy and sell, the adviser considers both broad economic and issuer specific factors. In assessing the appropriate maturity, credit quality and sector weighting of the fund's portfolio, the adviser considers a variety of factors that are expected to influence economic activity and interest rates. The adviser selects individual securities to buy and sell based upon such factors as a security's yield, liquidity and rating, an assessment of credit quality, and sector and issuer diversification.

PRINCIPAL RISKS OF INVESTING IN THE FUND

You could lose money on your investment in the fund. As with any mutual fund, there is no guarantee that the fund will achieve its objectives.

MARKET RISK. The value of securities held by the fund may go up or down, sometimes rapidly or unpredictably, due to general market conditions, such as real or perceived adverse economic, political, or regulatory conditions, inflation, changes in interest or currency rates, lack of liquidity in the bond markets or adverse investor sentiment. In the past decade, financial markets throughout the world have experienced increased volatility, depressed valuations, decreased liquidity and heightened uncertainty. Governmental and non-governmental issuers have defaulted on, or been forced to restructure, their debts. These conditions may continue, recur, worsen or spread. Events that have contributed to these market conditions include, but are not limited to, major cybersecurity events; geopolitical events (including wars and terror attacks); measures to address budget deficits; downgrading of sovereign debt; declines in oil and commodity prices; dramatic changes in currency exchange rates; and public sentiment. The U.S. government and the Federal Reserve, as well as certain foreign governments and their central banks, have taken steps to support financial markets, including by keeping interest rates at historically low levels. This and other government intervention may not work as intended, particularly if the efforts are perceived by investors as being unlikely to achieve the desired results. The Federal Reserve has reduced its market support activities and has begun raising interest rates. Certain foreign governments and central banks are implementing or discussing so-called negative interest rates (e.g., charging depositors who keep their cash at a bank) to spur economic growth. Further Federal Reserve or other U.S. or non-U.S. governmental or central bank actions, including interest rate increases or contrary actions by different governments, could negatively affect financial markets generally, increase market volatility and reduce the value and liquidity of securities in which the fund invests. Policy and legislative changes in the U.S. and in other countries are affecting many aspects of financial regulation, and may in some instances contribute to decreased liquidity and increased volatility in the financial markets. The impact of these changes on the markets, and the practical implications for market participants, may not be fully known for some time. Economies and financial markets throughout the world are increasingly interconnected. Economic, financial or political events, trading and tariff arrangements, terrorism, natural disasters and other circumstances in one country or region could have profound impacts on global economies or markets. As a result, whether or not the fund invests in securities of issuers located in or with significant exposure to the countries directly affected, the value and liquidity of the fund's investments may be negatively affected. The fund may experience a substantial or complete loss on any individual security or derivative position.

VALUE STYLE RISK. The prices of securities the adviser believes are undervalued may not appreciate as expected or may go down. Value stocks may fall out of favor with investors and underperform the overall equity market.

PORTFOLIO SELECTION RISK. The adviser's judgment about a particular security or issuer, or about the economy or a particular sector, region or market segment, or about an investment strategy, may prove to be incorrect.

INTEREST RATE RISK. Interest rates may go up, causing the value of the fund's investments to decline (this risk generally will be greater for securities with longer maturities or durations). For example, if interest rates increase by 1%, the value of a fund's portfolio with a portfolio duration of ten years would be expected to decrease by 10%, all other things being equal. Interest rates in the U.S. recently have been historically low, so the fund faces a heightened risk that interest rates may rise. A general rise in interest rates may cause investors to move out of fixed income securities on a large scale, which could adversely affect the price and liquidity of fixed income securities and could also result in increased redemptions from the fund. The maturity of a security may be significantly longer than its effective duration. A security's maturity and other features may be more relevant than its effective duration in determining the security's sensitivity to other factors affecting the issuer or markets generally such as changes in credit quality or in the yield premium that the market may establish for certain types of securities.

CREDIT RISK. If an issuer or guarantor of a security held by the fund or a counterparty to a financial contract with the fund defaults on its obligation to pay principal and/or interest, has its credit rating downgraded or is perceived to be less creditworthy, or the credit quality or value of any underlying assets declines, the value of your investment will typically decline.

PREPAYMENT OR CALL RISK. Many issuers have a right to prepay their securities. If interest rates fall, an issuer may exercise this right. If this happens, the fund will not benefit from the rise in market price that normally accompanies a decline in interest rates, and will be forced to reinvest prepayment proceeds at a time when yields on securities available in the market are lower than the yield on the prepaid security. The fund also may lose any premium it paid on the security.

EXTENSION RISK. During periods of rising interest rates, the average life of certain types of securities may be extended because of slower than expected principal payments. This may lock in a below market interest rate, increase the security's duration and reduce the value of the security.

LIQUIDITY RISK. Some securities and derivatives held by the fund may be impossible or difficult to purchase, sell or unwind, particularly during times of market turmoil. An instrument's liquidity may be affected by reduced trading volume, a relative lack of market makers or legal restrictions, and illiquid securities and derivatives also may be difficult to value. Liquidity risk may be magnified in a rising interest rate environment. If the fund is forced to sell an illiquid asset or unwind a derivatives position to meet redemption requests or other cash needs, the fund may be forced to sell at a loss. The fund may not receive its proceeds from the sale of certain securities for an extended period (for example, several weeks or even longer). In extreme cases, this may constrain the fund's ability to meet its obligations (including obligations to redeeming shareholders).

U.S. TREASURY OBLIGATIONS RISK. The market value of direct obligations of the U.S. Treasury may vary due to changes in interest rates. In addition, changes to the financial condition or credit rating of the U.S. government may cause the value of the fund's investments in obligations issued by the U.S. Treasury to decline.

U.S. GOVERNMENT AGENCY OBLIGATIONS RISK. The fund invests in obligations issued by agencies and instrumentalities of the U.S. government. Government-sponsored entities such as FNMA, FHLMC and the FHLBs, although chartered or sponsored by Congress, are not funded by congressional appropriations and the debt and mortgage-backed securities issued by them are neither guaranteed nor issued by the U.S. government. The maximum potential liability of the issuers of some U.S. government obligations may greatly exceed their current resources, including any legal right to support from the U.S. government. Such debt and mortgage-backed securities are subject to the risk of default on the payment of interest and/or principal, similar to debt of private issuers. Although the U.S. government has provided financial support to FNMA and FHLMC in the past, there can be no assurance that it will support these or other government-sponsored entities in the future.

MORTGAGE-RELATED AND ASSET-BACKED SECURITIES RISK. The value of mortgage-related and asset-backed securities will be influenced by factors affecting the housing market and the assets underlying such securities. As a result, during periods of declining asset value, difficult or frozen credit markets, swings in interest rates, or deteriorating economic conditions, mortgage-related and asset-backed securities may decline in value, face valuation difficulties, become more volatile and/or become illiquid. Mortgage-backed securities tend to be more sensitive to changes in interest rate than other types of debt securities. These securities are also subject to prepayment and extension risks. Some of these securities may receive little or no collateral protection from the underlying assets and are thus subject to the risk of default. The risk of such defaults is generally higher in the case of mortgage-backed investments that include so-called "sub-prime" mortgages. The structure of some of these securities may be complex and there may be less available information than for other types of debt securities. Upon the occurrence of certain triggering events or defaults, the fund may become the holder of underlying assets at a time when those assets may be difficult to sell or may be sold only at a loss.

RISKS OF INSTRUMENTS THAT ALLOW FOR BALLOON PAYMENTS OR NEGATIVE AMORTIZATION PAYMENTS. Certain debt instruments allow for balloon payments or negative amortization payments. Such instruments permit the borrower to avoid paying currently a portion of the interest accruing on the instrument. While these features make the debt instrument more affordable to the borrower in the near term, they increase the risk that the borrower will be unable to make the resulting higher payment or payments that become due at the maturity of the loan.

HIGH YIELD OR "JUNK" BOND RISK. Debt securities that are below investment grade, called "junk bonds," are speculative, have a higher risk of default or are already in default, tend to be less liquid and are more difficult to value than higher grade securities. Junk bonds tend to be volatile and more susceptible to adverse events and negative sentiments. These risks are more pronounced for securities that are already in default.

RISKS OF INVESTING IN FLOATING RATE LOANS. Floating rate loans and similar investments may be illiquid or less liquid than other investments and difficult to value. The value of collateral, if any, securing a floating rate loan can decline or may be insufficient to meet the issuer's obligations or may be difficult to liquidate. Market quotations for these securities may be volatile and/or subject to large spreads between bid and ask prices. No active trading market may exist for many floating rate loans, and many loans are subject to restrictions on resale. Any secondary market may be subject to irregular trading activity and extended trade settlement periods. In particular, loans may take longer than seven days to settle, potentially leading to the sale proceeds of loans not being available to meet redemptions for a substantial period of time after the sale of the loans. To the extent that sale proceeds of loans are not available, the fund may sell securities that have shorter settlement periods or may access other sources of liquidity to meet redemption requests. Loans may not be considered "securities," and purchasers, such as the fund, therefore may not be entitled to rely on the anti-fraud protections afforded by federal securities laws.

RISKS OF INVESTING IN INSURANCE-LINKED SECURITIES. The return of principal and the payment of interest on "event-linked" bonds and other insurance-linked securities are contingent on the non-occurrence of a pre-defined "trigger" event, such as a hurricane or an earthquake of a specific magnitude or other event that leads to physical or economic loss. If a trigger event, as defined within the terms of an event-linked bond, involves losses or other metrics exceeding a specific magnitude in the geographic region and time period specified, the fund may lose a portion or all of its accrued interest and/or principal invested in the event-linked bond. In addition to the specified trigger events, event-linked bonds may expose the fund to other risks, including but not limited to issuer (credit) default, adverse regulatory or jurisdictional interpretations and adverse tax consequences. Certain insurance-linked securities may have limited liquidity, or may be illiquid. The fund has limited transparency into the individual contracts underlying certain insurance-linked securities, which may make the risk assessment of such securities more difficult. Certain insurance-linked securities may be difficult to value.

RISKS OF SUBORDINATED SECURITIES. A holder of securities that are subordinated or "junior" to more senior securities of an issuer is entitled to payment after holders of more senior securities of the issuer. Subordinated securities are more likely to suffer a credit loss than non-subordinated securities of the same issuer, any loss incurred by the subordinated securities is likely to be proportionately greater, and any recovery of interest or principal may take more time. As a result, even a perceived decline in creditworthiness of the issuer is likely to have a greater impact on subordinated securities.

MUNICIPAL SECURITIES RISK. The municipal bond market can be susceptible to unusual volatility, particularly for lower-rated and unrated securities. Liquidity can be reduced unpredictably in response to overall economic conditions or credit tightening. Municipal issuers may be adversely affected by rising health care costs, increasing unfunded pension liabilities, and by the phasing out of federal programs providing financial support. Unfavorable conditions and developments relating to projects financed with municipal securities can result in lower revenues to issuers of municipal securities, potentially resulting in defaults. Issuers often depend on revenues from these projects to make principal and interest payments. The value of municipal securities can also be adversely affected by changes in the financial condition of one or more individual municipal issuers or insurers of municipal issuers, regulatory and political developments, tax law changes or other legislative actions, and by uncertainties and public perceptions concerning these and other factors. Municipal issuers may be more susceptible to downgrades or defaults during recessions or similar periods of economic stress. In recent periods, an increasing number of municipal issuers in the United States have defaulted on obligations and commenced insolvency proceedings. Financial difficulties of municipal issuers may continue or get worse. To the extent the fund invests significantly in a single state or in securities the payments on which are dependent upon a single project or source of revenues, or that relate to a sector or industry, the fund will be more susceptible to associated risks and developments.

RISKS OF ZERO COUPON BONDS, PAYMENT IN KIND, DEFERRED AND CONTINGENT PAYMENT SECURITIES. These securities may be more speculative and may fluctuate more in value than securities which pay income periodically and in cash. In addition, although the fund receives no periodic cash payments on such securities, the fund is deemed for tax purposes to receive income from such securities, which applicable tax rules require the fund to distribute to shareholders. Such distributions may be taxable when distributed to shareholders.

RISKS OF NON-U.S. INVESTMENTS. Investing in non-U.S. issuers, or in U.S. issuers that have significant exposure to foreign markets, may involve unique risks compared to investing in securities of U.S. issuers. These risks are more pronounced for issuers in emerging markets or to the extent that the fund invests significantly in one region or country. These risks may include different financial reporting practices and regulatory standards, less liquid trading markets, extreme price volatility, currency risks, changes in economic, political, regulatory and social conditions, terrorism, sustained economic downturns, financial instability, tax burdens, and investment and repatriation restrictions. Lack of information and less market regulation also may affect the value of these securities. Withholding and other non-U.S. taxes may decrease the fund's return. Non-U.S. issuers may be located in parts of the world that have historically been prone to natural disasters. Investing in depositary receipts is subject to many of the same risks as investing directly in non-U.S. issuers. Depositary receipts may involve higher expenses and may trade at a discount (or premium) to the underlying security. A number of countries in the European Union (EU) have experienced, and may continue to experience, severe economic and financial difficulties. In addition, voters in the United Kingdom have approved withdrawal from the EU. Other countries may seek to withdraw from the EU and/or abandon the euro, the common currency of the EU.

RISKS OF INVESTMENTS IN REAL ESTATE RELATED SECURITIES. Investments in real estate securities are affected by economic conditions, interest rates, governmental actions and other factors. In addition, investing in REITs involves unique risks. They are significantly affected by the market for real estate and are dependent upon management skills and cash flow. REITs may have lower trading volumes and may be subject to more abrupt or erratic price movements than the overall securities markets. Mortgage REITs are particularly subject to interest rate and credit risks. In addition to its own expenses, the fund will indirectly bear its proportionate share of any management and other expenses paid by REITs in which it invests. Many real estate companies, including REITs, utilize leverage.

RISKS OF CONVERTIBLE SECURITIES. The market values of convertible securities tend to decline as interest rates increase and, conversely, to increase as interest rates decline. A downturn in equity markets may cause the price of convertible securities to decrease relative to other fixed income securities.

PREFERRED STOCKS RISK. Preferred stocks may pay fixed or adjustable rates of return. Preferred stocks are subject to issuer-specific and market risks applicable generally to equity securities. In addition, a company's preferred stocks generally pay dividends only after the company makes required payments to holders of its bonds and other debt. Thus, the value of preferred stocks will usually react more strongly than bonds and other debt to actual or perceived changes in the company's financial condition or prospects. The market value of preferred stocks generally decreases when interest rates rise. Preferred stocks of smaller companies may be more vulnerable to adverse developments than preferred stocks of larger companies.

RISKS OF INITIAL PUBLIC OFFERINGS. Companies involved in initial public offerings (IPOs) generally have limited operating histories, and prospects for future profitability are uncertain. The market for IPO issuers has been volatile, and share prices of newly public companies have fluctuated significantly over short periods of time. The purchase of IPO shares may involve high transaction costs.

RISKS OF INVESTMENT IN OTHER FUNDS. Investing in other investment companies, including exchange-traded funds (ETFs), subjects the fund to the risks of investing in the underlying securities or assets held by those funds. When investing in another fund, the fund will bear a pro rata portion of the underlying fund's expenses, in addition to its own expenses.

DERIVATIVES RISK. Using swaps and other derivatives can increase fund losses and reduce opportunities for gains when market prices, interest rates or the derivative instruments themselves behave in a way not anticipated by the fund. Using derivatives may increase the volatility of the fund's net asset value and may not provide the result intended. Derivatives may have a leveraging effect on the fund. Some derivatives have the potential for unlimited loss, regardless of the size of the fund's initial investment. Changes in a derivative's value may not correlate well with the referenced asset or metric. The fund also may have to sell assets at inopportune times to satisfy its obligations. Derivatives may be difficult to sell, unwind or value, and the counterparty may default on its obligations to the fund. Use of derivatives may have different tax consequences for the fund than an investment in the underlying security, and such differences may affect the amount, timing and character of income distributed to shareholders. The U.S. government and foreign governments are in the process of adopting and implementing regulations governing derivatives markets, including mandatory clearing of certain derivatives, margin and reporting requirements. The ultimate impact of the regulations remains unclear. Additional regulation of derivatives may make them more costly, limit their availability or utility, otherwise adversely affect their performance or disrupt markets.

CREDIT DEFAULT SWAP RISK. Credit default swap contracts, a type of derivative instrument, involve special risks and may result in losses to the fund. Credit default swaps may in some cases be illiquid, and they increase credit risk since the fund has exposure to the issuer of the referenced obligation and either the counterparty to the credit default swap or, if it is a cleared transaction, the brokerage firm through which the trade was cleared and the clearing organization that is the counterparty to that trade.

RISKS OF INVESTING IN INVERSE FLOATING RATE OBLIGATIONS. The interest rate on inverse floating rate obligations will generally decrease as short-term interest rates increase, and increase as short-term rates decrease. Due to their leveraged structure, the sensitivity of the market value of an inverse floating rate obligation to changes in interest rates is generally greater than a comparable long-term bond issued by the same issuer and with similar credit quality, redemption and maturity provisions. Inverse floating rate obligations may be volatile and involve leverage risk.

LEVERAGING RISK. The value of your investment may be more volatile and other risks tend to be compounded if the fund borrows or uses derivatives or other investments, such as ETFs, that have embedded leverage. Leverage generally magnifies the effect of any increase or decrease in the value of the fund's underlying assets and creates a risk of loss of value on a larger pool of assets than the fund would otherwise have, potentially resulting in the loss of all assets. Engaging in such transactions may cause the fund to liquidate positions when it may not be advantageous to do so to satisfy its obligations or meet segregation requirements.

MARKET SEGMENT RISK. To the extent the fund emphasizes, from time to time, investments in a market segment, the fund will be subject to a greater degree to the risks particular to that segment, and may experience greater market fluctuation than a fund without the same focus.

REPURCHASE AGREEMENT RISK. In the event that the other party to a repurchase agreement defaults on its obligations, the fund may encounter delay and incur costs before being able to sell the security. Such a delay may involve loss of interest or a decline in price of the security. In addition, if the fund is characterized by a court as an unsecured creditor, it would be at risk of losing some or all of the principal and interest involved in the transaction.

VALUATION RISK. The sales price the fund could receive for any particular portfolio investment may differ from the fund's valuation of the investment, particularly for illiquid securities and securities that trade in thin or volatile markets or that are valued using a fair value methodology. Investors who purchase or redeem fund shares on days when the fund is holding fair-valued securities may receive fewer or more shares or lower or higher redemption proceeds than they would have received if the fund had not fair-valued the securities or had used a different valuation methodology. The fund's ability to value its investments may also be impacted by technological issues and/or errors by pricing services or other third party service providers.

REDEMPTION RISK. The fund may experience heavy redemptions that could cause the fund to liquidate its assets at inopportune times or at a loss or depressed value, which could cause the value of your investment to decline.

EXPENSE RISK. Your actual costs of investing in the fund may be higher than the expenses shown in "Annual fund operating expenses" for a variety of reasons. For example, expense ratios may be higher than those shown if overall net assets decrease. Net assets are more likely to decrease and fund expense ratios are more likely to increase when markets are volatile.

Please note that there are many other factors that could adversely affect your investment and that could prevent the fund from achieving its goals.

An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

THE FUND'S PAST PERFORMANCE

The bar chart and table indicate the risks and volatility of an investment in the fund by showing how the fund has performed in the past. The bar chart shows changes in the performance of the fund's Class A shares from calendar year to calendar year. The table shows the average annual total returns for each class of the fund over time and compares these returns to the returns of the Standard and Poor's 500 Index and the Bloomberg Barclays Capital U.S. Government/Credit Index, each a broad-based measure of market performance that has characteristics relevant to the fund's investment strategies. You can obtain updated performance information by visiting https://us.pioneerinvestments.com/performance or by calling 1-800-225-6292.

The fund acquired the assets and liabilities of AmSouth Balanced Fund (the predecessor fund) on September 23, 2005. Prior to September 23, 2005, the fund was advised by a different investment adviser.

The performance of Class A shares of the fund includes the net asset value performance of the predecessor fund's Class A shares prior to the reorganization, which has been restated to reflect differences in any applicable sales charges (but not differences in expenses). The performance of Class Y shares of the fund includes the net asset value performance of the predecessor fund's Class I shares prior to the reorganization, which has not been restated to reflect differences in expenses. The predecessor fund did not offer Class C shares. The performance of the fund's Class C shares is based upon the net asset value performance of the predecessor fund's Class B shares, which has been restated to reflect sales charges applicable to Class C shares (but not other differences in expenses). If all the expenses of the Pioneer fund were reflected, the performance would be lower.

The fund's past performance (before and after taxes) does not necessarily indicate how it will perform in the future.

The bar chart does not reflect any sales charge you may pay when you buy fund shares. If this amount was reflected, returns would be less than those shown.

ANNUAL RETURN CLASS A SHARES (%)
(Year ended December 31)

For the period covered by the bar chart:
THE HIGHEST CALENDAR QUARTERLY RETURN WAS 12.88% (07/01/2009 TO 09/30/2009).
THE LOWEST CALENDAR QUARTERLY RETURN WAS -12.71% (10/01/2008 TO 12/31/2008).

At September 30, 2017, the year-to-date return was 10.09%.

AVERAGE ANNUAL TOTAL RETURN (%)

(for periods ended December 31, 2016)

Average Annual Total Returns - Pioneer Classic Balanced Fund	1 YEAR	5 YEARS	10 YEARS	SINCE INCEPTION	INCEPTION DATE
Class A	1.23%	7.79%	5.01%	7.69%	Dec. 19, 1991
Class A | Return after taxes on distributions	0.54%	5.55%	3.28%	5.55%	Dec. 19, 1991
Class A | Return after taxes on distributions and sale of shares	1.09%	5.79%	3.64%	5.71%	Dec. 19, 1991
Class C	5.21%	7.93%	4.61%	5.41%	Sep. 03, 1997
Class K	6.16%			3.62%	Dec. 01, 2015
Class R	5.80%			2.01%	Jul. 01, 2015
Class Y	6.20%	9.08%	5.81%	8.04%	Dec. 19, 1991
Standard & Poor's 500 Index (reflects no deduction for fees, expenses or taxes)	11.96%	14.66%	6.95%	9.52%	Dec. 19, 1991
Bloomberg Barclays U.S. Government/Credit Bond Index (reflects no deduction for fees, expenses or taxes)	3.05%	2.29%	4.40%	5.82%	Dec. 19, 1991

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor's tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.

After-tax returns are shown only for Class A shares. After-tax returns for Class C, Class K, Class R and Class Y shares will vary.

[1] Class A purchases of $500,000 or more that are not subject to an initial sales charge may be subject to a contingent deferred sales charge of 1%. See "Sales charges."

[1] Total annual fund operating expenses in the table, before and after fee waiver and expense reimbursement, may be higher than the corresponding ratio of expenses to average net assets shown in the "Financial Highlights" section, which does not include acquired fund fees and expenses.

[2] The fund's investment adviser has contractually agreed to limit ordinary operating expenses (ordinary operating expenses means all fund expenses other than taxes, brokerage commissions, acquired fund fees and expenses, and extraordinary expenses, such as litigation) to the extent required to reduce fund expenses to 1.16% and 1.30% of the average daily net assets attributable to Class A and Class R shares, respectively. These expense limitations are in effect through December 1, 2019. There can be no assurance that the adviser will extend the expense limitations beyond such time. While in effect, the arrangement may be terminated for a class only by agreement of the adviser and the Board of Trustees.

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Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	Pioneer Series Trust IV
Prospectus Date	rr_ProspectusDate	Dec. 01, 2017
Pioneer Classic Balanced Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	PIONEER CLASSIC BALANCED FUND
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVES
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Capital growth and current income.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the fund. You may qualify for sales charge discounts if you or your family invest, or agree to invest in the future, at least $100,000 in Class A shares of the Pioneer funds. More information about these and other discounts is available from your investment professional and in the "Sales charges" section of the prospectus beginning on page 60, the "Intermediary defined sales charge waiver policies" section of the prospectus beginning on page 100, and the "Sales charges" section of the statement of additional information beginning on page 67.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	SHAREOWNER FEES (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	December 1, 2019
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	PORTFOLIO TURNOVER
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 51% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	51.00%
Expenses Deferred Charges [Text Block]	rr_ExpensesDeferredChargesTextBlock	Class A purchases of $500,000 or more that are not subject to an initial sales charge may be subject to a contingent deferred sales charge of 1%. See "Sales charges."
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	You may qualify for sales charge discounts if you or your family invest, or agree to invest in the future, at least $100,000 in Class A shares of the Pioneer funds.
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	$ 100,000
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]	rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees	Total annual fund operating expenses in the table, before and after fee waiver and expense reimbursement, may be higher than the corresponding ratio of expenses to average net assets shown in the "Financial Highlights" section, which does not include acquired fund fees and expenses.
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE
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 in the fund for the time periods shown and then, except as indicated, redeem all of your shares at the end of those periods. It also assumes that (a) your investment has a 5% return each year and (b) the fund's total annual operating expenses remain the same except for year one (which considers the effect of the expense limitation). Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	IF YOU REDEEM YOUR SHARES NUMBER OF YEARS YOU OWN YOUR SHARES
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	IF YOU DO NOT REDEEM YOUR SHARES NUMBER OF YEARS YOU OWN YOUR SHARES
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The fund's investment adviser allocates the fund's assets between equity and debt securities based on its assessment of current business, economic and market conditions. Normally, equity and debt securities each represent 35% to 65% of the fund's net assets. Equity securities in which the fund invests include common stocks and securities with common stock characteristics, such as equity interests in real estate investment trusts (REITs), funds that invest primarily in equity securities, and preferred stocks. Debt securities in which the fund invests include instruments and obligations of U.S. and non-U.S. corporate and other non-governmental entities, those of U.S. and non-U.S. governmental entities, mortgage-related or mortgage-backed securities (including "sub-prime" mortgages), asset-backed securities, municipal securities, floating rate loans, debt convertible to equity securities, subordinated debt securities, event-linked bonds and other insurance-linked securities, funds that invest primarily in debt securities, short-term debt securities, cash and cash equivalents. The fund may invest in debt securities with a broad range of maturities and maintains an average portfolio maturity which varies based upon the judgment of the fund's investment adviser. Debt securities in which the fund invests may have fixed or variable principal payments and all types of interest rate payment and reset terms, including fixed rate, adjustable rate, floating rate, inverse floating rate, zero coupon, contingent, deferred, payment in kind and auction rate features. The fund's investments may include instruments that allow for balloon payments or negative amortization payments. The fund may invest up to 20% of its net assets in securities that are below investment grade (also known as "junk bonds"), including convertible debt. The fund may invest up to 20% of its net assets in real estate investment trusts (REITs). The fund may invest up to 25% of its total assets in equity and debt securities of non-U.S. issuers. The fund will not invest more than 5% of its total assets in the securities of emerging markets issuers. The fund may, but is not required to, use derivatives, such as credit default swaps. The fund may use derivatives for a variety of purposes, including: in an attempt to hedge against adverse changes in the market price of securities, interest rates or currency exchange rates; as a substitute for purchasing or selling securities; to attempt to increase the fund's return as a non-hedging strategy that may be considered speculative; to manage portfolio characteristics; and as a cash flow management technique. The fund may choose not to make use of derivatives for a variety of reasons, and any use may be limited by applicable law and regulations. The fund may also hold cash or other short-term investments. In selecting equity securities to buy and sell, the fund's investment adviser uses a value approach to select the fund's investments. Using this investment style, the adviser seeks securities selling at reasonable prices or substantial discounts to their underlying values and then holds these securities until the market values reflect their intrinsic values. In selecting debt securities to buy and sell, the adviser considers both broad economic and issuer specific factors. In assessing the appropriate maturity, credit quality and sector weighting of the fund's portfolio, the adviser considers a variety of factors that are expected to influence economic activity and interest rates. The adviser selects individual securities to buy and sell based upon such factors as a security's yield, liquidity and rating, an assessment of credit quality, and sector and issuer diversification.
Risk [Heading]	rr_RiskHeading	PRINCIPAL RISKS OF INVESTING IN THE FUND
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	You could lose money on your investment in the fund. As with any mutual fund, there is no guarantee that the fund will achieve its objectives. MARKET RISK. The value of securities held by the fund may go up or down, sometimes rapidly or unpredictably, due to general market conditions, such as real or perceived adverse economic, political, or regulatory conditions, inflation, changes in interest or currency rates, lack of liquidity in the bond markets or adverse investor sentiment. In the past decade, financial markets throughout the world have experienced increased volatility, depressed valuations, decreased liquidity and heightened uncertainty. Governmental and non-governmental issuers have defaulted on, or been forced to restructure, their debts. These conditions may continue, recur, worsen or spread. Events that have contributed to these market conditions include, but are not limited to, major cybersecurity events; geopolitical events (including wars and terror attacks); measures to address budget deficits; downgrading of sovereign debt; declines in oil and commodity prices; dramatic changes in currency exchange rates; and public sentiment. The U.S. government and the Federal Reserve, as well as certain foreign governments and their central banks, have taken steps to support financial markets, including by keeping interest rates at historically low levels. This and other government intervention may not work as intended, particularly if the efforts are perceived by investors as being unlikely to achieve the desired results. The Federal Reserve has reduced its market support activities and has begun raising interest rates. Certain foreign governments and central banks are implementing or discussing so-called negative interest rates (e.g., charging depositors who keep their cash at a bank) to spur economic growth. Further Federal Reserve or other U.S. or non-U.S. governmental or central bank actions, including interest rate increases or contrary actions by different governments, could negatively affect financial markets generally, increase market volatility and reduce the value and liquidity of securities in which the fund invests. Policy and legislative changes in the U.S. and in other countries are affecting many aspects of financial regulation, and may in some instances contribute to decreased liquidity and increased volatility in the financial markets. The impact of these changes on the markets, and the practical implications for market participants, may not be fully known for some time. Economies and financial markets throughout the world are increasingly interconnected. Economic, financial or political events, trading and tariff arrangements, terrorism, natural disasters and other circumstances in one country or region could have profound impacts on global economies or markets. As a result, whether or not the fund invests in securities of issuers located in or with significant exposure to the countries directly affected, the value and liquidity of the fund's investments may be negatively affected. The fund may experience a substantial or complete loss on any individual security or derivative position. VALUE STYLE RISK. The prices of securities the adviser believes are undervalued may not appreciate as expected or may go down. Value stocks may fall out of favor with investors and underperform the overall equity market. PORTFOLIO SELECTION RISK. The adviser's judgment about a particular security or issuer, or about the economy or a particular sector, region or market segment, or about an investment strategy, may prove to be incorrect. INTEREST RATE RISK. Interest rates may go up, causing the value of the fund's investments to decline (this risk generally will be greater for securities with longer maturities or durations). For example, if interest rates increase by 1%, the value of a fund's portfolio with a portfolio duration of ten years would be expected to decrease by 10%, all other things being equal. Interest rates in the U.S. recently have been historically low, so the fund faces a heightened risk that interest rates may rise. A general rise in interest rates may cause investors to move out of fixed income securities on a large scale, which could adversely affect the price and liquidity of fixed income securities and could also result in increased redemptions from the fund. The maturity of a security may be significantly longer than its effective duration. A security's maturity and other features may be more relevant than its effective duration in determining the security's sensitivity to other factors affecting the issuer or markets generally such as changes in credit quality or in the yield premium that the market may establish for certain types of securities. CREDIT RISK. If an issuer or guarantor of a security held by the fund or a counterparty to a financial contract with the fund defaults on its obligation to pay principal and/or interest, has its credit rating downgraded or is perceived to be less creditworthy, or the credit quality or value of any underlying assets declines, the value of your investment will typically decline. PREPAYMENT OR CALL RISK. Many issuers have a right to prepay their securities. If interest rates fall, an issuer may exercise this right. If this happens, the fund will not benefit from the rise in market price that normally accompanies a decline in interest rates, and will be forced to reinvest prepayment proceeds at a time when yields on securities available in the market are lower than the yield on the prepaid security. The fund also may lose any premium it paid on the security. EXTENSION RISK. During periods of rising interest rates, the average life of certain types of securities may be extended because of slower than expected principal payments. This may lock in a below market interest rate, increase the security's duration and reduce the value of the security. LIQUIDITY RISK. Some securities and derivatives held by the fund may be impossible or difficult to purchase, sell or unwind, particularly during times of market turmoil. An instrument's liquidity may be affected by reduced trading volume, a relative lack of market makers or legal restrictions, and illiquid securities and derivatives also may be difficult to value. Liquidity risk may be magnified in a rising interest rate environment. If the fund is forced to sell an illiquid asset or unwind a derivatives position to meet redemption requests or other cash needs, the fund may be forced to sell at a loss. The fund may not receive its proceeds from the sale of certain securities for an extended period (for example, several weeks or even longer). In extreme cases, this may constrain the fund's ability to meet its obligations (including obligations to redeeming shareholders). U.S. TREASURY OBLIGATIONS RISK. The market value of direct obligations of the U.S. Treasury may vary due to changes in interest rates. In addition, changes to the financial condition or credit rating of the U.S. government may cause the value of the fund's investments in obligations issued by the U.S. Treasury to decline. U.S. GOVERNMENT AGENCY OBLIGATIONS RISK. The fund invests in obligations issued by agencies and instrumentalities of the U.S. government. Government-sponsored entities such as FNMA, FHLMC and the FHLBs, although chartered or sponsored by Congress, are not funded by congressional appropriations and the debt and mortgage-backed securities issued by them are neither guaranteed nor issued by the U.S. government. The maximum potential liability of the issuers of some U.S. government obligations may greatly exceed their current resources, including any legal right to support from the U.S. government. Such debt and mortgage-backed securities are subject to the risk of default on the payment of interest and/or principal, similar to debt of private issuers. Although the U.S. government has provided financial support to FNMA and FHLMC in the past, there can be no assurance that it will support these or other government-sponsored entities in the future. MORTGAGE-RELATED AND ASSET-BACKED SECURITIES RISK. The value of mortgage-related and asset-backed securities will be influenced by factors affecting the housing market and the assets underlying such securities. As a result, during periods of declining asset value, difficult or frozen credit markets, swings in interest rates, or deteriorating economic conditions, mortgage-related and asset-backed securities may decline in value, face valuation difficulties, become more volatile and/or become illiquid. Mortgage-backed securities tend to be more sensitive to changes in interest rate than other types of debt securities. These securities are also subject to prepayment and extension risks. Some of these securities may receive little or no collateral protection from the underlying assets and are thus subject to the risk of default. The risk of such defaults is generally higher in the case of mortgage-backed investments that include so-called "sub-prime" mortgages. The structure of some of these securities may be complex and there may be less available information than for other types of debt securities. Upon the occurrence of certain triggering events or defaults, the fund may become the holder of underlying assets at a time when those assets may be difficult to sell or may be sold only at a loss. RISKS OF INSTRUMENTS THAT ALLOW FOR BALLOON PAYMENTS OR NEGATIVE AMORTIZATION PAYMENTS. Certain debt instruments allow for balloon payments or negative amortization payments. Such instruments permit the borrower to avoid paying currently a portion of the interest accruing on the instrument. While these features make the debt instrument more affordable to the borrower in the near term, they increase the risk that the borrower will be unable to make the resulting higher payment or payments that become due at the maturity of the loan. HIGH YIELD OR "JUNK" BOND RISK. Debt securities that are below investment grade, called "junk bonds," are speculative, have a higher risk of default or are already in default, tend to be less liquid and are more difficult to value than higher grade securities. Junk bonds tend to be volatile and more susceptible to adverse events and negative sentiments. These risks are more pronounced for securities that are already in default. RISKS OF INVESTING IN FLOATING RATE LOANS. Floating rate loans and similar investments may be illiquid or less liquid than other investments and difficult to value. The value of collateral, if any, securing a floating rate loan can decline or may be insufficient to meet the issuer's obligations or may be difficult to liquidate. Market quotations for these securities may be volatile and/or subject to large spreads between bid and ask prices. No active trading market may exist for many floating rate loans, and many loans are subject to restrictions on resale. Any secondary market may be subject to irregular trading activity and extended trade settlement periods. In particular, loans may take longer than seven days to settle, potentially leading to the sale proceeds of loans not being available to meet redemptions for a substantial period of time after the sale of the loans. To the extent that sale proceeds of loans are not available, the fund may sell securities that have shorter settlement periods or may access other sources of liquidity to meet redemption requests. Loans may not be considered "securities," and purchasers, such as the fund, therefore may not be entitled to rely on the anti-fraud protections afforded by federal securities laws. RISKS OF INVESTING IN INSURANCE-LINKED SECURITIES. The return of principal and the payment of interest on "event-linked" bonds and other insurance-linked securities are contingent on the non-occurrence of a pre-defined "trigger" event, such as a hurricane or an earthquake of a specific magnitude or other event that leads to physical or economic loss. If a trigger event, as defined within the terms of an event-linked bond, involves losses or other metrics exceeding a specific magnitude in the geographic region and time period specified, the fund may lose a portion or all of its accrued interest and/or principal invested in the event-linked bond. In addition to the specified trigger events, event-linked bonds may expose the fund to other risks, including but not limited to issuer (credit) default, adverse regulatory or jurisdictional interpretations and adverse tax consequences. Certain insurance-linked securities may have limited liquidity, or may be illiquid. The fund has limited transparency into the individual contracts underlying certain insurance-linked securities, which may make the risk assessment of such securities more difficult. Certain insurance-linked securities may be difficult to value. RISKS OF SUBORDINATED SECURITIES. A holder of securities that are subordinated or "junior" to more senior securities of an issuer is entitled to payment after holders of more senior securities of the issuer. Subordinated securities are more likely to suffer a credit loss than non-subordinated securities of the same issuer, any loss incurred by the subordinated securities is likely to be proportionately greater, and any recovery of interest or principal may take more time. As a result, even a perceived decline in creditworthiness of the issuer is likely to have a greater impact on subordinated securities. MUNICIPAL SECURITIES RISK. The municipal bond market can be susceptible to unusual volatility, particularly for lower-rated and unrated securities. Liquidity can be reduced unpredictably in response to overall economic conditions or credit tightening. Municipal issuers may be adversely affected by rising health care costs, increasing unfunded pension liabilities, and by the phasing out of federal programs providing financial support. Unfavorable conditions and developments relating to projects financed with municipal securities can result in lower revenues to issuers of municipal securities, potentially resulting in defaults. Issuers often depend on revenues from these projects to make principal and interest payments. The value of municipal securities can also be adversely affected by changes in the financial condition of one or more individual municipal issuers or insurers of municipal issuers, regulatory and political developments, tax law changes or other legislative actions, and by uncertainties and public perceptions concerning these and other factors. Municipal issuers may be more susceptible to downgrades or defaults during recessions or similar periods of economic stress. In recent periods, an increasing number of municipal issuers in the United States have defaulted on obligations and commenced insolvency proceedings. Financial difficulties of municipal issuers may continue or get worse. To the extent the fund invests significantly in a single state or in securities the payments on which are dependent upon a single project or source of revenues, or that relate to a sector or industry, the fund will be more susceptible to associated risks and developments. RISKS OF ZERO COUPON BONDS, PAYMENT IN KIND, DEFERRED AND CONTINGENT PAYMENT SECURITIES. These securities may be more speculative and may fluctuate more in value than securities which pay income periodically and in cash. In addition, although the fund receives no periodic cash payments on such securities, the fund is deemed for tax purposes to receive income from such securities, which applicable tax rules require the fund to distribute to shareholders. Such distributions may be taxable when distributed to shareholders. RISKS OF NON-U.S. INVESTMENTS. Investing in non-U.S. issuers, or in U.S. issuers that have significant exposure to foreign markets, may involve unique risks compared to investing in securities of U.S. issuers. These risks are more pronounced for issuers in emerging markets or to the extent that the fund invests significantly in one region or country. These risks may include different financial reporting practices and regulatory standards, less liquid trading markets, extreme price volatility, currency risks, changes in economic, political, regulatory and social conditions, terrorism, sustained economic downturns, financial instability, tax burdens, and investment and repatriation restrictions. Lack of information and less market regulation also may affect the value of these securities. Withholding and other non-U.S. taxes may decrease the fund's return. Non-U.S. issuers may be located in parts of the world that have historically been prone to natural disasters. Investing in depositary receipts is subject to many of the same risks as investing directly in non-U.S. issuers. Depositary receipts may involve higher expenses and may trade at a discount (or premium) to the underlying security. A number of countries in the European Union (EU) have experienced, and may continue to experience, severe economic and financial difficulties. In addition, voters in the United Kingdom have approved withdrawal from the EU. Other countries may seek to withdraw from the EU and/or abandon the euro, the common currency of the EU. RISKS OF INVESTMENTS IN REAL ESTATE RELATED SECURITIES. Investments in real estate securities are affected by economic conditions, interest rates, governmental actions and other factors. In addition, investing in REITs involves unique risks. They are significantly affected by the market for real estate and are dependent upon management skills and cash flow. REITs may have lower trading volumes and may be subject to more abrupt or erratic price movements than the overall securities markets. Mortgage REITs are particularly subject to interest rate and credit risks. In addition to its own expenses, the fund will indirectly bear its proportionate share of any management and other expenses paid by REITs in which it invests. Many real estate companies, including REITs, utilize leverage. RISKS OF CONVERTIBLE SECURITIES. The market values of convertible securities tend to decline as interest rates increase and, conversely, to increase as interest rates decline. A downturn in equity markets may cause the price of convertible securities to decrease relative to other fixed income securities. PREFERRED STOCKS RISK. Preferred stocks may pay fixed or adjustable rates of return. Preferred stocks are subject to issuer-specific and market risks applicable generally to equity securities. In addition, a company's preferred stocks generally pay dividends only after the company makes required payments to holders of its bonds and other debt. Thus, the value of preferred stocks will usually react more strongly than bonds and other debt to actual or perceived changes in the company's financial condition or prospects. The market value of preferred stocks generally decreases when interest rates rise. Preferred stocks of smaller companies may be more vulnerable to adverse developments than preferred stocks of larger companies. RISKS OF INITIAL PUBLIC OFFERINGS. Companies involved in initial public offerings (IPOs) generally have limited operating histories, and prospects for future profitability are uncertain. The market for IPO issuers has been volatile, and share prices of newly public companies have fluctuated significantly over short periods of time. The purchase of IPO shares may involve high transaction costs. RISKS OF INVESTMENT IN OTHER FUNDS. Investing in other investment companies, including exchange-traded funds (ETFs), subjects the fund to the risks of investing in the underlying securities or assets held by those funds. When investing in another fund, the fund will bear a pro rata portion of the underlying fund's expenses, in addition to its own expenses. DERIVATIVES RISK. Using swaps and other derivatives can increase fund losses and reduce opportunities for gains when market prices, interest rates or the derivative instruments themselves behave in a way not anticipated by the fund. Using derivatives may increase the volatility of the fund's net asset value and may not provide the result intended. Derivatives may have a leveraging effect on the fund. Some derivatives have the potential for unlimited loss, regardless of the size of the fund's initial investment. Changes in a derivative's value may not correlate well with the referenced asset or metric. The fund also may have to sell assets at inopportune times to satisfy its obligations. Derivatives may be difficult to sell, unwind or value, and the counterparty may default on its obligations to the fund. Use of derivatives may have different tax consequences for the fund than an investment in the underlying security, and such differences may affect the amount, timing and character of income distributed to shareholders. The U.S. government and foreign governments are in the process of adopting and implementing regulations governing derivatives markets, including mandatory clearing of certain derivatives, margin and reporting requirements. The ultimate impact of the regulations remains unclear. Additional regulation of derivatives may make them more costly, limit their availability or utility, otherwise adversely affect their performance or disrupt markets. CREDIT DEFAULT SWAP RISK. Credit default swap contracts, a type of derivative instrument, involve special risks and may result in losses to the fund. Credit default swaps may in some cases be illiquid, and they increase credit risk since the fund has exposure to the issuer of the referenced obligation and either the counterparty to the credit default swap or, if it is a cleared transaction, the brokerage firm through which the trade was cleared and the clearing organization that is the counterparty to that trade. RISKS OF INVESTING IN INVERSE FLOATING RATE OBLIGATIONS. The interest rate on inverse floating rate obligations will generally decrease as short-term interest rates increase, and increase as short-term rates decrease. Due to their leveraged structure, the sensitivity of the market value of an inverse floating rate obligation to changes in interest rates is generally greater than a comparable long-term bond issued by the same issuer and with similar credit quality, redemption and maturity provisions. Inverse floating rate obligations may be volatile and involve leverage risk. LEVERAGING RISK. The value of your investment may be more volatile and other risks tend to be compounded if the fund borrows or uses derivatives or other investments, such as ETFs, that have embedded leverage. Leverage generally magnifies the effect of any increase or decrease in the value of the fund's underlying assets and creates a risk of loss of value on a larger pool of assets than the fund would otherwise have, potentially resulting in the loss of all assets. Engaging in such transactions may cause the fund to liquidate positions when it may not be advantageous to do so to satisfy its obligations or meet segregation requirements. MARKET SEGMENT RISK. To the extent the fund emphasizes, from time to time, investments in a market segment, the fund will be subject to a greater degree to the risks particular to that segment, and may experience greater market fluctuation than a fund without the same focus. REPURCHASE AGREEMENT RISK. In the event that the other party to a repurchase agreement defaults on its obligations, the fund may encounter delay and incur costs before being able to sell the security. Such a delay may involve loss of interest or a decline in price of the security. In addition, if the fund is characterized by a court as an unsecured creditor, it would be at risk of losing some or all of the principal and interest involved in the transaction. VALUATION RISK. The sales price the fund could receive for any particular portfolio investment may differ from the fund's valuation of the investment, particularly for illiquid securities and securities that trade in thin or volatile markets or that are valued using a fair value methodology. Investors who purchase or redeem fund shares on days when the fund is holding fair-valued securities may receive fewer or more shares or lower or higher redemption proceeds than they would have received if the fund had not fair-valued the securities or had used a different valuation methodology. The fund's ability to value its investments may also be impacted by technological issues and/or errors by pricing services or other third party service providers. REDEMPTION RISK. The fund may experience heavy redemptions that could cause the fund to liquidate its assets at inopportune times or at a loss or depressed value, which could cause the value of your investment to decline. EXPENSE RISK. Your actual costs of investing in the fund may be higher than the expenses shown in "Annual fund operating expenses" for a variety of reasons. For example, expense ratios may be higher than those shown if overall net assets decrease. Net assets are more likely to decrease and fund expense ratios are more likely to increase when markets are volatile. Please note that there are many other factors that could adversely affect your investment and that could prevent the fund from achieving its goals. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	You could lose money on your investment in the fund.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	THE FUND'S PAST PERFORMANCE
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table indicate the risks and volatility of an investment in the fund by showing how the fund has performed in the past. The bar chart shows changes in the performance of the fund's Class A shares from calendar year to calendar year. The table shows the average annual total returns for each class of the fund over time and compares these returns to the returns of the Standard and Poor's 500 Index and the Bloomberg Barclays Capital U.S. Government/Credit Index, each a broad-based measure of market performance that has characteristics relevant to the fund's investment strategies. You can obtain updated performance information by visiting https://us.pioneerinvestments.com/performance or by calling 1-800-225-6292. The fund acquired the assets and liabilities of AmSouth Balanced Fund (the predecessor fund) on September 23, 2005. Prior to September 23, 2005, the fund was advised by a different investment adviser. The performance of Class A shares of the fund includes the net asset value performance of the predecessor fund's Class A shares prior to the reorganization, which has been restated to reflect differences in any applicable sales charges (but not differences in expenses). The performance of Class Y shares of the fund includes the net asset value performance of the predecessor fund's Class I shares prior to the reorganization, which has not been restated to reflect differences in expenses. The predecessor fund did not offer Class C shares. The performance of the fund's Class C shares is based upon the net asset value performance of the predecessor fund's Class B shares, which has been restated to reflect sales charges applicable to Class C shares (but not other differences in expenses). If all the expenses of the Pioneer fund were reflected, the performance would be lower. The fund's past performance (before and after taxes) does not necessarily indicate how it will perform in the future. The bar chart does not reflect any sales charge you may pay when you buy fund shares. If this amount was reflected, returns would be less than those shown.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table indicate the risks and volatility of an investment in the fund by showing how the fund has performed in the past. The bar chart shows changes in the performance of the fund's Class A shares from calendar year to calendar year. The table shows the average annual total returns for each class of the fund over time and compares these returns to the returns of the Standard and Poor's 500 Index and the Bloomberg Barclays Capital U.S. Government/Credit Index, each a broad-based measure of market performance that has characteristics relevant to the fund's investment strategies.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table shows the average annual total returns for each class of the fund over time and compares these returns to the returns of the Standard and Poor's 500 Index and the Bloomberg Barclays Capital U.S. Government/Credit Index, each a broad-based measure of market performance that has characteristics relevant to the fund's investment strategies.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-800-225-6292
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	https://us.pioneerinvestments.com/performance
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The fund's past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	ANNUAL RETURN CLASS A SHARES (%) (Year ended December 31)
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The bar chart does not reflect any sales charge you may pay when you buy fund shares. If this amount was reflected, returns would be less than those shown.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	For the period covered by the bar chart: THE HIGHEST CALENDAR QUARTERLY RETURN WAS 12.88% (07/01/2009 TO 09/30/2009). THE LOWEST CALENDAR QUARTERLY RETURN WAS -12.71% (10/01/2008 TO 12/31/2008). At September 30, 2017, the year-to-date return was 10.09%.
Performance Table Heading	rr_PerformanceTableHeading	AVERAGE ANNUAL TOTAL RETURN (%) (for periods ended December 31, 2016)
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	The performance of Class A shares of the fund includes the net asset value performance of the predecessor fund's Class A shares prior to the reorganization, which has been restated to reflect differences in any applicable sales charges (but not differences in expenses). The performance of the fund's Class C shares is based upon the net asset value performance of the predecessor fund's Class B shares, which has been restated to reflect sales charges applicable to Class C shares (but not other differences in expenses).
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on the investor's tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown only for Class A shares. After-tax returns for Class C, Class K, Class R and Class Y shares will vary.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor's tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown only for Class A shares. After-tax returns for Class C, Class K, Class R and Class Y shares will vary.
Pioneer Classic Balanced Fund | CLASS A
Risk/Return:	rr_RiskReturnAbstract
Maximum sales charge (load) when you buy shares (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	4.50%
Maximum deferred sales charge (load) (as a percentage of offering price or the amount you receive when you sell shares, whichever is less)	rr_MaximumDeferredSalesChargeOverOther	none	[1]
Management Fees	rr_ManagementFeesOverAssets	0.65%
Distribution and Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.29%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.13%	[2]
Total Annual Fund Operating Expenses Plus Acquired Fund Fees and Expenses	rr_ExpensesOverAssets	1.32%	[2]
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.03%)	[3]
Net Expenses Plus Acquired Fund Fees and Expenses	rr_NetExpensesOverAssets	1.29%	[3]
1	rr_ExpenseExampleYear01	$ 575
3	rr_ExpenseExampleYear03	847
5	rr_ExpenseExampleYear05	1,138
10	rr_ExpenseExampleYear10	1,966
1	rr_ExpenseExampleNoRedemptionYear01	575
3	rr_ExpenseExampleNoRedemptionYear03	847
5	rr_ExpenseExampleNoRedemptionYear05	1,138
10	rr_ExpenseExampleNoRedemptionYear10	$ 1,966
2007	rr_AnnualReturn2007	4.82%
2008	rr_AnnualReturn2008	(24.84%)
2009	rr_AnnualReturn2009	27.37%
2010	rr_AnnualReturn2010	9.88%
2011	rr_AnnualReturn2011	1.60%
2012	rr_AnnualReturn2012	10.36%
2013	rr_AnnualReturn2013	18.83%
2014	rr_AnnualReturn2014	10.51%
2015	rr_AnnualReturn2015	(0.82%)
2016	rr_AnnualReturn2016	5.97%
Year to Date Return, Label	rr_YearToDateReturnLabel	year-to-date return
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2017
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	10.09%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	HIGHEST CALENDAR QUARTERLY RETURN
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	12.88%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	LOWEST CALENDAR QUARTERLY RETURN
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(12.71%)
1 YEAR	rr_AverageAnnualReturnYear01	1.23%
5 YEARS	rr_AverageAnnualReturnYear05	7.79%
10 YEARS	rr_AverageAnnualReturnYear10	5.01%
SINCE INCEPTION	rr_AverageAnnualReturnSinceInception	7.69%
INCEPTION DATE	rr_AverageAnnualReturnInceptionDate	Dec. 19, 1991
Pioneer Classic Balanced Fund | CLASS C
Risk/Return:	rr_RiskReturnAbstract
Maximum sales charge (load) when you buy shares (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum deferred sales charge (load) (as a percentage of offering price or the amount you receive when you sell shares, whichever is less)	rr_MaximumDeferredSalesChargeOverOther	1.00%
Management Fees	rr_ManagementFeesOverAssets	0.65%
Distribution and Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.26%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.13%	[2]
Total Annual Fund Operating Expenses Plus Acquired Fund Fees and Expenses	rr_ExpensesOverAssets	2.04%	[2]
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[3]
Net Expenses Plus Acquired Fund Fees and Expenses	rr_NetExpensesOverAssets	2.04%	[3]
1	rr_ExpenseExampleYear01	$ 307
3	rr_ExpenseExampleYear03	640
5	rr_ExpenseExampleYear05	1,098
10	rr_ExpenseExampleYear10	2,369
1	rr_ExpenseExampleNoRedemptionYear01	207
3	rr_ExpenseExampleNoRedemptionYear03	640
5	rr_ExpenseExampleNoRedemptionYear05	1,098
10	rr_ExpenseExampleNoRedemptionYear10	$ 2,369
1 YEAR	rr_AverageAnnualReturnYear01	5.21%
5 YEARS	rr_AverageAnnualReturnYear05	7.93%
10 YEARS	rr_AverageAnnualReturnYear10	4.61%
SINCE INCEPTION	rr_AverageAnnualReturnSinceInception	5.41%
INCEPTION DATE	rr_AverageAnnualReturnInceptionDate	Sep. 03, 1997
Pioneer Classic Balanced Fund | CLASS K
Risk/Return:	rr_RiskReturnAbstract
Maximum sales charge (load) when you buy shares (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum deferred sales charge (load) (as a percentage of offering price or the amount you receive when you sell shares, whichever is less)	rr_MaximumDeferredSalesChargeOverOther	none
Management Fees	rr_ManagementFeesOverAssets	0.65%
Distribution and Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.20%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.13%	[2]
Total Annual Fund Operating Expenses Plus Acquired Fund Fees and Expenses	rr_ExpensesOverAssets	0.98%	[2]
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[3]
Net Expenses Plus Acquired Fund Fees and Expenses	rr_NetExpensesOverAssets	0.98%	[3]
1	rr_ExpenseExampleYear01	$ 100
3	rr_ExpenseExampleYear03	312
5	rr_ExpenseExampleYear05	542
10	rr_ExpenseExampleYear10	1,201
1	rr_ExpenseExampleNoRedemptionYear01	100
3	rr_ExpenseExampleNoRedemptionYear03	312
5	rr_ExpenseExampleNoRedemptionYear05	542
10	rr_ExpenseExampleNoRedemptionYear10	$ 1,201
1 YEAR	rr_AverageAnnualReturnYear01	6.16%
5 YEARS	rr_AverageAnnualReturnYear05
10 YEARS	rr_AverageAnnualReturnYear10
SINCE INCEPTION	rr_AverageAnnualReturnSinceInception	3.62%
INCEPTION DATE	rr_AverageAnnualReturnInceptionDate	Dec. 01, 2015
Pioneer Classic Balanced Fund | CLASS R
Risk/Return:	rr_RiskReturnAbstract
Maximum sales charge (load) when you buy shares (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum deferred sales charge (load) (as a percentage of offering price or the amount you receive when you sell shares, whichever is less)	rr_MaximumDeferredSalesChargeOverOther	none
Management Fees	rr_ManagementFeesOverAssets	0.65%
Distribution and Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.50%
Other Expenses	rr_OtherExpensesOverAssets	0.41%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.13%	[2]
Total Annual Fund Operating Expenses Plus Acquired Fund Fees and Expenses	rr_ExpensesOverAssets	1.69%	[2]
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.26%)	[3]
Net Expenses Plus Acquired Fund Fees and Expenses	rr_NetExpensesOverAssets	1.43%	[3]
1	rr_ExpenseExampleYear01	$ 146
3	rr_ExpenseExampleYear03	507
5	rr_ExpenseExampleYear05	893
10	rr_ExpenseExampleYear10	1,976
1	rr_ExpenseExampleNoRedemptionYear01	146
3	rr_ExpenseExampleNoRedemptionYear03	507
5	rr_ExpenseExampleNoRedemptionYear05	893
10	rr_ExpenseExampleNoRedemptionYear10	$ 1,976
1 YEAR	rr_AverageAnnualReturnYear01	5.80%
5 YEARS	rr_AverageAnnualReturnYear05
10 YEARS	rr_AverageAnnualReturnYear10
SINCE INCEPTION	rr_AverageAnnualReturnSinceInception	2.01%
INCEPTION DATE	rr_AverageAnnualReturnInceptionDate	Jul. 01, 2015
Pioneer Classic Balanced Fund | CLASS Y
Risk/Return:	rr_RiskReturnAbstract
Maximum sales charge (load) when you buy shares (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum deferred sales charge (load) (as a percentage of offering price or the amount you receive when you sell shares, whichever is less)	rr_MaximumDeferredSalesChargeOverOther	none
Management Fees	rr_ManagementFeesOverAssets	0.65%
Distribution and Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.30%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.13%	[2]
Total Annual Fund Operating Expenses Plus Acquired Fund Fees and Expenses	rr_ExpensesOverAssets	1.08%	[2]
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[3]
Net Expenses Plus Acquired Fund Fees and Expenses	rr_NetExpensesOverAssets	1.08%	[3]
1	rr_ExpenseExampleYear01	$ 110
3	rr_ExpenseExampleYear03	343
5	rr_ExpenseExampleYear05	595
10	rr_ExpenseExampleYear10	1,317
1	rr_ExpenseExampleNoRedemptionYear01	110
3	rr_ExpenseExampleNoRedemptionYear03	343
5	rr_ExpenseExampleNoRedemptionYear05	595
10	rr_ExpenseExampleNoRedemptionYear10	$ 1,317
1 YEAR	rr_AverageAnnualReturnYear01	6.20%
5 YEARS	rr_AverageAnnualReturnYear05	9.08%
10 YEARS	rr_AverageAnnualReturnYear10	5.81%
SINCE INCEPTION	rr_AverageAnnualReturnSinceInception	8.04%
INCEPTION DATE	rr_AverageAnnualReturnInceptionDate	Dec. 19, 1991
Pioneer Classic Balanced Fund | Return after taxes on distributions | CLASS A
Risk/Return:	rr_RiskReturnAbstract
1 YEAR	rr_AverageAnnualReturnYear01	0.54%
5 YEARS	rr_AverageAnnualReturnYear05	5.55%
10 YEARS	rr_AverageAnnualReturnYear10	3.28%
SINCE INCEPTION	rr_AverageAnnualReturnSinceInception	5.55%
INCEPTION DATE	rr_AverageAnnualReturnInceptionDate	Dec. 19, 1991
Pioneer Classic Balanced Fund | Return after taxes on distributions and sale of shares | CLASS A
Risk/Return:	rr_RiskReturnAbstract
1 YEAR	rr_AverageAnnualReturnYear01	1.09%
5 YEARS	rr_AverageAnnualReturnYear05	5.79%
10 YEARS	rr_AverageAnnualReturnYear10	3.64%
SINCE INCEPTION	rr_AverageAnnualReturnSinceInception	5.71%
INCEPTION DATE	rr_AverageAnnualReturnInceptionDate	Dec. 19, 1991
Pioneer Classic Balanced Fund | Standard & Poor's 500 Index (reflects no deduction for fees, expenses or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 YEAR	rr_AverageAnnualReturnYear01	11.96%
5 YEARS	rr_AverageAnnualReturnYear05	14.66%
10 YEARS	rr_AverageAnnualReturnYear10	6.95%
SINCE INCEPTION	rr_AverageAnnualReturnSinceInception	9.52%
INCEPTION DATE	rr_AverageAnnualReturnInceptionDate	Dec. 19, 1991
Pioneer Classic Balanced Fund | Bloomberg Barclays U.S. Government/Credit Bond Index (reflects no deduction for fees, expenses or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 YEAR	rr_AverageAnnualReturnYear01	3.05%
5 YEARS	rr_AverageAnnualReturnYear05	2.29%
10 YEARS	rr_AverageAnnualReturnYear10	4.40%
SINCE INCEPTION	rr_AverageAnnualReturnSinceInception	5.82%
INCEPTION DATE	rr_AverageAnnualReturnInceptionDate	Dec. 19, 1991

[1] Class A purchases of $500,000 or more that are not subject to an initial sales charge may be subject to a contingent deferred sales charge of 1%. See "Sales charges."

[2] Total annual fund operating expenses in the table, before and after fee waiver and expense reimbursement, may be higher than the corresponding ratio of expenses to average net assets shown in the "Financial Highlights" section, which does not include acquired fund fees and expenses.

[3] The fund's investment adviser has contractually agreed to limit ordinary operating expenses (ordinary operating expenses means all fund expenses other than taxes, brokerage commissions, acquired fund fees and expenses, and extraordinary expenses, such as litigation) to the extent required to reduce fund expenses to 1.16% and 1.30% of the average daily net assets attributable to Class A and Class R shares, respectively. These expense limitations are in effect through December 1, 2019. There can be no assurance that the adviser will extend the expense limitations beyond such time. While in effect, the arrangement may be terminated for a class only by agreement of the adviser and the Board of Trustees.

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Pioneer Multi-Asset Income Fund

PIONEER MULTI-ASSET INCOME FUND

INVESTMENT OBJECTIVES

A high level of current income.

Capital appreciation is a secondary objective.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund.

You may qualify for sales charge discounts if you or your family invest, or agree to invest in the future, at least $100,000 in Class A shares of the Pioneer funds. More information about these and other discounts is available from your investment professional and in the "Sales charges" section of the prospectus beginning on page 67, the "Intermediary defined sales charge waiver policies" section of the prospectus beginning on page 107, and the "Sales charges" section of the statement of additional information beginning on page 67.

SHAREOWNER FEES
(fees paid directly from your
investment)

Shareholder Fees - Pioneer Multi-Asset Income Fund	CLASS A		CLASS C	CLASS K	CLASS R	CLASS T	CLASS Y
Maximum sales charge (load) when you buy shares (as a percentage of offering price)	4.50%		none	none	none	2.50%	none
Maximum deferred sales charge (load) (as a percentage of offering price or the amount you receive when you sell shares, whichever is less)	none	[1]	1.00%	none	none	none	none

ANNUAL FUND OPERATING
EXPENSES
(expenses that you pay each year as a
percentage of the value of your
investment)

Annual Fund Operating Expenses - Pioneer Multi-Asset Income Fund		CLASS A	CLASS C	CLASS K	CLASS R	CLASS T	CLASS Y
Management Fees		0.50%	0.50%	0.50%	0.50%	0.50%	0.50%
Distribution and Service (12b-1) Fees		0.25%	1.00%	none	0.50%	0.25%	none
Other Expenses	[1]	0.17%	0.19%	0.13%	0.37%	0.17%	0.22%
Acquired Fund Fees and Expenses	[2]	0.31%	0.31%	0.31%	0.31%	0.31%	0.31%
Total Annual Fund Operating Expenses Plus Acquired Fund Fees and Expenses	[2]	1.23%	2.00%	0.94%	1.68%	1.23%	1.03%
Less: Fee Waiver and Expense Reimbursement	[3]	(0.07%)	none	none	none	(0.07%)	(0.07%)
Net Expenses Plus Acquired Fund Fees and Expenses	[3]	1.16%	2.00%	0.94%	1.68%	1.16%	0.96%

EXAMPLE

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 in the fund for the time periods shown and then, except as indicated, redeem all of your shares at the end of those periods. It also assumes that (a) your investment has a 5% return each year and (b) the fund's total annual operating expenses remain the same except for year one (which considers the effect of the expense limitation). Although your actual costs may be higher or lower, based on these assumptions your costs would be:

IF YOU REDEEM YOUR SHARES
NUMBER OF YEARS YOU OWN YOUR SHARES

Expense Example - Pioneer Multi-Asset Income Fund - USD ($)	1	3	5	10
Class A	563	816	1,089	1,866
Class C	303	627	1,078	2,327
Class K	96	300	520	1,155
Class R	171	530	913	1,987
Class T	365	624	902	1,695
Class Y	98	321	562	1,253

IF YOU DO NOT REDEEM YOUR SHARES
NUMBER OF YEARS YOU OWN YOUR SHARES

Expense Example, No Redemption - Pioneer Multi-Asset Income Fund - USD ($)	1	3	5	10
Class A	563	816	1,089	1,866
Class C	203	627	1,078	2,327
Class K	96	300	520	1,155
Class R	171	530	913	1,987
Class T	365	624	902	1,695
Class Y	98	321	562	1,253

PORTFOLIO TURNOVER

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 131% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The fund has the flexibility to invest in a broad range of income-producing investments, including both debt securities and equity securities. The fund may invest in the securities of issuers located throughout the world, including in emerging markets. In selecting investments, the fund's investment adviser considers both broad economic and investment-specific factors.

The fund may invest in a broad range of issuers and segments of the debt securities markets. The adviser allocates the fund's debt securities among different instruments and segments of the debt markets, based on its outlook for economic, interest rate and political trends. Debt securities may include instruments and obligations of U.S. and non-U.S. corporate and other non-governmental entities, those of U.S. and non-U.S. governmental entities, mortgage-related or mortgage-backed securities (including "sub-prime" mortgages), asset-backed securities, floating rate loans, convertible securities, Treasury Inflation Protected Securities ("TIPS") and other inflation-linked debt securities, subordinated debt securities, event-linked bonds and other insurance-linked securities, and funds that invest primarily in debt securities. The fund may invest without limit in debt securities of any credit quality, including those rated below investment grade (known as "junk bonds") or, if unrated, of equivalent credit quality as determined by the adviser. The fund's investments in debt securities rated below investment grade may include securities that are in default.

The fund invests in debt securities with a broad range of maturities. The fund's investments may have fixed or variable principal payments and all types of interest rate payment and reset terms, including fixed rate, adjustable rate, floating rate, zero coupon, contingent, deferred, payment in kind and auction rate features. The fund's investments may include instruments that allow for balloon payments or negative amortization payments. The fund may invest without limit in debt securities.

The fund may invest up to 60% of its total assets in equity securities. Equity securities include common stocks, rights, warrants, depositary receipts, funds that invest primarily in equity securities, preferred stock, equity interests in real estate trusts (REITs), equity-linked notes and master limited partnerships. Derivative instruments that provide exposure to equity securities or have similar economic characteristics may be considered equity securities under this policy.

The fund may invest without limit in debt and equity securities of non-U.S. issuers, including up to 30% of its total assets in debt and equity securities of emerging market issuers.

Equity-linked notes (ELNs) are hybrid structured investments that combine the characteristics of one or more reference underlying securities (usually a single stock, a basket of stocks or a stock index) and a related equity derivative, typically in the form of a note paying a stated interest rate.

In allocating assets among debt and equity securities, the adviser considers a variety of factors expected to influence global economic activity, including fundamental economic indicators, such as the rates of economic growth and inflation, monetary policy, geo-political factors, the performance of securities markets, and the relative value of the U.S. dollar compared to other currencies. The fund is not required to allocate its investments among debt and equity securities in any fixed proportion, nor is it limited by the issuer's geographic location, size or market capitalization. The relative proportions of the fund's investments in debt and equity securities may change over time based upon market and economic conditions.

In selecting individual securities to buy and sell, the adviser considers a security's income prospects relative to perceived risk. The adviser selects debt securities based upon such factors as a security's yield, liquidity and rating, an assessment of credit quality, and sector and issuer diversification. The adviser considers an equity security's potential to provide income in view of the sustainability of the issuer's earnings and financial condition. In selecting equity and debt securities, the adviser generally favors those securities it perceives to be undervalued. The adviser employs fundamental research in evaluating issuers, taking into account financial condition and profitability, future capital needs, potential for change in rating, industry outlook, the competitive environment and management ability. In making these portfolio decisions, the adviser relies on the knowledge, experience and judgment of its staff and the staff of its affiliates who have access to a wide variety of fundamental and quantitative research. In selecting among market segments and instruments, the adviser considers the relative value of particular investments. Investments typically are sold when the adviser's overall assessment of market and economic conditions changes or the assessments of the attributes of asset classes or individual holdings change.

The fund may invest in securities and instruments that are not income-producing for purposes of seeking capital appreciation or managing risk or other portfolio characteristics. The fund may, but is not required to, use derivatives, such as options, credit default swaps and interest rate swaps, forward currency exchange contracts and bond, index, interest rate and currency futures. The fund may use derivatives for a variety of purposes, including: in an attempt to hedge against adverse changes in the market price of securities, interest rates or currency exchange rates; as a substitute for purchasing or selling securities; to attempt to increase the fund's return as a non-hedging strategy that may be considered speculative; to manage portfolio characteristics; and as a cash flow management technique. In addition to investing in securities denominated in non-U.S. currencies, the fund may hold non-U.S. currencies and purchase and sell forward currency exchange contracts in non-U.S. currencies. The fund may invest without limit in derivative instruments. The fund may choose not to make use of derivatives for a variety of reasons, and any use may be limited to applicable law and regulations. The fund also may hold cash or other short-term investments.

PRINCIPAL RISKS OF INVESTING IN THE FUND

You could lose money on your investment in the fund. As with any mutual fund, there is no guarantee that the fund will achieve its objectives.

MARKET RISK. The value of securities held by the fund may go up or down, sometimes rapidly or unpredictably, due to general market conditions, such as real or perceived adverse economic, political, or regulatory conditions, inflation, changes in interest or currency rates, lack of liquidity in the bond markets or adverse investor sentiment. In the past decade, financial markets throughout the world have experienced increased volatility, depressed valuations, decreased liquidity and heightened uncertainty. Governmental and non-governmental issuers have defaulted on, or been forced to restructure, their debts. These conditions may continue, recur, worsen or spread. Events that have contributed to these market conditions include, but are not limited to, major cybersecurity events; geopolitical events (including wars and terror attacks); measures to address budget deficits; downgrading of sovereign debt; declines in oil and commodity prices; dramatic changes in currency exchange rates; and public sentiment. The U.S. government and the Federal Reserve, as well as certain foreign governments and their central banks, have taken steps to support financial markets, including by keeping interest rates at historically low levels. This and other government intervention may not work as intended, particularly if the efforts are perceived by investors as being unlikely to achieve the desired results. The Federal Reserve has reduced its market support activities and has begun raising interest rates. Certain foreign governments and central banks are implementing or discussing so-called negative interest rates (e.g., charging depositors who keep their cash at a bank) to spur economic growth. Further Federal Reserve or other U.S. or non-U.S. governmental or central bank actions, including interest rate increases or contrary actions by different governments, could negatively affect financial markets generally, increase market volatility and reduce the value and liquidity of securities in which the fund invests. Policy and legislative changes in the U.S. and in other countries are affecting many aspects of financial regulation, and may in some instances contribute to decreased liquidity and increased volatility in the financial markets. The impact of these changes on the markets, and the practical implications for market participants, may not be fully known for some time. Economies and financial markets throughout the world are increasingly interconnected. Economic, financial or political events, trading and tariff arrangements, terrorism, natural disasters and other circumstances in one country or region could have profound impacts on global economies or markets. As a result, whether or not the fund invests in securities of issuers located in or with significant exposure to the countries directly affected, the value and liquidity of the fund's investments may be negatively affected. The fund may experience a substantial or complete loss on any individual security or derivative position.

HIGH YIELD OR "JUNK" BOND RISK. Debt securities that are below investment grade, called "junk bonds," are speculative, have a higher risk of default or are already in default, tend to be less liquid and are more difficult to value than higher grade securities. Junk bonds tend to be volatile and more susceptible to adverse events and negative sentiments. These risks are more pronounced for securities that are already in default.

INTEREST RATE RISK. Interest rates may go up, causing the value of the fund's investments to decline (this risk generally will be greater for securities with longer maturities or durations). For example, if interest rates increase by 1%, the value of a fund's portfolio with a portfolio duration of ten years would be expected to decrease by 10%, all other things being equal. Interest rates in the U.S. recently have been historically low, so the fund faces a heightened risk that interest rates may rise. A general rise in interest rates may cause investors to move out of fixed income securities on a large scale, which could adversely affect the price and liquidity of fixed income securities and could also result in increased redemptions from the fund. The maturity of a security may be significantly longer than its effective duration. A security's maturity and other features may be more relevant than its effective duration in determining the security's sensitivity to other factors affecting the issuer or markets generally such as changes in credit quality or in the yield premium that the market may establish for certain types of securities.

Rising interest rates can lead to increased default rates, as issuers of floating rate securities find themselves faced with higher payments. Unlike fixed rate securities, floating rate securities generally will not increase in value if interest rates decline. Changes in interest rates also will affect the amount of interest income the fund earns on its floating rate investments.

CREDIT RISK. If an issuer or guarantor of a security held by the fund or a counterparty to a financial contract with the fund defaults on its obligation to pay principal and/or interest, has its credit rating downgraded or is perceived to be less creditworthy, or the credit quality or value of any underlying assets declines, the value of your investment will typically decline.

PREPAYMENT OR CALL RISK. Many issuers have a right to prepay their securities. If interest rates fall, an issuer may exercise this right. If this happens, the fund will not benefit from the rise in market price that normally accompanies a decline in interest rates, and will be forced to reinvest prepayment proceeds at a time when yields on securities available in the market are lower than the yield on the prepaid security. The fund also may lose any premium it paid on the security.

EXTENSION RISK. During periods of rising interest rates, the average life of certain types of securities may be extended because of slower than expected principal payments. This may lock in a below market interest rate, increase the security's duration and reduce the value of the security.

LIQUIDITY RISK. Some securities and derivatives held by the fund may be impossible or difficult to purchase, sell or unwind, particularly during times of market turmoil. An instrument's liquidity may be affected by reduced trading volume, a relative lack of market makers or legal restrictions, and illiquid securities and derivatives also may be difficult to value. Liquidity risk may be magnified in a rising interest rate environment. If the fund is forced to sell an illiquid asset or unwind a derivatives position to meet redemption requests or other cash needs, the fund may be forced to sell at a loss. The fund may not receive its proceeds from the sale of certain securities for an extended period (for example, several weeks or even longer). In extreme cases, this may constrain the fund's ability to meet its obligations (including obligations to redeeming shareholders).

PORTFOLIO SELECTION RISK. The adviser's judgment about the quality, relative yield, relative value or market trends affecting a particular sector or region, market segment, security or about interest rates generally may prove to be incorrect.

U.S. TREASURY OBLIGATIONS RISK. The market value of direct obligations of the U.S. Treasury may vary due to changes in interest rates. In addition, changes to the financial condition or credit rating of the U.S. government may cause the value of the fund's investments in obligations issued by the U.S. Treasury to decline.

U.S. GOVERNMENT AGENCY OBLIGATIONS RISK. The fund invests in obligations issued by agencies and instrumentalities of the U.S. government. Government-sponsored entities such as FNMA, FHLMC and the FHLBs, although chartered or sponsored by Congress, are not funded by congressional appropriations and the debt and mortgage-backed securities issued by them are neither guaranteed nor issued by the U.S. government. The maximum potential liability of the issuers of some U.S. government obligations may greatly exceed their current resources, including any legal right to support from the U.S. government. Such debt and mortgage-backed securities are subject to the risk of default on the payment of interest and/or principal, similar to debt of private issuers. Although the U.S. government has provided financial support to FNMA and FHLMC in the past, there can be no assurance that it will support these or other government-sponsored entities in the future.

MORTGAGE-RELATED AND ASSET-BACKED SECURITIES RISK. The value of mortgage-related and asset-backed securities will be influenced by factors affecting the housing market and the assets underlying such securities. As a result, during periods of declining asset value, difficult or frozen credit markets, swings in interest rates, or deteriorating economic conditions, mortgage-related and asset-backed securities may decline in value, face valuation difficulties, become more volatile and/or become illiquid. Mortgage-backed securities tend to be more sensitive to changes in interest rate than other types of debt securities. These securities are also subject to prepayment and extension risks. Some of these securities may receive little or no collateral protection from the underlying assets and are thus subject to the risk of default. The risk of such defaults is generally higher in the case of mortgage-backed investments that include so-called "sub-prime" mortgages. The structure of some of these securities may be complex and there may be less available information than for other types of debt securities. Upon the occurrence of certain triggering events or defaults, the fund may become the holder of underlying assets at a time when those assets may be difficult to sell or may be sold only at a loss.

RISKS OF INSTRUMENTS THAT ALLOW FOR BALLOON PAYMENTS OR NEGATIVE AMORTIZATION PAYMENTS. Certain debt instruments allow for balloon payments or negative amortization payments. Such instruments permit the borrower to avoid paying currently a portion of the interest accruing on the instrument. While these features make the debt instrument more affordable to the borrower in the near term, they increase the risk that the borrower will be unable to make the resulting higher payment or payments that become due at the maturity of the loan.

RISKS OF INVESTING IN FLOATING RATE LOANS. Floating rate loans and similar investments may be illiquid or less liquid than other investments and difficult to value. Market quotations for these securities may be volatile and/or subject to large spreads between bid and ask prices. No active trading market may exist for many floating rate loans, and many loans are subject to restrictions on resale. Any secondary market may be subject to irregular trading activity and extended trade settlement periods. In particular, loans may take longer than seven days to settle, potentially leading to the sale proceeds of loans not being available to meet redemptions for a substantial period of time after the sale of the loans. To the extent that sale proceeds of loans are not available, the fund may sell securities that have shorter settlement periods or may access other sources of liquidity to meet redemption requests. Loans may not be considered "securities," and purchasers, such as the fund, therefore may not be entitled to rely on the anti-fraud protections afforded by federal securities laws.

COLLATERAL RISK. The value of collateral, if any, securing a floating rate loan can decline, and may be insufficient to meet the issuer's obligations or may be difficult to liquidate. In addition, the fund's access to collateral may be limited by bankruptcy or other insolvency laws. Uncollateralized loans involve a greater risk of loss.

RISK OF DISADVANTAGED ACCESS TO CONFIDENTIAL INFORMATION. The adviser's decision not to receive material, non-public information about an issuer of a loan either held by, or considered for investment by, the fund, under normal circumstances could place it at a disadvantage, relative to other loan investors, in assessing a loan or the loan's issuer, and adversely affect the fund's investment performance.

RISKS OF INVESTING IN INSURANCE-LINKED SECURITIES. The return of principal and the payment of interest on "event-linked" bonds and other insurance-linked securities are contingent on the non-occurrence of a pre-defined "trigger" event, such as a hurricane or an earthquake of a specific magnitude or other event that leads to physical or economic loss. If a trigger event, as defined within the terms of an event-linked bond, involves losses or other metrics exceeding a specific magnitude in the geographic region and time period specified, the fund may lose a portion or all of its accrued interest and/or principal invested in the event-linked bond. In addition to the specified trigger events, event-linked bonds may expose the fund to other risks, including but not limited to issuer (credit) default, adverse regulatory or jurisdictional interpretations and adverse tax consequences. Certain insurance-linked securities may have limited liquidity, or may be illiquid. The fund has limited transparency into the individual contracts underlying certain insurance-linked securities, which may make the risk assessment of such securities more difficult. Certain insurance-linked securities may be difficult to value.

INFLATION-LINKED SECURITIES RISK. The principal or interest of inflation-linked securities such as TIPS is adjusted periodically to a specified rate of inflation. The inflation index used may not accurately measure the real rate of inflation. Inflation-linked securities may lose value or interest payments on such securities may decline in the event that the actual rate of inflation is different than the rate of the inflation index, and losses may exceed those experienced by other debt securities with similar durations. The values of inflation-linked securities may not be directly correlated to changes in interest rates, for example if interest rates rise for reasons other than inflation.

RISKS OF SUBORDINATED SECURITIES. A holder of securities that are subordinated or "junior" to more senior securities of an issuer is entitled to payment after holders of more senior securities of the issuer. Subordinated securities are more likely to suffer a credit loss than non-subordinated securities of the same issuer, any loss incurred by the subordinated securities is likely to be proportionately greater, and any recovery of interest or principal may take more time. As a result, even a perceived decline in creditworthiness of the issuer is likely to have a greater impact on subordinated securities.

RISKS OF ZERO COUPON BONDS, PAYMENT IN KIND, DEFERRED AND CONTINGENT PAYMENT SECURITIES. These securities may be more speculative and may fluctuate more in value than securities which pay income periodically and in cash. In addition, although the fund receives no periodic cash payments on such securities, the fund is deemed for tax purposes to receive income from such securities, which applicable tax rules require the fund to distribute to shareholders. Such distributions may be taxable when distributed to shareholders.

RISKS OF NON-U.S. INVESTMENTS. Investing in non-U.S. issuers, or in U.S. issuers that have significant exposure to foreign markets, may involve unique risks compared to investing in securities of U.S. issuers. These risks are more pronounced for issuers in emerging markets or to the extent that the fund invests significantly in one region or country. These risks may include different financial reporting practices and regulatory standards, less liquid trading markets, extreme price volatility, currency risks, changes in economic, political, regulatory and social conditions, terrorism, sustained economic downturns, financial instability, tax burdens, and investment and repatriation restrictions. Lack of information and less market regulation also may affect the value of these securities. Withholding and other non-U.S. taxes may decrease the fund's return. Non-U.S. issuers may be located in parts of the world that have historically been prone to natural disasters. Investing in depositary receipts is subject to many of the same risks as investing directly in non-U.S. issuers. Depositary receipts may involve higher expenses and may trade at a discount (or premium) to the underlying security. A number of countries in the European Union (EU) have experienced, and may continue to experience, severe economic and financial difficulties. In addition, voters in the United Kingdom have approved withdrawal from the EU. Other countries may seek to withdraw from the EU and/or abandon the euro, the common currency of the EU.

SOVEREIGN DEBT RISK. A governmental entity may delay, refuse or be unable to pay interest or principal on its sovereign debt due to cash flow problems, insufficient foreign currency reserves, political considerations, the relative size of the governmental entity's debt position in relation to the economy or the failure to put in place economic reforms. There may be no legal or bankruptcy process for collecting sovereign debt. Emerging markets countries tend to have economic, political and legal systems that are less fully developed and are less stable than those of more advanced countries.

CURRENCY RISK. The fund could experience losses based on changes in the exchange rate between non-U.S. currencies and the U.S. dollar or as a result of currency conversion costs. Currency exchange rates can be volatile, and are affected by factors such as general economic conditions, the actions of the U.S. and foreign governments or central banks, the imposition of currency controls and speculation.

EQUITY SECURITIES RISK. Equity securities represent an ownership interest in an issuer, rank junior in a company's capital structure to debt securities and consequently may entail greater risk of loss than debt securities. Equity securities are subject to the risk that stock prices may rise and fall in periodic cycles and may perform poorly relative to other investments. This risk may be greater in the short term.

SMALL AND MID-SIZE COMPANIES RISK. Compared to large companies, small- and mid-size companies, and the market for their equity securities, may be more sensitive to changes in earnings results and investor expectations, have more limited product lines and capital resources, experience sharper swings in market values, have limited liquidity, be harder to value or to sell at the times and prices the adviser thinks appropriate, and offer greater potential for gain and loss.

RISKS OF INVESTMENTS IN REAL ESTATE RELATED SECURITIES. Investments in real estate securities are affected by economic conditions, interest rates, governmental actions and other factors. In addition, investing in REITs involves unique risks. They are significantly affected by the market for real estate and are dependent upon management skills and cash flow. REITs may have lower trading volumes and may be subject to more abrupt or erratic price movements than the overall securities markets. Mortgage REITs are particularly subject to interest rate and credit risks. In addition to its own expenses, the fund will indirectly bear its proportionate share of any management and other expenses paid by REITs in which it invests. Many real estate companies, including REITs, utilize leverage.

MASTER LIMITED PARTNERSHIP RISK. Investments in securities of master limited partnerships can be less liquid than, and involve other risks that differ from, investments in common stock. Holders of the units of master limited partnerships have limited ability to influence management and limited rights to vote on matters affecting the partnership. Conflicts of interest may exist between common unit holders, the general partner of a master limited partnership and other unit holders. Master limited partnerships may be subject to less regulation (and less protection for investors) under state laws than corporations. There also are tax risks associated with investments in master limited partnerships.

RISKS OF CONVERTIBLE SECURITIES. The market values of convertible securities tend to decline as interest rates increase and, conversely, to increase as interest rates decline. A downturn in equity markets may cause the price of convertible securities to decrease relative to other fixed income securities.

RISKS OF WARRANTS AND RIGHTS. If the price of the underlying stock does not rise above the exercise price before the warrant expires, the warrant generally expires without any value and the fund loses any amount it paid for the warrant. The failure to exercise subscription rights to purchase common shares would result in the dilution of the fund's interest in the issuing company.

PREFERRED STOCKS RISK. Preferred stocks may pay fixed or adjustable rates of return. Preferred stocks are subject to issuer-specific and market risks applicable generally to equity securities. In addition, a company's preferred stocks generally pay dividends only after the company makes required payments to holders of its bonds and other debt. Thus, the value of preferred stocks will usually react more strongly than bonds and other debt to actual or perceived changes in the company's financial condition or prospects. The market value of preferred stocks generally decreases when interest rates rise. Preferred stocks of smaller companies may be more vulnerable to adverse developments than preferred stocks of larger companies.

RISKS OF INVESTMENT IN OTHER FUNDS. Investing in other investment companies, including exchange-traded funds (ETFs), subjects the fund to the risks of investing in the underlying securities or assets held by those funds. When investing in another fund, the fund will bear a pro rata portion of the underlying fund's expenses, in addition to its own expenses.

DERIVATIVES RISK. Using options, swaps, forward currency exchange contracts, futures and other derivatives can increase fund losses and reduce opportunities for gains when market prices, interest rates or the derivative instruments themselves behave in a way not anticipated by the fund. Using derivatives may increase the volatility of the fund's net asset value and may not provide the result intended. Derivatives may have a leveraging effect on the fund. Some derivatives have the potential for unlimited loss, regardless of the size of the fund's initial investment. Changes in a derivative's value may not correlate well with the referenced asset or metric. The fund also may have to sell assets at inopportune times to satisfy its obligations. Derivatives may be difficult to sell, unwind or value, and the counterparty may default on its obligations to the fund. Use of derivatives may have different tax consequences for the fund than an investment in the underlying security, and such differences may affect the amount, timing and character of income distributed to shareholders. The U.S. government and foreign governments are in the process of adopting and implementing regulations governing derivatives markets, including mandatory clearing of certain derivatives, margin and reporting requirements. The ultimate impact of the regulations remains unclear. Additional regulation of derivatives may make them more costly, limit their availability or utility, otherwise adversely affect their performance or disrupt markets.

EQUITY-LINKED NOTES RISK. Equity-linked notes (ELNs) may not perform as expected and could cause the fund to realize significant losses including its entire principal investment. Other risks include the risk of counterparty default, liquidity risk and imperfect correlation between ELNs and the underlying securities.

CREDIT DEFAULT SWAP RISK. Credit default swap contracts, a type of derivative instrument, involve special risks and may result in losses to the fund. Credit default swaps may in some cases be illiquid, and they increase credit risk since the fund has exposure to the issuer of the referenced obligation and either the counterparty to the credit default swap or, if it is a cleared transaction, the brokerage firm through which the trade was cleared and the clearing organization that is the counterparty to that trade.

FORWARD FOREIGN CURRENCY TRANSACTIONS RISK. The fund may not fully benefit from or may lose money on forward foreign currency transactions if changes in currency rates do not occur as anticipated or do not correspond accurately to changes in the value of the fund's holdings, or if the counterparty defaults. Such transactions may also prevent the fund from realizing profits on favorable movements in exchange rates. Risk of counterparty default is greater for counterparties located in emerging markets.

LEVERAGING RISK. The value of your investment may be more volatile and other risks tend to be compounded if the fund borrows or uses derivatives or other investments, such as ETFs, that have embedded leverage. Leverage generally magnifies the effect of any increase or decrease in the value of the fund's underlying assets and creates a risk of loss of value on a larger pool of assets than the fund would otherwise have, potentially resulting in the loss of all assets. Engaging in such transactions may cause the fund to liquidate positions when it may not be advantageous to do so to satisfy its obligations or meet segregation requirements.

REPURCHASE AGREEMENT RISK. In the event that the other party to a repurchase agreement defaults on its obligations, the fund may encounter delay and incur costs before being able to sell the security. Such a delay may involve loss of interest or a decline in price of the security. In addition, if the fund is characterized by a court as an unsecured creditor, it would be at risk of losing some or all of the principal and interest involved in the transaction.

MARKET SEGMENT RISK. To the extent the fund emphasizes, from time to time, investments in a market segment, the fund will be subject to a greater degree to the risks particular to that segment, and may experience greater market fluctuation, than a fund without the same focus. For example, industries in the financial segment, such as banks, insurance companies, broker-dealers and real estate investment trusts (REITs), may be sensitive to changes in interest rates and general economic activity and are generally subject to extensive government regulation.

PORTFOLIO TURNOVER RISK. If the fund does a lot of trading, it may incur additional operating expenses, which would reduce performance. A higher level of portfolio turnover may also cause shareholders to incur a higher level of taxable income or capital gains.

VALUATION RISK. The sales price the fund could receive for any particular portfolio investment may differ from the fund's valuation of the investment, particularly for illiquid securities and securities that trade in thin or volatile markets or that are valued using a fair value methodology. Investors who purchase or redeem fund shares on days when the fund is holding fair-valued securities may receive fewer or more shares or lower or higher redemption proceeds than they would have received if the fund had not fair-valued the securities or had used a different valuation methodology. The fund's ability to value its investments may also be impacted by technological issues and/or errors by pricing services or other third party service providers.

REDEMPTION RISK. The fund may experience heavy redemptions that could cause the fund to liquidate its assets at inopportune times or at a loss or depressed value, which could cause the value of your investment to decline.

EXPENSE RISK. Your actual costs of investing in the fund may be higher than the expenses shown in "Annual fund operating expenses" for a variety of reasons. For example, expense ratios may be higher than those shown if overall net assets decrease. Net assets are more likely to decrease and fund expense ratios are more likely to increase when markets are volatile.

Please note that there are many other factors that could adversely affect your investment and that could prevent the fund from achieving its goals.

An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

THE FUND'S PAST PERFORMANCE

The bar chart and table indicate the risks and volatility of an investment in the fund by showing how the fund has performed in the past. The bar chart shows changes in the performance of the fund's Class A shares from calendar year to calendar year. The table shows the average annual total returns for each class of the fund over time and compares these returns to the returns of the Bloomberg Barclays U.S. Aggregate Bond Index and the Morgan Stanley Capital International (MSCI) All Country World Index, each a broad-based measure of market performance that has characteristics relevant to the fund's investment strategies. You can obtain updated performance information by visiting https://us.pioneerinvestments.com/performance or by calling 1-800-225-6292.

The fund's past performance (before and after taxes) does not necessarily indicate how it will perform in the future.

The bar chart does not reflect any sales charge you may pay when you buy fund shares. If this amount was reflected, returns would be less than those shown.

ANNUAL RETURN CLASS A SHARES (%)
(Year ended December 31)

For the period covered by the bar chart:
THE HIGHEST CALENDAR QUARTERLY RETURN WAS 6.73% (01/01/2012 TO 03/31/2012).
THE LOWEST CALENDAR QUARTERLY RETURN WAS -7.51% (07/01/2015 TO 09/30/2015).

At September 30, 2017, the year-to-date return was 13.43%.

No performance information is presented for Class T shares in the table below because Class T shares do not have annual returns for at least one calendar year. The returns for Class T shares would differ from those of other classes of shares because they have different expenses.

AVERAGE ANNUAL TOTAL RETURN (%)
(for periods ended December 31, 2016)

Average Annual Total Returns - Pioneer Multi-Asset Income Fund	1 YEAR	5 YEARS	SINCE INCEPTION	INCEPTION DATE
Class A	7.11%	6.88%	6.91%	Dec. 22, 2011
Class A | Return after taxes on distributions	4.87%	4.53%	4.56%	Dec. 22, 2011
Class A | Return after taxes on distributions and sale of shares	4.32%	4.42%	4.45%	Dec. 22, 2011
Class C	11.28%	6.95%	6.98%	Dec. 22, 2011
Class K	13.88%		3.86%	Dec. 01, 2014
Class R	11.49%		2.72%	Dec. 01, 2014
Class Y	12.28%	8.03%	8.06%	Dec. 22, 2011
Bloomberg Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)	2.65%	2.23%	2.31%	Dec. 22, 2011
MSCI All Country World Index (reflects no deduction for fees, expenses or taxes)	7.86%	9.36%	9.45%	Dec. 22, 2011

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor's tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.

After-tax returns are shown only for Class A shares. After-tax returns for Class C, Class K, Class R, Class T and Class Y shares will vary.

[1] Class A purchases of $500,000 or more that are not subject to an initial sales charge may be subject to a contingent deferred sales charge of 1%. See "Sales charges."

[1] Other Expenses for Class T shares are based on estimated amounts for the current fiscal year.

[2] Total annual fund operating expenses in the table, before and after fee waiver and expense reimbursement, may be higher than the corresponding ratio of expenses to average net assets shown in the "Financial Highlights" section, which does not include acquired fund fees and expenses.

[3] The fund's investment adviser has contractually agreed to limit ordinary operating expenses (ordinary operating expenses means all fund expenses other than taxes, brokerage commissions, acquired fund fees and expenses, and extraordinary expenses, such as litigation) to the extent required to reduce fund expenses to 0.85%, 0.85% and 0.65% of the average daily net assets attributable to Class A, Class T and Class Y shares, respectively. The expense limitations for Class A, Class T and Class Y are in effect through December 1, 2019. There can be no assurance that the adviser will extend the expense limitations beyond such time. While in effect, the arrangement may be terminated for a class only by agreement of the adviser and the Board of Trustees.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	Pioneer Series Trust IV
Prospectus Date	rr_ProspectusDate	Dec. 01, 2017
Pioneer Multi-Asset Income Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	PIONEER MULTI-ASSET INCOME FUND
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVES
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	A high level of current income.
Objective, Secondary [Text Block]	rr_ObjectiveSecondaryTextBlock	Capital appreciation is a secondary objective.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the fund. You may qualify for sales charge discounts if you or your family invest, or agree to invest in the future, at least $100,000 in Class A shares of the Pioneer funds. More information about these and other discounts is available from your investment professional and in the "Sales charges" section of the prospectus beginning on page 67, the "Intermediary defined sales charge waiver policies" section of the prospectus beginning on page 107, and the "Sales charges" section of the statement of additional information beginning on page 67.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	SHAREOWNER FEES (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	December 1, 2019
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	PORTFOLIO TURNOVER
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 131% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	131.00%
Expenses Deferred Charges [Text Block]	rr_ExpensesDeferredChargesTextBlock	Class A purchases of $500,000 or more that are not subject to an initial sales charge may be subject to a contingent deferred sales charge of 1%. See "Sales charges."
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	You may qualify for sales charge discounts if you or your family invest, or agree to invest in the future, at least $100,000 in Class A shares of the Pioneer funds.
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	$ 100,000
Other Expenses, New Fund, Based on Estimates [Text]	rr_OtherExpensesNewFundBasedOnEstimates	Other Expenses for Class T shares are based on estimated amounts for the current fiscal year.
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]	rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees	Total annual fund operating expenses in the table, before and after fee waiver and expense reimbursement, may be higher than the corresponding ratio of expenses to average net assets shown in the "Financial Highlights" section, which does not include acquired fund fees and expenses.
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE
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 in the fund for the time periods shown and then, except as indicated, redeem all of your shares at the end of those periods. It also assumes that (a) your investment has a 5% return each year and (b) the fund's total annual operating expenses remain the same except for year one (which considers the effect of the expense limitation). Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	IF YOU REDEEM YOUR SHARES NUMBER OF YEARS YOU OWN YOUR SHARES
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	IF YOU DO NOT REDEEM YOUR SHARES NUMBER OF YEARS YOU OWN YOUR SHARES
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The fund has the flexibility to invest in a broad range of income-producing investments, including both debt securities and equity securities. The fund may invest in the securities of issuers located throughout the world, including in emerging markets. In selecting investments, the fund's investment adviser considers both broad economic and investment-specific factors. The fund may invest in a broad range of issuers and segments of the debt securities markets. The adviser allocates the fund's debt securities among different instruments and segments of the debt markets, based on its outlook for economic, interest rate and political trends. Debt securities may include instruments and obligations of U.S. and non-U.S. corporate and other non-governmental entities, those of U.S. and non-U.S. governmental entities, mortgage-related or mortgage-backed securities (including "sub-prime" mortgages), asset-backed securities, floating rate loans, convertible securities, Treasury Inflation Protected Securities ("TIPS") and other inflation-linked debt securities, subordinated debt securities, event-linked bonds and other insurance-linked securities, and funds that invest primarily in debt securities. The fund may invest without limit in debt securities of any credit quality, including those rated below investment grade (known as "junk bonds") or, if unrated, of equivalent credit quality as determined by the adviser. The fund's investments in debt securities rated below investment grade may include securities that are in default. The fund invests in debt securities with a broad range of maturities. The fund's investments may have fixed or variable principal payments and all types of interest rate payment and reset terms, including fixed rate, adjustable rate, floating rate, zero coupon, contingent, deferred, payment in kind and auction rate features. The fund's investments may include instruments that allow for balloon payments or negative amortization payments. The fund may invest without limit in debt securities. The fund may invest up to 60% of its total assets in equity securities. Equity securities include common stocks, rights, warrants, depositary receipts, funds that invest primarily in equity securities, preferred stock, equity interests in real estate trusts (REITs), equity-linked notes and master limited partnerships. Derivative instruments that provide exposure to equity securities or have similar economic characteristics may be considered equity securities under this policy. The fund may invest without limit in debt and equity securities of non-U.S. issuers, including up to 30% of its total assets in debt and equity securities of emerging market issuers. Equity-linked notes (ELNs) are hybrid structured investments that combine the characteristics of one or more reference underlying securities (usually a single stock, a basket of stocks or a stock index) and a related equity derivative, typically in the form of a note paying a stated interest rate. In allocating assets among debt and equity securities, the adviser considers a variety of factors expected to influence global economic activity, including fundamental economic indicators, such as the rates of economic growth and inflation, monetary policy, geo-political factors, the performance of securities markets, and the relative value of the U.S. dollar compared to other currencies. The fund is not required to allocate its investments among debt and equity securities in any fixed proportion, nor is it limited by the issuer's geographic location, size or market capitalization. The relative proportions of the fund's investments in debt and equity securities may change over time based upon market and economic conditions. In selecting individual securities to buy and sell, the adviser considers a security's income prospects relative to perceived risk. The adviser selects debt securities based upon such factors as a security's yield, liquidity and rating, an assessment of credit quality, and sector and issuer diversification. The adviser considers an equity security's potential to provide income in view of the sustainability of the issuer's earnings and financial condition. In selecting equity and debt securities, the adviser generally favors those securities it perceives to be undervalued. The adviser employs fundamental research in evaluating issuers, taking into account financial condition and profitability, future capital needs, potential for change in rating, industry outlook, the competitive environment and management ability. In making these portfolio decisions, the adviser relies on the knowledge, experience and judgment of its staff and the staff of its affiliates who have access to a wide variety of fundamental and quantitative research. In selecting among market segments and instruments, the adviser considers the relative value of particular investments. Investments typically are sold when the adviser's overall assessment of market and economic conditions changes or the assessments of the attributes of asset classes or individual holdings change. The fund may invest in securities and instruments that are not income-producing for purposes of seeking capital appreciation or managing risk or other portfolio characteristics. The fund may, but is not required to, use derivatives, such as options, credit default swaps and interest rate swaps, forward currency exchange contracts and bond, index, interest rate and currency futures. The fund may use derivatives for a variety of purposes, including: in an attempt to hedge against adverse changes in the market price of securities, interest rates or currency exchange rates; as a substitute for purchasing or selling securities; to attempt to increase the fund's return as a non-hedging strategy that may be considered speculative; to manage portfolio characteristics; and as a cash flow management technique. In addition to investing in securities denominated in non-U.S. currencies, the fund may hold non-U.S. currencies and purchase and sell forward currency exchange contracts in non-U.S. currencies. The fund may invest without limit in derivative instruments. The fund may choose not to make use of derivatives for a variety of reasons, and any use may be limited to applicable law and regulations. The fund also may hold cash or other short-term investments.
Risk [Heading]	rr_RiskHeading	PRINCIPAL RISKS OF INVESTING IN THE FUND
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	You could lose money on your investment in the fund. As with any mutual fund, there is no guarantee that the fund will achieve its objectives. MARKET RISK. The value of securities held by the fund may go up or down, sometimes rapidly or unpredictably, due to general market conditions, such as real or perceived adverse economic, political, or regulatory conditions, inflation, changes in interest or currency rates, lack of liquidity in the bond markets or adverse investor sentiment. In the past decade, financial markets throughout the world have experienced increased volatility, depressed valuations, decreased liquidity and heightened uncertainty. Governmental and non-governmental issuers have defaulted on, or been forced to restructure, their debts. These conditions may continue, recur, worsen or spread. Events that have contributed to these market conditions include, but are not limited to, major cybersecurity events; geopolitical events (including wars and terror attacks); measures to address budget deficits; downgrading of sovereign debt; declines in oil and commodity prices; dramatic changes in currency exchange rates; and public sentiment. The U.S. government and the Federal Reserve, as well as certain foreign governments and their central banks, have taken steps to support financial markets, including by keeping interest rates at historically low levels. This and other government intervention may not work as intended, particularly if the efforts are perceived by investors as being unlikely to achieve the desired results. The Federal Reserve has reduced its market support activities and has begun raising interest rates. Certain foreign governments and central banks are implementing or discussing so-called negative interest rates (e.g., charging depositors who keep their cash at a bank) to spur economic growth. Further Federal Reserve or other U.S. or non-U.S. governmental or central bank actions, including interest rate increases or contrary actions by different governments, could negatively affect financial markets generally, increase market volatility and reduce the value and liquidity of securities in which the fund invests. Policy and legislative changes in the U.S. and in other countries are affecting many aspects of financial regulation, and may in some instances contribute to decreased liquidity and increased volatility in the financial markets. The impact of these changes on the markets, and the practical implications for market participants, may not be fully known for some time. Economies and financial markets throughout the world are increasingly interconnected. Economic, financial or political events, trading and tariff arrangements, terrorism, natural disasters and other circumstances in one country or region could have profound impacts on global economies or markets. As a result, whether or not the fund invests in securities of issuers located in or with significant exposure to the countries directly affected, the value and liquidity of the fund's investments may be negatively affected. The fund may experience a substantial or complete loss on any individual security or derivative position. HIGH YIELD OR "JUNK" BOND RISK. Debt securities that are below investment grade, called "junk bonds," are speculative, have a higher risk of default or are already in default, tend to be less liquid and are more difficult to value than higher grade securities. Junk bonds tend to be volatile and more susceptible to adverse events and negative sentiments. These risks are more pronounced for securities that are already in default. INTEREST RATE RISK. Interest rates may go up, causing the value of the fund's investments to decline (this risk generally will be greater for securities with longer maturities or durations). For example, if interest rates increase by 1%, the value of a fund's portfolio with a portfolio duration of ten years would be expected to decrease by 10%, all other things being equal. Interest rates in the U.S. recently have been historically low, so the fund faces a heightened risk that interest rates may rise. A general rise in interest rates may cause investors to move out of fixed income securities on a large scale, which could adversely affect the price and liquidity of fixed income securities and could also result in increased redemptions from the fund. The maturity of a security may be significantly longer than its effective duration. A security's maturity and other features may be more relevant than its effective duration in determining the security's sensitivity to other factors affecting the issuer or markets generally such as changes in credit quality or in the yield premium that the market may establish for certain types of securities. Rising interest rates can lead to increased default rates, as issuers of floating rate securities find themselves faced with higher payments. Unlike fixed rate securities, floating rate securities generally will not increase in value if interest rates decline. Changes in interest rates also will affect the amount of interest income the fund earns on its floating rate investments. CREDIT RISK. If an issuer or guarantor of a security held by the fund or a counterparty to a financial contract with the fund defaults on its obligation to pay principal and/or interest, has its credit rating downgraded or is perceived to be less creditworthy, or the credit quality or value of any underlying assets declines, the value of your investment will typically decline. PREPAYMENT OR CALL RISK. Many issuers have a right to prepay their securities. If interest rates fall, an issuer may exercise this right. If this happens, the fund will not benefit from the rise in market price that normally accompanies a decline in interest rates, and will be forced to reinvest prepayment proceeds at a time when yields on securities available in the market are lower than the yield on the prepaid security. The fund also may lose any premium it paid on the security. EXTENSION RISK. During periods of rising interest rates, the average life of certain types of securities may be extended because of slower than expected principal payments. This may lock in a below market interest rate, increase the security's duration and reduce the value of the security. LIQUIDITY RISK. Some securities and derivatives held by the fund may be impossible or difficult to purchase, sell or unwind, particularly during times of market turmoil. An instrument's liquidity may be affected by reduced trading volume, a relative lack of market makers or legal restrictions, and illiquid securities and derivatives also may be difficult to value. Liquidity risk may be magnified in a rising interest rate environment. If the fund is forced to sell an illiquid asset or unwind a derivatives position to meet redemption requests or other cash needs, the fund may be forced to sell at a loss. The fund may not receive its proceeds from the sale of certain securities for an extended period (for example, several weeks or even longer). In extreme cases, this may constrain the fund's ability to meet its obligations (including obligations to redeeming shareholders). PORTFOLIO SELECTION RISK. The adviser's judgment about the quality, relative yield, relative value or market trends affecting a particular sector or region, market segment, security or about interest rates generally may prove to be incorrect. U.S. TREASURY OBLIGATIONS RISK. The market value of direct obligations of the U.S. Treasury may vary due to changes in interest rates. In addition, changes to the financial condition or credit rating of the U.S. government may cause the value of the fund's investments in obligations issued by the U.S. Treasury to decline. U.S. GOVERNMENT AGENCY OBLIGATIONS RISK. The fund invests in obligations issued by agencies and instrumentalities of the U.S. government. Government-sponsored entities such as FNMA, FHLMC and the FHLBs, although chartered or sponsored by Congress, are not funded by congressional appropriations and the debt and mortgage-backed securities issued by them are neither guaranteed nor issued by the U.S. government. The maximum potential liability of the issuers of some U.S. government obligations may greatly exceed their current resources, including any legal right to support from the U.S. government. Such debt and mortgage-backed securities are subject to the risk of default on the payment of interest and/or principal, similar to debt of private issuers. Although the U.S. government has provided financial support to FNMA and FHLMC in the past, there can be no assurance that it will support these or other government-sponsored entities in the future. MORTGAGE-RELATED AND ASSET-BACKED SECURITIES RISK. The value of mortgage-related and asset-backed securities will be influenced by factors affecting the housing market and the assets underlying such securities. As a result, during periods of declining asset value, difficult or frozen credit markets, swings in interest rates, or deteriorating economic conditions, mortgage-related and asset-backed securities may decline in value, face valuation difficulties, become more volatile and/or become illiquid. Mortgage-backed securities tend to be more sensitive to changes in interest rate than other types of debt securities. These securities are also subject to prepayment and extension risks. Some of these securities may receive little or no collateral protection from the underlying assets and are thus subject to the risk of default. The risk of such defaults is generally higher in the case of mortgage-backed investments that include so-called "sub-prime" mortgages. The structure of some of these securities may be complex and there may be less available information than for other types of debt securities. Upon the occurrence of certain triggering events or defaults, the fund may become the holder of underlying assets at a time when those assets may be difficult to sell or may be sold only at a loss. RISKS OF INSTRUMENTS THAT ALLOW FOR BALLOON PAYMENTS OR NEGATIVE AMORTIZATION PAYMENTS. Certain debt instruments allow for balloon payments or negative amortization payments. Such instruments permit the borrower to avoid paying currently a portion of the interest accruing on the instrument. While these features make the debt instrument more affordable to the borrower in the near term, they increase the risk that the borrower will be unable to make the resulting higher payment or payments that become due at the maturity of the loan. RISKS OF INVESTING IN FLOATING RATE LOANS. Floating rate loans and similar investments may be illiquid or less liquid than other investments and difficult to value. Market quotations for these securities may be volatile and/or subject to large spreads between bid and ask prices. No active trading market may exist for many floating rate loans, and many loans are subject to restrictions on resale. Any secondary market may be subject to irregular trading activity and extended trade settlement periods. In particular, loans may take longer than seven days to settle, potentially leading to the sale proceeds of loans not being available to meet redemptions for a substantial period of time after the sale of the loans. To the extent that sale proceeds of loans are not available, the fund may sell securities that have shorter settlement periods or may access other sources of liquidity to meet redemption requests. Loans may not be considered "securities," and purchasers, such as the fund, therefore may not be entitled to rely on the anti-fraud protections afforded by federal securities laws. COLLATERAL RISK. The value of collateral, if any, securing a floating rate loan can decline, and may be insufficient to meet the issuer's obligations or may be difficult to liquidate. In addition, the fund's access to collateral may be limited by bankruptcy or other insolvency laws. Uncollateralized loans involve a greater risk of loss. RISK OF DISADVANTAGED ACCESS TO CONFIDENTIAL INFORMATION. The adviser's decision not to receive material, non-public information about an issuer of a loan either held by, or considered for investment by, the fund, under normal circumstances could place it at a disadvantage, relative to other loan investors, in assessing a loan or the loan's issuer, and adversely affect the fund's investment performance. RISKS OF INVESTING IN INSURANCE-LINKED SECURITIES. The return of principal and the payment of interest on "event-linked" bonds and other insurance-linked securities are contingent on the non-occurrence of a pre-defined "trigger" event, such as a hurricane or an earthquake of a specific magnitude or other event that leads to physical or economic loss. If a trigger event, as defined within the terms of an event-linked bond, involves losses or other metrics exceeding a specific magnitude in the geographic region and time period specified, the fund may lose a portion or all of its accrued interest and/or principal invested in the event-linked bond. In addition to the specified trigger events, event-linked bonds may expose the fund to other risks, including but not limited to issuer (credit) default, adverse regulatory or jurisdictional interpretations and adverse tax consequences. Certain insurance-linked securities may have limited liquidity, or may be illiquid. The fund has limited transparency into the individual contracts underlying certain insurance-linked securities, which may make the risk assessment of such securities more difficult. Certain insurance-linked securities may be difficult to value. INFLATION-LINKED SECURITIES RISK. The principal or interest of inflation-linked securities such as TIPS is adjusted periodically to a specified rate of inflation. The inflation index used may not accurately measure the real rate of inflation. Inflation-linked securities may lose value or interest payments on such securities may decline in the event that the actual rate of inflation is different than the rate of the inflation index, and losses may exceed those experienced by other debt securities with similar durations. The values of inflation-linked securities may not be directly correlated to changes in interest rates, for example if interest rates rise for reasons other than inflation. RISKS OF SUBORDINATED SECURITIES. A holder of securities that are subordinated or "junior" to more senior securities of an issuer is entitled to payment after holders of more senior securities of the issuer. Subordinated securities are more likely to suffer a credit loss than non-subordinated securities of the same issuer, any loss incurred by the subordinated securities is likely to be proportionately greater, and any recovery of interest or principal may take more time. As a result, even a perceived decline in creditworthiness of the issuer is likely to have a greater impact on subordinated securities. RISKS OF ZERO COUPON BONDS, PAYMENT IN KIND, DEFERRED AND CONTINGENT PAYMENT SECURITIES. These securities may be more speculative and may fluctuate more in value than securities which pay income periodically and in cash. In addition, although the fund receives no periodic cash payments on such securities, the fund is deemed for tax purposes to receive income from such securities, which applicable tax rules require the fund to distribute to shareholders. Such distributions may be taxable when distributed to shareholders. RISKS OF NON-U.S. INVESTMENTS. Investing in non-U.S. issuers, or in U.S. issuers that have significant exposure to foreign markets, may involve unique risks compared to investing in securities of U.S. issuers. These risks are more pronounced for issuers in emerging markets or to the extent that the fund invests significantly in one region or country. These risks may include different financial reporting practices and regulatory standards, less liquid trading markets, extreme price volatility, currency risks, changes in economic, political, regulatory and social conditions, terrorism, sustained economic downturns, financial instability, tax burdens, and investment and repatriation restrictions. Lack of information and less market regulation also may affect the value of these securities. Withholding and other non-U.S. taxes may decrease the fund's return. Non-U.S. issuers may be located in parts of the world that have historically been prone to natural disasters. Investing in depositary receipts is subject to many of the same risks as investing directly in non-U.S. issuers. Depositary receipts may involve higher expenses and may trade at a discount (or premium) to the underlying security. A number of countries in the European Union (EU) have experienced, and may continue to experience, severe economic and financial difficulties. In addition, voters in the United Kingdom have approved withdrawal from the EU. Other countries may seek to withdraw from the EU and/or abandon the euro, the common currency of the EU. SOVEREIGN DEBT RISK. A governmental entity may delay, refuse or be unable to pay interest or principal on its sovereign debt due to cash flow problems, insufficient foreign currency reserves, political considerations, the relative size of the governmental entity's debt position in relation to the economy or the failure to put in place economic reforms. There may be no legal or bankruptcy process for collecting sovereign debt. Emerging markets countries tend to have economic, political and legal systems that are less fully developed and are less stable than those of more advanced countries. CURRENCY RISK. The fund could experience losses based on changes in the exchange rate between non-U.S. currencies and the U.S. dollar or as a result of currency conversion costs. Currency exchange rates can be volatile, and are affected by factors such as general economic conditions, the actions of the U.S. and foreign governments or central banks, the imposition of currency controls and speculation. EQUITY SECURITIES RISK. Equity securities represent an ownership interest in an issuer, rank junior in a company's capital structure to debt securities and consequently may entail greater risk of loss than debt securities. Equity securities are subject to the risk that stock prices may rise and fall in periodic cycles and may perform poorly relative to other investments. This risk may be greater in the short term. SMALL AND MID-SIZE COMPANIES RISK. Compared to large companies, small- and mid-size companies, and the market for their equity securities, may be more sensitive to changes in earnings results and investor expectations, have more limited product lines and capital resources, experience sharper swings in market values, have limited liquidity, be harder to value or to sell at the times and prices the adviser thinks appropriate, and offer greater potential for gain and loss. RISKS OF INVESTMENTS IN REAL ESTATE RELATED SECURITIES. Investments in real estate securities are affected by economic conditions, interest rates, governmental actions and other factors. In addition, investing in REITs involves unique risks. They are significantly affected by the market for real estate and are dependent upon management skills and cash flow. REITs may have lower trading volumes and may be subject to more abrupt or erratic price movements than the overall securities markets. Mortgage REITs are particularly subject to interest rate and credit risks. In addition to its own expenses, the fund will indirectly bear its proportionate share of any management and other expenses paid by REITs in which it invests. Many real estate companies, including REITs, utilize leverage. MASTER LIMITED PARTNERSHIP RISK. Investments in securities of master limited partnerships can be less liquid than, and involve other risks that differ from, investments in common stock. Holders of the units of master limited partnerships have limited ability to influence management and limited rights to vote on matters affecting the partnership. Conflicts of interest may exist between common unit holders, the general partner of a master limited partnership and other unit holders. Master limited partnerships may be subject to less regulation (and less protection for investors) under state laws than corporations. There also are tax risks associated with investments in master limited partnerships. RISKS OF CONVERTIBLE SECURITIES. The market values of convertible securities tend to decline as interest rates increase and, conversely, to increase as interest rates decline. A downturn in equity markets may cause the price of convertible securities to decrease relative to other fixed income securities. RISKS OF WARRANTS AND RIGHTS. If the price of the underlying stock does not rise above the exercise price before the warrant expires, the warrant generally expires without any value and the fund loses any amount it paid for the warrant. The failure to exercise subscription rights to purchase common shares would result in the dilution of the fund's interest in the issuing company. PREFERRED STOCKS RISK. Preferred stocks may pay fixed or adjustable rates of return. Preferred stocks are subject to issuer-specific and market risks applicable generally to equity securities. In addition, a company's preferred stocks generally pay dividends only after the company makes required payments to holders of its bonds and other debt. Thus, the value of preferred stocks will usually react more strongly than bonds and other debt to actual or perceived changes in the company's financial condition or prospects. The market value of preferred stocks generally decreases when interest rates rise. Preferred stocks of smaller companies may be more vulnerable to adverse developments than preferred stocks of larger companies. RISKS OF INVESTMENT IN OTHER FUNDS. Investing in other investment companies, including exchange-traded funds (ETFs), subjects the fund to the risks of investing in the underlying securities or assets held by those funds. When investing in another fund, the fund will bear a pro rata portion of the underlying fund's expenses, in addition to its own expenses. DERIVATIVES RISK. Using options, swaps, forward currency exchange contracts, futures and other derivatives can increase fund losses and reduce opportunities for gains when market prices, interest rates or the derivative instruments themselves behave in a way not anticipated by the fund. Using derivatives may increase the volatility of the fund's net asset value and may not provide the result intended. Derivatives may have a leveraging effect on the fund. Some derivatives have the potential for unlimited loss, regardless of the size of the fund's initial investment. Changes in a derivative's value may not correlate well with the referenced asset or metric. The fund also may have to sell assets at inopportune times to satisfy its obligations. Derivatives may be difficult to sell, unwind or value, and the counterparty may default on its obligations to the fund. Use of derivatives may have different tax consequences for the fund than an investment in the underlying security, and such differences may affect the amount, timing and character of income distributed to shareholders. The U.S. government and foreign governments are in the process of adopting and implementing regulations governing derivatives markets, including mandatory clearing of certain derivatives, margin and reporting requirements. The ultimate impact of the regulations remains unclear. Additional regulation of derivatives may make them more costly, limit their availability or utility, otherwise adversely affect their performance or disrupt markets. EQUITY-LINKED NOTES RISK. Equity-linked notes (ELNs) may not perform as expected and could cause the fund to realize significant losses including its entire principal investment. Other risks include the risk of counterparty default, liquidity risk and imperfect correlation between ELNs and the underlying securities. CREDIT DEFAULT SWAP RISK. Credit default swap contracts, a type of derivative instrument, involve special risks and may result in losses to the fund. Credit default swaps may in some cases be illiquid, and they increase credit risk since the fund has exposure to the issuer of the referenced obligation and either the counterparty to the credit default swap or, if it is a cleared transaction, the brokerage firm through which the trade was cleared and the clearing organization that is the counterparty to that trade. FORWARD FOREIGN CURRENCY TRANSACTIONS RISK. The fund may not fully benefit from or may lose money on forward foreign currency transactions if changes in currency rates do not occur as anticipated or do not correspond accurately to changes in the value of the fund's holdings, or if the counterparty defaults. Such transactions may also prevent the fund from realizing profits on favorable movements in exchange rates. Risk of counterparty default is greater for counterparties located in emerging markets. LEVERAGING RISK. The value of your investment may be more volatile and other risks tend to be compounded if the fund borrows or uses derivatives or other investments, such as ETFs, that have embedded leverage. Leverage generally magnifies the effect of any increase or decrease in the value of the fund's underlying assets and creates a risk of loss of value on a larger pool of assets than the fund would otherwise have, potentially resulting in the loss of all assets. Engaging in such transactions may cause the fund to liquidate positions when it may not be advantageous to do so to satisfy its obligations or meet segregation requirements. REPURCHASE AGREEMENT RISK. In the event that the other party to a repurchase agreement defaults on its obligations, the fund may encounter delay and incur costs before being able to sell the security. Such a delay may involve loss of interest or a decline in price of the security. In addition, if the fund is characterized by a court as an unsecured creditor, it would be at risk of losing some or all of the principal and interest involved in the transaction. MARKET SEGMENT RISK. To the extent the fund emphasizes, from time to time, investments in a market segment, the fund will be subject to a greater degree to the risks particular to that segment, and may experience greater market fluctuation, than a fund without the same focus. For example, industries in the financial segment, such as banks, insurance companies, broker-dealers and real estate investment trusts (REITs), may be sensitive to changes in interest rates and general economic activity and are generally subject to extensive government regulation. PORTFOLIO TURNOVER RISK. If the fund does a lot of trading, it may incur additional operating expenses, which would reduce performance. A higher level of portfolio turnover may also cause shareholders to incur a higher level of taxable income or capital gains. VALUATION RISK. The sales price the fund could receive for any particular portfolio investment may differ from the fund's valuation of the investment, particularly for illiquid securities and securities that trade in thin or volatile markets or that are valued using a fair value methodology. Investors who purchase or redeem fund shares on days when the fund is holding fair-valued securities may receive fewer or more shares or lower or higher redemption proceeds than they would have received if the fund had not fair-valued the securities or had used a different valuation methodology. The fund's ability to value its investments may also be impacted by technological issues and/or errors by pricing services or other third party service providers. REDEMPTION RISK. The fund may experience heavy redemptions that could cause the fund to liquidate its assets at inopportune times or at a loss or depressed value, which could cause the value of your investment to decline. EXPENSE RISK. Your actual costs of investing in the fund may be higher than the expenses shown in "Annual fund operating expenses" for a variety of reasons. For example, expense ratios may be higher than those shown if overall net assets decrease. Net assets are more likely to decrease and fund expense ratios are more likely to increase when markets are volatile. Please note that there are many other factors that could adversely affect your investment and that could prevent the fund from achieving its goals. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	You could lose money on your investment in the fund.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	THE FUND'S PAST PERFORMANCE
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table indicate the risks and volatility of an investment in the fund by showing how the fund has performed in the past. The bar chart shows changes in the performance of the fund's Class A shares from calendar year to calendar year. The table shows the average annual total returns for each class of the fund over time and compares these returns to the returns of the Bloomberg Barclays U.S. Aggregate Bond Index and the Morgan Stanley Capital International (MSCI) All Country World Index, each a broad-based measure of market performance that has characteristics relevant to the fund's investment strategies. You can obtain updated performance information by visiting https://us.pioneerinvestments.com/performance or by calling 1-800-225-6292. The fund's past performance (before and after taxes) does not necessarily indicate how it will perform in the future. The bar chart does not reflect any sales charge you may pay when you buy fund shares. If this amount was reflected, returns would be less than those shown.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table indicate the risks and volatility of an investment in the fund by showing how the fund has performed in the past. The bar chart shows changes in the performance of the fund's Class A shares from calendar year to calendar year. The table shows the average annual total returns for each class of the fund over time and compares these returns to the returns of the Bloomberg Barclays U.S. Aggregate Bond Index and the Morgan Stanley Capital International (MSCI) All Country World Index, each a broad-based measure of market performance that has characteristics relevant to the fund's investment strategies.
Performance One Year or Less [Text]	rr_PerformanceOneYearOrLess	No performance information is presented for Class T shares in the table below because Class T shares do not have annual returns for at least one calendar year.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table shows the average annual total returns for each class of the fund over time and compares these returns to the returns of the Bloomberg Barclays U.S. Aggregate Bond Index and the Morgan Stanley Capital International (MSCI) All Country World Index, each a broad-based measure of market performance that has characteristics relevant to the fund's investment strategies.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-800-225-6292
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	https://us.pioneerinvestments.com/performance
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The fund's past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	ANNUAL RETURN CLASS A SHARES (%) (Year ended December 31)
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The bar chart does not reflect any sales charge you may pay when you buy fund shares. If this amount was reflected, returns would be less than those shown.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	For the period covered by the bar chart: THE HIGHEST CALENDAR QUARTERLY RETURN WAS 6.73% (01/01/2012 TO 03/31/2012). THE LOWEST CALENDAR QUARTERLY RETURN WAS -7.51% (07/01/2015 TO 09/30/2015). At September 30, 2017, the year-to-date return was 13.43%.
Performance Table Heading	rr_PerformanceTableHeading	AVERAGE ANNUAL TOTAL RETURN (%) (for periods ended December 31, 2016)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on the investor's tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown only for Class A shares. After-tax returns for Class C, Class K, Class R, Class T and Class Y shares will vary.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor's tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown only for Class A shares. After-tax returns for Class C, Class K, Class R, Class T and Class Y shares will vary.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	No performance information is presented for Class T shares in the table below because Class T shares do not have annual returns for at least one calendar year. The returns for Class T shares would differ from those of other classes of shares because they have different expenses.
Pioneer Multi-Asset Income Fund | CLASS A
Risk/Return:	rr_RiskReturnAbstract
Maximum sales charge (load) when you buy shares (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	4.50%
Maximum deferred sales charge (load) (as a percentage of offering price or the amount you receive when you sell shares, whichever is less)	rr_MaximumDeferredSalesChargeOverOther	none	[1]
Management Fees	rr_ManagementFeesOverAssets	0.50%
Distribution and Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.17%	[2]
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.31%	[3]
Total Annual Fund Operating Expenses Plus Acquired Fund Fees and Expenses	rr_ExpensesOverAssets	1.23%	[3]
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.07%)	[4]
Net Expenses Plus Acquired Fund Fees and Expenses	rr_NetExpensesOverAssets	1.16%	[4]
1	rr_ExpenseExampleYear01	$ 563
3	rr_ExpenseExampleYear03	816
5	rr_ExpenseExampleYear05	1,089
10	rr_ExpenseExampleYear10	1,866
1	rr_ExpenseExampleNoRedemptionYear01	563
3	rr_ExpenseExampleNoRedemptionYear03	816
5	rr_ExpenseExampleNoRedemptionYear05	1,089
10	rr_ExpenseExampleNoRedemptionYear10	$ 1,866
2012	rr_AnnualReturn2012	15.79%
2013	rr_AnnualReturn2013	14.75%
2014	rr_AnnualReturn2014	1.35%
2015	rr_AnnualReturn2015	(3.33%)
2016	rr_AnnualReturn2016	12.16%
Year to Date Return, Label	rr_YearToDateReturnLabel	year-to-date return
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2017
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	13.43%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	HIGHEST CALENDAR QUARTERLY RETURN
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Mar. 31, 2012
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	6.73%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	LOWEST CALENDAR QUARTERLY RETURN
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2015
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(7.51%)
1 YEAR	rr_AverageAnnualReturnYear01	7.11%
5 YEARS	rr_AverageAnnualReturnYear05	6.88%
SINCE INCEPTION	rr_AverageAnnualReturnSinceInception	6.91%
INCEPTION DATE	rr_AverageAnnualReturnInceptionDate	Dec. 22, 2011
Pioneer Multi-Asset Income Fund | CLASS C
Risk/Return:	rr_RiskReturnAbstract
Maximum sales charge (load) when you buy shares (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum deferred sales charge (load) (as a percentage of offering price or the amount you receive when you sell shares, whichever is less)	rr_MaximumDeferredSalesChargeOverOther	1.00%
Management Fees	rr_ManagementFeesOverAssets	0.50%
Distribution and Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.19%	[2]
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.31%	[3]
Total Annual Fund Operating Expenses Plus Acquired Fund Fees and Expenses	rr_ExpensesOverAssets	2.00%	[3]
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[4]
Net Expenses Plus Acquired Fund Fees and Expenses	rr_NetExpensesOverAssets	2.00%	[4]
1	rr_ExpenseExampleYear01	$ 303
3	rr_ExpenseExampleYear03	627
5	rr_ExpenseExampleYear05	1,078
10	rr_ExpenseExampleYear10	2,327
1	rr_ExpenseExampleNoRedemptionYear01	203
3	rr_ExpenseExampleNoRedemptionYear03	627
5	rr_ExpenseExampleNoRedemptionYear05	1,078
10	rr_ExpenseExampleNoRedemptionYear10	$ 2,327
1 YEAR	rr_AverageAnnualReturnYear01	11.28%
5 YEARS	rr_AverageAnnualReturnYear05	6.95%
SINCE INCEPTION	rr_AverageAnnualReturnSinceInception	6.98%
INCEPTION DATE	rr_AverageAnnualReturnInceptionDate	Dec. 22, 2011
Pioneer Multi-Asset Income Fund | CLASS K
Risk/Return:	rr_RiskReturnAbstract
Maximum sales charge (load) when you buy shares (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum deferred sales charge (load) (as a percentage of offering price or the amount you receive when you sell shares, whichever is less)	rr_MaximumDeferredSalesChargeOverOther	none
Management Fees	rr_ManagementFeesOverAssets	0.50%
Distribution and Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.13%	[2]
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.31%	[3]
Total Annual Fund Operating Expenses Plus Acquired Fund Fees and Expenses	rr_ExpensesOverAssets	0.94%	[3]
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[4]
Net Expenses Plus Acquired Fund Fees and Expenses	rr_NetExpensesOverAssets	0.94%	[4]
1	rr_ExpenseExampleYear01	$ 96
3	rr_ExpenseExampleYear03	300
5	rr_ExpenseExampleYear05	520
10	rr_ExpenseExampleYear10	1,155
1	rr_ExpenseExampleNoRedemptionYear01	96
3	rr_ExpenseExampleNoRedemptionYear03	300
5	rr_ExpenseExampleNoRedemptionYear05	520
10	rr_ExpenseExampleNoRedemptionYear10	$ 1,155
1 YEAR	rr_AverageAnnualReturnYear01	13.88%
5 YEARS	rr_AverageAnnualReturnYear05
SINCE INCEPTION	rr_AverageAnnualReturnSinceInception	3.86%
INCEPTION DATE	rr_AverageAnnualReturnInceptionDate	Dec. 01, 2014
Pioneer Multi-Asset Income Fund | CLASS R
Risk/Return:	rr_RiskReturnAbstract
Maximum sales charge (load) when you buy shares (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum deferred sales charge (load) (as a percentage of offering price or the amount you receive when you sell shares, whichever is less)	rr_MaximumDeferredSalesChargeOverOther	none
Management Fees	rr_ManagementFeesOverAssets	0.50%
Distribution and Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.50%
Other Expenses	rr_OtherExpensesOverAssets	0.37%	[2]
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.31%	[3]
Total Annual Fund Operating Expenses Plus Acquired Fund Fees and Expenses	rr_ExpensesOverAssets	1.68%	[3]
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[4]
Net Expenses Plus Acquired Fund Fees and Expenses	rr_NetExpensesOverAssets	1.68%	[4]
1	rr_ExpenseExampleYear01	$ 171
3	rr_ExpenseExampleYear03	530
5	rr_ExpenseExampleYear05	913
10	rr_ExpenseExampleYear10	1,987
1	rr_ExpenseExampleNoRedemptionYear01	171
3	rr_ExpenseExampleNoRedemptionYear03	530
5	rr_ExpenseExampleNoRedemptionYear05	913
10	rr_ExpenseExampleNoRedemptionYear10	$ 1,987
1 YEAR	rr_AverageAnnualReturnYear01	11.49%
5 YEARS	rr_AverageAnnualReturnYear05
SINCE INCEPTION	rr_AverageAnnualReturnSinceInception	2.72%
INCEPTION DATE	rr_AverageAnnualReturnInceptionDate	Dec. 01, 2014
Pioneer Multi-Asset Income Fund | CLASS T
Risk/Return:	rr_RiskReturnAbstract
Maximum sales charge (load) when you buy shares (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	2.50%
Maximum deferred sales charge (load) (as a percentage of offering price or the amount you receive when you sell shares, whichever is less)	rr_MaximumDeferredSalesChargeOverOther	none
Management Fees	rr_ManagementFeesOverAssets	0.50%
Distribution and Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.17%	[2]
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.31%	[3]
Total Annual Fund Operating Expenses Plus Acquired Fund Fees and Expenses	rr_ExpensesOverAssets	1.23%	[3]
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.07%)	[4]
Net Expenses Plus Acquired Fund Fees and Expenses	rr_NetExpensesOverAssets	1.16%	[4]
1	rr_ExpenseExampleYear01	$ 365
3	rr_ExpenseExampleYear03	624
5	rr_ExpenseExampleYear05	902
10	rr_ExpenseExampleYear10	1,695
1	rr_ExpenseExampleNoRedemptionYear01	365
3	rr_ExpenseExampleNoRedemptionYear03	624
5	rr_ExpenseExampleNoRedemptionYear05	902
10	rr_ExpenseExampleNoRedemptionYear10	$ 1,695
Pioneer Multi-Asset Income Fund | CLASS Y
Risk/Return:	rr_RiskReturnAbstract
Maximum sales charge (load) when you buy shares (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum deferred sales charge (load) (as a percentage of offering price or the amount you receive when you sell shares, whichever is less)	rr_MaximumDeferredSalesChargeOverOther	none
Management Fees	rr_ManagementFeesOverAssets	0.50%
Distribution and Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.22%	[2]
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.31%	[3]
Total Annual Fund Operating Expenses Plus Acquired Fund Fees and Expenses	rr_ExpensesOverAssets	1.03%	[3]
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.07%)	[4]
Net Expenses Plus Acquired Fund Fees and Expenses	rr_NetExpensesOverAssets	0.96%	[4]
1	rr_ExpenseExampleYear01	$ 98
3	rr_ExpenseExampleYear03	321
5	rr_ExpenseExampleYear05	562
10	rr_ExpenseExampleYear10	1,253
1	rr_ExpenseExampleNoRedemptionYear01	98
3	rr_ExpenseExampleNoRedemptionYear03	321
5	rr_ExpenseExampleNoRedemptionYear05	562
10	rr_ExpenseExampleNoRedemptionYear10	$ 1,253
1 YEAR	rr_AverageAnnualReturnYear01	12.28%
5 YEARS	rr_AverageAnnualReturnYear05	8.03%
SINCE INCEPTION	rr_AverageAnnualReturnSinceInception	8.06%
INCEPTION DATE	rr_AverageAnnualReturnInceptionDate	Dec. 22, 2011
Pioneer Multi-Asset Income Fund | Return after taxes on distributions | CLASS A
Risk/Return:	rr_RiskReturnAbstract
1 YEAR	rr_AverageAnnualReturnYear01	4.87%
5 YEARS	rr_AverageAnnualReturnYear05	4.53%
SINCE INCEPTION	rr_AverageAnnualReturnSinceInception	4.56%
INCEPTION DATE	rr_AverageAnnualReturnInceptionDate	Dec. 22, 2011
Pioneer Multi-Asset Income Fund | Return after taxes on distributions and sale of shares | CLASS A
Risk/Return:	rr_RiskReturnAbstract
1 YEAR	rr_AverageAnnualReturnYear01	4.32%
5 YEARS	rr_AverageAnnualReturnYear05	4.42%
SINCE INCEPTION	rr_AverageAnnualReturnSinceInception	4.45%
INCEPTION DATE	rr_AverageAnnualReturnInceptionDate	Dec. 22, 2011
Pioneer Multi-Asset Income Fund | Bloomberg Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 YEAR	rr_AverageAnnualReturnYear01	2.65%
5 YEARS	rr_AverageAnnualReturnYear05	2.23%
SINCE INCEPTION	rr_AverageAnnualReturnSinceInception	2.31%
INCEPTION DATE	rr_AverageAnnualReturnInceptionDate	Dec. 22, 2011
Pioneer Multi-Asset Income Fund | MSCI All Country World Index (reflects no deduction for fees, expenses or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 YEAR	rr_AverageAnnualReturnYear01	7.86%
5 YEARS	rr_AverageAnnualReturnYear05	9.36%
SINCE INCEPTION	rr_AverageAnnualReturnSinceInception	9.45%
INCEPTION DATE	rr_AverageAnnualReturnInceptionDate	Dec. 22, 2011

[1] Class A purchases of $500,000 or more that are not subject to an initial sales charge may be subject to a contingent deferred sales charge of 1%. See "Sales charges."

[2] Other Expenses for Class T shares are based on estimated amounts for the current fiscal year.

[3] Total annual fund operating expenses in the table, before and after fee waiver and expense reimbursement, may be higher than the corresponding ratio of expenses to average net assets shown in the "Financial Highlights" section, which does not include acquired fund fees and expenses.

[4] The fund's investment adviser has contractually agreed to limit ordinary operating expenses (ordinary operating expenses means all fund expenses other than taxes, brokerage commissions, acquired fund fees and expenses, and extraordinary expenses, such as litigation) to the extent required to reduce fund expenses to 0.85%, 0.85% and 0.65% of the average daily net assets attributable to Class A, Class T and Class Y shares, respectively. The expense limitations for Class A, Class T and Class Y are in effect through December 1, 2019. There can be no assurance that the adviser will extend the expense limitations beyond such time. While in effect, the arrangement may be terminated for a class only by agreement of the adviser and the Board of Trustees.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	Pioneer Series Trust IV
Prospectus Date	rr_ProspectusDate	Dec. 01, 2017
Document Creation Date	dei_DocumentCreationDate	Nov. 27, 2017