485BPOS

Registration No. 2-33043
File No. 811-01512

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, DC 20549

FORM N-1A

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933	☒
Pre­Effective Amendment No.	□
Post­Effective Amendment No. 85	☒

and/or

REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT OF 1940	☒
Amendment No. 69	☒

Oppenheimer Capital Income Fund

(Exact Name of Registrant as Specified in Charter)

6803 South Tucson Way, Centennial, Colorado 80112-3924
(Address of Principal Executive Offices) (Zip Code)

(303) 768-3200

(Registrant’s Telephone Number, including Area Code)

Cynthia Lo Bessette, Esq.

OFI Global Asset Management, Inc.

225 Liberty Street, New York, New York 10281-1008
(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  pursuant to paragraph (b)

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

□ on pursuant to paragraph (a)(1)

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

□ on pursuant to paragraph (a)(2) of Rule 485.

If appropriate, check the following box:

□ This post-effective amendment designates a new effective date for a previously filed post-effective amendment.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933 and the Investment Company Act of 1940, the Registrant certifies that it meets all the requirements for effectiveness of this Registration Statement pursuant to Rule 485(b) under the Securities Act of 1933 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of New York and State of New York on the 12th day of January 2018.

	Oppenheimer Capital Income Fund
By:	Arthur P. Steinmetz*
	Arthur P. Steinmetz Trustee, President and Principal Executive Officer

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

Signatures	Title	Date
Robert J. Malone*Robert J. Malone	Chairman of the Board of Trustees	January 12, 2018
Arthur P. Steinmetz*Arthur P. Steinmetz	Trustee, President and Principal Executive Officer	January 12, 2018
Brian S. Petersen*Brian S. Petersen	Treasurer, Principal Financial & Accounting Officer	January 12, 2018
Andrew J. Donohue*Andrew J. Donohue	Trustee	January 12, 2018
Jon S. Fossel*Jon S. Fossel	Trustee	January 12, 2018
Richard F. Grabish*Richard F. Grabish	Trustee	January 12, 2018
Beverly L. Hamilton*Beverly L. Hamilton	Trustee	January 12, 2018
Victoria J. Herget*Victoria J. Herget	Trustee	January 12, 2018
F. William Marshall, Jr.*F. William Marshall, Jr.	Trustee	January 12, 2018
Karen L. Stuckey*Karen L. Stuckey	Trustee	January 12, 2018
James D. Vaughn*James D. Vaughn	Trustee	January 12, 2018
*By: /s/ Taylor V. EdwardsTaylor V. Edwards, 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 Document
Ex-101.DEF	XBRL Taxonomy Extension Definition Linkbase
Ex-101.LAB	XBRL Taxonomy Extension Labels Linkbase
Ex-101.PRE	XBRL Taxonomy Extension Presentation Linkbase Document

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Document Type	dei_DocumentType	485BPOS
Document Period End Date	dei_DocumentPeriodEndDate	Aug. 31, 2017
Registrant Name	dei_EntityRegistrantName	OPPENHEIMER CAPITAL INCOME FUND
Central Index Key	dei_EntityCentralIndexKey	0000045156
Amendment Flag	dei_AmendmentFlag	false
Document Creation Date	dei_DocumentCreationDate	Dec. 27, 2017
Document Effective Date	dei_DocumentEffectiveDate	Dec. 29, 2017
Prospectus Date	rr_ProspectusDate	Dec. 29, 2017

XML

OPPENHEIMER CAPITAL INCOME FUND

The Fund Summary

Investment Objective.

The Fund seeks total return.

Fees and Expenses of the Fund.

This table describes the fees and expenses that you may pay if you buy and hold or redeem shares of the Fund. You may qualify for sales charge discounts if you (or you and your spouse) invest, or agree to invest in the future, at least $25,000 in certain funds in the Oppenheimer family of funds. More information about these and other discounts and sales charge waivers is available from your financial professional and in the section “About Your Account” beginning on page 28 of the prospectus, in the appendix to the prospectus titled “Special Sales Charge Arrangements and Waivers” and in the section “How to Buy Shares” beginning on page 65 in the Fund’s Statement of Additional Information.

Shareholder Fees

(fees paid directly from your investment)

Shareholder Fees - OPPENHEIMER CAPITAL INCOME FUND	Class A	Class B	Class C	Class R	Class Y	Class I
Maximum Sales Charge (Load) imposed on purchases (as % of offering price)	5.75%	none	none	none	none	none
Maximum Deferred Sales Charge (Load) (as % of the lower of original offering price or redemption proceeds)	none	5.00%	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 - OPPENHEIMER CAPITAL INCOME FUND		Class A	Class B	Class C	Class R	Class Y	Class I
Management Fees	[1],[2]	0.54%	0.54%	0.54%	0.54%	0.54%	0.54%
Distribution and/or Service (12b-1) Fees	[1]	0.25%	1.00%	1.00%	0.50%	none	none
Acquired Fund Fees and Expenses	[1]	0.02%	0.02%	0.02%	0.02%	0.02%	0.02%
Other Expenses of the Fund	[1]	0.28%	0.29%	0.27%	0.27%	0.27%	0.08%
Other Expenses of the Subsidiary	[1]	none	none	none	none	none	none
Total Annual Fund Operating Expenses	[1]	1.09%	1.85%	1.83%	1.33%	0.83%	0.64%
Fee Waiver and/or Expense Reimbursement	[1],[3]	(0.05%)	(0.05%)	(0.05%)	(0.05%)	(0.05%)	(0.05%)
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	[1]	1.04%	1.80%	1.78%	1.28%	0.78%	0.59%

Example.

The following 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 a class of shares of the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Any applicable fee waivers and/or expense reimbursements would be reflected in the below examples for the first year only. Although your actual costs may be higher or lower, based on these assumptions your expenses would be as follows:

If shares are redeemed

Expense Example - OPPENHEIMER CAPITAL INCOME FUND - USD ($)	1 Year	3 Years	5 Years	10 Years
Class A	675	899	1,140	1,830
Class B	685	882	1,205	1,798
Class C	282	576	995	2,163
Class R	131	419	729	1,607
Class Y	80	261	457	1,025
Class I	60	200	353	796

If shares are not redeemed

Expense Example, No Redemption - OPPENHEIMER CAPITAL INCOME FUND - USD ($)	1 Year	3 Years	5 Years	10 Years
Class A	675	899	1,140	1,830
Class B	185	582	1,005	1,798
Class C	182	576	995	2,163
Class R	131	419	729	1,607
Class Y	80	261	457	1,025
Class I	60	200	353	796

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 the 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 92% of the average value of its portfolio.

Principal Investment Strategies.

The Fund invests in equity, debt and other securities of domestic and foreign issuers in different capitalization ranges and in developed or developing countries. Under normal market conditions, the Fund invests at least 65% of its total assets in equity and debt securities that are expected to generate income. The percentages of equity and debt securities the Fund holds may vary from time to time. There is no limit on the Fund’s investments in foreign securities. The Fund employs multiple strategies: an equity/equity-like strategy, which may include common stocks, convertible bonds, preferred stocks, structured notes and other derivatives like options and futures on equities and equity indices; a high grade fixed income strategy, which may include corporate bonds, government bonds, mortgage-related securities and structured products; and an opportunistic strategy, which seeks asymmetric risk/reward opportunities where the portfolio managers believe the return profile has a low correlation to traditional investment strategies, as well as opportunistically selecting positions to seek total return, income, or capital appreciation. The opportunistic strategy may include convertible bonds, corporate bonds, asset-backed securities, derivatives, such as currency and commodity-linked derivatives, cash and other securities. The opportunistic strategy may also include floating rate loans (sometimes referred to as “adjustable rate loans”) that hold a senior position in the capital structure of U.S. and foreign corporations, partnerships or other business entities that, under normal circumstances, allow them to have priority of claim ahead of other obligations of a borrower in the event of liquidation. These investments are referred to as “Senior Loans.” Senior Loans may be collateralized or uncollateralized. They typically pay interest at rates that are reset periodically based on a reference benchmark that reflects current interest rates, plus a margin or premium.

Equity Securities. In selecting equity securities, the portfolio manager mainly uses value-oriented and core investing styles. A security may be undervalued because the market does not yet recognize its potential or the issuer is temporarily out of favor. The Fund seeks to realize gains when other investors recognize the real or prospective worth of the security. Value securities may offer higher than average dividends and the Fund may invest in equity securities to seek both current income and capital growth. The Fund may also invest in equity securities solely for the purpose of seeking dividend yields, which may include engaging in dividend capture strategies, in which the portfolio manager purchases securities prior to the record date for a dividend and sells them within a short time thereafter. The portfolio manager typically looks for securities that can deliver attractive risk-adjusted returns, which may include securities that: have high current income, are believed to have substantial earnings possibilities, have low price/earnings ratios, or have a low price relative to the underlying value of the issuer’s assets, earnings, cash flow or other factors.

Debt Securities. In connection with the high grade fixed income strategy, the portfolio manager looks for high current yields and typically searches for corporate and government debt securities that offer: attractive relative value, more income than U.S. treasury obligations, a balance of risk and return, high income potential and portfolio diversification. The Fund may also invest in zero-coupon and stripped securities. In connection with the opportunistic strategy, the portfolio manager looks for high yield, below-investment-grade securities, senior loans and asset-backed securities, among other debt securities, that may offer attractive returns on a risk-adjusted basis, with lower interest rate sensitivity. The Fund can invest up to 40% of its total assets in below-investment-grade securities, also referred to as “junk bonds.”

The Fund’s debt securities may be rated by a nationally recognized statistical rating organization or may be unrated. “Investment grade” securities are rated in one of the top four rating categories.

Other Securities. In pursuing its strategies, the Fund may also use derivative instruments, including to seek income or returns, or to try to manage market or other investment risks. These derivatives may include options, futures, swaps, “structured” notes, mortgage-related securities, equity-linked debt securities and commodity-linked derivatives. The Fund may also invest in convertible bonds, asset-backed securities, Senior Loans, participation interests in loans, pooled investment entities that invest in loans and currency derivatives, among other types of investments.

          The Fund may sell securities that no longer meet the above criteria.

The Fund’s holdings may at times differ significantly from the weightings of the indices comprising its reference index (the “Reference Index”). The Fund’s Reference Index is a customized weighted index currently comprised of the following underlying broad-based security indices: 65% of the Bloomberg Barclays U.S. Aggregate Bond Index and 35% of the Russell 3000 Index. The Fund is not managed to be invested in the same percentages as those indices comprising the Reference Index.

The Fund has established a Cayman Islands company that is wholly-owned and controlled by the Fund (the “Subsidiary”). The Fund may invest up to 25% of its total assets in the Subsidiary. The Subsidiary invests primarily in commodity-linked derivatives (including commodity futures, financial futures, options and swap contracts) and exchange-traded funds related to gold or other special minerals (“Gold ETFs”). The Subsidiary may also invest in certain fixed-income securities and other investments that may serve as margin or collateral for its derivatives positions. Investments in the Subsidiary are intended to provide the Fund with exposure to commodities market returns within the limitations of the federal tax requirements that apply to the Fund. The Fund applies its investment restrictions and compliance policies and procedures, on a look-through basis, to the Subsidiary. The Fund’s investment in the Subsidiary may vary based on the portfolio manager’s use of different types of commodity-linked derivatives, fixed-income securities, Gold ETFs, and other investments. Since the Fund may invest a substantial portion of its assets in the Subsidiary, which may hold certain of the investments described in this prospectus, the Fund may be considered to be investing indirectly in those investments through its Subsidiary. Therefore, references in this prospectus to investments by the Fund also may be deemed to include the Fund’s indirect investments through the Subsidiary.

Principal Risks.

The price of the Fund’s shares can go up and down substantially. The value of the Fund’s investments may fall due to adverse changes in the markets in which the Fund invests or because of poor investment selection, which could cause the Fund to underperform other funds with similar investment objectives. There is no assurance that the Fund will achieve its investment objective. When you redeem your shares, they may be worth less than what you paid for them. These risks mean that you can lose money by investing in the Fund.

Risks of Investing in Stocks. The value of the Fund’s portfolio may be affected by changes in the stock markets. Stock markets may experience significant short-term volatility and may fall sharply at times. Adverse events in any part of the equity or fixed-income markets may have unexpected negative effects on other market segments. Different stock markets may behave differently from each other and U.S. stock markets may move in the opposite direction from one or more foreign stock markets.

The prices of individual stocks generally do not all move in the same direction at the same time. A variety of factors can negatively affect the price of a particular company’s stock. These factors may include, but are not limited to: poor earnings reports, a loss of customers, litigation against the company, general unfavorable performance of the company’s sector or industry, or changes in government regulations affecting the company or its industry. To the extent that securities of a particular type are emphasized (for example foreign stocks, stocks of small- or mid-cap companies, growth or value stocks, or stocks of companies in a particular industry), fund share values may fluctuate more in response to events affecting the market for those types of securities.

Risks of Value Investing. Value investing entails the risk that if the market does not recognize that a fund’s securities are undervalued, the prices of those securities might not appreciate as anticipated. A value approach could also result in fewer investments that increase rapidly during times of market gains and could cause a fund to underperform funds that use a growth or non-value approach to investing. Value investing has gone in and out of favor during past market cycles and when value investing is out of favor or when markets are unstable, the securities of “value” companies may underperform the securities of “growth” companies.

Risks of Investing in Debt Securities. Debt securities may be subject to interest rate risk, duration risk, credit risk, credit spread risk, extension risk, reinvestment risk, prepayment risk and event risk. Interest rate risk is the risk that when prevailing interest rates fall, the values of already-issued debt securities generally rise; and when prevailing interest rates rise, the values of already-issued debt securities generally fall, and therefore, those debt securities may be worth less than the amount the Fund paid for them or valued them. When interest rates change, the values of longer-term debt securities usually change more than the values of shorter-term debt securities. Risks associated with rising interest rates are heightened given that interest rates in the U.S. are near historic lows. Duration is a measure of the price sensitivity of a debt security or portfolio to interest rate changes. Duration risk is the risk that longer-duration debt securities will be more volatile and thus more likely to decline in price, and to a greater extent, in a rising interest rate environment than shorter-duration debt securities. Credit risk is the risk that the issuer of a security might not make interest and principal payments on the security as they become due. If an issuer fails to pay interest or repay principal, the Fund’s income or share value might be reduced. Adverse news about an issuer or a downgrade in an issuer’s credit rating, for any reason, can also reduce the market value of the issuer’s securities. “Credit spread” is the difference in yield between securities that is due to differences in their credit quality. There is a risk that credit spreads may increase when the market expects lower-grade bonds to default more frequently. Widening credit spreads may quickly reduce the market values of the Fund’s lower-rated and unrated securities. Some unrated securities may not have an active trading market or may trade less actively than rated securities, which means that the Fund might have difficulty selling them promptly at an acceptable price. Extension risk is the risk that an increase in interest rates could cause prepayments on a debt security to occur at a slower rate than expected. Extension risk is particularly prevalent for a callable security where an increase in interest rates could result in the issuer of that security choosing not to redeem the security as anticipated on the security’s call date. Such a decision by the issuer could have the effect of lengthening the debt security’s expected maturity, making it more vulnerable to interest rate risk and reducing its market value. Reinvestment risk is the risk that when interest rates fall the Fund may be required to reinvest the proceeds from a security’s sale or redemption at a lower interest rate. Callable bonds are generally subject to greater reinvestment risk than non-callable bonds. Prepayment risk is the risk that the issuer may redeem the security prior to the expected maturity or that borrowers may repay the loans that underlie these securities more quickly than expected, thereby causing the issuer of the security to repay the principal prior to the expected maturity. The Fund may need to reinvest the proceeds at a lower interest rate, reducing its income. Event risk is the risk that an issuer could be subject to an event, such as a buyout or debt restructuring, that interferes with its ability to make timely interest and principal payments and cause the value of its debt securities to fall.

Fixed-Income Market Risks. The fixed-income securities market can be susceptible to increases in volatility and decreases in liquidity. Liquidity may decline unpredictably in response to overall economic conditions or credit tightening. During times of reduced market liquidity, the Fund may not be able to readily sell bonds at the prices at which they are carried on the Fund’s books and could experience a loss. If the Fund needed to sell large blocks of bonds to meet shareholder redemption requests or to raise cash, those sales could further reduce the bonds’ prices, particularly for lower-rated and unrated securities. An unexpected increase in redemptions by Fund shareholders (including requests from shareholders who may own a significant percentage of the Fund’s shares), which may be triggered by general market turmoil or an increase in interest rates, as well as other adverse market and economic developments, could cause the Fund to sell its holdings at a loss or at undesirable prices and adversely affect the Fund’s share price and increase the Fund’s liquidity risk, Fund expenses and/or taxable distributions. As of the date of this prospectus, interest rates in the U.S. are near historically low levels, increasing the exposure of bond investors to the risks associated with rising interest rates.

Economic and other market developments can adversely affect fixed-income securities markets in the United States, Europe and elsewhere. At times, participants in debt securities markets may develop concerns about the ability of certain issuers of debt securities to make timely principal and interest payments, or they may develop concerns about the ability of financial institutions that make markets in certain debt securities to facilitate an orderly market. Those concerns may impact the market price or value of those debt securities and may cause increased volatility in those debt securities or debt securities markets. Under some circumstances, those concerns may cause reduced liquidity in certain debt securities markets, reducing the willingness of some lenders to extend credit, and making it more difficult for borrowers to obtain financing on attractive terms (or at all). A lack of liquidity or other adverse credit market conditions may hamper the Fund’s ability to sell the debt securities in which it invests or to find and purchase suitable debt instruments.

Risks of Below-Investment-Grade Securities. As compared to investment-grade debt securities, below-investment-grade debt securities (also referred to as “junk” bonds), whether rated or unrated, may be subject to greater price fluctuations and increased credit risk, as the issuer might not be able to pay interest and principal when due, especially during times of weakening economic conditions or rising interest rates. Credit rating downgrades of a single issuer or related similar issuers whose securities the Fund holds in significant amounts could substantially and unexpectedly increase the Fund’s exposure to below-investment-grade securities and the risks associated with them, especially liquidity and default risk. The market for below-investment-grade securities may be less liquid and therefore these securities may be harder to value or sell at an acceptable price, especially during times of market volatility or decline.

Risks of Senior Loans and Other Loans. The Fund may invest in loans, and in particular, in floating rate loans (sometimes referred to as “adjustable rate loans”) that hold (or in the judgment of the investment adviser, hold) a senior position in the capital structure of U.S. and foreign corporations, partnerships or other business entities that, under normal circumstances, allow them to have priority of claim ahead of (or at least as high as) other obligations of a borrower in the event of liquidation. These investments are referred to as “Senior Loans.” Loans may be collateralized or uncollateralized. They typically pay interest at rates that are reset periodically based on a reference benchmark that reflects current interest rates, plus a margin or premium. In addition to the risks typically associated with debt securities, such as credit and interest rate risk, senior loans are also subject to the risk that a court could subordinate a senior loan, which typically holds a senior position in the capital structure of a borrower, to presently existing or future indebtedness or take other action detrimental to the holders of senior loans. Loans usually have mandatory and optional prepayment provisions. If a borrower prepays a loan, the Fund will have to reinvest the proceeds in other loans or financial assets that may pay lower rates of return.

Loans are subject to the risk that the value of the collateral, if any, securing a loan may decline, be insufficient to meet the obligations of the borrower, or be difficult to liquidate. In the event of a default, the Fund may have difficulty collecting on any collateral and would not have the ability to collect on any collateral for an uncollateralized loan. In addition, the lenders’ security interest or their enforcement of their security under the loan agreement may be found by a court to be invalid or the collateral may be used to pay other outstanding obligations of the borrower. The Fund’s access to collateral, if any, may be limited by bankruptcy, other insolvency laws, or by the type of loan the Fund has purchased. As a result, a collateralized loan may not be fully collateralized and can decline significantly in value.

Loan investments are often issued in connection with highly leveraged transactions. Such transactions include leveraged buyout loans, leveraged recapitalization loans, and other types of acquisition financing. These obligations are subject to greater credit risks than other investments including a greater possibility that the borrower may default or enter bankruptcy.

Due to restrictions on transfers in loan agreements and the nature of the private syndication of loans including, for example, the lack of publicly-available information, some loans are not as easily purchased or sold as publicly-traded securities. Some loans are illiquid, which may make it difficult for the Fund to value them or dispose of them at an acceptable price when it wants to. The market price of investments in floating rate loans are expected to be less affected by changes in interest rates than fixed-rate investments because floating rate loans pay a floating rate of interest that will fluctuate as market interests rates do and therefore should more closely track market movements in interest rates.

Compared to securities and to certain other types of financial assets, purchases and sales of loans take relatively longer to settle. This extended settlement process can (i) increase the counterparty credit risk borne by the Fund; (ii) leave the Fund unable to timely vote, or otherwise act with respect to, loans it has agreed to purchase; (iii) delay the Fund from realizing the proceeds of a sale of a loan; (iv) inhibit the Fund’s ability to re-sell a loan that it has agreed to purchase if conditions change (leaving the Fund more exposed to price fluctuations); (v) prevent the Fund from timely collecting principal and interest payments; and (vi) expose the Fund to adverse tax or regulatory consequences.

To the extent the extended loan settlement process gives rise to short-term liquidity needs, such as the need to satisfy redemption requests, the Fund may hold cash, sell investments or temporarily borrow from banks or other lenders.

If the Fund invests in a loan via a participation, the Fund will be exposed to the ongoing counterparty risk of the entity providing exposure to the loan (and, in certain circumstances, such entity’s credit risk), in addition to the exposure the Fund has to the creditworthiness of the borrower.

In certain circumstances, loans may not be deemed to be securities, and in the event of fraud or misrepresentation by a borrower or an arranger, lenders will not have the protection of the anti-fraud provisions of the federal securities laws, as would be the case for bonds or stocks. Instead, in such cases, lenders generally rely on the contractual provisions in the loan agreement itself, and common-law fraud protections under applicable state law.

Risks of Mortgage-Related Securities. The Fund can buy interests in pools of residential or commercial mortgages in the form of “pass-through” mortgage securities. They may be issued or guaranteed by the U.S. government, or its agencies and instrumentalities, or by private issuers. The prices and yields of mortgage-related securities are determined, in part, by assumptions about the rate of payments of the underlying mortgages and are subject to the risks of unanticipated prepayment and extension risks. Mortgage-backed securities are also subject to interest rate risk, and the market for mortgage-backed securities may be volatile at times and may be less liquid than the markets for other types of securities. Mortgage-related securities issued by private issuers are not U.S. government securities, and are subject to greater credit risks than mortgage-related securities that are U.S. government securities. In addition, a substantial portion of the Fund’s assets may be subject to “forward roll” transactions (also referred to as “mortgage dollar rolls”) at any given time, which subject the Fund to the risk that market value of the mortgage-related securities involved might decline, and that the counterparty might default in its obligations.

Asset-Backed Securities Risk. The Fund can buy asset-backed securities, which are fractional interests in pools of loans and are collateralized by the loans, other assets or receivables. They are typically issued by trusts and special purpose corporations that pass the income from the underlying pool to the purchasers. These securities are subject to the risk of default by the issuer as well as by the borrowers of the underlying loans in the pool, and to interest rate and prepayment risks.

Risks of Foreign Investing. Foreign securities are subject to special risks. Securities traded in foreign markets may be less liquid and more volatile than those traded in U.S. markets. Foreign issuers are usually not subject to the same accounting and disclosure requirements that U.S. companies are subject to, which may make it difficult for the Fund to evaluate a foreign company’s operations or financial condition. A change in the value of a foreign currency against the U.S. dollar will result in a change in the U.S. dollar value of investments denominated in that foreign currency and in the value of any income or distributions the Fund may receive on those investments. The value of foreign investments may be affected by exchange control regulations, foreign taxes, higher transaction and other costs, delays in the settlement of transactions, changes in economic or monetary policy in the United States or abroad, expropriation or nationalization of a company’s assets, or other political and economic factors. In addition, due to the inter-relationship of global economies and financial markets, changes in political and economic factors in one country or region could adversely affect conditions in another country or region. Investments in foreign securities may also expose the Fund to time-zone arbitrage risk. Foreign securities may trade on weekends or other days when the Fund does not price its shares. As a result, the value of the Fund’s net assets may change on days when you will not be able to purchase or redeem the Fund’s shares. At times, the Fund may emphasize investments in a particular country or region and may be subject to greater risks from adverse events that occur in that country or region. Foreign securities and foreign currencies held in foreign banks and securities depositories may be subject to only limited or no regulatory oversight.

          Risks of Developing and Emerging Markets. Investments in developing and emerging markets are subject to all the risks associated with foreign investing, however, these risks may be magnified in developing and emerging markets. Developing or emerging market countries may have less well-developed securities markets and exchanges that may be substantially less liquid than those of more developed markets. Settlement procedures in developing or emerging markets may differ from those of more established securities markets, and settlement delays may result in the inability to invest assets or to dispose of portfolio securities in a timely manner. Securities prices in developing or emerging markets may be significantly more volatile than is the case in more developed nations of the world, and governments of developing or emerging market countries may also be more unstable than the governments of more developed countries. Such countries’ economies may be more dependent on relatively few industries or investors that may be highly vulnerable to local and global changes. Developing or emerging market countries also may be subject to social, political or economic instability. The value of developing or emerging market countries’ currencies may fluctuate more than the currencies of countries with more mature markets. Investments in developing or emerging market countries may be subject to greater risks of government restrictions, including confiscatory taxation, expropriation or nationalization of a company’s assets, restrictions on foreign ownership of local companies, restrictions on withdrawing assets from the country, protectionist measures, and practices such as share blocking. In addition, the ability of foreign entities to participate in privatization programs of certain developing or emerging market countries may be limited by local law. Investments in securities of issuers in developing or emerging market countries may be considered speculative.

          Eurozone Investment Risks. Certain of the regions in which the Fund may invest, including the European Union (EU), currently experience significant financial difficulties. Following the global economic crisis that began in 2008, some of these countries have depended on, and may continue to be dependent on, the assistance from others such as the European Central Bank (ECB) or other governments or institutions, and failure to implement reforms as a condition of assistance could have a significant adverse effect on the value of investments in those and other European countries. In addition, countries that have adopted the euro are subject to fiscal and monetary controls that could limit the ability to implement their own economic policies, and could voluntarily abandon, or be forced out of, the euro. Such events could impact the market values of Eurozone and various other securities and currencies, cause redenomination of certain securities into less valuable local currencies, and create more volatile and illiquid markets. Additionally, the United Kingdom’s intended departure from the EU, commonly known as “Brexit,” may have significant political and financial consequences for Eurozone markets, including greater market volatility and illiquidity, currency fluctuations, deterioration in economic activity, a decrease in business confidence and an increased likelihood of a recession in the United Kingdom.

Risks of Small- and Mid-Cap Companies. Small-cap companies may be either established or newer companies, including “unseasoned” companies that have typically been in operation for less than three years. Mid-cap companies are generally companies that have completed their initial start-up cycle, and in many cases have established markets and developed seasoned market teams. While smaller companies might offer greater opportunities for gain than larger companies, they also may involve greater risk of loss. They may be more sensitive to changes in a company’s earnings expectations and may experience more abrupt and erratic price movements. Small- and mid-cap companies’ securities may trade in lower volumes and it might be harder for the Fund to dispose of its holdings at an acceptable price when it wants to sell them. Small- and mid-cap companies may not have established markets for their products or services and may have fewer customers and product lines. They may have more limited access to financial resources and may not have the financial strength to sustain them through business downturns or adverse market conditions. Since small- and mid-cap companies typically reinvest a high proportion of their earnings in their business, they may not pay dividends for some time, particularly if they are newer companies. Small- and mid-cap companies may have unseasoned management or less depth in management skill than larger, more established companies. They may be more reliant on the efforts of particular members of their management team and management changes may pose a greater risk to the success of the business. It may take a substantial period of time before the Fund realizes a gain on an investment in a small- or mid-cap company, if it realizes any gain at all.

Risks of Commodity-Linked Investments. Commodity-linked investments are considered speculative and have substantial risks, including the risk of loss of a significant portion of their principal value. Prices of commodities and commodity-linked investments may fluctuate significantly over short periods due to a variety of factors, including for example agricultural, economic and regulatory developments. These risks may make commodity-linked investments more volatile than other types of investments. Commodity-linked investments entail the risk that the Fund might not qualify as a “regulated investment company” under the Internal Revenue Code and its income may become subject to income taxes, reducing returns to shareholders.

Risks of Investments In The Fund’s Wholly-Owned Subsidiary. The Subsidiary is not registered under the Investment Company Act of 1940 and is not subject to its investor protections (except as otherwise noted in this prospectus). As an investor in the Subsidiary, the Fund does not have all of the protections offered to investors by the Investment Company Act of 1940. However, the Subsidiary is wholly-owned and controlled by the Fund and managed by the Manager and the Sub-Adviser. Therefore, the Fund’s ownership and control of the Subsidiary make it unlikely that the Subsidiary would take actions contrary to the interests of the Fund or its shareholders. In addition, changes in the laws of the United States and/or the Cayman Islands could result in the inability of the Fund and/or the Subsidiary to operate as described in this prospectus and the Statement of Additional Information and could adversely affect the Fund. Changes in the laws of the United States and/or the Cayman Islands could adversely affect the performance of the Fund and/or the Subsidiary. For example, the Cayman Islands currently does not impose certain taxes on exempted companies like the Subsidiary, including income and capital gains tax, among others. If Cayman Islands laws were changed to require such entities to pay Cayman Islands taxes, the investment returns of the Fund would likely decrease.

Risks of Derivative Investments. Derivatives may involve significant risks. Derivatives may be more volatile than other types of investments, may require the payment of premiums, may increase portfolio turnover, may be illiquid, and may not perform as expected. Derivatives are subject to counterparty risk and the Fund may lose money on a derivative investment if the issuer or counterparty fails to pay the amount due. Some derivatives have the potential for unlimited loss, regardless of the size of the Fund’s initial investment. As a result of these risks, the Fund could realize little or no income or lose money from its investment, or a hedge might be unsuccessful. In addition, under new rules enacted and currently being implemented under financial reform legislation, certain over-the-counter derivatives are (or soon will be) required to be executed on a regulated market and/or cleared through a clearinghouse. It is unclear how these regulatory changes will affect counterparty risk, and entering into a derivative transaction with a clearinghouse may entail further risks and costs.

Risks of Leverage. Leverage may be created when an investment exposes the Fund to a risk of loss that exceeds the amount invested. Certain derivatives and other investments provide the potential for investment gain or loss that may be several times than the value of the underlying security, index or other investment.

Who is the Fund Designed For? The Fund is designed primarily for investors seeking total return. Those investors should be willing to assume the risks of short-term share price fluctuations that are typical for a fund that has substantial investments in equity securities. Although the Fund seeks total return, it is not designed for investors needing an assured level of current income. The Fund is not a complete investment program. You should carefully consider your own investment goals and risk tolerance before investing in the Fund.

An investment in the Fund is not a deposit of any bank 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 below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance (for Class A Shares) from calendar year to calendar year and by showing how the Fund’s average annual returns for the periods of time shown in the table compare with those of a broad measure of market performance and those of the Reference Index, which has characteristics of those markets in which the Fund can invest. The Fund’s past investment performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. Sales charges are not reflected in the bar chart and if those charges were included, returns would be less than those shown. More recent performance information is available by calling the toll-free number on the back of this prospectus and on the Fund’s website: https://www.oppenheimerfunds.com/fund/CapitalIncomeFund

Sales charges and taxes are not included and the returns would be lower if they were. During the period shown, the highest return for a calendar quarter was 11.94% (2nd Qtr 09) and the lowest return for a calendar quarter was -24.23% (4th Qtr 08). For the period from January 1, 2017 to September 30, 2017 the return before sales charges and taxes was 5.15%.

The following table shows the average annual total returns for each class of the Fund’s shares. After-tax returns are calculated using the highest individual federal marginal income tax rates and do not reflect the impact of state or local taxes. Your actual after-tax returns, depending on your individual tax situation, may differ from those shown and after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns are shown for only one class and after-tax returns for other classes will vary.

Average Annual Total Returns for the periods ending December 31, 2016

Average Annual Total Returns - OPPENHEIMER CAPITAL INCOME FUND		1 Year	5 Years	10 Years	(or life of class, if less)		Inception Date
Class A Shares		1.08%	4.97%	0.79%			Dec. 01, 1970
Class A Shares | Return After Taxes on Distributions		0.06%	3.77%	(0.43%)			Dec. 01, 1970
Class A Shares | Return After Taxes on Distributions and Sale of Fund Shares		0.76%	3.39%	0.27%			Dec. 01, 1970
Class B Shares		1.50%	5.01%	0.84%			Aug. 17, 1993
Class C Shares		5.46%	5.39%	0.57%			Nov. 01, 1995
Class R Shares		6.99%	5.91%	1.06%			Mar. 01, 2001
Class Y Shares		7.51%	6.48%		6.02%		Jan. 28, 2011
Class I Shares		7.72%			4.19%		Dec. 27, 2013
Russell 3000 Index (reflects no deduction for fees, expenses, or taxes)		12.74%	14.67%	7.07%	8.55%	[1]
Russell 3000 Index (reflects no deduction for fees, expenses, or taxes)	[2]				12.17%
Bloomberg Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)		2.65%	2.23%	4.34%	3.05%	[1]
Bloomberg Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)	[2]				3.14%
Reference Index (reflects no deduction for fees, expenses, or taxes)		6.34%	6.67%	5.92%	5.21%	[1]
Reference Index (reflects no deduction for fees, expenses, or taxes)	[2]				6.57%

[1] Expenses have been restated to reflect current fees.

[2] “Management Fees” reflects the gross management fees paid to the Manager by the Fund and the gross management fee of the Subsidiary for its most recent fiscal year.

[3] After discussions with the Fund’s Board, the Manager has contractually agreed to waive fees and/or reimburse Fund expenses in an amount equal to the indirect management fees incurred through the Fund’s investments in funds managed by the Manager or its affiliates. After discussions with the Fund’s Board, the Manager has also contractually agreed to waive and/or reimburse the management fee it receives from the Fund in an amount equal to the management fee it receives from the Subsidiary. Each of these fee waivers and/or expense reimbursements may not be amended or withdrawn for one year from the date of this prospectus, unless approved by the Fund’s Board.

[1] From 12/27/13

[2] From 01/28/11

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	OPPENHEIMER CAPITAL INCOME FUND
Prospectus Date	rr_ProspectusDate	Dec. 29, 2017
OPPENHEIMER CAPITAL INCOME FUND
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	The Fund Summary
Objective [Heading]	rr_ObjectiveHeading	Investment Objective.
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Fund seeks total return.
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 or redeem shares of the Fund. You may qualify for sales charge discounts if you (or you and your spouse) invest, or agree to invest in the future, at least $25,000 in certain funds in the Oppenheimer family of funds. More information about these and other discounts and sales charge waivers is available from your financial professional and in the section “About Your Account” beginning on page 28 of the prospectus, in the appendix to the prospectus titled “Special Sales Charge Arrangements and Waivers” and in the section “How to Buy Shares” beginning on page 65 in the Fund’s Statement of Additional Information.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses 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	one year from the date of this prospectus
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 the 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 92% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	92.00%
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	You may qualify for sales charge discounts if you (or you and your spouse) invest, or agree to invest in the future, at least $25,000 in certain funds in the Oppenheimer family of funds.
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	$ 25,000
Expenses Restated to Reflect Current [Text]	rr_ExpensesRestatedToReflectCurrent	Expenses have been restated to reflect current fees.
Expense Example [Heading]	rr_ExpenseExampleHeading	Example.
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The following 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 a class of shares of the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Any applicable fee waivers and/or expense reimbursements would be reflected in the below examples for the first year only. Although your actual costs may be higher or lower, based on these assumptions your expenses would be as follows:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If shares are redeemed
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If shares are not redeemed
Strategy [Heading]	rr_StrategyHeading	Principal Investment Strategies.
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund invests in equity, debt and other securities of domestic and foreign issuers in different capitalization ranges and in developed or developing countries. Under normal market conditions, the Fund invests at least 65% of its total assets in equity and debt securities that are expected to generate income. The percentages of equity and debt securities the Fund holds may vary from time to time. There is no limit on the Fund’s investments in foreign securities. The Fund employs multiple strategies: an equity/equity-like strategy, which may include common stocks, convertible bonds, preferred stocks, structured notes and other derivatives like options and futures on equities and equity indices; a high grade fixed income strategy, which may include corporate bonds, government bonds, mortgage-related securities and structured products; and an opportunistic strategy, which seeks asymmetric risk/reward opportunities where the portfolio managers believe the return profile has a low correlation to traditional investment strategies, as well as opportunistically selecting positions to seek total return, income, or capital appreciation. The opportunistic strategy may include convertible bonds, corporate bonds, asset-backed securities, derivatives, such as currency and commodity-linked derivatives, cash and other securities. The opportunistic strategy may also include floating rate loans (sometimes referred to as “adjustable rate loans”) that hold a senior position in the capital structure of U.S. and foreign corporations, partnerships or other business entities that, under normal circumstances, allow them to have priority of claim ahead of other obligations of a borrower in the event of liquidation. These investments are referred to as “Senior Loans.” Senior Loans may be collateralized or uncollateralized. They typically pay interest at rates that are reset periodically based on a reference benchmark that reflects current interest rates, plus a margin or premium. Equity Securities. In selecting equity securities, the portfolio manager mainly uses value-oriented and core investing styles. A security may be undervalued because the market does not yet recognize its potential or the issuer is temporarily out of favor. The Fund seeks to realize gains when other investors recognize the real or prospective worth of the security. Value securities may offer higher than average dividends and the Fund may invest in equity securities to seek both current income and capital growth. The Fund may also invest in equity securities solely for the purpose of seeking dividend yields, which may include engaging in dividend capture strategies, in which the portfolio manager purchases securities prior to the record date for a dividend and sells them within a short time thereafter. The portfolio manager typically looks for securities that can deliver attractive risk-adjusted returns, which may include securities that: have high current income, are believed to have substantial earnings possibilities, have low price/earnings ratios, or have a low price relative to the underlying value of the issuer’s assets, earnings, cash flow or other factors. Debt Securities. In connection with the high grade fixed income strategy, the portfolio manager looks for high current yields and typically searches for corporate and government debt securities that offer: attractive relative value, more income than U.S. treasury obligations, a balance of risk and return, high income potential and portfolio diversification. The Fund may also invest in zero-coupon and stripped securities. In connection with the opportunistic strategy, the portfolio manager looks for high yield, below-investment-grade securities, senior loans and asset-backed securities, among other debt securities, that may offer attractive returns on a risk-adjusted basis, with lower interest rate sensitivity. The Fund can invest up to 40% of its total assets in below-investment-grade securities, also referred to as “junk bonds.” The Fund’s debt securities may be rated by a nationally recognized statistical rating organization or may be unrated. “Investment grade” securities are rated in one of the top four rating categories. Other Securities. In pursuing its strategies, the Fund may also use derivative instruments, including to seek income or returns, or to try to manage market or other investment risks. These derivatives may include options, futures, swaps, “structured” notes, mortgage-related securities, equity-linked debt securities and commodity-linked derivatives. The Fund may also invest in convertible bonds, asset-backed securities, Senior Loans, participation interests in loans, pooled investment entities that invest in loans and currency derivatives, among other types of investments.           The Fund may sell securities that no longer meet the above criteria. The Fund’s holdings may at times differ significantly from the weightings of the indices comprising its reference index (the “Reference Index”). The Fund’s Reference Index is a customized weighted index currently comprised of the following underlying broad-based security indices: 65% of the Bloomberg Barclays U.S. Aggregate Bond Index and 35% of the Russell 3000 Index. The Fund is not managed to be invested in the same percentages as those indices comprising the Reference Index. The Fund has established a Cayman Islands company that is wholly-owned and controlled by the Fund (the “Subsidiary”). The Fund may invest up to 25% of its total assets in the Subsidiary. The Subsidiary invests primarily in commodity-linked derivatives (including commodity futures, financial futures, options and swap contracts) and exchange-traded funds related to gold or other special minerals (“Gold ETFs”). The Subsidiary may also invest in certain fixed-income securities and other investments that may serve as margin or collateral for its derivatives positions. Investments in the Subsidiary are intended to provide the Fund with exposure to commodities market returns within the limitations of the federal tax requirements that apply to the Fund. The Fund applies its investment restrictions and compliance policies and procedures, on a look-through basis, to the Subsidiary. The Fund’s investment in the Subsidiary may vary based on the portfolio manager’s use of different types of commodity-linked derivatives, fixed-income securities, Gold ETFs, and other investments. Since the Fund may invest a substantial portion of its assets in the Subsidiary, which may hold certain of the investments described in this prospectus, the Fund may be considered to be investing indirectly in those investments through its Subsidiary. Therefore, references in this prospectus to investments by the Fund also may be deemed to include the Fund’s indirect investments through the Subsidiary.
Risk [Heading]	rr_RiskHeading	Principal Risks.
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The price of the Fund’s shares can go up and down substantially. The value of the Fund’s investments may fall due to adverse changes in the markets in which the Fund invests or because of poor investment selection, which could cause the Fund to underperform other funds with similar investment objectives. There is no assurance that the Fund will achieve its investment objective. When you redeem your shares, they may be worth less than what you paid for them. These risks mean that you can lose money by investing in the Fund. Risks of Investing in Stocks. The value of the Fund’s portfolio may be affected by changes in the stock markets. Stock markets may experience significant short-term volatility and may fall sharply at times. Adverse events in any part of the equity or fixed-income markets may have unexpected negative effects on other market segments. Different stock markets may behave differently from each other and U.S. stock markets may move in the opposite direction from one or more foreign stock markets. The prices of individual stocks generally do not all move in the same direction at the same time. A variety of factors can negatively affect the price of a particular company’s stock. These factors may include, but are not limited to: poor earnings reports, a loss of customers, litigation against the company, general unfavorable performance of the company’s sector or industry, or changes in government regulations affecting the company or its industry. To the extent that securities of a particular type are emphasized (for example foreign stocks, stocks of small- or mid-cap companies, growth or value stocks, or stocks of companies in a particular industry), fund share values may fluctuate more in response to events affecting the market for those types of securities. Risks of Value Investing. Value investing entails the risk that if the market does not recognize that a fund’s securities are undervalued, the prices of those securities might not appreciate as anticipated. A value approach could also result in fewer investments that increase rapidly during times of market gains and could cause a fund to underperform funds that use a growth or non-value approach to investing. Value investing has gone in and out of favor during past market cycles and when value investing is out of favor or when markets are unstable, the securities of “value” companies may underperform the securities of “growth” companies. Risks of Investing in Debt Securities. Debt securities may be subject to interest rate risk, duration risk, credit risk, credit spread risk, extension risk, reinvestment risk, prepayment risk and event risk. Interest rate risk is the risk that when prevailing interest rates fall, the values of already-issued debt securities generally rise; and when prevailing interest rates rise, the values of already-issued debt securities generally fall, and therefore, those debt securities may be worth less than the amount the Fund paid for them or valued them. When interest rates change, the values of longer-term debt securities usually change more than the values of shorter-term debt securities. Risks associated with rising interest rates are heightened given that interest rates in the U.S. are near historic lows. Duration is a measure of the price sensitivity of a debt security or portfolio to interest rate changes. Duration risk is the risk that longer-duration debt securities will be more volatile and thus more likely to decline in price, and to a greater extent, in a rising interest rate environment than shorter-duration debt securities. Credit risk is the risk that the issuer of a security might not make interest and principal payments on the security as they become due. If an issuer fails to pay interest or repay principal, the Fund’s income or share value might be reduced. Adverse news about an issuer or a downgrade in an issuer’s credit rating, for any reason, can also reduce the market value of the issuer’s securities. “Credit spread” is the difference in yield between securities that is due to differences in their credit quality. There is a risk that credit spreads may increase when the market expects lower-grade bonds to default more frequently. Widening credit spreads may quickly reduce the market values of the Fund’s lower-rated and unrated securities. Some unrated securities may not have an active trading market or may trade less actively than rated securities, which means that the Fund might have difficulty selling them promptly at an acceptable price. Extension risk is the risk that an increase in interest rates could cause prepayments on a debt security to occur at a slower rate than expected. Extension risk is particularly prevalent for a callable security where an increase in interest rates could result in the issuer of that security choosing not to redeem the security as anticipated on the security’s call date. Such a decision by the issuer could have the effect of lengthening the debt security’s expected maturity, making it more vulnerable to interest rate risk and reducing its market value. Reinvestment risk is the risk that when interest rates fall the Fund may be required to reinvest the proceeds from a security’s sale or redemption at a lower interest rate. Callable bonds are generally subject to greater reinvestment risk than non-callable bonds. Prepayment risk is the risk that the issuer may redeem the security prior to the expected maturity or that borrowers may repay the loans that underlie these securities more quickly than expected, thereby causing the issuer of the security to repay the principal prior to the expected maturity. The Fund may need to reinvest the proceeds at a lower interest rate, reducing its income. Event risk is the risk that an issuer could be subject to an event, such as a buyout or debt restructuring, that interferes with its ability to make timely interest and principal payments and cause the value of its debt securities to fall. Fixed-Income Market Risks. The fixed-income securities market can be susceptible to increases in volatility and decreases in liquidity. Liquidity may decline unpredictably in response to overall economic conditions or credit tightening. During times of reduced market liquidity, the Fund may not be able to readily sell bonds at the prices at which they are carried on the Fund’s books and could experience a loss. If the Fund needed to sell large blocks of bonds to meet shareholder redemption requests or to raise cash, those sales could further reduce the bonds’ prices, particularly for lower-rated and unrated securities. An unexpected increase in redemptions by Fund shareholders (including requests from shareholders who may own a significant percentage of the Fund’s shares), which may be triggered by general market turmoil or an increase in interest rates, as well as other adverse market and economic developments, could cause the Fund to sell its holdings at a loss or at undesirable prices and adversely affect the Fund’s share price and increase the Fund’s liquidity risk, Fund expenses and/or taxable distributions. As of the date of this prospectus, interest rates in the U.S. are near historically low levels, increasing the exposure of bond investors to the risks associated with rising interest rates. Economic and other market developments can adversely affect fixed-income securities markets in the United States, Europe and elsewhere. At times, participants in debt securities markets may develop concerns about the ability of certain issuers of debt securities to make timely principal and interest payments, or they may develop concerns about the ability of financial institutions that make markets in certain debt securities to facilitate an orderly market. Those concerns may impact the market price or value of those debt securities and may cause increased volatility in those debt securities or debt securities markets. Under some circumstances, those concerns may cause reduced liquidity in certain debt securities markets, reducing the willingness of some lenders to extend credit, and making it more difficult for borrowers to obtain financing on attractive terms (or at all). A lack of liquidity or other adverse credit market conditions may hamper the Fund’s ability to sell the debt securities in which it invests or to find and purchase suitable debt instruments. Risks of Below-Investment-Grade Securities. As compared to investment-grade debt securities, below-investment-grade debt securities (also referred to as “junk” bonds), whether rated or unrated, may be subject to greater price fluctuations and increased credit risk, as the issuer might not be able to pay interest and principal when due, especially during times of weakening economic conditions or rising interest rates. Credit rating downgrades of a single issuer or related similar issuers whose securities the Fund holds in significant amounts could substantially and unexpectedly increase the Fund’s exposure to below-investment-grade securities and the risks associated with them, especially liquidity and default risk. The market for below-investment-grade securities may be less liquid and therefore these securities may be harder to value or sell at an acceptable price, especially during times of market volatility or decline. Risks of Senior Loans and Other Loans. The Fund may invest in loans, and in particular, in floating rate loans (sometimes referred to as “adjustable rate loans”) that hold (or in the judgment of the investment adviser, hold) a senior position in the capital structure of U.S. and foreign corporations, partnerships or other business entities that, under normal circumstances, allow them to have priority of claim ahead of (or at least as high as) other obligations of a borrower in the event of liquidation. These investments are referred to as “Senior Loans.” Loans may be collateralized or uncollateralized. They typically pay interest at rates that are reset periodically based on a reference benchmark that reflects current interest rates, plus a margin or premium. In addition to the risks typically associated with debt securities, such as credit and interest rate risk, senior loans are also subject to the risk that a court could subordinate a senior loan, which typically holds a senior position in the capital structure of a borrower, to presently existing or future indebtedness or take other action detrimental to the holders of senior loans. Loans usually have mandatory and optional prepayment provisions. If a borrower prepays a loan, the Fund will have to reinvest the proceeds in other loans or financial assets that may pay lower rates of return. Loans are subject to the risk that the value of the collateral, if any, securing a loan may decline, be insufficient to meet the obligations of the borrower, or be difficult to liquidate. In the event of a default, the Fund may have difficulty collecting on any collateral and would not have the ability to collect on any collateral for an uncollateralized loan. In addition, the lenders’ security interest or their enforcement of their security under the loan agreement may be found by a court to be invalid or the collateral may be used to pay other outstanding obligations of the borrower. The Fund’s access to collateral, if any, may be limited by bankruptcy, other insolvency laws, or by the type of loan the Fund has purchased. As a result, a collateralized loan may not be fully collateralized and can decline significantly in value. Loan investments are often issued in connection with highly leveraged transactions. Such transactions include leveraged buyout loans, leveraged recapitalization loans, and other types of acquisition financing. These obligations are subject to greater credit risks than other investments including a greater possibility that the borrower may default or enter bankruptcy. Due to restrictions on transfers in loan agreements and the nature of the private syndication of loans including, for example, the lack of publicly-available information, some loans are not as easily purchased or sold as publicly-traded securities. Some loans are illiquid, which may make it difficult for the Fund to value them or dispose of them at an acceptable price when it wants to. The market price of investments in floating rate loans are expected to be less affected by changes in interest rates than fixed-rate investments because floating rate loans pay a floating rate of interest that will fluctuate as market interests rates do and therefore should more closely track market movements in interest rates. Compared to securities and to certain other types of financial assets, purchases and sales of loans take relatively longer to settle. This extended settlement process can (i) increase the counterparty credit risk borne by the Fund; (ii) leave the Fund unable to timely vote, or otherwise act with respect to, loans it has agreed to purchase; (iii) delay the Fund from realizing the proceeds of a sale of a loan; (iv) inhibit the Fund’s ability to re-sell a loan that it has agreed to purchase if conditions change (leaving the Fund more exposed to price fluctuations); (v) prevent the Fund from timely collecting principal and interest payments; and (vi) expose the Fund to adverse tax or regulatory consequences. To the extent the extended loan settlement process gives rise to short-term liquidity needs, such as the need to satisfy redemption requests, the Fund may hold cash, sell investments or temporarily borrow from banks or other lenders. If the Fund invests in a loan via a participation, the Fund will be exposed to the ongoing counterparty risk of the entity providing exposure to the loan (and, in certain circumstances, such entity’s credit risk), in addition to the exposure the Fund has to the creditworthiness of the borrower. In certain circumstances, loans may not be deemed to be securities, and in the event of fraud or misrepresentation by a borrower or an arranger, lenders will not have the protection of the anti-fraud provisions of the federal securities laws, as would be the case for bonds or stocks. Instead, in such cases, lenders generally rely on the contractual provisions in the loan agreement itself, and common-law fraud protections under applicable state law. Risks of Mortgage-Related Securities. The Fund can buy interests in pools of residential or commercial mortgages in the form of “pass-through” mortgage securities. They may be issued or guaranteed by the U.S. government, or its agencies and instrumentalities, or by private issuers. The prices and yields of mortgage-related securities are determined, in part, by assumptions about the rate of payments of the underlying mortgages and are subject to the risks of unanticipated prepayment and extension risks. Mortgage-backed securities are also subject to interest rate risk, and the market for mortgage-backed securities may be volatile at times and may be less liquid than the markets for other types of securities. Mortgage-related securities issued by private issuers are not U.S. government securities, and are subject to greater credit risks than mortgage-related securities that are U.S. government securities. In addition, a substantial portion of the Fund’s assets may be subject to “forward roll” transactions (also referred to as “mortgage dollar rolls”) at any given time, which subject the Fund to the risk that market value of the mortgage-related securities involved might decline, and that the counterparty might default in its obligations. Asset-Backed Securities Risk. The Fund can buy asset-backed securities, which are fractional interests in pools of loans and are collateralized by the loans, other assets or receivables. They are typically issued by trusts and special purpose corporations that pass the income from the underlying pool to the purchasers. These securities are subject to the risk of default by the issuer as well as by the borrowers of the underlying loans in the pool, and to interest rate and prepayment risks. Risks of Foreign Investing. Foreign securities are subject to special risks. Securities traded in foreign markets may be less liquid and more volatile than those traded in U.S. markets. Foreign issuers are usually not subject to the same accounting and disclosure requirements that U.S. companies are subject to, which may make it difficult for the Fund to evaluate a foreign company’s operations or financial condition. A change in the value of a foreign currency against the U.S. dollar will result in a change in the U.S. dollar value of investments denominated in that foreign currency and in the value of any income or distributions the Fund may receive on those investments. The value of foreign investments may be affected by exchange control regulations, foreign taxes, higher transaction and other costs, delays in the settlement of transactions, changes in economic or monetary policy in the United States or abroad, expropriation or nationalization of a company’s assets, or other political and economic factors. In addition, due to the inter-relationship of global economies and financial markets, changes in political and economic factors in one country or region could adversely affect conditions in another country or region. Investments in foreign securities may also expose the Fund to time-zone arbitrage risk. Foreign securities may trade on weekends or other days when the Fund does not price its shares. As a result, the value of the Fund’s net assets may change on days when you will not be able to purchase or redeem the Fund’s shares. At times, the Fund may emphasize investments in a particular country or region and may be subject to greater risks from adverse events that occur in that country or region. Foreign securities and foreign currencies held in foreign banks and securities depositories may be subject to only limited or no regulatory oversight.           Risks of Developing and Emerging Markets. Investments in developing and emerging markets are subject to all the risks associated with foreign investing, however, these risks may be magnified in developing and emerging markets. Developing or emerging market countries may have less well-developed securities markets and exchanges that may be substantially less liquid than those of more developed markets. Settlement procedures in developing or emerging markets may differ from those of more established securities markets, and settlement delays may result in the inability to invest assets or to dispose of portfolio securities in a timely manner. Securities prices in developing or emerging markets may be significantly more volatile than is the case in more developed nations of the world, and governments of developing or emerging market countries may also be more unstable than the governments of more developed countries. Such countries’ economies may be more dependent on relatively few industries or investors that may be highly vulnerable to local and global changes. Developing or emerging market countries also may be subject to social, political or economic instability. The value of developing or emerging market countries’ currencies may fluctuate more than the currencies of countries with more mature markets. Investments in developing or emerging market countries may be subject to greater risks of government restrictions, including confiscatory taxation, expropriation or nationalization of a company’s assets, restrictions on foreign ownership of local companies, restrictions on withdrawing assets from the country, protectionist measures, and practices such as share blocking. In addition, the ability of foreign entities to participate in privatization programs of certain developing or emerging market countries may be limited by local law. Investments in securities of issuers in developing or emerging market countries may be considered speculative.           Eurozone Investment Risks. Certain of the regions in which the Fund may invest, including the European Union (EU), currently experience significant financial difficulties. Following the global economic crisis that began in 2008, some of these countries have depended on, and may continue to be dependent on, the assistance from others such as the European Central Bank (ECB) or other governments or institutions, and failure to implement reforms as a condition of assistance could have a significant adverse effect on the value of investments in those and other European countries. In addition, countries that have adopted the euro are subject to fiscal and monetary controls that could limit the ability to implement their own economic policies, and could voluntarily abandon, or be forced out of, the euro. Such events could impact the market values of Eurozone and various other securities and currencies, cause redenomination of certain securities into less valuable local currencies, and create more volatile and illiquid markets. Additionally, the United Kingdom’s intended departure from the EU, commonly known as “Brexit,” may have significant political and financial consequences for Eurozone markets, including greater market volatility and illiquidity, currency fluctuations, deterioration in economic activity, a decrease in business confidence and an increased likelihood of a recession in the United Kingdom. Risks of Small- and Mid-Cap Companies. Small-cap companies may be either established or newer companies, including “unseasoned” companies that have typically been in operation for less than three years. Mid-cap companies are generally companies that have completed their initial start-up cycle, and in many cases have established markets and developed seasoned market teams. While smaller companies might offer greater opportunities for gain than larger companies, they also may involve greater risk of loss. They may be more sensitive to changes in a company’s earnings expectations and may experience more abrupt and erratic price movements. Small- and mid-cap companies’ securities may trade in lower volumes and it might be harder for the Fund to dispose of its holdings at an acceptable price when it wants to sell them. Small- and mid-cap companies may not have established markets for their products or services and may have fewer customers and product lines. They may have more limited access to financial resources and may not have the financial strength to sustain them through business downturns or adverse market conditions. Since small- and mid-cap companies typically reinvest a high proportion of their earnings in their business, they may not pay dividends for some time, particularly if they are newer companies. Small- and mid-cap companies may have unseasoned management or less depth in management skill than larger, more established companies. They may be more reliant on the efforts of particular members of their management team and management changes may pose a greater risk to the success of the business. It may take a substantial period of time before the Fund realizes a gain on an investment in a small- or mid-cap company, if it realizes any gain at all. Risks of Commodity-Linked Investments. Commodity-linked investments are considered speculative and have substantial risks, including the risk of loss of a significant portion of their principal value. Prices of commodities and commodity-linked investments may fluctuate significantly over short periods due to a variety of factors, including for example agricultural, economic and regulatory developments. These risks may make commodity-linked investments more volatile than other types of investments. Commodity-linked investments entail the risk that the Fund might not qualify as a “regulated investment company” under the Internal Revenue Code and its income may become subject to income taxes, reducing returns to shareholders. Risks of Investments In The Fund’s Wholly-Owned Subsidiary. The Subsidiary is not registered under the Investment Company Act of 1940 and is not subject to its investor protections (except as otherwise noted in this prospectus). As an investor in the Subsidiary, the Fund does not have all of the protections offered to investors by the Investment Company Act of 1940. However, the Subsidiary is wholly-owned and controlled by the Fund and managed by the Manager and the Sub-Adviser. Therefore, the Fund’s ownership and control of the Subsidiary make it unlikely that the Subsidiary would take actions contrary to the interests of the Fund or its shareholders. In addition, changes in the laws of the United States and/or the Cayman Islands could result in the inability of the Fund and/or the Subsidiary to operate as described in this prospectus and the Statement of Additional Information and could adversely affect the Fund. Changes in the laws of the United States and/or the Cayman Islands could adversely affect the performance of the Fund and/or the Subsidiary. For example, the Cayman Islands currently does not impose certain taxes on exempted companies like the Subsidiary, including income and capital gains tax, among others. If Cayman Islands laws were changed to require such entities to pay Cayman Islands taxes, the investment returns of the Fund would likely decrease. Risks of Derivative Investments. Derivatives may involve significant risks. Derivatives may be more volatile than other types of investments, may require the payment of premiums, may increase portfolio turnover, may be illiquid, and may not perform as expected. Derivatives are subject to counterparty risk and the Fund may lose money on a derivative investment if the issuer or counterparty fails to pay the amount due. Some derivatives have the potential for unlimited loss, regardless of the size of the Fund’s initial investment. As a result of these risks, the Fund could realize little or no income or lose money from its investment, or a hedge might be unsuccessful. In addition, under new rules enacted and currently being implemented under financial reform legislation, certain over-the-counter derivatives are (or soon will be) required to be executed on a regulated market and/or cleared through a clearinghouse. It is unclear how these regulatory changes will affect counterparty risk, and entering into a derivative transaction with a clearinghouse may entail further risks and costs. Risks of Leverage. Leverage may be created when an investment exposes the Fund to a risk of loss that exceeds the amount invested. Certain derivatives and other investments provide the potential for investment gain or loss that may be several times than the value of the underlying security, index or other investment. Who is the Fund Designed For? The Fund is designed primarily for investors seeking total return. Those investors should be willing to assume the risks of short-term share price fluctuations that are typical for a fund that has substantial investments in equity securities. Although the Fund seeks total return, it is not designed for investors needing an assured level of current income. The Fund is not a complete investment program. You should carefully consider your own investment goals and risk tolerance before investing in the Fund. An investment in the Fund is not a deposit of any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	These risks mean that you can lose money by investing in the Fund.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a deposit of any bank 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 below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance (for Class A Shares) from calendar year to calendar year and by showing how the Fund’s average annual returns for the periods of time shown in the table compare with those of a broad measure of market performance and those of the Reference Index, which has characteristics of those markets in which the Fund can invest. The Fund’s past investment performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. Sales charges are not reflected in the bar chart and if those charges were included, returns would be less than those shown. More recent performance information is available by calling the toll-free number on the back of this prospectus and on the Fund’s website: https://www.oppenheimerfunds.com/fund/CapitalIncomeFund
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance (for Class A Shares) from calendar year to calendar year and by showing how the Fund’s average annual returns for the periods of time shown in the table compare with those of a broad measure of market performance and those of the Reference Index, which has characteristics of those markets in which the Fund can invest.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	https://www.oppenheimerfunds.com/fund/CapitalIncomeFund
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past investment performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Sales charges are not reflected in the bar chart and if those charges were included, returns would be less than those shown.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Sales charges and taxes are not included and the returns would be lower if they were. During the period shown, the highest return for a calendar quarter was 11.94% (2nd Qtr 09) and the lowest return for a calendar quarter was -24.23% (4th Qtr 08). For the period from January 1, 2017 to September 30, 2017 the return before sales charges and taxes was 5.15%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns for the periods ending December 31, 2016
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the highest individual federal marginal income tax rates and do not reflect the impact of state or local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Your actual after-tax returns, depending on your individual tax situation, may differ from those shown and after-tax returns shown are not relevant to investors who hold their 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 for only one class and after-tax returns for other classes will vary.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The following table shows the average annual total returns for each class of the Fund’s shares. After-tax returns are calculated using the highest individual federal marginal income tax rates and do not reflect the impact of state or local taxes. Your actual after-tax returns, depending on your individual tax situation, may differ from those shown and after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns are shown for only one class and after-tax returns for other classes will vary.
OPPENHEIMER CAPITAL INCOME FUND | Class A
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) imposed on purchases (as % of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	5.75%
Maximum Deferred Sales Charge (Load) (as % of the lower of original offering price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Management Fees	rr_ManagementFeesOverAssets	0.54%	[1],[2]
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%	[1]
Other Expenses of the Fund	rr_Component1OtherExpensesOverAssets	0.28%	[1]
Other Expenses of the Subsidiary	rr_Component2OtherExpensesOverAssets	none	[1]
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.02%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.09%	[1]
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.05%)	[1],[3]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	1.04%	[1]
1 Year	rr_ExpenseExampleYear01	$ 675
3 Years	rr_ExpenseExampleYear03	899
5 Years	rr_ExpenseExampleYear05	1,140
10 Years	rr_ExpenseExampleYear10	1,830
1 Year	rr_ExpenseExampleNoRedemptionYear01	675
3 Years	rr_ExpenseExampleNoRedemptionYear03	899
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,140
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,830
2007	rr_AnnualReturn2007	(1.85%)
2008	rr_AnnualReturn2008	(37.05%)
2009	rr_AnnualReturn2009	18.10%
2010	rr_AnnualReturn2010	11.63%
2011	rr_AnnualReturn2011	4.21%
2012	rr_AnnualReturn2012	11.09%
2013	rr_AnnualReturn2013	9.19%
2014	rr_AnnualReturn2014	4.75%
2015	rr_AnnualReturn2015	(0.77%)
2016	rr_AnnualReturn2016	7.25%
Year to Date Return, Label	rr_YearToDateReturnLabel	For the period from January 1, 2017 to September 30, 2017
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2017
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	5.15%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	highest return
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	11.94%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	lowest return
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(24.23%)
1 Year	rr_AverageAnnualReturnYear01	1.08%
5 Years	rr_AverageAnnualReturnYear05	4.97%
10 Years	rr_AverageAnnualReturnYear10	0.79%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 01, 1970
OPPENHEIMER CAPITAL INCOME FUND | Class B
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) imposed on purchases (as % of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as % of the lower of original offering price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	5.00%
Management Fees	rr_ManagementFeesOverAssets	0.54%	[1],[2]
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%	[1]
Other Expenses of the Fund	rr_Component1OtherExpensesOverAssets	0.29%	[1]
Other Expenses of the Subsidiary	rr_Component2OtherExpensesOverAssets	none	[1]
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.02%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.85%	[1]
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.05%)	[1],[3]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	1.80%	[1]
1 Year	rr_ExpenseExampleYear01	$ 685
3 Years	rr_ExpenseExampleYear03	882
5 Years	rr_ExpenseExampleYear05	1,205
10 Years	rr_ExpenseExampleYear10	1,798
1 Year	rr_ExpenseExampleNoRedemptionYear01	185
3 Years	rr_ExpenseExampleNoRedemptionYear03	582
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,005
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,798
1 Year	rr_AverageAnnualReturnYear01	1.50%
5 Years	rr_AverageAnnualReturnYear05	5.01%
10 Years	rr_AverageAnnualReturnYear10	0.84%
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 17, 1993
OPPENHEIMER CAPITAL INCOME FUND | Class C
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) imposed on purchases (as % of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as % of the lower of original offering price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	1.00%
Management Fees	rr_ManagementFeesOverAssets	0.54%	[1],[2]
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%	[1]
Other Expenses of the Fund	rr_Component1OtherExpensesOverAssets	0.27%	[1]
Other Expenses of the Subsidiary	rr_Component2OtherExpensesOverAssets	none	[1]
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.02%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.83%	[1]
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.05%)	[1],[3]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	1.78%	[1]
1 Year	rr_ExpenseExampleYear01	$ 282
3 Years	rr_ExpenseExampleYear03	576
5 Years	rr_ExpenseExampleYear05	995
10 Years	rr_ExpenseExampleYear10	2,163
1 Year	rr_ExpenseExampleNoRedemptionYear01	182
3 Years	rr_ExpenseExampleNoRedemptionYear03	576
5 Years	rr_ExpenseExampleNoRedemptionYear05	995
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 2,163
1 Year	rr_AverageAnnualReturnYear01	5.46%
5 Years	rr_AverageAnnualReturnYear05	5.39%
10 Years	rr_AverageAnnualReturnYear10	0.57%
Inception Date	rr_AverageAnnualReturnInceptionDate	Nov. 01, 1995
OPPENHEIMER CAPITAL INCOME FUND | Class R
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) imposed on purchases (as % of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as % of the lower of original offering price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Management Fees	rr_ManagementFeesOverAssets	0.54%	[1],[2]
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.50%	[1]
Other Expenses of the Fund	rr_Component1OtherExpensesOverAssets	0.27%	[1]
Other Expenses of the Subsidiary	rr_Component2OtherExpensesOverAssets	none	[1]
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.02%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.33%	[1]
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.05%)	[1],[3]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	1.28%	[1]
1 Year	rr_ExpenseExampleYear01	$ 131
3 Years	rr_ExpenseExampleYear03	419
5 Years	rr_ExpenseExampleYear05	729
10 Years	rr_ExpenseExampleYear10	1,607
1 Year	rr_ExpenseExampleNoRedemptionYear01	131
3 Years	rr_ExpenseExampleNoRedemptionYear03	419
5 Years	rr_ExpenseExampleNoRedemptionYear05	729
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,607
1 Year	rr_AverageAnnualReturnYear01	6.99%
5 Years	rr_AverageAnnualReturnYear05	5.91%
10 Years	rr_AverageAnnualReturnYear10	1.06%
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 01, 2001
OPPENHEIMER CAPITAL INCOME FUND | Class Y
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) imposed on purchases (as % of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as % of the lower of original offering price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Management Fees	rr_ManagementFeesOverAssets	0.54%	[1],[2]
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none	[1]
Other Expenses of the Fund	rr_Component1OtherExpensesOverAssets	0.27%	[1]
Other Expenses of the Subsidiary	rr_Component2OtherExpensesOverAssets	none	[1]
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.02%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.83%	[1]
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.05%)	[1],[3]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	0.78%	[1]
1 Year	rr_ExpenseExampleYear01	$ 80
3 Years	rr_ExpenseExampleYear03	261
5 Years	rr_ExpenseExampleYear05	457
10 Years	rr_ExpenseExampleYear10	1,025
1 Year	rr_ExpenseExampleNoRedemptionYear01	80
3 Years	rr_ExpenseExampleNoRedemptionYear03	261
5 Years	rr_ExpenseExampleNoRedemptionYear05	457
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,025
1 Year	rr_AverageAnnualReturnYear01	7.51%
5 Years	rr_AverageAnnualReturnYear05	6.48%
(or life of class, if less)	rr_AverageAnnualReturnSinceInception	6.02%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 28, 2011
OPPENHEIMER CAPITAL INCOME FUND | Class I
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) imposed on purchases (as % of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as % of the lower of original offering price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Management Fees	rr_ManagementFeesOverAssets	0.54%	[1],[2]
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none	[1]
Other Expenses of the Fund	rr_Component1OtherExpensesOverAssets	0.08%	[1]
Other Expenses of the Subsidiary	rr_Component2OtherExpensesOverAssets	none	[1]
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.02%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.64%	[1]
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.05%)	[1],[3]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	0.59%	[1]
1 Year	rr_ExpenseExampleYear01	$ 60
3 Years	rr_ExpenseExampleYear03	200
5 Years	rr_ExpenseExampleYear05	353
10 Years	rr_ExpenseExampleYear10	796
1 Year	rr_ExpenseExampleNoRedemptionYear01	60
3 Years	rr_ExpenseExampleNoRedemptionYear03	200
5 Years	rr_ExpenseExampleNoRedemptionYear05	353
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 796
1 Year	rr_AverageAnnualReturnYear01	7.72%
10 Years	rr_AverageAnnualReturnYear10
(or life of class, if less)	rr_AverageAnnualReturnSinceInception	4.19%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 27, 2013
OPPENHEIMER CAPITAL INCOME FUND | Return After Taxes on Distributions | Class A
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.06%
5 Years	rr_AverageAnnualReturnYear05	3.77%
10 Years	rr_AverageAnnualReturnYear10	(0.43%)
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 01, 1970
OPPENHEIMER CAPITAL INCOME FUND | Return After Taxes on Distributions and Sale of Fund Shares | Class A
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.76%
5 Years	rr_AverageAnnualReturnYear05	3.39%
10 Years	rr_AverageAnnualReturnYear10	0.27%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 01, 1970
OPPENHEIMER CAPITAL INCOME FUND | Russell 3000 Index (reflects no deduction for fees, expenses, or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	12.74%
5 Years	rr_AverageAnnualReturnYear05	14.67%
10 Years	rr_AverageAnnualReturnYear10	7.07%
(or life of class, if less)	rr_AverageAnnualReturnSinceInception	8.55%	[4]
OPPENHEIMER CAPITAL INCOME FUND | Russell 3000 Index (reflects no deduction for fees, expenses, or taxes)
Risk/Return:	rr_RiskReturnAbstract
(or life of class, if less)	rr_AverageAnnualReturnSinceInception	12.17%	[5]
OPPENHEIMER CAPITAL 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%
10 Years	rr_AverageAnnualReturnYear10	4.34%
(or life of class, if less)	rr_AverageAnnualReturnSinceInception	3.05%	[4]
OPPENHEIMER CAPITAL INCOME FUND | Bloomberg Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)
Risk/Return:	rr_RiskReturnAbstract
(or life of class, if less)	rr_AverageAnnualReturnSinceInception	3.14%	[5]
OPPENHEIMER CAPITAL INCOME FUND | Reference Index (reflects no deduction for fees, expenses, or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	6.34%
5 Years	rr_AverageAnnualReturnYear05	6.67%
10 Years	rr_AverageAnnualReturnYear10	5.92%
(or life of class, if less)	rr_AverageAnnualReturnSinceInception	5.21%	[4]
OPPENHEIMER CAPITAL INCOME FUND | Reference Index (reflects no deduction for fees, expenses, or taxes)
Risk/Return:	rr_RiskReturnAbstract
(or life of class, if less)	rr_AverageAnnualReturnSinceInception	6.57%	[5]

[1] Expenses have been restated to reflect current fees.

[2] “Management Fees” reflects the gross management fees paid to the Manager by the Fund and the gross management fee of the Subsidiary for its most recent fiscal year.

[3] After discussions with the Fund’s Board, the Manager has contractually agreed to waive fees and/or reimburse Fund expenses in an amount equal to the indirect management fees incurred through the Fund’s investments in funds managed by the Manager or its affiliates. After discussions with the Fund’s Board, the Manager has also contractually agreed to waive and/or reimburse the management fee it receives from the Fund in an amount equal to the management fee it receives from the Subsidiary. Each of these fee waivers and/or expense reimbursements may not be amended or withdrawn for one year from the date of this prospectus, unless approved by the Fund’s Board.

[4] From 12/27/13

[5] From 01/28/11

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	OPPENHEIMER CAPITAL INCOME FUND
Prospectus Date	rr_ProspectusDate	Dec. 29, 2017
Document Creation Date	dei_DocumentCreationDate	Dec. 27, 2017