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State Street Small Cap Equity VIS Fund Investment Risks - State Street Small Cap Equity VIS Fund
Dec. 31, 2025
Market Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] Market Risk: The Fund's investments are subject to changes in general economic conditions, general market fluctuations and the risks inherent in investment in securities markets. Investment markets can be volatile and prices of investments can change substantially due to various factors including, but not limited to, economic growth or recession, changes in interest rates, inflation, changes in the actual or perceived creditworthiness of issuers, and general market liquidity. The Fund is subject to the risk that geopolitical events will disrupt securities markets and adversely affect global economies and markets. Local, regional or global events such as war, military conflicts, acts of terror ism, trade policy changes or disputes, the threat or actual imposition of tariffs, natural disasters, the spread of infectious illness or other public health issues, or other events could have a significant impact on the Fund and its investments.
Equity Investing Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] Equity Investing Risk: The market prices of equity securities owned by the Fund may go up or down, sometimes rapidly or unpredictably. The value of a security may decline for a number of reasons that may directly relate to the issuer and also may decline due to general industry or market conditions that are not specifically related to a particular company. In addition, equity markets tend to move in cycles, which may cause stock prices to fall over short or extended periods of time.
Small Mid and Micro Capitalization Securities Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] Small-, Mid-, and Micro-Capitalization Securities Risk: The securities of small-, mid- and micro-capitalization companies may be more volatile and may involve more risk than the securities of larger companies. These companies may have limited product lines, markets or financial resources, may lack the competitive strength of larger companies, and may depend on a few key employees. In addition, these companies may have been recently organized and may have little or no track record of success. The securities of smaller companies may trade less frequently and in smaller volumes than more widely held securities. Some securities of smaller issuers may be illiquid or may be restricted as to resale, and their values may have significant volatility. The Fund may be unable to liquidate its positions in such securities at any time, or at a favorable price, in order to meet the Fund's obligations. Returns on investments in securities of small-, mid- and micro-capitalization companies could trail the returns on investments in securities of larger companies.
Asset Allocation Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] Asset Allocation Risk: The Fund's investment performance depends upon the successful allocation by the Adviser of the Fund's assets among asset classes, geographical regions, industry sectors, and specific issuers and investments. There is no guarantee that the Adviser's allocation techniques and decisions will produce the desired results.
Company Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] Company Risk: Changes in the financial condition of a company or other issuer, changes in specific market, economic, political, regulatory, geopolitical, and other conditions that affect a particular type of investment or issuer, and changes in general market, economic, political, regulatory, geopolitical and other conditions can adversely affect the price of an investment. The price of securities of smaller, less well-known issuers can be more volatile than the price of securities of larger issuers or the market in general.
Counterparty Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] Counterparty Risk: The Fund will be subject to credit risk with respect to the counterparties with which the Fund enters into derivatives contracts, repurchase agreements, reverse repurchase agreements, and other transactions. If a counterparty fails to meet its contractual obligations, the Fund may be unable to terminate or realize any gain on the investment or transaction, or to recover collateral posted to the counterparty, resulting in a loss to the Fund. If the Fund holds collateral posted by its counterparty, it may be delayed or prevented from realizing on the collateral in the event of a bankruptcy or insolvency proceeding relating to the counterparty.
Currency Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] Currency Risk: The value of the Fund's assets may be affected favorably or unfavorably by currency exchange rates, currency exchange control regulations, and delays, restrictions or prohibitions on the repatriation of foreign currencies. Foreign currency exchange rates may have significant volatility, and changes in the values of foreign currencies against the U.S. dollar may result in substantial declines in the values of the Fund's assets denominated in foreign currencies.
Debt Securities Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] Debt Securities Risk: The values of debt securities may increase or decrease as a result of the following: market fluctuations, changes in interest rates, actual or perceived inability or unwillingness of issuers, guarantors or liquidity providers to make scheduled principal or interest payments, or illiquidity in debt securities markets. To the extent that interest rates rise, certain underlying obligations may be paid off substantially slower than originally anticipated and the value of those securities may fall sharply. A rising interest rate environment may cause the value of the Fund's fixed income securities to decrease, an adverse impact on the liquidity of the Fund's fixed income securities, and increased volatility of the fixed income markets. During periods when interest rates are at low levels, the Fund's yield can be low, and the Fund may have a negative yield (i.e., it may lose money on an operating basis). To the extent that interest rates fall, certain underlying obligations may be paid off substantially faster than originally anticipated. If the principal on a debt obligation is prepaid before expected, the prepayments of principal may have to be reinvested in obligations paying interest at lower rates. During periods of falling interest rates, the income received by the Fund may decline. Changes in interest rates will likely have a greater effect on the values of debt securities of longer durations. Returns on investments in debt securities could trail the returns on other investment options, including investments in equity securities. High levels of inflation and/or a significantly changing interest rate environment can lead to heightened levels of volatility and reduced liquidity.
Derivatives Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] Derivatives Risk: Derivative transactions can create investment leverage and may have significant volatility. It is possible that a derivative transaction will result in a much greater loss than the principal amount invested, that changes in the value of a derivative transaction may not correlate perfectly with the underlying asset, and that the Fund may not be able to close out a derivative transaction at a favorable time or price. The counterparty to a derivatives contract may be unable or unwilling to make timely settlement payments, return the Fund's margin, or otherwise honor its obligations. A derivatives transaction may not behave in the manner anticipated by the Adviser or sub-adviser or may not have the effect on the Fund anticipated by the Adviser or sub-adviser.
Focused Investment Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] Focused Investment Risk: To the extent the Fund invests a large percentage of its assets in securities within the same country, state, region, or economic sector its investment strategy could result in more risk or greater volatility in returns than if the Fund's investments were less focused.
Growth Stock Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] Growth Stock Risk: The prices of growth stocks may be based largely on expectations of future earnings, and their prices can decline rapidly and significantly in reaction to negative news. Growth stocks may underperform value stocks and stocks in other broad style categories (and the stock market as a whole) over any period of time and may shift in and out of favor with investors generally, sometimes rapidly, depending on changes in market, economic, and other factors.
Information Technology Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] Information Technology Sector Risk: Market or economic factors impacting information technology companies could have a major effect on the value of the Fund's investments. The value of stocks of information technology companies is particularly vulnerable to rapid changes in technology product cycles, rapid product obsolescence, government regulation and competition, both domestically and internationally, including competition from foreign competitors with lower production costs. Like other technology companies, information technology companies may have limited product lines, markets, financial resources or personnel. Stocks of technology companies and companies that rely heavily on technology, especially those of smaller, less-seasoned companies, tend to be more volatile than the overall market. Information technology companies are heavily dependent on patent and intellectual property rights, the loss or impairment of which may adversely affect profitability. Additionally, companies in the information technology sector may face dramatic and often unpredictable changes in growth rates and competition for the services of qualified personnel.
Large Transactions Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] Large Transactions Risk: To the extent a large proportion of the shares of the Fund are held by a small number of shareholders (or a single shareholder), including funds or accounts over which the Adviser has investment discretion, the Fund is subject to the risk that these shareholders will purchase or redeem Fund Shares in large amounts rapidly or unexpectedly, including as a result of an asset allocation decision made by the Adviser. In addition, a large number of shareholders collectively may purchase or redeem Fund Shares in large amounts rapidly or unexpectedly (collectively, such transactions are referred to as “large shareholder transactions”). Large shareholder transactions could adversely affect the ability of the Fund to conduct its investment program.
Liquidity Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] Liquidity Risk: Lack of a ready market, stressed market conditions, or restrictions on resale may limit the ability of the Fund to sell a security at an advantageous time or price or at all. Illiquid investments may trade at a discount from comparable, more liquid investments and may be subject to wide fluctuations in market value. Illiquidity of the Fund's holdings may also limit the ability of the Fund to obtain cash to meet redemptions on a timely basis. In addition, the Fund, due to limitations on investments in any illiquid investments and/or the difficulty in purchasing and selling such investments, may be unable to achieve its desired level of exposure to a certain market or sector.
Management Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] Management Risk: The Fund is actively managed by the Adviser and multiple sub-advisers. The Adviser's or sub-advisers' judgments about the attractiveness, relative value, or potential appreciation of a particular sector, security, commodity or investment strategy may prove to be incorrect, and may cause the Fund to incur losses. There can be no assurance that the Adviser's or sub-advisers' investment techniques and decisions will produce the desired results. Additionally, because portions of the Fund's assets are managed by the Adviser and multiple sub-advisers, each using different investment styles, the Fund could engage in overlapping security transactions, potentially leading to the Fund holding a more concentrated position in these securities.
Non U S Securities Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] Non-U.S. Securities Risk: Non-U.S. securities (including depositary receipts) are subject to political, regulatory, and economic risks not present in domestic investments. There may be less information publicly available about a non-U.S. entity than about a U.S. entity, and many non-U.S. entities are not subject to accounting, auditing, legal and financial report standards comparable to those in the United States. Further, such entities and/or their securities may be subject to risks associated with currency controls; expropriation; changes in tax policy; greater market volatility; differing securities market structures; higher transaction costs; and various administrative difficulties, such as delays in clearing and settling portfolio transactions or in receiving payment of dividends. Securities traded on foreign markets may be less liquid (harder to sell) than securities traded domestically. Foreign governments may impose restrictions on the repatriation of capital to the U.S. In addition, to the extent that the Fund buys securities denominated in a foreign currency, there are special risks such as changes in currency exchange rates and the risk that a foreign government could regulate foreign exchange transactions. In addition, to the extent investments are made in a limited number of countries, events in those countries will have a more significant impact on the Fund. Investments in depositary receipts may be less liquid and more volatile than the underlying shares in their primary trading market.
Unconstrained Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] Unconstrained Sector Risk: The Fund may invest a substantial portion of its assets within one or more economic sectors or industries, which may change from time to time. Greater investment focus on one or more sectors or industries increases the potential for volatility and the risk that events negatively affecting such sectors or industries could reduce returns, potentially causing the value of the Fund's Shares to decrease, perhaps significantly.
Value Stock Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] Value Stock Risk: A “value” style of investing is subject to the risk that the returns on “value” equity securities are less than returns on other styles of investing or the overall stock market. Value stocks present the risk that they may decline in price or never reach their expected full market value, either because the market fails to recognize a stock's intrinsic worth or the Adviser or sub-adviser overestimates the stock's expected value.
Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] You could lose money by investing in the Fund.
Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items]  
Risk [Text Block] An investment in the Fund is subject to investment risks, including possible loss of principal, is not a deposit in a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation (“FDIC”) or any other government agency.