Brighthouse Franklin Low Duration Total Return Portfolio Investment Strategy - Brighthouse Franklin Low Duration Total Return Portfolio	Dec. 31, 2025
Prospectus [Line Items]
Strategy [Heading]	<span style="color:#000000;font-family:Times New Roman;font-size:11.5pt;font-weight:bold;">Principal Investment Strategies</span>
Strategy Narrative [Text Block]	Franklin Advisers, Inc. (“Franklin Advisers” or “Subadviser”), subadviser to the Portfolio, invests the Portfolio’s assets, under normal circumstances, primarily in debt securities, including derivative instruments that provide exposure to debt securities such as futures, options and swap agreements, and in other investments, including government and corporate debt securities, mortgage- and asset-backed securities, collateralized loan obligations and other collateralized debt obligations, investment grade corporate loans and floating rate corporate loans, municipal securities and futures with reference securities that are investment grade, targeting an estimated average portfolio duration of three (3) years or less. Under normal market conditions, the Portfolio invests primarily in investment grade debt securities and in unrated securities that the investment manager deems are of comparable quality. Duration is a measure of the expected price volatility of a debt instrument as a result of changes in market rates of interest, based on the weighted average timing of the instrument’s expected principal and interest payments and other factors. Debt securities represent the obligation of the issuer to repay a loan of money to it, and generally pay interest to the holder. Bonds, notes and debentures are examples of debt securities. Some of the mortgage securities purchased by the Portfolio are issued or guaranteed by the U.S. Government, its agencies or instrumentalities; others are issued by private issuers. These mortgage-backed securities may include credit risk transfer securities, which are fixed- or floating-rate unsecured obligations. The Portfolio may also invest in mortgage dollar rolls, through which the Portfolio sells mortgage-backed securities for delivery in the current month and simultaneously contracts to repurchase substantially similar (same type, coupon, and maturity) securities on a specified future date. During the period between the sale and repurchase, the Portfolio forgoes principal and interest paid on the mortgage-backed securities. In addition, the Portfolio may invest a portion of its assets in corporate loans made to, or issued by, borrowers that are U.S. companies, foreign borrowers and U.S. subsidiaries of foreign borrowers and that typically have floating interest rates. The Portfolio may also invest in inflation-indexed securities issued by the U.S. Treasury and securities issued pursuant to Rule 144A under the Securities Act of 1933. In choosing investments, Franklin Advisers selects securities in various market sectors based on its assessment of changing economic, market, industry and issuer conditions. Franklin Advisers uses a “top-down” analysis of macroeconomic trends, combined with a “bottom-up” fundamental analysis of market sectors, industries and issuers, to try to take advantage of varying sector reactions to economic events. Franklin Advisers evaluates business cycles, changes in yield curves and apparent imbalances in values between and within markets. These factors can impact both income and potential for capital appreciation. The Portfolio focuses on investment grade securities and investments or in unrated securities and investments that Franklin Advisers determines are comparable. Securities rated in the top four ratings categories by independent rating organizations such as Standard & Poor’s Ratings Services (S&P®) (rated BBB or better) or Moody’s Ratings (Moody’s) (rated Baa or higher) are considered investment grade. Securities rated Ba or lower by Moody’s or BB or lower by S&P® are considered to be below investment grade. The Portfolio may invest up to 20% of its total assets in high yield debt securities (commonly referred to as “junk bonds”), including up to 5% in securities rated lower than B by S&P® or Moody’s, which may include defaulted securities. The Portfolio may invest up to 25% of its total assets in foreign securities, including up to 20% of its total assets in non-U.S. dollar denominated securities and up to 10% of its total assets in emerging market securities. To pursue its investment goals, the Portfolio regularly enters into (which may include purchasing or selling) various derivative transactions, including currency and cross-currency forwards, currency options, currency, currency index, bond and interest rate futures contracts and options thereon, swap agreements (including currency, interest rate, fixed-income total return, and credit default swaps) and options thereon and futures contracts on credit default swaps on indices (also known as credit index futures). The use of these derivative transactions may allow the Portfolio to obtain net long or short exposures to select currencies, interest rates, countries, duration or credit risks. These derivatives may be used to enhance Portfolio returns, increase liquidity, gain exposure to certain instruments or markets in a more efficient or less expensive way and/or hedge risks associated with its other portfolio investments.

Brighthouse Franklin Low Duration Total Return Portfolio Investment Strategy - Brighthouse Franklin Low Duration Total Return Portfolio

Dec. 31, 2025

<span style="color:#000000;font-family:Times New Roman;font-size:11.5pt;font-weight:bold;">Principal Investment Strategies</span>

Strategy Narrative [Text Block]

Franklin Advisers, Inc. (“Franklin Advisers” or “Subadviser”), subadviser to the Portfolio, invests the Portfolio’s assets, under normal circumstances, primarily in debt securities, including derivative instruments that provide exposure to debt securities such as futures, options and swap agreements, and in other investments, including government and corporate debt securities, mortgage- and asset-backed securities, collateralized loan obligations and other collateralized debt obligations, investment grade corporate loans and floating rate corporate loans, municipal securities and futures with reference securities that are investment grade, targeting an estimated average portfolio duration of three (3) years or less. Under normal market conditions, the Portfolio invests primarily in investment grade debt securities and in unrated securities that the investment manager deems are of comparable quality. Duration is a measure of the expected price volatility of a debt instrument as a result of changes in market rates of interest, based on the weighted average timing of the instrument’s expected principal and interest payments and other factors. Debt securities represent the obligation of the issuer to repay a loan of money to it, and generally pay interest to the holder. Bonds, notes and debentures are examples of debt securities. Some of the mortgage securities purchased by the Portfolio are issued or guaranteed by the U.S. Government, its agencies or instrumentalities; others are issued by private issuers. These mortgage-backed securities may include credit risk transfer securities, which are fixed- or floating-rate unsecured obligations. The Portfolio may also invest in mortgage dollar rolls, through which the Portfolio sells mortgage-backed securities for delivery in the current month and simultaneously contracts to repurchase substantially similar (same type, coupon, and maturity) securities on a specified future date. During the period between the sale and repurchase, the Portfolio forgoes principal and interest paid on the mortgage-backed securities. In addition, the Portfolio may invest a portion of its assets in corporate loans made to, or issued by, borrowers that are U.S. companies, foreign borrowers and U.S. subsidiaries of foreign borrowers and that typically have floating interest rates. The Portfolio may also invest in inflation-indexed securities issued by the U.S. Treasury and securities issued pursuant to Rule 144A under the Securities Act of 1933. In choosing investments, Franklin Advisers selects securities in various market sectors based on its assessment of changing economic, market, industry and issuer conditions. Franklin Advisers uses a “top-down” analysis of macroeconomic trends, combined with a “bottom-up” fundamental analysis of market sectors, industries and issuers, to try to take advantage of varying sector reactions to economic events. Franklin Advisers evaluates business cycles, changes in yield curves and apparent imbalances in values between and within markets. These factors can impact both income and potential for capital appreciation. The Portfolio focuses on investment grade securities and investments or in unrated securities and investments that Franklin Advisers determines are comparable. Securities rated in the top four ratings categories by independent rating organizations such as Standard & Poor’s Ratings Services (S&P®) (rated BBB or better) or Moody’s Ratings (Moody’s) (rated Baa or higher) are considered investment grade. Securities rated Ba or lower by Moody’s or BB or lower by S&P® are considered to be below investment grade. The Portfolio may invest up to 20% of its total assets in high yield debt securities (commonly referred to as “junk bonds”), including up to 5% in securities rated lower than B by S&P® or Moody’s, which may include defaulted securities. The Portfolio may invest up to 25% of its total assets in foreign securities, including up to 20% of its total assets in non-U.S. dollar denominated securities and up to 10% of its total assets in emerging market securities. To pursue its investment goals, the Portfolio regularly enters into (which may include purchasing or selling) various derivative transactions, including currency and cross-currency forwards, currency options, currency, currency index, bond and interest rate futures contracts and options thereon, swap agreements (including currency, interest rate, fixed-income total return, and credit default swaps) and options thereon and futures contracts on credit default swaps on indices (also known as credit index futures). The use of these derivative transactions may allow the Portfolio to obtain net long or short exposures to select currencies, interest rates, countries, duration or credit risks. These derivatives may be used to enhance Portfolio returns, increase liquidity, gain exposure to certain instruments or markets in a more efficient or less expensive way and/or hedge risks associated with its other portfolio investments.