Strategy. Under normal circumstances, the Portfolio invests at least 80% of its net assets, plus borrowings for investment purposes, in debt securities. For this Portfolio, debt securities include direct and indirect investments in debt securities and investments in other investment companies and financial instruments that derive their value from such securities. The Portfolio invests primarily (either directly or indirectly through other investments) in securities, including government, corporate and agency mortgage- and asset-backed securities, that are rated investment grade at the time of purchase (i.e., at least Baa by Moodys Investors Service, Inc. (Moodys) or BBB by Standard & Poors Global Ratings (S&P) or Fitch Ratings Ltd. (Fitch)), or if unrated, fixed income securities that the Adviser or Sub-Adviser determines to be … Show more… Under normal circumstances, the Portfolio invests at least 80% of its net assets, plus borrowings for investment purposes, in debt securities. For this Portfolio, debt securities include direct and indirect investments in debt securities and investments in other investment companies and financial instruments that derive their value from such securities. The Portfolio invests primarily (either directly or indirectly through other investments) in securities, including government, corporate and agency mortgage- and asset-backed securities, that are rated investment grade at the time of purchase (i.e., at least Baa by Moodys Investors Service, Inc. (Moodys) or BBB by Standard & Poors Global Ratings (S&P) or Fitch Ratings Ltd. (Fitch)), or if unrated, fixed income securities that the Adviser or Sub-Adviser determines to be of comparable quality. Split rated securities, which are securities that receive different ratings from two or more rating agencies, will be considered to have the higher credit rating. The Portfolio also seeks to maintain an average aggregate quality rating of its portfolio securities of at least A (Moodys or S&P or Fitch). In the event that the credit rating of a security held by the Portfolio falls below investment grade (or, in the case of unrated securities, the Sub-Adviser determines that the quality of such security has deteriorated below investment grade), the Portfolio will not be obligated to dispose of such security and may continue to hold the obligation if the Sub-Adviser believes such an investment is appropriate under the circumstances. The Portfolio may also purchase or sell futures contracts on fixed-income securities in lieu of investment directly in fixed-income securities themselves, and may utilize other types of derivatives, including swaps. The Portfolio may engage in active and frequent trading of portfolio securities to achieve its investment objective. The Portfolios assets normally are allocated among two portions, each of which is managed using a different but complementary investment strategy. One portion of the Portfolio is actively managed (Active Allocated Portion) and one portion of the Portfolio seeks to track the performance of a particular index (Passive Allocated Portion). Under normal circumstances, the Active Allocated Portion consists of approximately 30% of the Portfolios net assets and the Passive Allocated Portion consists of approximately 70% of the Portfolios net assets. These percentages are targets established by the Adviser; actual allocations may deviate from these targets. The Active Allocated Portion may invest in debt securities of U.S. and foreign issuers, including issuers located in emerging markets. The Active Allocated Portions investments may include government securities, corporate bonds, bonds of foreign issuers (including those denominated in foreign currencies or U.S. dollars), commercial and residential mortgage-backed securities, and asset-backed securities. The Active Allocated Portion may purchase or sell securities on a when-issued, delayed delivery, or forward commitment basis. The Active Allocated Portion may use investment techniques such as sale-buybacks or dollar rolls to obtain market exposure to certain securities. In sale-buyback and dollar roll transactions, the Portfolio sells a security to another party and simultaneously agrees to repurchase the same security (in the case of a sale-buyback) or a similar, but not the same, security (in the case of a dollar roll) on a specified date and predetermined price. Foreign currency exposure (from non-U.S. dollar-denominated securities or currencies) normally will be limited to 10% of the Portfolios total assets. Securities are purchased for the Active Allocated Portion when a Sub-Adviser determines that they have the potential for above-average total return. A Sub-Adviser may sell a security for a variety of reasons, such as to make other investments believed by the Sub-Adviser to offer superior investment opportunities. The Passive Allocated Portions investments will consist primarily of debt securities that are included in the Bloomberg U.S. Intermediate Government Bond Index (Intermediate Government Bond Index), or other financial instruments that derive their value from those securities. The Portfolio will invest in these securities and other instruments in a manner that is intended to track the performance (before fees and expenses) of this index. The Intermediate Government Bond Index is an unmanaged index that measures the performance of securities consisting of all U.S. Treasury and agency securities with remaining maturities of from one to ten years and issue amounts of at least $ 300 million outstanding, which may include zero-coupon securities. Individual securities holdings may differ from the Intermediate Government Bond Index, and the Portfolio may not track the performance of the Intermediate Government Bond Index perfectly due to expenses and transaction costs, the size and frequency of cash flow into and out of the Portfolio, and differences between how and when the Portfolio and the Intermediate Government Bond Index are valued. The Portfolio may invest in derivative instruments, such as options, futures contracts or swap agreements. The Portfolios investments in derivatives may be deemed to involve the use of leverage because the Portfolio is not required to invest the full market value of the contract upon entering into the contract but participates in gains and losses on the full contract price. The use of derivatives also may be deemed to involve the use of leverage because the heightened price sensitivity of some derivatives to market changes may magnify the Portfolios gain or loss. It is not expected, however, that the Portfolio will be leveraged by borrowing money for investment purposes. The Portfolios investments in derivatives may require it to maintain a percentage of its assets in cash, cash equivalent instruments or other liquid assets to serve as margin or collateral for the Portfolios obligations under derivative transactions. Show less