SA Fixed Income Intermediate Index Portfolio Investment Strategy - SA Fixed Income Intermediate Index Portfolio	Dec. 31, 2025
Prospectus [Line Items]
Strategy [Heading]	<span style="color:#000000;font-family:Arial;font-size:12pt;font-style:italic;font-weight:bold;">Principal Investment Strategies of the Portfolio</span>
Strategy Narrative [Text Block]	The Portfolio seeks to provide investment results that correspond with the performance of the Bloomberg Intermediate U.S. Government/Credit Index (the “Index”). The Index measures the performance of U.S. dollar-denominated U.S. Treasury bonds, government-related bonds and investment-grade U.S. corporate bonds that have a remaining maturity of greater than one year and less than ten years. The subadviser may achieve the Portfolio’s objective by investing in a sampling of securities included in the Index by utilizing a statistical technique known as “optimization.” The goal of optimization is to select securities which ensure that characteristics such as industry weightings, average market capitalizations and fundamental characteristics (e.g., return variability, duration, maturity, credit rating and yield) closely approximate those of the Index. Securities not in the Index may be held before or after changes in the composition of the Index or if they have characteristics similar to securities in the Index. Under normal circumstances, all of the Portfolio’s investments will be selected through the optimization process, and at least 80% of its net assets will be invested in securities included in the Index or in securities that the subadviser determines have economic characteristics that are comparable to the economic characteristics of securities included in the Index, including derivatives, such as contracts for difference. The Portfolio will not concentrate, except to approximately the same extent as the Index may concentrate, in the securities of any industry. It is not anticipated, however, that the Portfolio will, under normal circumstances, be concentrated in the securities of any industry. Because the Portfolio will generally not hold all of the securities included in the Index, and because the Portfolio has expenses and the Index does not, the Portfolio will not duplicate the Index’s performance precisely. However, the subadviser believes there should be a close correlation between the Portfolio’s performance and that of the Index in both rising and falling markets.

SA Fixed Income Intermediate Index Portfolio Investment Strategy - SA Fixed Income Intermediate Index Portfolio

Dec. 31, 2025

<span style="color:#000000;font-family:Arial;font-size:12pt;font-style:italic;font-weight:bold;">Principal Investment Strategies of the Portfolio</span>

Strategy Narrative [Text Block]

The Portfolio seeks to provide investment results that correspond with the performance of the Bloomberg Intermediate U.S. Government/Credit Index (the “Index”). The Index measures the performance of U.S. dollar-denominated U.S. Treasury bonds, government-related bonds and investment-grade U.S. corporate bonds that have a remaining maturity of greater than one year and less than ten years. The subadviser may achieve the Portfolio’s objective by investing in a sampling of securities included in the Index by utilizing a statistical technique known as “optimization.” The goal of optimization is to select securities which ensure that characteristics such as industry weightings, average market capitalizations and fundamental characteristics (e.g., return variability, duration, maturity, credit rating and yield) closely approximate those of the Index. Securities not in the Index may be held before or after changes in the composition of the Index or if they have characteristics similar to securities in the Index. Under normal circumstances, all of the Portfolio’s investments will be selected through the optimization process, and at least 80% of its net assets will be invested in securities included in the Index or in securities that the subadviser determines have economic characteristics that are comparable to the economic characteristics of securities included in the Index, including derivatives, such as contracts for difference. The Portfolio will not concentrate, except to approximately the same extent as the Index may concentrate, in the securities of any industry. It is not anticipated, however, that the Portfolio will, under normal circumstances, be concentrated in the securities of any industry. Because the Portfolio will generally not hold all of the securities included in the Index, and because the Portfolio has expenses and the Index does not, the Portfolio will not duplicate the Index’s performance precisely. However, the subadviser believes there should be a close correlation between the Portfolio’s performance and that of the Index in both rising and falling markets.