SA Large Cap Growth Index Portfolio Investment Strategy - SA Large Cap Growth 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 S&P 500® Growth Index (the “Index”). The Index measures the performance of large-cap U.S. dollar-denominated U.S. equities as determined using three factors: sales growth, the ratio of earnings change to price, and momentum. The subadviser primarily seeks to achieve the Portfolio’s objective by investing in all or substantially all of the stocks included in the Index, a strategy known as “replication.” The subadviser may, however, utilize an “optimization” strategy in circumstances in which replication is difficult or impossible, such as if the Portfolio has low asset levels and cannot replicate, to reduce trading costs or to gain exposure to securities that the Portfolio cannot access directly. The goal of optimization is to select stocks which ensure that characteristics such as industry weightings, average market capitalizations and fundamental characteristics (e.g., price-to-book, price-to-earnings, debt-to-asset ratios and dividend yields) closely approximate those of the Index. Stocks not in the Index may be held before or after changes in the composition of the Index or if they have characteristics similar to stocks in the Index. Under normal circumstances, the Portfolio invests substantially all, but at least 80%, of its net assets 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 stocks 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. The Portfolio may become non-diversified (which means that it can invest a greater percentage of its assets in the securities of fewer issuers than can a diversified fund), solely as a result of a change in the relative market capitalization or index weighting of one or more of the Index constituents.

SA Large Cap Growth Index Portfolio Investment Strategy - SA Large Cap Growth 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 S&P 500® Growth Index (the “Index”). The Index measures the performance of large-cap U.S. dollar-denominated U.S. equities as determined using three factors: sales growth, the ratio of earnings change to price, and momentum. The subadviser primarily seeks to achieve the Portfolio’s objective by investing in all or substantially all of the stocks included in the Index, a strategy known as “replication.” The subadviser may, however, utilize an “optimization” strategy in circumstances in which replication is difficult or impossible, such as if the Portfolio has low asset levels and cannot replicate, to reduce trading costs or to gain exposure to securities that the Portfolio cannot access directly. The goal of optimization is to select stocks which ensure that characteristics such as industry weightings, average market capitalizations and fundamental characteristics (e.g., price-to-book, price-to-earnings, debt-to-asset ratios and dividend yields) closely approximate those of the Index. Stocks not in the Index may be held before or after changes in the composition of the Index or if they have characteristics similar to stocks in the Index. Under normal circumstances, the Portfolio invests substantially all, but at least 80%, of its net assets 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 stocks 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. The Portfolio may become non-diversified (which means that it can invest a greater percentage of its assets in the securities of fewer issuers than can a diversified fund), solely as a result of a change in the relative market capitalization or index weighting of one or more of the Index constituents.