Small Cap Core Fund Performance Management - Small Cap Core Fund |
May 31, 2026 |
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| Prospectus [Line Items] | |
| Bar Chart and Performance Table [Heading] | <span style="font-family:Arial;font-size:12pt;font-weight:bold;">Performance Information</span> |
| Performance Narrative [Text Block] | The below bar chart and table illustrate the risks of investing in the Fund by showing changes in the Fund’s performance from calendar year to calendar year and comparing the Fund’s average annual returns to those of the Russell 3000® Index (a broad-based securities market index), the Russell 2000® Index, and the Russell 2000® Value Index. Effective April 30, 2026, the Fund changed its benchmark index from the Russell 2000® Value Index to the Russell 2000® Index, which is relevant to the Fund because it has characteristics similar to the Fund’s investment strategies. Fund management believes that the Russell 2000® Index is more representative of the securities in which the Fund invests. The Fund’s returns prior to April 30, 2026, as reflected in the bar chart and table, are the returns of the Fund when it followed a different investment objective and different investment strategies under the name, “Small Cap Special Values Fund.” Fees and expenses incurred at the contract level are not reflected in the bar chart or table. If these amounts were reflected, returns would be less than those shown. Of course, past performance of the Fund is not necessarily an indication of how the Fund will perform in the future.Since the Fund’s inception, Wells Capital Management Incorporated (“WellsCap”) served as the Fund’s subadviser. In the fourth quarter of 2021, WellsCap changed its name to Allspring Global Investments, LLC (“Allspring”). Beginning December 7, 2015, Allspring (formerly WellsCap) served as the Fund’s sole subadviser. Effective April 30, 2026, Invesco Advisers, Inc. (“Invesco”) replaced Allspring as the Fund’s subadviser. |
| Performance Past Does Not Indicate Future [Text] | <span style="font-family:Arial;font-size:10pt;margin-left:0%;">Of course, past performance of the Fund is not </span><span style="font-family:Arial;font-size:10pt;margin-left:0%;">necessarily an indication of how the Fund will perform in </span><span style="font-family:Arial;font-size:10pt;">the future.</span> |
| Performance Information Illustrates Variability of Returns [Text] | <span style="font-family:Arial;font-size:10pt;margin-left:0%;">The below bar chart and table illustrate the risks of investing in the Fund by showing changes in the Fund’s performance from calendar year to calendar year and comparing the Fund’s average annual returns to those of the Russell 3000® Index (a broad-based securities market index), the Russell 2000® Index, and the Russell 2000® Value Index. </span><span style="font-family:Arial;font-size:10pt;">Effective April 30, 2026, the Fund changed its </span><span style="font-family:Arial;font-size:10pt;margin-left:0%;">benchmark index from the Russell 2000® Value Index to the Russell 2000® Index, which is relevant to the Fund because it has characteristics similar to the Fund’s investment strategies.</span> |
| Bar Chart Does Not Reflect Sales Loads [Text] | <span style="font-family:Arial;font-size:10pt;">Fees and expenses incurred at the contract level </span><span style="font-family:Arial;font-size:10pt;margin-left:0%;">are not reflected in the bar chart or table. If these amounts were reflected, returns would be less than those shown. </span> |
| Bar Chart Closing [Text Block] | During the period shown in the bar chart:Highest Quarterly Return:December 31, 202028.56%Lowest Quarterly Return:March 31, 2020-33.63%Year to Date Most Recent Quarter:June 30, 202617.91% |
| Performance Table Heading | <span style="font-family:Arial;font-size:10pt;font-weight:bold;margin-left:0%;">Average Annual Total Returns</span><span style="font-family:Arial;font-size:10pt;"> (For the periods ended December 31, 2025)</span> |
| Performance Table Market Index Changed | <span style="font-family:Arial;font-size:10pt;">Effective April 30, 2026, the Fund changed its </span><span style="font-family:Arial;font-size:10pt;margin-left:0%;">benchmark index from the Russell 2000® Value Index to the Russell 2000® Index, which is relevant to the Fund because it has characteristics similar to the Fund’s investment strategies.</span> |
| None | |
| Prospectus [Line Items] | |
| Year to Date Return, Label [Optional Text] | <span style="font-family:Arial;font-size:10pt;margin-left:0.0pt;">Year to Date Most </span><span style="font-family:Arial;font-size:10pt;margin-left:0.0pt;">Recent Quarter:</span> |
| Bar Chart, Year to Date Return | 17.91% |
| Bar Chart, Year to Date Return, Date | Jun. 30, 2026 |
| Highest Quarterly Return, Label [Optional Text] | <span style="font-family:Arial;font-size:10pt;margin-left:0.0pt;">Highest Quarterly </span><span style="font-family:Arial;font-size:10pt;margin-left:0.0pt;">Return:</span> |
| Highest Quarterly Return | 28.56% |
| Highest Quarterly Return, Date | Dec. 31, 2020 |
| Lowest Quarterly Return, Label [Optional Text] | <span style="font-family:Arial;font-size:10pt;margin-left:0.0pt;">Lowest Quarterly </span><span style="font-family:Arial;font-size:10pt;margin-left:0.0pt;">Return:</span> |
| Lowest Quarterly Return | (33.63%) |
| Lowest Quarterly Return, Date | Mar. 31, 2020 |