v3.25.4
Transamerica Mid Cap Growth Average Annual Total Returns - Retail Class [Member]
 12 Months Ended 55 Months Ended 60 Months Ended 104 Months Ended 106 Months Ended 120 Months Ended 140 Months Ended
Oct. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
 [2]
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
 [3]
Dec. 31, 2025
 [4]
Dec. 31, 2025
Dec. 31, 2025
 [1]
Dec. 31, 2025
 [5]
Russell 3000® Index (reflects no deduction for fees, expenses or taxes)[Member]                    
Prospectus [Line Items]                    
Average Annual Return, Percent   17.15% [1] 11.55%   13.15% [1] 14.28% 14.09%   14.29%
Performance Inception Date Apr. 21, 2017 [3]   May 28, 2021       Mar. 10, 2017      
Russell Midcap® Growth Index (reflects no deduction for fees, expenses or taxes)[Member]                    
Prospectus [Line Items]                    
Average Annual Return, Percent   8.66%     6.65%     12.66%    
Performance Inception Date Mar. 10, 2017                  
A                    
Prospectus [Line Items]                    
Average Annual Return, Percent   1.21%     2.14%     7.55%    
Performance Inception Date Mar. 10, 2017                  
A | After Taxes on Distributions                    
Prospectus [Line Items]                    
Average Annual Return, Percent   (4.92%)     (1.28%)     4.12%    
A | After Taxes on Distributions and Sales                    
Prospectus [Line Items]                    
Average Annual Return, Percent   3.15%     0.91%     5.02%    
C                    
Prospectus [Line Items]                    
Average Annual Return, Percent   5.52%     2.80%     7.60%    
Performance Inception Date Mar. 10, 2017                  
I                    
Prospectus [Line Items]                    
Average Annual Return, Percent   7.53%     3.71%     8.61%    
Performance Inception Date Mar. 10, 2017                  
I2                    
Prospectus [Line Items]                    
Average Annual Return, Percent   7.50%     3.75%     8.64%    
Performance Inception Date Mar. 10, 2017                  
R6                    
Prospectus [Line Items]                    
Average Annual Return, Percent   7.49%   3.67%          
Performance Inception Date May 28, 2021                  
[1] “Russell®” and other service marks and trademarks related to the Russell indexes are trademarks of the London Stock Exchange Group companies.
[2] “Russell®” and other service marks and trademarks related to the Russell indexes are trademarks of the London Stock Exchange Group companies.
[3] “Russell®” and other service marks and trademarks related to the Russell indexes are trademarks of the London Stock Exchange Group companies.
[4] “Russell®” and other service marks and trademarks related to the Russell indexes are trademarks of the London Stock Exchange Group companies.
[5] “Russell®” and other service marks and trademarks related to the Russell indexes are trademarks of the London Stock Exchange Group companies.