v3.26.1
Average Annual Total Returns - Optimum Fund Trust Classes A, C, Institutional
 12 Months Ended 60 Months Ended 120 Months Ended
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Optimum Large Cap Growth Fund | Russell 1000 Index (reflects no deduction for fees, expenses or taxes)      
Prospectus [Line Items]      
Average Annual Return, Percent 17.37% 13.59% 14.59%
Optimum Large Cap Growth Fund | Russell 1000 Growth Index (reflects no deduction for fees, expenses, or taxes)      
Prospectus [Line Items]      
Average Annual Return, Percent 18.56% 15.32% 18.13%
Optimum Large Cap Growth Fund | A      
Prospectus [Line Items]      
Average Annual Return, Percent 9.03% 9.16% 13.56%
Optimum Large Cap Growth Fund | C      
Prospectus [Line Items]      
Average Annual Return, Percent 13.92% 9.62% 13.37%
Optimum Large Cap Growth Fund | Institutional      
Prospectus [Line Items]      
Average Annual Return, Percent 15.93% 10.73% 14.52%
Optimum Large Cap Growth Fund | Institutional | After Taxes on Distributions      
Prospectus [Line Items]      
Average Annual Return, Percent 12.28% 8.05% 11.97%
Optimum Large Cap Growth Fund | Institutional | After Taxes on Distributions and Sales      
Prospectus [Line Items]      
Average Annual Return, Percent 11.59% 7.93% 11.33%
Optimum Small-Mid Cap Growth Fund | Russell 3000 Index (reflects no deduction for fees, expenses, or taxes)      
Prospectus [Line Items]      
Average Annual Return, Percent 17.15% 13.15% 14.29%
Optimum Small-Mid Cap Growth Fund | Russell 2500 Growth Index (reflects no deduction for fees, expenses, or taxes)      
Prospectus [Line Items]      
Average Annual Return, Percent 10.31% 2.98% 10.55%
Optimum Small-Mid Cap Growth Fund | A      
Prospectus [Line Items]      
Average Annual Return, Percent 2.91% 1.43% 10.27%
Optimum Small-Mid Cap Growth Fund | C      
Prospectus [Line Items]      
Average Annual Return, Percent 7.41% 1.88% 10.10%
Optimum Small-Mid Cap Growth Fund | Institutional      
Prospectus [Line Items]      
Average Annual Return, Percent 9.52% 2.89% 11.21%
Optimum Small-Mid Cap Growth Fund | Institutional | After Taxes on Distributions      
Prospectus [Line Items]      
Average Annual Return, Percent 8.86% 0.78% 8.73%
Optimum Small-Mid Cap Growth Fund | Institutional | After Taxes on Distributions and Sales      
Prospectus [Line Items]      
Average Annual Return, Percent 6.13% 1.78% 8.51%
Optimum Small-Mid Cap Value Fund | Russell 3000 Index (reflects no deduction for fees, expenses, or taxes)      
Prospectus [Line Items]      
Average Annual Return, Percent 17.15% 13.15% 14.29%
Optimum Small-Mid Cap Value Fund | Russell 2500 Value Index (reflects no deduction for fees, expenses, or taxes)      
Prospectus [Line Items]      
Average Annual Return, Percent 12.73% 10.02% 9.72%
Optimum Small-Mid Cap Value Fund | A      
Prospectus [Line Items]      
Average Annual Return, Percent (3.56%) 5.22% 5.75%
Optimum Small-Mid Cap Value Fund | C      
Prospectus [Line Items]      
Average Annual Return, Percent 0.58% 5.66% 5.57%
Optimum Small-Mid Cap Value Fund | Institutional      
Prospectus [Line Items]      
Average Annual Return, Percent 2.47% 6.73% 6.64%
Optimum Small-Mid Cap Value Fund | Institutional | After Taxes on Distributions      
Prospectus [Line Items]      
Average Annual Return, Percent 0.38% 4.98% 5.24%
Optimum Small-Mid Cap Value Fund | Institutional | After Taxes on Distributions and Sales      
Prospectus [Line Items]      
Average Annual Return, Percent 1.94% 4.93% 5.04%
Optimum International Fund | MSCI ACWI (All Country World Index) ex USA Index (net) (reflects no deduction for fees or expenses but reflects the deduction of foreign withholding taxes on dividends)      
Prospectus [Line Items]      
Average Annual Return, Percent 22.34% 11.19% 11.72%
Optimum International Fund | MSCI ACWI (All Country World Index) ex USA Index (gross) (reflects no deduction for fees, expenses, or foreign withholding taxes on dividends)      
Prospectus [Line Items]      
Average Annual Return, Percent 22.87% 11.70% 12.28%
Optimum International Fund | A      
Prospectus [Line Items]      
Average Annual Return, Percent 18.32% 4.47% 6.72%
Optimum International Fund | C      
Prospectus [Line Items]      
Average Annual Return, Percent 23.66% 4.91% 6.56%
Optimum International Fund | Institutional      
Prospectus [Line Items]      
Average Annual Return, Percent 25.98% 5.99% 7.64%
Optimum International Fund | Institutional | After Taxes on Distributions      
Prospectus [Line Items]      
Average Annual Return, Percent 25.26% 4.93% 6.77%
Optimum International Fund | Institutional | After Taxes on Distributions and Sales      
Prospectus [Line Items]      
Average Annual Return, Percent 15.37% 4.50% 6.06%
Optimum Fixed Income Fund | Bloomberg US Aggregate Index (reflects no deduction for fees, expenses, or taxes)      
Prospectus [Line Items]      
Average Annual Return, Percent 7.30% (0.36%) 2.01%
Optimum Fixed Income Fund | A      
Prospectus [Line Items]      
Average Annual Return, Percent 2.45% (1.61%) 1.45%
Optimum Fixed Income Fund | C      
Prospectus [Line Items]      
Average Annual Return, Percent 5.47% (1.46%) 1.15%
Optimum Fixed Income Fund | Institutional      
Prospectus [Line Items]      
Average Annual Return, Percent 7.63% (0.45%) 2.17%
Optimum Fixed Income Fund | Institutional | After Taxes on Distributions      
Prospectus [Line Items]      
Average Annual Return, Percent 6.00% (1.75%) 0.87%
Optimum Fixed Income Fund | Institutional | After Taxes on Distributions and Sales      
Prospectus [Line Items]      
Average Annual Return, Percent 4.52% (0.89%) 1.11%
Optimum Large Cap Value Fund | Russell 1000 Index (reflects no deduction for fees, expenses or taxes)      
Prospectus [Line Items]      
Average Annual Return, Percent 17.37% 13.59% 14.59%
Optimum Large Cap Value Fund | Russell 1000 Value Index (reflects no deduction for fees, expenses or taxes)      
Prospectus [Line Items]      
Average Annual Return, Percent 15.91% 11.33% 10.53%
Optimum Large Cap Value Fund | A      
Prospectus [Line Items]      
Average Annual Return, Percent 7.90% 9.75% 9.24%
Optimum Large Cap Value Fund | C      
Prospectus [Line Items]      
Average Annual Return, Percent 12.61% 10.22% 9.07%
Optimum Large Cap Value Fund | Institutional      
Prospectus [Line Items]      
Average Annual Return, Percent 14.67% 11.34% 10.17%
Optimum Large Cap Value Fund | Institutional | After Taxes on Distributions      
Prospectus [Line Items]      
Average Annual Return, Percent 12.42% 9.07% 8.38%
Optimum Large Cap Value Fund | Institutional | After Taxes on Distributions and Sales      
Prospectus [Line Items]      
Average Annual Return, Percent 9.81% 8.63% 7.90%