v3.25.3
Average Annual Total Returns
 12 Months Ended 60 Months Ended 120 Months Ended
Jul. 31, 2025
Dec. 31, 2024
Dec. 31, 2024
Dec. 31, 2024
(Nomura Corporate Bond Fund and Nomura Extended Duration Bond Fund - Classes A, C, R, Institutional, and R6) | Nomura Corporate Bond Fund | Bloomberg US Corporate Bond Index (reflects no deduction for fees, expenses, or taxes)        
Prospectus [Line Items]        
Average Annual Return, Percent   2.13% 0.30% 2.43%
(Nomura Corporate Bond Fund and Nomura Extended Duration Bond Fund - Classes A, C, R, Institutional, and R6) | Nomura Corporate Bond Fund | Bloomberg US Aggregate Index (reflects no deduction for fees, expenses, or taxes)        
Prospectus [Line Items]        
Average Annual Return, Percent   1.25% (0.33%) 1.35%
(Nomura Corporate Bond Fund and Nomura Extended Duration Bond Fund - Classes A, C, R, Institutional, and R6) | Nomura Corporate Bond Fund | Class A        
Prospectus [Line Items]        
Average Annual Return, Percent   (2.09%) (0.81%) 1.70%
(Nomura Corporate Bond Fund and Nomura Extended Duration Bond Fund - Classes A, C, R, Institutional, and R6) | Nomura Corporate Bond Fund | Class A | After Taxes on Distributions        
Prospectus [Line Items]        
Average Annual Return, Percent   (3.88%) (2.35%) 0.15%
(Nomura Corporate Bond Fund and Nomura Extended Duration Bond Fund - Classes A, C, R, Institutional, and R6) | Nomura Corporate Bond Fund | Class A | After Taxes on Distributions and Sales        
Prospectus [Line Items]        
Average Annual Return, Percent   (1.25%) (1.22%) 0.63%
(Nomura Corporate Bond Fund and Nomura Extended Duration Bond Fund - Classes A, C, R, Institutional, and R6) | Nomura Corporate Bond Fund | Class C        
Prospectus [Line Items]        
Average Annual Return, Percent   0.79% (0.62%) 1.42%
(Nomura Corporate Bond Fund and Nomura Extended Duration Bond Fund - Classes A, C, R, Institutional, and R6) | Nomura Corporate Bond Fund | Class R        
Prospectus [Line Items]        
Average Annual Return, Percent   2.28% (0.14%) 1.93%
(Nomura Corporate Bond Fund and Nomura Extended Duration Bond Fund - Classes A, C, R, Institutional, and R6) | Nomura Corporate Bond Fund | Institutional Class        
Prospectus [Line Items]        
Average Annual Return, Percent   2.79% 0.37% 2.43%
(Nomura Corporate Bond Fund and Nomura Extended Duration Bond Fund - Classes A, C, R, Institutional, and R6) | Nomura Corporate Bond Fund | Class R6        
Prospectus [Line Items]        
Average Annual Return, Percent   2.91% 0.45% 2.47%
Performance Inception Date Jan. 31, 2019      
(Nomura Corporate Bond Fund and Nomura Extended Duration Bond Fund - Classes A, C, R, Institutional, and R6) | Nomura Extended Duration Bond Fund | Bloomberg US Aggregate Index (reflects no deduction for fees, expenses, or taxes)        
Prospectus [Line Items]        
Average Annual Return, Percent   1.25% (0.33%) 1.35%
(Nomura Corporate Bond Fund and Nomura Extended Duration Bond Fund - Classes A, C, R, Institutional, and R6) | Nomura Extended Duration Bond Fund | Bloomberg Long US Corporate Index (reflects no deduction for fees, expenses, or taxes)        
Prospectus [Line Items]        
Average Annual Return, Percent   (1.95%) (1.84%) 2.20%
(Nomura Corporate Bond Fund and Nomura Extended Duration Bond Fund - Classes A, C, R, Institutional, and R6) | Nomura Extended Duration Bond Fund | Class A        
Prospectus [Line Items]        
Average Annual Return, Percent   (5.99%) (3.07%) 1.00%
(Nomura Corporate Bond Fund and Nomura Extended Duration Bond Fund - Classes A, C, R, Institutional, and R6) | Nomura Extended Duration Bond Fund | Class A | After Taxes on Distributions        
Prospectus [Line Items]        
Average Annual Return, Percent   (7.69%) (5.09%) (0.91%)
(Nomura Corporate Bond Fund and Nomura Extended Duration Bond Fund - Classes A, C, R, Institutional, and R6) | Nomura Extended Duration Bond Fund | Class A | After Taxes on Distributions and Sales        
Prospectus [Line Items]        
Average Annual Return, Percent   (3.54%) (2.83%) 0.11%
(Nomura Corporate Bond Fund and Nomura Extended Duration Bond Fund - Classes A, C, R, Institutional, and R6) | Nomura Extended Duration Bond Fund | Class C        
Prospectus [Line Items]        
Average Annual Return, Percent   (3.30%) (2.92%) 0.69%
(Nomura Corporate Bond Fund and Nomura Extended Duration Bond Fund - Classes A, C, R, Institutional, and R6) | Nomura Extended Duration Bond Fund | Class R        
Prospectus [Line Items]        
Average Annual Return, Percent   (1.85%) (2.41%) 1.21%
(Nomura Corporate Bond Fund and Nomura Extended Duration Bond Fund - Classes A, C, R, Institutional, and R6) | Nomura Extended Duration Bond Fund | Institutional Class        
Prospectus [Line Items]        
Average Annual Return, Percent   (1.32%) (1.93%) 1.71%
(Nomura Corporate Bond Fund and Nomura Extended Duration Bond Fund - Classes A, C, R, Institutional, and R6) | Nomura Extended Duration Bond Fund | Class R6        
Prospectus [Line Items]        
Average Annual Return, Percent   (1.27%) (1.86%) 1.83%
Performance Inception Date May 02, 2016      
(Nomura Floating Rate Fund - Classes A, C, R, Institutional and R6) | Nomura Floating Rate Fund | Morningstar LSTA US Leveraged Loan Index (reflects no deduction for fees, expenses, or taxes)        
Prospectus [Line Items]        
Average Annual Return, Percent   8.95% 5.86% 5.15%
(Nomura Floating Rate Fund - Classes A, C, R, Institutional and R6) | Nomura Floating Rate Fund | Bloomberg US Aggregate Index (reflects no deduction for fees, expenses, or taxes)        
Prospectus [Line Items]        
Average Annual Return, Percent   1.25% (0.33%) 1.35%
(Nomura Floating Rate Fund - Classes A, C, R, Institutional and R6) | Nomura Floating Rate Fund | Class A        
Prospectus [Line Items]        
Average Annual Return, Percent   5.57% 4.78% 3.95%
(Nomura Floating Rate Fund - Classes A, C, R, Institutional and R6) | Nomura Floating Rate Fund | Class A | After Taxes on Distributions        
Prospectus [Line Items]        
Average Annual Return, Percent   2.04% 2.34% 2.01%
(Nomura Floating Rate Fund - Classes A, C, R, Institutional and R6) | Nomura Floating Rate Fund | Class A | After Taxes on Distributions and Sales        
Prospectus [Line Items]        
Average Annual Return, Percent   3.22% 2.57% 2.15%
(Nomura Floating Rate Fund - Classes A, C, R, Institutional and R6) | Nomura Floating Rate Fund | Class C        
Prospectus [Line Items]        
Average Annual Return, Percent   6.79% 4.60% 3.46%
(Nomura Floating Rate Fund - Classes A, C, R, Institutional and R6) | Nomura Floating Rate Fund | Class R        
Prospectus [Line Items]        
Average Annual Return, Percent   8.33% 5.12% 3.98%
(Nomura Floating Rate Fund - Classes A, C, R, Institutional and R6) | Nomura Floating Rate Fund | Institutional Class        
Prospectus [Line Items]        
Average Annual Return, Percent   8.87% 5.62% 4.50%
(Nomura Floating Rate Fund - Classes A, C, R, Institutional and R6) | Nomura Floating Rate Fund | Class R6        
Prospectus [Line Items]        
Average Annual Return, Percent   8.96%   6.62%
Performance Inception Date Aug. 31, 2021