| 
                                Sep 2021
                             | 
                            
                                
                                    Employees' Retirement Plan Of Duke University
                                
                             | 
                            
                                186,652
                             | 
                            
                            
                                1.24%
                             | 
                            
                                
                                    0
                                 | 
                                
                                    0.00%
                                 | 
                            
                            
                                
                                    0
                                 | 
                                
                                    0.00%
                                 | 
                            
                        
                    
                        
                            
                                
                                    | 
                                     | 
                                    
                                        
                                         | 
                                    
                                    
                                        
                                         | 
                                    
                                
                                
                        
                        
                            | 
                                Jun 2021
                             | 
                            
                                
                                    Employees' Retirement Plan Of Duke University
                                
                             | 
                            
                                186,652
                             | 
                            
                            
                                1.24%
                             | 
                            
                                
                                    0
                                 | 
                                
                                    0.00%
                                 | 
                            
                            
                                
                                    0
                                 | 
                                
                                    0.00%
                                 | 
                            
                        
                    
                        
                            
                                
                                    | 
                                     | 
                                    
                                        
                                         | 
                                    
                                    
                                        
                                         | 
                                    
                                
                                
                        
                        
                            | 
                                Mar 2021
                             | 
                            
                                
                                    Employees' Retirement Plan Of Duke University
                                
                             | 
                            
                                186,652
                             | 
                            
                            
                                1.24%
                             | 
                            
                                
                                    0
                                 | 
                                
                                    0.00%
                                 | 
                            
                            
                                
                                    0
                                 | 
                                
                                    0.00%
                                 | 
                            
                        
                    
                        
                            
                                
                                    | 
                                     | 
                                    
                                        
                                         | 
                                    
                                    
                                        
                                         | 
                                    
                                
                                
                        
                        
                            | 
                                Dec 2020
                             | 
                            
                                
                                    Employees' Retirement Plan Of Duke University
                                
                             | 
                            
                                186,652
                             | 
                            
                            
                                1.24%
                             | 
                            
                                
                                    0
                                 | 
                                
                                    0.00%
                                 | 
                            
                            
                                
                                    0
                                 | 
                                
                                    0.00%
                                 | 
                            
                        
                    
                        
                            
                                
                                    | 
                                     | 
                                    
                                        
                                         | 
                                    
                                    
                                        
                                         | 
                                    
                                
                                
                        
                        
                            | 
                                Sep 2020
                             | 
                            
                                
                                    Employees' Retirement Plan Of Duke University
                                
                             | 
                            
                                186,652
                             | 
                            
                            
                                1.24%
                             | 
                            
                                
                                    0
                                 | 
                                
                                    0.00%
                                 | 
                            
                            
                                
                                    0
                                 | 
                                
                                    0.00%
                                 | 
                            
                        
                    
                        
                            
                                
                                    | 
                                     | 
                                    
                                        
                                         | 
                                    
                                    
                                        
                                         | 
                                    
                                
                                
                        
                        
                            | 
                                Jun 2020
                             | 
                            
                                
                                    Employees' Retirement Plan Of Duke University
                                
                             | 
                            
                                186,652
                             | 
                            
                            
                                1.24%
                             | 
                            
                                
                                    0
                                 | 
                                
                                    0.00%
                                 | 
                            
                            
                                
                                    0
                                 | 
                                
                                    0.00%
                                 | 
                            
                        
                    
                        
                            
                                
                                    | 
                                     | 
                                    
                                        
                                         | 
                                    
                                    
                                        
                                         | 
                                    
                                
                                
                        
                        
                            | 
                                Mar 2020
                             | 
                            
                                
                                    Employees' Retirement Plan Of Duke University
                                
                             | 
                            
                                186,652
                             | 
                            
                            
                                1.24%
                             | 
                            
                                
                                    0
                                 | 
                                
                                    0.00%
                                 | 
                            
                            
                                
                                    0
                                 | 
                                
                                    0.00%
                                 | 
                            
                        
                    
                        
                            
                                
                                    | 
                                     | 
                                    
                                        
                                         | 
                                    
                                    
                                        
                                         | 
                                    
                                
                                
                        
                        
                            | 
                                Dec 2019
                             | 
                            
                                
                                    Employees' Retirement Plan Of Duke University
                                
                             | 
                            
                                186,652
                             | 
                            
                            
                                1.24%
                             | 
                            
                                
                                    0
                                 | 
                                
                                    0.00%
                                 | 
                            
                            
                                
                                    0
                                 | 
                                
                                    0.00%
                                 | 
                            
                        
                    
                        
                            
                                
                                    | 
                                     | 
                                    
                                        
                                         | 
                                    
                                    
                                        
                                         | 
                                    
                                
                                
                        
                        
                            | 
                                Nov 15, 2019
                             | 
                            
                                
                                    Employees' Retirement Plan Of Duke University
                                
                             | 
                            
                                186,652
                             | 
                            
                            
                                1.24%
                             | 
                            
                                
                                    0
                                 | 
                                
                                    0.00%
                                 | 
                            
                            
                                
                                    0
                                 | 
                                
                                    0.00%
                                 | 
                            
                        
                    
                        
                            
                                
                                    | 
                                     | 
                                    
                                        
                                         | 
                                    
                                    
                                        
                                         | 
                                    
                                
                                
                        
                        
                            | 
                                Sep 2019
                             | 
                            
                                
                                    Employees' Retirement Plan Of Duke University
                                
                             | 
                            
                                186,652
                             | 
                            
                            
                                1.09%
                             | 
                            
                                
                                    0
                                 | 
                                
                                    0.00%
                                 | 
                            
                            
                                
                                    0
                                 | 
                                
                                    0.00%
                                 | 
                            
                        
                    
                        
                            
                                
                                    | 
                                     | 
                                    
                                        
                                         | 
                                    
                                    
                                        
                                         | 
                                    
                                
                                
                        
                        
                            | 
                                Jun 2019
                             | 
                            
                                
                                    Employees' Retirement Plan Of Duke University
                                
                             | 
                            
                                186,652
                             | 
                            
                            
                                1.09%
                             | 
                            
                                
                                    0
                                 | 
                                
                                    0.00%
                                 | 
                            
                            
                                
                                    0
                                 | 
                                
                                    0.00%
                                 | 
                            
                        
                    
                        
                            
                                
                                    | 
                                     | 
                                    
                                        
                                         | 
                                    
                                    
                                        
                                         | 
                                    
                                
                                
                        
                        
                            | 
                                Mar 2019
                             | 
                            
                                
                                    Employees' Retirement Plan Of Duke University
                                
                             | 
                            
                                186,652
                             | 
                            
                            
                                1.09%
                             | 
                            
                                
                                    0
                                 | 
                                
                                    0.00%
                                 | 
                            
                            
                                
                                    0
                                 | 
                                
                                    0.00%
                                 | 
                            
                        
                    
                        
                            
                                
                                    | 
                                     | 
                                    
                                        
                                         | 
                                    
                                    
                                        
                                         | 
                                    
                                
                                
                        
                        
                            | 
                                Dec 2018
                             | 
                            
                                
                                    Employees' Retirement Plan Of Duke University
                                
                             | 
                            
                                186,652
                             | 
                            
                            
                                1.09%
                             | 
                            
                                
                                    0
                                 | 
                                
                                    0.00%
                                 | 
                            
                            
                                
                                    0
                                 | 
                                
                                    0.00%
                                 |