v3.24.3
Shareholder Report, Line Graph (Details) - USD ($)
12 Months Ended 60 Months Ended 120 Months Ended
Sep. 30, 2024
Sep. 30, 2024
Sep. 30, 2024
Sep. 30, 2023
Sep. 30, 2022
Sep. 30, 2021
Sep. 30, 2020
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2015
Sep. 30, 2014
Northeast Investors Trust                          
Account Value [Line Items]                          
Line Graph and Table Measure Name     NTHEX                    
Account Value $ 10,211 $ 10,211 $ 10,211 $ 9,290 $ 8,469 $ 8,894 $ 8,323 $ 8,733 $ 9,123 $ 9,158 $ 8,193 $ 8,088 $ 10,000
Average Annual Return, Percent 9.91% 3.17% 0.21%                    
Northeast Investors Trust Northeast Investors Trust U S High Yield Index [Member]                          
Account Value [Line Items]                          
Line Graph and Table Measure Name     US High Yield Index                    
Account Value $ 16,219 $ 16,219 $ 16,219 $ 14,021 $ 12,723 $ 14,805 $ 13,282 $ 12,984 $ 12,214 $ 11,866 $ 10,880 $ 9,644 $ 10,000
Average Annual Return, Percent 15.68% 4.54% 4.95%