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Shareholder Report, Line Graph (Details) 74200172000_Putnam Strategic Intermediate Municipal Fund_Class C_TSR Annual {Class C} - USD ($)
12 Months Ended
Jul. 31, 2025
Jul. 31, 2024
Jul. 31, 2023
Jul. 31, 2022
Jul. 31, 2021
Jul. 31, 2020
Jul. 31, 2019
Jul. 31, 2018
Jul. 31, 2017
Jul. 31, 2016
Jul. 31, 2026
Class C                      
Account Value [Line Items]                      
Line Graph and Table Measure Name                     Class C (with sales charge)
Accumulated Value $ 11,080 $ 11,078 $ 10,627 $ 10,577 $ 11,342 $ 10,922 $ 10,561 $ 9,938 $ 9,875 $ 10,000 $ 11,580
Bloomberg Municipal Bond Index [Member]                      
Account Value [Line Items]                      
Line Graph and Table Measure Name                     Bloomberg Municipal Bond Index
Accumulated Value 11,522 11,523 11,107 11,005 11,824 11,447 10,865 10,125 10,026 10,000 $ 12,129
Putnam Strategic Intermediate Municipal Linked Benchmark [Member]                      
Account Value [Line Items]                      
Line Graph and Table Measure Name                     Putnam Strategic Intermediate Municipal Linked Benchmark
Accumulated Value 11,752 11,537 11,186 11,080 11,734 11,447 10,865 10,125 10,026 10,000 $ 12,192
Bloomberg 3-15 Year Blend Municipal Bond Index [Member]                      
Account Value [Line Items]                      
Line Graph and Table Measure Name                     Bloomberg 3-15 Year Blend Municipal Bond Index
Accumulated Value $ 11,671 $ 11,458 $ 11,109 $ 11,003 $ 11,653 $ 11,358 $ 10,809 $ 10,099 $ 10,043 $ 10,000 $ 12,108