v3.25.4
S000003996 [Member] Expense Example - Putnam Sustainable Retirement Maturity Fund
Jul. 31, 2025
USD ($)
Class R3 Shares  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year $ 112
Expense Example, with Redemption, 3 Years 350
Expense Example, with Redemption, 5 Years 728
Expense Example, with Redemption, 10 Years 1,790
Class R4 Shares  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 87
Expense Example, with Redemption, 3 Years 271
Expense Example, with Redemption, 5 Years 594
Expense Example, with Redemption, 10 Years 1,510
Class R5 Shares  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 72
Expense Example, with Redemption, 3 Years 225
Expense Example, with Redemption, 5 Years 517
Expense Example, with Redemption, 10 Years 1,348
Class A Shares  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 493
Expense Example, with Redemption, 3 Years 691
Expense Example, with Redemption, 5 Years 1,025
Expense Example, with Redemption, 10 Years 1,968
Class C Shares  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 273
Expense Example, with Redemption, 3 Years 536
Expense Example, with Redemption, 5 Years 1,041
Expense Example, with Redemption, 10 Years 2,243
Class R Shares  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 137
Expense Example, with Redemption, 3 Years 427
Expense Example, with Redemption, 5 Years 861
Expense Example, with Redemption, 10 Years 2,070
Class Y Shares  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 72
Expense Example, with Redemption, 3 Years 225
Expense Example, with Redemption, 5 Years 517
Expense Example, with Redemption, 10 Years 1,348
Class R6 Shares  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 61
Expense Example, with Redemption, 3 Years 192
Expense Example, with Redemption, 5 Years 461
Expense Example, with Redemption, 10 Years $ 1,232