v3.25.3
S000003998 [Member] Expense Example - Putnam Sustainable Retirement 2040 Fund
Jul. 31, 2025
USD ($)
Class R4  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year $ 77
Expense Example, with Redemption, 3 Years 240
Expense Example, with Redemption, 5 Years 550
Expense Example, with Redemption, 10 Years 1,431
Class R3  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 102
Expense Example, with Redemption, 3 Years 318
Expense Example, with Redemption, 5 Years 684
Expense Example, with Redemption, 10 Years 1,714
Class R5  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 61
Expense Example, with Redemption, 3 Years 192
Expense Example, with Redemption, 5 Years 469
Expense Example, with Redemption, 10 Years 1,259
Class A  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 657
Expense Example, with Redemption, 3 Years 831
Expense Example, with Redemption, 5 Years 1,144
Expense Example, with Redemption, 10 Years 2,030
Class C  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 263
Expense Example, with Redemption, 3 Years 505
Expense Example, with Redemption, 5 Years 998
Expense Example, with Redemption, 10 Years 2,166
Class R  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 127
Expense Example, with Redemption, 3 Years 396
Expense Example, with Redemption, 5 Years 813
Expense Example, with Redemption, 10 Years 1,979
Class Y  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 61
Expense Example, with Redemption, 3 Years 192
Expense Example, with Redemption, 5 Years 469
Expense Example, with Redemption, 10 Years 1,259
Class R6  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 51
Expense Example, with Redemption, 3 Years 160
Expense Example, with Redemption, 5 Years 414
Expense Example, with Redemption, 10 Years $ 1,141