v3.26.1
Regulatory Capital Requirements (Details)
$ in Thousands
Mar. 31, 2026
USD ($)
Dec. 31, 2025
USD ($)
Total Capital (to Risk-Weighted Assets)    
Total Capital (to Risk-Weighted Assets), Actual Amount $ 863,940 $ 871,043
Total Capital (to Risk-Weighted Assets), Actual Ratio 0.13 0.136
Total Capital (to Risk-Weighted Assets), For minimum capital adequacy purposes, Amount $ 531,338 $ 512,904
Total Capital (to Risk-Weighted Assets), For minimum capital adequacy purposes, Ratio 0.08 0.08
Total Capital (to Risk-Weighted Assets), To be well capitalized under prompt corrective action provisions, Amount $ 664,173 $ 641,130
Total Capital (to Risk-Weighted Assets), To be well capitalized under prompt corrective action provisions, Ratio 0.10 0.10
Tier I Capital (to Risk-Weighted Assets)    
Tier I Capital (to Risk-Weighted Assets), Actual Amount $ 809,607 $ 822,626
Tier I Capital (to Risk-Weighted Assets), Actual Ratio 0.122 0.128
Tier I Capital (to Risk-Weighted Assets), For minimum capital adequacy purposes, Amount $ 398,504 $ 384,678
Tier I Capital (to Risk-Weighted Assets), For minimum capital adequacy purposes, Ratio 0.06 0.06
Tier I Capital (to Risk-Weighted Assets), To be well capitalized under prompt corrective action provisions, Amount $ 531,338 $ 512,904
Tier I Capital (to Risk-Weighted Assets), To be well capitalized under prompt corrective action provisions, Ratio 0.08 0.08
Common Equity Tier I Capital (to Risk-Weighted Assets)    
Common Equity Tier I Capital (to Risk-Weighted Assets), Actual Amount $ 809,607 $ 822,626
Common Equity Tier I Capital (to Risk-Weighted Assets), Actual Ratio 0.122 0.128
Common Equity Tier I Capital (to Risk-Weighted Assets), For minimum capital adequacy purposes, Amount $ 298,878 $ 288,508
Common Equity Tier I Capital (to Risk-Weighted Assets), For minimum capital adequacy purposes, Ratio 0.045 0.045
Common Equity Tier I Capital (to Risk-Weighted Assets), To be well capitalized under prompt corrective action provisions, Amount $ 431,713 $ 416,734
Common Equity Tier I Capital (to Risk-Weighted Assets), To be well capitalized under prompt corrective action provisions, Ratio 0.065 0.065
Tier I Capital (to Total Average Assets)    
Tier I Capital (to Total Average Assets), Actual Amount $ 809,607 $ 822,626
Tier I Capital (to Total Average Assets), Actual Ratio 0.117 0.133
Tier I Capital (to Total Average Assets), For minimum capital adequacy purposes, Amount $ 277,376 $ 247,709
Tier I Capital (to Total Average Assets), For minimum capital adequacy purposes, Ratio 0.04 0.04
Tier I Capital (to Total Average Assets), To be well capitalized under prompt corrective action provisions, Amount $ 346,720 $ 309,636
Tier I Capital (to Total Average Assets), To be well capitalized under prompt corrective action provisions, Ratio 0.05 0.05
Needham Bank [Member]    
Total Capital (to Risk-Weighted Assets)    
Total Capital (to Risk-Weighted Assets), Actual Amount $ 812,238 $ 791,298
Total Capital (to Risk-Weighted Assets), Actual Ratio 0.122 0.124
Total Capital (to Risk-Weighted Assets), For minimum capital adequacy purposes, Amount $ 531,937 $ 511,589
Total Capital (to Risk-Weighted Assets), For minimum capital adequacy purposes, Ratio 0.08 0.08
Total Capital (to Risk-Weighted Assets), To be well capitalized under prompt corrective action provisions, Amount $ 664,922 $ 639,486
Total Capital (to Risk-Weighted Assets), To be well capitalized under prompt corrective action provisions, Ratio 0.10 0.10
Tier I Capital (to Risk-Weighted Assets)    
Tier I Capital (to Risk-Weighted Assets), Actual Amount $ 757,905 $ 742,881
Tier I Capital (to Risk-Weighted Assets), Actual Ratio 0.114 0.116
Tier I Capital (to Risk-Weighted Assets), For minimum capital adequacy purposes, Amount $ 398,953 $ 383,692
Tier I Capital (to Risk-Weighted Assets), For minimum capital adequacy purposes, Ratio 0.06 0.06
Tier I Capital (to Risk-Weighted Assets), To be well capitalized under prompt corrective action provisions, Amount $ 531,937 $ 511,589
Tier I Capital (to Risk-Weighted Assets), To be well capitalized under prompt corrective action provisions, Ratio 0.08 0.08
Common Equity Tier I Capital (to Risk-Weighted Assets)    
Common Equity Tier I Capital (to Risk-Weighted Assets), Actual Amount $ 757,905 $ 742,881
Common Equity Tier I Capital (to Risk-Weighted Assets), Actual Ratio 0.114 0.116
Common Equity Tier I Capital (to Risk-Weighted Assets), For minimum capital adequacy purposes, Amount $ 299,215 $ 287,769
Common Equity Tier I Capital (to Risk-Weighted Assets), For minimum capital adequacy purposes, Ratio 0.045 0.045
Common Equity Tier I Capital (to Risk-Weighted Assets), To be well capitalized under prompt corrective action provisions, Amount $ 432,199 $ 415,666
Common Equity Tier I Capital (to Risk-Weighted Assets), To be well capitalized under prompt corrective action provisions, Ratio 0.065 0.065
Tier I Capital (to Total Average Assets)    
Tier I Capital (to Total Average Assets), Actual Amount $ 757,905 $ 742,881
Tier I Capital (to Total Average Assets), Actual Ratio 0.11 0.122
Tier I Capital (to Total Average Assets), For minimum capital adequacy purposes, Amount $ 274,662 $ 244,395
Tier I Capital (to Total Average Assets), For minimum capital adequacy purposes, Ratio 0.04 0.04
Tier I Capital (to Total Average Assets), To be well capitalized under prompt corrective action provisions, Amount $ 343,328 $ 305,494
Tier I Capital (to Total Average Assets), To be well capitalized under prompt corrective action provisions, Ratio 0.05 0.05