v3.26.1
Mortgage Servicing Rights - MSRs and Related Characteristics by Portfolio (Detail) - USD ($)
$ in Millions
 6 Months Ended 9 Months Ended
Jun. 30, 2026
Sep. 30, 2025
Mar. 31, 2026
Dec. 31, 2025
Jun. 30, 2025
Mar. 31, 2025
Dec. 31, 2024
Servicing Assets at Fair Value [Line Items]              
Fair value $ 3,177   $ 3,152 $ 3,159 $ 3,305 $ 3,312 $ 3,369
MSR portfolio              
Servicing Assets at Fair Value [Line Items]              
Servicing portfolio 206,031     207,237      
Fair value $ 3,177     $ 3,159      
Value (bps) 1.54%     1.52%      
Weighted-average servicing fees (bps) 0.30%     0.30%      
Multiple (value/servicing fees) 5.09     5.03      
Weighted-average note rate 4.45%     4.39%      
Weighted-average age (in years) 5 years 9 months 18 days 5 years 7 months 6 days          
Weighted-average expected prepayment (constant prepayment rate) 9.00% 9.00%          
Weighted-average expected life (in years) 7 years 1 month 6 days 7 years 2 months 12 days          
Weighted-average option adjusted spread 5.70% 5.90%          
MSR portfolio | HFA              
Servicing Assets at Fair Value [Line Items]              
Servicing portfolio $ 58,251     $ 56,993      
Fair value $ 874     $ 849      
Value (bps) 1.50%     1.49%      
Weighted-average servicing fees (bps) 0.35%     0.35%      
Multiple (value/servicing fees) 4.27     4.22      
Weighted-average note rate 5.23%     5.17%      
Weighted-average age (in years) 4 years 10 months 24 days 4 years 9 months 18 days          
Weighted-average expected prepayment (constant prepayment rate) 10.20% 10.20%          
Weighted-average expected life (in years) 7 years 4 months 24 days 7 years 4 months 24 days          
Weighted-average option adjusted spread 7.10% 7.30%          
MSR portfolio | Government              
Servicing Assets at Fair Value [Line Items]              
Servicing portfolio $ 22,862     $ 23,630      
Fair value $ 459     $ 465      
Value (bps) 2.01%     1.97%      
Weighted-average servicing fees (bps) 0.45%     0.45%      
Multiple (value/servicing fees) 4.50     4.41      
Weighted-average note rate 4.42%     4.41%      
Weighted-average age (in years) 7 years 1 month 6 days 6 years 9 months 18 days          
Weighted-average expected prepayment (constant prepayment rate) 9.90% 10.10%          
Weighted-average expected life (in years) 6 years 8 months 12 days 6 years 8 months 12 days          
Weighted-average option adjusted spread 6.60% 6.90%          
MSR portfolio | Conventional              
Servicing Assets at Fair Value [Line Items]              
Servicing portfolio $ 124,918     $ 126,614      
Fair value $ 1,844     $ 1,845      
Value (bps) 1.48%     1.46%      
Weighted-average servicing fees (bps) 0.25%     0.25%      
Multiple (value/servicing fees) 5.81     5.75      
Weighted-average note rate 4.10%     4.04%      
Weighted-average age (in years) 5 years 10 months 24 days 5 years 8 months 12 days          
Weighted-average expected prepayment (constant prepayment rate) 8.20% 8.20%          
Weighted-average expected life (in years) 7 years 1 month 6 days 7 years 2 months 12 days          
Weighted-average option adjusted spread 4.80% 5.10%