v3.26.3
Fair Value - Fair Values and Related Principal Amounts Due upon Maturity of Loans Accounted for Under Fair Value Option (Detail) - USD ($)
$ in Thousands
Sep. 30, 2026
Dec. 31, 2025
Loans, fair value [Abstract]    
Fair value, Total $ 14,401,385 $ 8,532,644
Loans, difference, [Abstract]    
Difference (305,474) 173,409
Loans held for sale [Member]    
Loans, fair value [Abstract]    
Current through 89 days delinquent 2,868,353 2,696,128
90 or more days delinquent, not in foreclosure 1,251 1,273
90 or more days delinquent, in foreclosure 1,147 1,997
Fair value, Total 2,870,751 2,699,398
Loans, principal amount due upon maturity [Abstract]    
Current through 89 days delinquent 2,915,235 2,627,441
90 or more days delinquent, not in foreclosure 1,242 1,271
90 or more days delinquent, in foreclosure 1,468 2,289
Principal amount due upon maturity 2,917,945 2,631,001
Loans, difference, [Abstract]    
Current through 89 days delinquent (46,882) 68,687
90 or more days delinquent, not in foreclosure 9 2
90 or more days delinquent, in foreclosure (321) (292)
Difference (47,194) 68,397
Loans held for sale [Member] | Nonperforming mortgage loans [Member]    
Loans, fair value [Abstract]    
Fair value 2,398 3,270
Loans, principal amount due upon maturity [Abstract]    
Principal amount due upon maturity 2,710 3,560
Loans, difference, [Abstract]    
Difference (312) (290)
Loans held for investment Held in consolidated VIEs [Member]    
Loans, fair value [Abstract]    
Current through 89 days delinquent 14,394,580 8,529,906
90 or more days delinquent, not in foreclosure 5,040 700
90 or more days delinquent, in foreclosure 404 333
Fair value 14,400,024 8,530,939
Loans, principal amount due upon maturity [Abstract]    
Current through 89 days delinquent 14,696,969 8,353,814
90 or more days delinquent, not in foreclosure 6,080 844
90 or more days delinquent, in foreclosure 478 428
Principal amount due upon maturity 14,703,527 8,355,086
Loans, difference, [Abstract]    
Current through 89 days delinquent (302,389) 176,092
90 or more days delinquent, not in foreclosure (1,040) (144)
90 or more days delinquent, in foreclosure (74) (95)
Difference (303,503) 175,853
Loans held for investment Held in consolidated VIEs [Member] | Nonperforming mortgage loans [Member]    
Loans, fair value [Abstract]    
Fair value 5,444 1,033
Loans, principal amount due upon maturity [Abstract]    
Principal amount due upon maturity 6,558 1,272
Loans, difference, [Abstract]    
Difference (1,114) (239)
Distressed at Fair Value [Member]    
Loans, fair value [Abstract]    
Current through 89 days delinquent 379 371
90 or more days delinquent, not in foreclosure 872 942
90 or more days delinquent, in foreclosure 110 392
Fair value 14,401,385 8,532,644
Fair value 1,361 1,705
Loans, principal amount due upon maturity [Abstract]    
Current through 89 days delinquent 378 476
90 or more days delinquent, not in foreclosure 2,566 2,553
90 or more days delinquent, in foreclosure 388 1,120
Principal amount due upon maturity 14,706,859 8,359,235
Principal amount due upon maturity 3,332 4,149
Loans, difference, [Abstract]    
Current through 89 days delinquent 1 (105)
90 or more days delinquent, not in foreclosure (1,694) (1,611)
90 or more days delinquent, in foreclosure (278) (728)
Difference (1,971) (2,444)
Distressed at Fair Value [Member] | Nonperforming mortgage loans [Member]    
Loans, fair value [Abstract]    
Fair value 982 1,334
Loans, principal amount due upon maturity [Abstract]    
Principal amount due upon maturity 2,954 3,673
Loans, difference, [Abstract]    
Difference $ (1,972) $ (2,339)