v3.26.3
Variable Interest Entities - Summary of Credit Risk Transfer Agreements (Detail) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2032
Sep. 30, 2031
Sep. 30, 2030
Sep. 30, 2029
Sep. 30, 2028
Sep. 30, 2027
Dec. 31, 2025
Credit risk transfer strips                      
Net investment income $ 36,244 $ 99,232 $ 191,107 $ 213,898              
Carrying value of credit risk transfer arrangements:                      
Interest-only security payable at fair value (34,608)   (34,608)   $ (34,608) $ 0 $ 0 $ 0 $ 0 $ 0 $ (37,650)
Variable Interest Entities [Member]                      
Carrying value of credit risk transfer arrangements:                      
Interest-only security payable at fair value (34,608)   (34,608)               (37,650)
Variable Interest Entities [Member] | Credit Risk Transfer Agreements [Member]                      
Credit risk transfer derivatives                      
Realized 2,008 2,599 6,600 8,034              
Valuation changes 496 348 (1,705) 2,268              
Gains recognized on gross derivative related to credit risk transactions 2,504 2,947 4,895 10,302              
Credit risk transfer strips                      
Realized 7,583 9,623 24,782 29,350              
Valuation changes 224 1,177 905 (5,124)              
Credit risk transfer strips 7,807 10,800 25,687 24,226              
Interest-only security payable at fair value - valuation changes (309) (5) 3,042 (2,336)              
Gains (losses) recognized on gross derivative related to credit risk transactions 10,002 13,742 33,624 32,192              
Interest income -- Deposits securing credit risk transfer arrangements 8,315 11,125 25,688 34,201              
Net investment income 18,317 24,867 59,312 66,393              
Net payments made to settle losses on credit risk transfer arrangements 1,769 $ 1,250 4,296 $ 3,718              
Carrying value of credit risk transfer arrangements:                      
Derivative assets - credit risk transfer derivatives 30,695   30,695               32,659
Derivative and credit risk transfer liabilities - credit risk transfer strips (5,231)   (5,231)               (5,999)
Derivative and credit risk transfer strip assets 878,044   878,044               998,344
Deposits securing credit risk transfer arrangements 887,188   887,188               1,009,334
Interest-only security payable at fair value (34,608)   (34,608)               (37,650)
Derivative assets 30,695   30,695               32,659
Derivative and credit risk transfer strip assets pledged to secure [1] 887,188   887,188               1,009,334
Unpaid principal balance of loans underlying credit risk transfer arrangements 16,878,161   16,878,161               19,517,530
Variable Interest Entities [Member] | Credit Risk Transfer Agreements [Member] | Purchase Commitment [Member]                      
Collection status (unpaid principal balance):                      
Current 16,389,390   16,389,390               18,908,261
30-89 days delinquent 340,112   340,112               413,295
90-179 days delinquent 78,773   78,773               110,486
180 or more days delinquent 50,689   50,689               57,798
Foreclosure 19,197   19,197               27,690
Bankruptcy $ 54,295   $ 54,295               $ 68,426
[1] Deposits securing credit risk transfer arrangements also secure $5.2 million and $6.0 million in CRT strip liabilities at September 30, 2026 and December 31, 2025, respectively.