v3.26.3
Assets Sold Under Agreements to Repurchase - Summary of Financial Information Relating to Assets Sold under Agreements to Repurchase (Detail) - USD ($)
3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Dec. 31, 2025
Assets Sold under Agreements to Repurchase [Line Items]          
Weighted average interest rate 4.66% 5.16% 4.64% 5.19%  
Average balance $ 8,074,731,000 $ 6,670,245,000 $ 7,792,572,000 $ 6,408,372,000  
Total interest expense 95,883,000 88,587,000 275,351,000 254,071,000  
Maximum daily amount outstanding 8,817,164,000 $ 8,082,484,000 9,146,860,000 $ 8,733,460,000  
Assets Sold Under Agreements To Repurchase 8,383,792,000   8,383,792,000   $ 8,023,156,000
Assets sold under agreements to repurchase, At year end 8,381,973,000   $ 8,381,973,000   $ 8,018,601,000
Weighted average interest rate     4.63%   4.71%
Available borrowing capacity, Committed     $ 311,299,000   $ 595,085,000
Available borrowing capacity, Uncommitted     5,127,775,000   5,032,598,000
Available borrowing capacity     5,439,074,000   5,627,683,000
Margin deposits placed with counterparties included in Other assets, net 177,806,000   177,806,000   174,598,000
Assets Sold Under Agreements to Repurchase [Member]          
Assets Sold under Agreements to Repurchase [Line Items]          
Unamortized debt issuance costs (1,819,000)   (1,819,000)   (4,555,000)
Mortgage Backed Securities at Fair Value [Member]          
Assets Sold under Agreements to Repurchase [Line Items]          
Assets Sold under Agreements to Repurchase, Market Value 4,305,991,000   4,305,991,000   4,452,859,000
Loans Held for Sale at Fair Value [Member]          
Assets Sold under Agreements to Repurchase [Line Items]          
Assets Sold under Agreements to Repurchase, Market Value 2,843,528,000   2,843,528,000   2,676,700,000
Loans Held for Investment at Fair Value [Member]          
Assets Sold under Agreements to Repurchase [Line Items]          
Assets Sold under Agreements to Repurchase, Market Value 1,214,056,000   1,214,056,000   648,159,000
Servicing advances [Member]          
Assets Sold under Agreements to Repurchase [Line Items]          
Assets Sold under Agreements to Repurchase, Market Value 27,940,000   27,940,000   44,653,000
Derivative Assets [Member]          
Assets Sold under Agreements to Repurchase [Line Items]          
Assets Sold under Agreements to Repurchase, Market Value 9,542,000   9,542,000   12,622,000
Deposits Securing Credit Risk Transfer Arrangements [Member]          
Assets Sold under Agreements to Repurchase [Line Items]          
Assets Sold under Agreements to Repurchase, Market Value 110,227,000   110,227,000   176,694,000
Mortgage Service Rights at Fair Value [Member]          
Assets Sold under Agreements to Repurchase [Line Items]          
Assets Sold under Agreements to Repurchase, Market Value $ 1,640,068,000   $ 1,640,068,000   $ 1,765,572,000