v3.26.3
Fair Value of Financial Instruments - Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($)
Sep. 30, 2026
Jun. 30, 2026
Dec. 31, 2025
Sep. 30, 2025
Jun. 30, 2025
Dec. 31, 2024
Assets carried at fair value            
Investment securities available for sale: $ 7,343,161,000   $ 6,904,781,000      
Residential loans held for sale 150,969,000   80,707,000      
Multi-family loans 36,868,000   55,476,000      
Equity investments 17,926,000   24,711,000      
Derivative assets:            
Total derivative assets 11,393,000   722,000      
Mortgage servicing rights 18,970,000 $ 19,093,000 20,893,000 $ 21,896,000 $ 19,449,000 $ 21,003,000
Total 12,368,226,000   11,445,465,000      
Liabilities carried at fair value            
Senior unsecured notes 434,607,000   260,852,000      
Derivative liabilities            
Derivative liabilities (14,039,000)   0      
Total 3,883,838,000   3,409,009,000      
Derivative assets 11,393,000   722,000      
Variation Margin 7,869,000   48,759,000      
Interest rate caps            
Derivative assets:            
Total derivative assets 1,021,000   31,000      
Options            
Derivative assets:            
Total derivative assets 386,000   0      
IRLCs            
Derivative assets:            
Total derivative assets 279,000   691,000      
Interest rate swaps            
Derivative assets:            
Total derivative assets 0   0      
Derivative liabilities            
Derivative liabilities 0   0      
Variation Margin 0   38,869,000      
U.S. Treasury futures            
Derivative assets:            
Total derivative assets 0   0      
Derivative liabilities            
Derivative assets 0   0      
Variation Margin 0   0      
Commodity futures            
Derivative assets:            
Total derivative assets 0   0      
Derivative liabilities            
Derivative liabilities 0   0      
Variation Margin 4,889,000   0      
TBAs            
Derivative assets:            
Total derivative assets 9,707,000   0      
Derivative liabilities            
Derivative liabilities (14,039,000)   0      
Variation Margin 0          
Credit default swaps            
Derivative liabilities            
Derivative liabilities 0   0      
Variation Margin 2,980,000   9,890,000      
Interest Rate Swaps, Credit Default Swaps, U.S. Treasury Futures            
Derivative liabilities            
Variation Margin 344,500,000   36,100,000      
Interest Rate Swaps, Credit Default Swaps, U.S. Treasury Futures | Central Clearing House            
Derivative liabilities            
Derivative liabilities (34,000,000.0)   (59,400,000)      
Derivative assets 378,600,000   23,300,000      
Agency RMBS            
Assets carried at fair value            
Investment securities available for sale: 6,736,751,000   6,633,476,000      
Non-Agency RMBS            
Assets carried at fair value            
Investment securities available for sale: 60,822,000   25,592,000      
U.S. Treasury securities            
Assets carried at fair value            
Investment securities available for sale: 545,588,000   245,713,000      
Residential loans            
Assets carried at fair value            
Residential loans: 781,758,000   583,963,000      
Consolidated SLST | Consolidated SLST | VIE, Primary Beneficiary            
Assets carried at fair value            
Residential loans: 1,047,558,000   1,165,677,000      
Liabilities carried at fair value            
Consolidated SLST 915,698,000   1,006,919,000      
Residential loans held in securitization trusts            
Assets carried at fair value            
Residential loans: 2,959,623,000   2,608,535,000      
Residential loan securitizations            
Liabilities carried at fair value            
Consolidated SLST 2,438,853,000   2,075,962,000      
Non-Agency RMBS re-securitization            
Liabilities carried at fair value            
Consolidated SLST 108,719,000   65,276,000      
Level 1            
Assets carried at fair value            
Residential loans held for sale 0   0      
Multi-family loans 0   0      
Equity investments 0   0      
Derivative assets:            
Mortgage servicing rights 0   0      
Total 0   0      
Liabilities carried at fair value            
Senior unsecured notes 0   0      
Derivative liabilities            
Total 0   0      
Level 1 | Interest rate caps            
Derivative assets:            
Total derivative assets 0   0      
Level 1 | Options            
Derivative assets:            
Total derivative assets 0   0      
Level 1 | IRLCs            
Derivative assets:            
Total derivative assets 0   0      
Level 1 | Interest rate swaps            
Derivative assets:            
Total derivative assets 0   0      
Derivative liabilities            
Derivative liabilities 0   0      
Level 1 | U.S. Treasury futures            
Derivative assets:            
Total derivative assets 0   0      
Level 1 | Commodity futures            
Derivative assets:            
Total derivative assets 0   0      
Derivative liabilities            
Derivative liabilities 0   0      
Level 1 | TBAs            
Derivative assets:            
Total derivative assets 0   0      
Derivative liabilities            
Derivative liabilities 0   0      
Level 1 | Credit default swaps            
Derivative liabilities            
Derivative liabilities 0   0      
Level 1 | Agency RMBS            
Assets carried at fair value            
Investment securities available for sale: 0   0      
Level 1 | Non-Agency RMBS            
Assets carried at fair value            
Investment securities available for sale: 0   0      
Level 1 | U.S. Treasury securities            
Assets carried at fair value            
Investment securities available for sale: 0   0      
Level 1 | Residential loans            
Assets carried at fair value            
Residential loans: 0   0      
Level 1 | Consolidated SLST | Consolidated SLST | VIE, Primary Beneficiary            
Assets carried at fair value            
Residential loans: 0   0      
Liabilities carried at fair value            
Consolidated SLST 0   0      
Level 1 | Residential loans held in securitization trusts            
Assets carried at fair value            
Residential loans: 0   0      
Level 1 | Residential loan securitizations            
Liabilities carried at fair value            
Consolidated SLST 0   0      
Level 1 | Non-Agency RMBS re-securitization            
Liabilities carried at fair value            
Consolidated SLST 0   0      
Level 2            
Assets carried at fair value            
Residential loans held for sale 0   0      
Multi-family loans 0   0      
Equity investments 0   0      
Derivative assets:            
Mortgage servicing rights 0   0      
Total 7,354,275,000   6,904,812,000      
Liabilities carried at fair value            
Senior unsecured notes 434,607,000   260,852,000      
Derivative liabilities            
Derivative liabilities (14,039,000)   0      
Total 2,968,140,000   2,402,090,000      
Derivative assets 11,114,000   31,000      
Level 2 | Interest rate caps            
Derivative assets:            
Total derivative assets 1,021,000   31,000      
Level 2 | Options            
Derivative assets:            
Total derivative assets 386,000   0      
Level 2 | IRLCs            
Derivative assets:            
Total derivative assets 0   0      
Level 2 | Interest rate swaps            
Derivative assets:            
Total derivative assets 0   0      
Derivative liabilities            
Derivative liabilities 0   0      
Level 2 | U.S. Treasury futures            
Derivative assets:            
Total derivative assets 0   0      
Level 2 | Commodity futures            
Derivative assets:            
Total derivative assets 0   0      
Derivative liabilities            
Derivative liabilities 0   0      
Level 2 | TBAs            
Derivative assets:            
Total derivative assets 9,707,000   0      
Derivative liabilities            
Derivative liabilities (14,039,000)   0      
Level 2 | Credit default swaps            
Derivative liabilities            
Derivative liabilities 0   0      
Level 2 | Agency RMBS            
Assets carried at fair value            
Investment securities available for sale: 6,736,751,000   6,633,476,000      
Level 2 | Non-Agency RMBS            
Assets carried at fair value            
Investment securities available for sale: 60,822,000   25,592,000      
Level 2 | U.S. Treasury securities            
Assets carried at fair value            
Investment securities available for sale: 545,588,000   245,713,000      
Level 2 | Residential loans            
Assets carried at fair value            
Residential loans: 0   0      
Level 2 | Consolidated SLST | Consolidated SLST | VIE, Primary Beneficiary            
Assets carried at fair value            
Residential loans: 0   0      
Liabilities carried at fair value            
Consolidated SLST 0   0      
Level 2 | Residential loans held in securitization trusts            
Assets carried at fair value            
Residential loans: 0   0      
Level 2 | Residential loan securitizations            
Liabilities carried at fair value            
Consolidated SLST 2,438,853,000   2,075,962,000      
Level 2 | Non-Agency RMBS re-securitization            
Liabilities carried at fair value            
Consolidated SLST 108,719,000   65,276,000      
Level 3            
Assets carried at fair value            
Residential loans held for sale 150,969,000   80,707,000      
Multi-family loans 36,868,000   55,476,000      
Equity investments 17,926,000   24,711,000      
Derivative assets:            
Mortgage servicing rights 18,970,000   20,893,000      
Total 5,013,951,000   4,540,653,000      
Liabilities carried at fair value            
Senior unsecured notes 0   0      
Derivative liabilities            
Total 915,698,000   1,006,919,000      
Level 3 | Interest rate caps            
Derivative assets:            
Total derivative assets 0   0      
Level 3 | Options            
Derivative assets:            
Total derivative assets 0   0      
Level 3 | IRLCs            
Derivative assets:            
Total derivative assets 279,000   691,000      
Level 3 | Interest rate swaps            
Derivative assets:            
Total derivative assets 0   0      
Derivative liabilities            
Derivative liabilities 0   0      
Level 3 | U.S. Treasury futures            
Derivative assets:            
Total derivative assets 0   0      
Level 3 | Commodity futures            
Derivative assets:            
Total derivative assets 0   0      
Derivative liabilities            
Derivative liabilities 0   0      
Level 3 | TBAs            
Derivative assets:            
Total derivative assets 0   0      
Derivative liabilities            
Derivative liabilities 0   0      
Level 3 | Credit default swaps            
Derivative liabilities            
Derivative liabilities 0   0      
Level 3 | Agency RMBS            
Assets carried at fair value            
Investment securities available for sale: 0   0      
Level 3 | Non-Agency RMBS            
Assets carried at fair value            
Investment securities available for sale: 0   0      
Level 3 | U.S. Treasury securities            
Assets carried at fair value            
Investment securities available for sale: 0   0      
Level 3 | Residential loans            
Assets carried at fair value            
Residential loans: 781,758,000   583,963,000      
Level 3 | Consolidated SLST | Consolidated SLST | VIE, Primary Beneficiary            
Assets carried at fair value            
Residential loans: 1,047,558,000   1,165,677,000      
Liabilities carried at fair value            
Consolidated SLST 915,698,000   1,006,919,000      
Level 3 | Residential loans held in securitization trusts            
Assets carried at fair value            
Residential loans: 2,959,623,000   2,608,535,000      
Level 3 | Residential loan securitizations            
Liabilities carried at fair value            
Consolidated SLST 0   0      
Level 3 | Non-Agency RMBS re-securitization            
Liabilities carried at fair value            
Consolidated SLST $ 0   $ 0