| Available-for-Sale Securities, at Fair Value (Details) - USD ($) $ in Thousands | Jun. 30, 2022 | Dec. 31, 2021 | 
|---|---|---|
| Debt Securities, Available-for-sale [Line Items] | ||
| Available-for-sale securities, at fair value | $ 8,789,437 | $ 7,161,703 | 
| Federal National Mortgage Association Certificates and Obligations (FNMA) [Member] | ||
| Debt Securities, Available-for-sale [Line Items] | ||
| Available-for-sale securities, at fair value | 5,711,203 | 5,040,988 | 
| Federal Home Loan Mortgage Corporation Certificates and Obligations (FHLMC) [Member] | ||
| Debt Securities, Available-for-sale [Line Items] | ||
| Available-for-sale securities, at fair value | 2,847,222 | 1,922,809 | 
| Government National Mortgage Association Certificates and Obligations (GNMA) [Member] | ||
| Debt Securities, Available-for-sale [Line Items] | ||
| Available-for-sale securities, at fair value | 143,522 | 185,602 | 
| Mortgage-backed Securities, Issued by Private Enterprises [Member] | ||
| Debt Securities, Available-for-sale [Line Items] | ||
| Available-for-sale securities, at fair value | $ 87,490 | $ 12,304 | 
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- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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