Derivative Instruments and Hedging Activities Put and Call Options for TBAs (Details) - USD ($) |
Sep. 30, 2021 |
Jun. 30, 2021 |
Dec. 31, 2020 |
Sep. 30, 2020 |
Jun. 30, 2020 |
Dec. 31, 2019 |
|---|---|---|---|---|---|---|
| Derivative Instruments and Hedging Activities Disclosure [Abstract] | ||||||
| Derivative, Notional Amount | $ 20,187,509,000 | $ 23,094,926,000 | $ 23,932,603,000 | $ 25,836,064,000 | $ 8,076,933,000 | $ 48,445,497,000 |
| Derivative [Line Items] | ||||||
| Derivative, Notional Amount | 20,187,509,000 | $ 23,094,926,000 | $ 23,932,603,000 | $ 25,836,064,000 | $ 8,076,933,000 | $ 48,445,497,000 |
| Put and Call Options for TBAs [Member] | ||||||
| Derivative Instruments and Hedging Activities Disclosure [Abstract] | ||||||
| Derivative, Notional Amount | 1,000,000,000 | |||||
| Derivative [Line Items] | ||||||
| Derivative, Notional Amount | 1,000,000,000 | |||||
| Fair Value | $ 4,000,000 |
| X | ||||||||||
- Definition Fair value of the assets less the liabilities of a derivative or group of derivatives. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- References No definition available.
|
| X | ||||||||||
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
|
| X | ||||||||||
- Definition Nominal or face amount used to calculate payment on derivative. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|
| X | ||||||||||
- Details
|