Investments In Securities - Carrying Value of Trading Securities (Details) - USD ($)
$ in Thousands |
Sep. 30, 2020 |
Dec. 31, 2019 |
| Debt and Equity Securities, FV-NI [Line Items] |
|
|
| Principal Amount |
$ 3,165,581
|
$ 848,452
|
| Amortized Cost |
3,371,974
|
824,844
|
| Gross Unrealized Loss |
(2,653)
|
(3)
|
| Gross Unrealized Gain |
23,847
|
58,760
|
| Credit Risk and Non-Agency Securities |
3,393,168
|
883,601
|
| Credit Risk Transfer |
|
|
| Debt and Equity Securities, FV-NI [Line Items] |
|
|
| Principal Amount |
|
754,729
|
| Amortized Cost |
|
751,940
|
| Gross Unrealized Loss |
|
0
|
| Gross Unrealized Gain |
|
52,024
|
| Credit Risk and Non-Agency Securities |
|
803,964
|
| Non-Agency Securities |
|
|
| Debt and Equity Securities, FV-NI [Line Items] |
|
|
| Principal Amount |
|
93,723
|
| Amortized Cost |
|
72,904
|
| Gross Unrealized Loss |
|
(3)
|
| Gross Unrealized Gain |
|
6,736
|
| Credit Risk and Non-Agency Securities |
|
$ 79,637
|
| Fannie Mae | Agency Securities |
|
|
| Debt and Equity Securities, FV-NI [Line Items] |
|
|
| Principal Amount |
2,562,859
|
|
| Amortized Cost |
2,736,811
|
|
| Gross Unrealized Loss |
(2,361)
|
|
| Gross Unrealized Gain |
18,360
|
|
| Credit Risk and Non-Agency Securities |
2,752,810
|
|
| Freddie Mac | Agency Securities |
|
|
| Debt and Equity Securities, FV-NI [Line Items] |
|
|
| Principal Amount |
602,722
|
|
| Amortized Cost |
635,163
|
|
| Gross Unrealized Loss |
(292)
|
|
| Gross Unrealized Gain |
5,487
|
|
| Credit Risk and Non-Agency Securities |
$ 640,358
|
|