Investment in Securities (Summary of Investment in Securities) (Details) - USD ($)
$ in Thousands |
9 Months Ended |
12 Months Ended |
Sep. 30, 2021 |
Dec. 31, 2020 |
| Securities, Available-for-sale [Line Items] |
|
|
|
| Current Principal |
|
$ 1,873,856
|
$ 1,408,233
|
| Unamortized Premium (Discount) |
|
(143,084)
|
(196,118)
|
| Amortized Cost |
|
1,856,210
|
1,474,155
|
| Gross Unrealized Gains |
|
46,083
|
60,617
|
| Gross Unrealized Losses |
|
(37,024)
|
(59,229)
|
| Investment Owned At Fair Value, Net |
|
1,865,269
|
1,475,543
|
| Securities, at fair value(1)(2) |
[1],[2] |
1,895,563
|
1,514,185
|
| Securities sold short, at fair value |
|
$ (30,294)
|
$ (38,642)
|
| Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
3.63%
|
3.92%
|
| Weighted Average Yield |
|
3.45%
|
4.77%
|
| Weighted average life |
|
5 years 11 months 4 days
|
4 years 5 months 26 days
|
| Long |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Current Principal |
|
$ 1,903,845
|
$ 1,446,237
|
| Unamortized Premium (Discount) |
|
(143,637)
|
(199,280)
|
| Amortized Cost |
|
1,885,646
|
1,508,997
|
| Gross Unrealized Gains |
|
45,856
|
60,617
|
| Gross Unrealized Losses |
|
(35,939)
|
(55,429)
|
| Securities, at fair value(1)(2) |
|
$ 1,895,563
|
$ 1,514,185
|
| Long | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
3.57%
|
3.84%
|
| Weighted Average Yield |
|
3.50%
|
4.88%
|
| Weighted average life |
|
5 years 10 months 20 days
|
4 years 5 months 12 days
|
| Long | 15-year fixed-rate mortgages |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Current Principal |
|
$ 219,169
|
$ 67,875
|
| Unamortized Premium (Discount) |
|
10,304
|
2,543
|
| Amortized Cost |
|
229,473
|
70,418
|
| Gross Unrealized Gains |
|
1,491
|
1,832
|
| Gross Unrealized Losses |
|
(1,033)
|
(36)
|
| Securities, at fair value(1)(2) |
|
$ 229,931
|
$ 72,214
|
| Long | 15-year fixed-rate mortgages | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
2.65%
|
3.30%
|
| Weighted Average Yield |
|
1.42%
|
1.83%
|
| Weighted average life |
|
4 years 5 months 19 days
|
3 years 2 months 26 days
|
| Long | 20-year fixed-rate mortgages |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Current Principal |
|
$ 48,893
|
$ 50,131
|
| Unamortized Premium (Discount) |
|
2,892
|
3,097
|
| Amortized Cost |
|
51,785
|
53,228
|
| Gross Unrealized Gains |
|
20
|
182
|
| Gross Unrealized Losses |
|
(852)
|
0
|
| Securities, at fair value(1)(2) |
|
$ 50,953
|
$ 53,410
|
| Long | 20-year fixed-rate mortgages | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
2.45%
|
2.57%
|
| Weighted Average Yield |
|
1.22%
|
1.08%
|
| Weighted average life |
|
5 years 6 months
|
4 years 5 months 15 days
|
| Long | 30-year fixed-rate mortgages |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Current Principal |
|
$ 1,079,522
|
$ 626,021
|
| Unamortized Premium (Discount) |
|
55,479
|
30,738
|
| Amortized Cost |
|
1,135,001
|
656,759
|
| Gross Unrealized Gains |
|
14,478
|
25,765
|
| Gross Unrealized Losses |
|
(5,847)
|
(444)
|
| Securities, at fair value(1)(2) |
|
$ 1,143,632
|
$ 682,080
|
| Long | 30-year fixed-rate mortgages | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
3.21%
|
3.99%
|
| Weighted Average Yield |
|
2.09%
|
2.35%
|
| Weighted average life |
|
6 years 7 months 9 days
|
4 years 2 months 1 day
|
| Long | Adjustable rate mortgages |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Current Principal |
|
$ 10,436
|
$ 6,171
|
| Unamortized Premium (Discount) |
|
558
|
159
|
| Amortized Cost |
|
10,994
|
6,330
|
| Gross Unrealized Gains |
|
36
|
124
|
| Gross Unrealized Losses |
|
(150)
|
0
|
| Securities, at fair value(1)(2) |
|
$ 10,880
|
$ 6,454
|
| Long | Adjustable rate mortgages | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
3.21%
|
3.66%
|
| Weighted Average Yield |
|
2.28%
|
2.27%
|
| Weighted average life |
|
4 years 7 months 24 days
|
3 years 5 months 1 day
|
| Long | Reverse mortgages |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Current Principal |
|
$ 59,894
|
$ 89,383
|
| Unamortized Premium (Discount) |
|
3,683
|
5,152
|
| Amortized Cost |
|
63,577
|
94,535
|
| Gross Unrealized Gains |
|
759
|
3,123
|
| Gross Unrealized Losses |
|
(802)
|
(29)
|
| Securities, at fair value(1)(2) |
|
$ 63,534
|
$ 97,629
|
| Long | Reverse mortgages | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
3.21%
|
3.97%
|
| Weighted Average Yield |
|
2.28%
|
2.37%
|
| Weighted average life |
|
4 years 3 months 10 days
|
4 years 7 months 6 days
|
| Long | Interest only securities |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Amortized Cost |
|
$ 35,948
|
$ 43,406
|
| Gross Unrealized Gains |
|
4,640
|
5,808
|
| Gross Unrealized Losses |
|
(2,511)
|
(1,558)
|
| Securities, at fair value(1)(2) |
|
$ 38,077
|
$ 47,656
|
| Long | Interest only securities | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
3.51%
|
3.36%
|
| Weighted Average Yield |
|
7.90%
|
10.01%
|
| Weighted average life |
|
4 years 6 months
|
4 years 10 months 6 days
|
| Long | Non-Agency RMBS |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Current Principal |
|
$ 311,561
|
$ 321,842
|
| Unamortized Premium (Discount) |
|
(131,975)
|
(131,083)
|
| Amortized Cost |
|
179,586
|
190,759
|
| Gross Unrealized Gains |
|
10,730
|
15,880
|
| Gross Unrealized Losses |
|
(5,306)
|
(5,549)
|
| Securities, at fair value(1)(2) |
|
$ 185,010
|
$ 201,090
|
| Long | Non-Agency RMBS | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
4.63%
|
3.15%
|
| Weighted Average Yield |
|
7.12%
|
6.40%
|
| Weighted average life |
|
7 years 1 month 17 days
|
5 years 5 months 15 days
|
| Long | CMBS |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Current Principal |
|
$ 33,801
|
$ 188,085
|
| Unamortized Premium (Discount) |
|
(22,359)
|
(61,763)
|
| Amortized Cost |
|
11,442
|
126,322
|
| Gross Unrealized Gains |
|
282
|
1,655
|
| Gross Unrealized Losses |
|
(926)
|
(16,910)
|
| Securities, at fair value(1)(2) |
|
$ 10,798
|
$ 111,067
|
| Long | CMBS | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
2.91%
|
2.71%
|
| Weighted Average Yield |
|
10.47%
|
7.47%
|
| Weighted average life |
|
8 years 8 months 8 days
|
8 years 1 month 2 days
|
| Long | Non-Agency IOs |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Amortized Cost |
|
$ 9,999
|
$ 8,123
|
| Gross Unrealized Gains |
|
1,598
|
1,792
|
| Gross Unrealized Losses |
|
(248)
|
(305)
|
| Securities, at fair value(1)(2) |
|
$ 11,349
|
$ 9,610
|
| Long | Non-Agency IOs | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
0.98%
|
1.17%
|
| Weighted Average Yield |
|
14.00%
|
18.85%
|
| Weighted average life |
|
6 years 3 months 10 days
|
3 years 5 months 26 days
|
| Long | CLOs |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Amortized Cost |
|
$ 74,021
|
$ 208,907
|
| Gross Unrealized Gains |
|
6,888
|
2,563
|
| Gross Unrealized Losses |
|
(13,631)
|
(30,199)
|
| Securities, at fair value(1)(2) |
|
$ 67,278
|
$ 181,271
|
| Long | CLOs | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
3.57%
|
3.67%
|
| Weighted Average Yield |
|
9.15%
|
8.50%
|
| Weighted average life |
|
3 years 2 months 23 days
|
3 years 6 months
|
| Long | Asset-backed securities, backed by consumer loans |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Current Principal |
|
$ 112,732
|
$ 69,646
|
| Unamortized Premium (Discount) |
|
(38,471)
|
(24,936)
|
| Amortized Cost |
|
74,261
|
44,710
|
| Gross Unrealized Gains |
|
1,383
|
221
|
| Gross Unrealized Losses |
|
(4,349)
|
(6)
|
| Securities, at fair value(1)(2) |
|
$ 71,295
|
$ 44,925
|
| Long | Asset-backed securities, backed by consumer loans | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
11.49%
|
11.95%
|
| Weighted Average Yield |
|
14.99%
|
18.57%
|
| Weighted average life |
|
1 year 3 months 3 days
|
1 year 1 month 9 days
|
| Long | Corporate debt securities |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Current Principal |
|
$ 27,837
|
$ 27,083
|
| Unamortized Premium (Discount) |
|
(23,748)
|
(23,187)
|
| Amortized Cost |
|
4,089
|
3,896
|
| Gross Unrealized Gains |
|
865
|
1,296
|
| Gross Unrealized Losses |
|
(122)
|
(3)
|
| Securities, at fair value(1)(2) |
|
$ 4,832
|
$ 5,189
|
| Long | Corporate debt securities | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
0.76%
|
2.13%
|
| Weighted Average Yield |
|
7.50%
|
6.75%
|
| Weighted average life |
|
2 years 1 month 17 days
|
3 years 1 month 6 days
|
| Long | Corporate equity securities |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Amortized Cost |
|
$ 5,470
|
$ 1,604
|
| Gross Unrealized Gains |
|
2,686
|
376
|
| Gross Unrealized Losses |
|
(162)
|
(390)
|
| Securities, at fair value(1)(2) |
|
7,994
|
1,590
|
| Short |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Current Principal |
|
(29,989)
|
(38,004)
|
| Unamortized Premium (Discount) |
|
553
|
3,162
|
| Investment Sold, Not yet Purchased, Sale Proceeds |
|
(29,436)
|
(34,842)
|
| Gross Unrealized Gains |
|
227
|
0
|
| Gross Unrealized Losses |
|
(1,085)
|
(3,800)
|
| Securities sold short, at fair value |
|
$ (30,294)
|
$ (38,642)
|
| Short | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
0.02%
|
0.26%
|
| Weighted Average Yield |
|
0.05%
|
0.09%
|
| Weighted average life |
|
3 years 5 months 23 days
|
3 years 1 month 17 days
|
| Short | Corporate debt securities |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Current Principal |
|
|
$ (200)
|
| Unamortized Premium (Discount) |
|
|
(1)
|
| Investment Sold, Not yet Purchased, Sale Proceeds |
|
|
(201)
|
| Gross Unrealized Gains |
|
|
0
|
| Gross Unrealized Losses |
|
|
(17)
|
| Securities sold short, at fair value |
|
|
$ (218)
|
| Short | Corporate debt securities | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
|
5.09%
|
| Weighted Average Yield |
|
|
4.67%
|
| Weighted average life |
|
|
6 years 5 months 1 day
|
| Short | European sovereign bonds |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Current Principal |
|
$ (29,989)
|
$ (37,804)
|
| Unamortized Premium (Discount) |
|
553
|
3,163
|
| Investment Sold, Not yet Purchased, Sale Proceeds |
|
(29,436)
|
(34,641)
|
| Gross Unrealized Gains |
|
227
|
0
|
| Gross Unrealized Losses |
|
(1,085)
|
(3,783)
|
| Securities sold short, at fair value |
|
$ (30,294)
|
$ (38,424)
|
| Short | European sovereign bonds | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
0.02%
|
0.23%
|
| Weighted Average Yield |
|
0.05%
|
0.06%
|
| Weighted average life |
|
3 years 5 months 23 days
|
3 years 1 month 9 days
|
|
|