Investment in Securities (Summary of Investment in Securities) (Details) - USD ($) $ in Thousands |
3 Months Ended |
12 Months Ended |
Mar. 31, 2020 |
Dec. 31, 2019 |
| Securities, Available-for-sale [Line Items] |
|
|
|
| Current Principal |
|
$ 1,437,517
|
$ 2,282,149
|
| Unamortized Premium (Discount) |
|
(174,092)
|
(150,821)
|
| Amortized Cost |
|
1,537,690
|
2,342,369
|
| Gross Unrealized Gains |
|
43,657
|
43,801
|
| Gross Unrealized Losses |
|
(113,243)
|
(9,638)
|
| Investment Owned At Fair Value, Net |
|
1,468,104
|
2,376,532
|
| Securities, at fair value(1) |
[1] |
1,481,395
|
2,449,941
|
| Securities sold short, at fair value |
|
$ (13,291)
|
$ (73,409)
|
| Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
4.13%
|
4.23%
|
| Weighted Average Yield |
|
4.96%
|
4.01%
|
| Weighted average life |
|
4 years 5 months 12 days
|
5 years 10 months 24 days
|
| Long |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Current Principal |
|
$ 1,450,751
|
$ 2,355,498
|
| Unamortized Premium (Discount) |
|
(174,157)
|
(151,329)
|
| Amortized Cost |
|
1,550,859
|
2,415,210
|
| Gross Unrealized Gains |
|
43,634
|
43,738
|
| Gross Unrealized Losses |
|
(113,098)
|
(9,007)
|
| Securities, at fair value(1) |
|
$ 1,481,395
|
$ 2,449,941
|
| Long | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
4.10%
|
4.15%
|
| Weighted Average Yield |
|
5.00%
|
4.09%
|
| Weighted average life |
|
4 years 5 months 15 days
|
5 years 10 months 17 days
|
| Long | 15-year fixed-rate mortgages |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Current Principal |
|
$ 74,791
|
$ 314,636
|
| Unamortized Premium (Discount) |
|
2,405
|
6,369
|
| Amortized Cost |
|
77,196
|
321,005
|
| Gross Unrealized Gains |
|
2,001
|
2,604
|
| Gross Unrealized Losses |
|
(7)
|
(203)
|
| Securities, at fair value(1) |
|
$ 79,190
|
$ 323,406
|
| Long | 15-year fixed-rate mortgages | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
3.55%
|
3.05%
|
| Weighted Average Yield |
|
2.47%
|
2.28%
|
| Weighted average life |
|
3 years 6 months 21 days
|
3 years 18 days
|
| Long | 20-year fixed-rate mortgages |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Current Principal |
|
$ 752
|
$ 804
|
| Unamortized Premium (Discount) |
|
46
|
49
|
| Amortized Cost |
|
798
|
853
|
| Gross Unrealized Gains |
|
30
|
24
|
| Gross Unrealized Losses |
|
0
|
0
|
| Securities, at fair value(1) |
|
$ 828
|
$ 877
|
| Long | 20-year fixed-rate mortgages | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
4.67%
|
4.62%
|
| Weighted Average Yield |
|
2.97%
|
2.99%
|
| Weighted average life |
|
3 years 11 months 15 days
|
4 years 9 months 18 days
|
| Long | 30-year fixed-rate mortgages |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Current Principal |
|
$ 699,907
|
$ 1,358,762
|
| Unamortized Premium (Discount) |
|
32,413
|
64,846
|
| Amortized Cost |
|
732,320
|
1,423,608
|
| Gross Unrealized Gains |
|
22,005
|
13,821
|
| Gross Unrealized Losses |
|
(341)
|
(2,830)
|
| Securities, at fair value(1) |
|
$ 753,984
|
$ 1,434,599
|
| Long | 30-year fixed-rate mortgages | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
4.17%
|
4.20%
|
| Weighted Average Yield |
|
2.89%
|
2.95%
|
| Weighted average life |
|
3 years 10 months 20 days
|
6 years 7 months 17 days
|
| Long | Adjustable rate mortgages |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Current Principal |
|
$ 8,645
|
$ 9,651
|
| Unamortized Premium (Discount) |
|
345
|
315
|
| Amortized Cost |
|
8,990
|
9,966
|
| Gross Unrealized Gains |
|
82
|
90
|
| Gross Unrealized Losses |
|
(18)
|
(54)
|
| Securities, at fair value(1) |
|
$ 9,054
|
$ 10,002
|
| Long | Adjustable rate mortgages | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
3.99%
|
3.99%
|
| Weighted Average Yield |
|
1.66%
|
2.03%
|
| Weighted average life |
|
3 years 29 days
|
4 years 1 month 2 days
|
| Long | Reverse mortgages |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Current Principal |
|
$ 122,183
|
$ 122,670
|
| Unamortized Premium (Discount) |
|
7,747
|
8,133
|
| Amortized Cost |
|
129,930
|
130,803
|
| Gross Unrealized Gains |
|
2,317
|
2,023
|
| Gross Unrealized Losses |
|
(1,646)
|
(26)
|
| Securities, at fair value(1) |
|
$ 130,601
|
$ 132,800
|
| Long | Reverse mortgages | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
4.23%
|
4.43%
|
| Weighted Average Yield |
|
2.80%
|
2.78%
|
| Weighted average life |
|
6 years 1 month 20 days
|
6 years 8 months 1 day
|
| Long | Interest only securities |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Amortized Cost |
|
$ 37,801
|
$ 34,044
|
| Gross Unrealized Gains |
|
5,442
|
1,624
|
| Gross Unrealized Losses |
|
(899)
|
(389)
|
| Securities, at fair value(1) |
|
$ 42,344
|
$ 35,279
|
| Long | Interest only securities | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
2.72%
|
2.81%
|
| Weighted Average Yield |
|
10.24%
|
9.27%
|
| Weighted average life |
|
3 years 6 months 10 days
|
3 years 10 months 9 days
|
| Long | Non-Agency RMBS |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Current Principal |
|
$ 278,092
|
$ 274,353
|
| Unamortized Premium (Discount) |
|
(112,903)
|
(122,685)
|
| Amortized Cost |
|
165,189
|
151,668
|
| Gross Unrealized Gains |
|
9,344
|
12,549
|
| Gross Unrealized Losses |
|
(15,301)
|
(1,081)
|
| Securities, at fair value(1) |
|
$ 159,232
|
$ 163,136
|
| Long | Non-Agency RMBS | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
3.01%
|
3.41%
|
| Weighted Average Yield |
|
6.02%
|
7.25%
|
| Weighted average life |
|
5 years 1 month 13 days
|
5 years 3 months 21 days
|
| Long | CMBS |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Current Principal |
|
$ 165,470
|
$ 185,417
|
| Unamortized Premium (Discount) |
|
(60,960)
|
(67,961)
|
| Amortized Cost |
|
104,510
|
117,456
|
| Gross Unrealized Gains |
|
0
|
2,990
|
| Gross Unrealized Losses |
|
(32,728)
|
(480)
|
| Securities, at fair value(1) |
|
$ 71,782
|
$ 119,966
|
| Long | CMBS | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
2.17%
|
3.31%
|
| Weighted Average Yield |
|
7.60%
|
6.62%
|
| Weighted average life |
|
8 years 11 months 15 days
|
8 years 11 months 8 days
|
| Long | Non-Agency IOs |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Amortized Cost |
|
$ 6,044
|
$ 6,517
|
| Gross Unrealized Gains |
|
1,776
|
1,817
|
| Gross Unrealized Losses |
|
(316)
|
(18)
|
| Securities, at fair value(1) |
|
$ 7,504
|
$ 8,316
|
| Long | Non-Agency IOs | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
0.98%
|
1.10%
|
| Weighted Average Yield |
|
21.18%
|
8.18%
|
| Weighted average life |
|
3 years 5 months 12 days
|
4 years 1 month 20 days
|
| Long | CLOs |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Amortized Cost |
|
$ 228,873
|
$ 169,238
|
| Gross Unrealized Gains |
|
156
|
4,219
|
| Gross Unrealized Losses |
|
(59,756)
|
(3,014)
|
| Securities, at fair value(1) |
|
$ 169,273
|
$ 170,443
|
| Long | CLOs | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
4.18%
|
5.05%
|
| Weighted Average Yield |
|
8.22%
|
9.62%
|
| Weighted average life |
|
4 years 9 months 10 days
|
4 years 9 months
|
| Long | Asset-backed securities, backed by consumer loans |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Current Principal |
|
$ 77,534
|
$ 67,080
|
| Unamortized Premium (Discount) |
|
(22,007)
|
(19,154)
|
| Amortized Cost |
|
55,527
|
47,926
|
| Gross Unrealized Gains |
|
193
|
1,596
|
| Gross Unrealized Losses |
|
(1,093)
|
(912)
|
| Securities, at fair value(1) |
|
$ 54,627
|
$ 48,610
|
| Long | Asset-backed securities, backed by consumer loans | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
11.68%
|
12.17%
|
| Weighted Average Yield |
|
15.13%
|
14.00%
|
| Weighted average life |
|
1 year 1 month 28 days
|
1 year 2 months 19 days
|
| Long | Corporate debt securities |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Current Principal |
|
$ 21,953
|
$ 22,125
|
| Unamortized Premium (Discount) |
|
(21,476)
|
(21,241)
|
| Amortized Cost |
|
477
|
884
|
| Gross Unrealized Gains |
|
133
|
229
|
| Gross Unrealized Losses |
|
0
|
0
|
| Securities, at fair value(1) |
|
$ 610
|
$ 1,113
|
| Long | Corporate debt securities | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
0.00%
|
0.00%
|
| Weighted Average Yield |
|
0.00%
|
0.00%
|
| Weighted average life |
|
1 month 28 days
|
3 months 29 days
|
| Long | Corporate equity securities |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Amortized Cost |
|
$ 1,547
|
$ 1,242
|
| Securities, at fair value(1) |
|
712
|
1,394
|
| Corporate equity, gross unrealized gains |
|
155
|
152
|
| Corporate equity, gross unrealized losses |
|
(990)
|
0
|
| Long | U.S. Treasury securities |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Current Principal |
|
1,424
|
|
| Unamortized Premium (Discount) |
|
233
|
|
| Amortized Cost |
|
1,657
|
|
| Gross Unrealized Gains |
|
0
|
|
| Gross Unrealized Losses |
|
(3)
|
|
| Securities, at fair value(1) |
|
$ 1,654
|
|
| Long | U.S. Treasury securities | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
2.00%
|
|
| Weighted Average Yield |
|
1.33%
|
|
| Weighted average life |
|
29 years 10 months 24 days
|
|
| Short |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Current Principal |
|
$ (13,234)
|
(73,349)
|
| Unamortized Premium (Discount) |
|
65
|
508
|
| Investment Sold, Not yet Purchased, Sale Proceeds |
|
(13,169)
|
(72,841)
|
| Gross Unrealized Gains |
|
23
|
63
|
| Gross Unrealized Losses |
|
(145)
|
(631)
|
| Securities sold short, at fair value |
|
$ (13,291)
|
$ (73,409)
|
| Short | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
1.22%
|
1.65%
|
| Weighted Average Yield |
|
0.41%
|
1.66%
|
| Weighted average life |
|
4 years 10 months 24 days
|
5 years 5 months 26 days
|
| Short | Corporate debt securities |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Current Principal |
|
$ (1,650)
|
$ (450)
|
| Unamortized Premium (Discount) |
|
244
|
(6)
|
| Investment Sold, Not yet Purchased, Sale Proceeds |
|
(1,406)
|
(456)
|
| Gross Unrealized Gains |
|
23
|
0
|
| Gross Unrealized Losses |
|
(36)
|
(15)
|
| Securities sold short, at fair value |
|
$ (1,419)
|
$ (471)
|
| Short | Corporate debt securities | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
3.91%
|
5.44%
|
| Weighted Average Yield |
|
5.21%
|
5.21%
|
| Weighted average life |
|
21 years 8 months 26 days
|
4 years 10 months 24 days
|
| Short | U.S. Treasury securities |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Current Principal |
|
$ (2,000)
|
$ (63,140)
|
| Unamortized Premium (Discount) |
|
(151)
|
381
|
| Investment Sold, Not yet Purchased, Sale Proceeds |
|
(2,151)
|
(62,759)
|
| Gross Unrealized Gains |
|
0
|
63
|
| Gross Unrealized Losses |
|
(3)
|
(298)
|
| Securities sold short, at fair value |
|
$ (2,154)
|
$ (62,994)
|
| Short | U.S. Treasury securities | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
1.50%
|
1.76%
|
| Weighted Average Yield |
|
0.71%
|
1.87%
|
| Weighted average life |
|
9 years 10 months 17 days
|
6 years 1 month 9 days
|
| Short | European sovereign bonds |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Current Principal |
|
$ (9,584)
|
$ (9,759)
|
| Unamortized Premium (Discount) |
|
(28)
|
133
|
| Investment Sold, Not yet Purchased, Sale Proceeds |
|
(9,612)
|
(9,626)
|
| Gross Unrealized Gains |
|
0
|
0
|
| Gross Unrealized Losses |
|
(106)
|
(318)
|
| Securities sold short, at fair value |
|
$ (9,718)
|
$ (9,944)
|
| Short | European sovereign bonds | Weighted Average |
|
|
|
| Securities, Available-for-sale [Line Items] |
|
|
|
| Weighted Average Coupon |
|
0.76%
|
0.77%
|
| Weighted Average Yield |
|
0.12%
|
0.12%
|
| Weighted average life |
|
1 year 3 months 29 days
|
1 year 6 months 29 days
|
|
|