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Schedule of Mortgage-Backed Securities by Weighted Average Life (Details) - USD ($) $ in Thousands | Mar. 31, 2018 | Dec. 31, 2017
--- | --- | ---
Mortgage-Backed Securities [Line Items] |  |
Mortgage-backed securities, at fair value | $ 1,630,575 | $ 1,685,998
Non-Agency RMBS [Member] |  |
Mortgage-Backed Securities [Line Items] |  |
Mortgage-backed securities, at fair value | 12,442 | 18,025
Amortized Cost | $ 10,503 | $ 15,278
Weighted Average Coupon Rate, Percent | 3.94% | 3.58%
Less than three years [Member] | Non-Agency RMBS [Member] |  |
Mortgage-Backed Securities [Line Items] |  |
Mortgage-backed securities, at fair value | $ 0 | $ 0
Amortized Cost | $ 0 | $ 0
Weighted Average Coupon Rate, Percent | 0.00% | 0.00%
Greater than three years and less than seven years [Member] | Non-Agency RMBS [Member] |  |
Mortgage-Backed Securities [Line Items] |  |
Mortgage-backed securities, at fair value | $ 7,784 | $ 9,625
Amortized Cost | $ 6,861 | $ 9,062
Weighted Average Coupon Rate, Percent | 4.89% | 5.00%
Greater than seven years and less than eleven years [Member] | Non-Agency RMBS [Member] |  |
Mortgage-Backed Securities [Line Items] |  |
Mortgage-backed securities, at fair value | $ 2,188 | $ 5,892
Amortized Cost | $ 1,111 | $ 3,697
Weighted Average Coupon Rate, Percent | 2.89% | 2.14%
Greater than eleven years [Member] | Non-Agency RMBS [Member] |  |
Mortgage-Backed Securities [Line Items] |  |
Mortgage-backed securities, at fair value | $ 2,470 | $ 2,508
Amortized Cost | $ 2,531 | $ 2,519
Weighted Average Coupon Rate, Percent | 2.50% | 2.18%
Fixed Rate [Member] | Agency RMBS [Member] |  |
Mortgage-Backed Securities [Line Items] |  |
Mortgage-backed securities, at fair value | $ 1,603,607 | $ 1,655,768
Amortized Cost | $ 1,643,485 | $ 1,669,060
Weighted Average Coupon Rate, Percent | 3.90% | 3.92%
Fixed Rate [Member] | Less than three years [Member] | Agency RMBS [Member] |  |
Mortgage-Backed Securities [Line Items] |  |
Mortgage-backed securities, at fair value | $ 6,903 | $ 7,931
Amortized Cost | $ 6,949 | $ 7,935
Weighted Average Coupon Rate, Percent | 3.59% | 3.70%
Fixed Rate [Member] | Greater than three years and less than seven years [Member] | Agency RMBS [Member] |  |
Mortgage-Backed Securities [Line Items] |  |
Mortgage-backed securities, at fair value | $ 331,586 | $ 419,295
Amortized Cost | $ 339,800 | $ 423,248
Weighted Average Coupon Rate, Percent | 3.87% | 3.93%
Fixed Rate [Member] | Greater than seven years and less than eleven years [Member] | Agency RMBS [Member] |  |
Mortgage-Backed Securities [Line Items] |  |
Mortgage-backed securities, at fair value | $ 1,253,210 | $ 1,221,160
Amortized Cost | $ 1,284,720 | $ 1,230,479
Weighted Average Coupon Rate, Percent | 3.91% | 3.92%
Fixed Rate [Member] | Greater than eleven years [Member] | Agency RMBS [Member] |  |
Mortgage-Backed Securities [Line Items] |  |
Mortgage-backed securities, at fair value | $ 11,908 | $ 7,382
Amortized Cost | $ 12,016 | $ 7,398
Weighted Average Coupon Rate, Percent | 4.05% | 3.68%
Interest-Only [Member] | Agency RMBS [Member] |  |
Mortgage-Backed Securities [Line Items] |  |
Mortgage-backed securities, at fair value | $ 14,526 | $ 12,205
Amortized Cost | $ 14,264 | $ 13,197
Weighted Average Coupon Rate, Percent | 4.46% | 4.36%
Interest-Only [Member] | Less than three years [Member] | Agency RMBS [Member] |  |
Mortgage-Backed Securities [Line Items] |  |
Mortgage-backed securities, at fair value | $ 1,508 | $ 3,357
Amortized Cost | $ 1,962 | $ 4,253
Weighted Average Coupon Rate, Percent | 4.08% | 4.15%
Interest-Only [Member] | Greater than three years and less than seven years [Member] | Agency RMBS [Member] |  |
Mortgage-Backed Securities [Line Items] |  |
Mortgage-backed securities, at fair value | $ 13,018 | $ 8,848
Amortized Cost | $ 12,302 | $ 8,944
Weighted Average Coupon Rate, Percent | 4.55% | 4.51%
Interest-Only [Member] | Greater than seven years and less than eleven years [Member] | Agency RMBS [Member] |  |
Mortgage-Backed Securities [Line Items] |  |
Mortgage-backed securities, at fair value | $ 0 | $ 0
Amortized Cost | $ 0 | $ 0
Weighted Average Coupon Rate, Percent | 0.00% | 0.00%
Interest-Only [Member] | Greater than eleven years [Member] | Agency RMBS [Member] |  |
Mortgage-Backed Securities [Line Items] |  |
Mortgage-backed securities, at fair value | $ 0 | $ 0
Amortized Cost | $ 0 | $ 0
Weighted Average Coupon Rate, Percent | 0.00% | 0.00%

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- Definition The fair value as of the balance sheet date of firm holdings in mortgages, mortgage backed securities (investment instruments that represent ownership of an undivided interest in a group of mortgages, where principal and interest from the individual mortgages are used to pay investors' principal and interest on the mortgage backed security) and asset-backed securities that are primarily paid from the cash flows of a discrete pool of receivables or other financial assets (such as credit-card receivables), either fixed or revolving, that by their terms convert into cash within a finite time period. Includes both pledged (to counterparties as collateral for financing transactions) and unpledged holdings. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 940 -SubTopic 320 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=35711157&loc=d3e42546-110969 + Details
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