| Mortgage-backed securities [Table Text Block] |
The following tables present details of the Company's mortgage-backed securities portfolio at December 31, 2015 and 2014, respectively. The Company's Agency RMBS include mortgage pass-through certificates and CMOs representing interests in or obligations backed by pools of residential mortgage loans issued or guaranteed by a U.S. government agency or GSE. The non-Agency RMBS portfolio is not issued or guaranteed by the Federal National Mortgage Association, the Federal Home Loan Mortgage Corporation, or any agency of the U.S. Government and is therefore subject to greater credit risk. By RMBS Type – December 31, 2015: | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | ($ in thousands) | | | | | | | Gross Unrealized | | | | Weighted Average | | Current Principal | | Unamortized Premium (Discount) | | Amortized Cost | | Gains | | Losses | | Fair Value | | Coupon | | Yield | | Life
(Years)(1) | Agency RMBS: | | | | | | | | | | | | | | | | | | 15-year fixed rate mortgages | $ | 162,546 |
| | $ | 7,839 |
| | $ | 170,385 |
| | $ | 531 |
| | $ | (655 | ) | | $ | 170,261 |
| | 3.38% | | 2.31% | | 4.99 | 20-year fixed rate mortgages | 18,477 |
| | 1,277 |
| | 19,754 |
| | 153 |
| | (77 | ) | | 19,830 |
| | 4.00% | | 2.75% | | 6.50 | 30-year fixed rate mortgages | 842,524 |
| | 53,832 |
| | 896,356 |
| | 8,117 |
| | (3,679 | ) | | 900,794 |
| | 4.12% | | 3.11% | | 8.29 | Adjustable rate mortgages | 36,433 |
| | 2,196 |
| | 38,629 |
| | 81 |
| | (180 | ) | | 38,530 |
| | 4.05% | | 2.68% | | 5.44 | Reverse mortgages | 68,690 |
| | 6,515 |
| | 75,205 |
| | 34 |
| | (1,547 | ) | | 73,692 |
| | 4.63% | | 2.54% | | 5.64 | Interest only securities | n/a | | n/a | | 8,491 |
| | 248 |
| | (981 | ) | | 7,758 |
| | 3.82% | | 3.30% | | 2.36 | Total Agency RMBS | 1,128,670 |
| | 71,659 |
| | 1,208,820 |
| | 9,164 |
| | (7,119 | ) | | 1,210,865 |
| | 4.03% | | 2.94% | | 7.16 | Non-Agency RMBS | 48,408 |
| | (18,013 | ) | | 30,395 |
| | 2,264 |
| | (1,258 | ) | | 31,401 |
| | 2.48% | | 20.97% | | 4.81 | Total RMBS | $ | 1,177,078 |
| | $ | 53,646 |
| | $ | 1,239,215 |
| | $ | 11,428 |
| | $ | (8,377 | ) | | $ | 1,242,266 |
| | 3.97% | | 3.39% | | 7.07 |
| | (1) | Average lives of RMBS are generally shorter than stated contractual maturities. Average lives are affected by the contractual maturities of the underlying mortgages, scheduled periodic payments of principal, and unscheduled prepayments of principal. |
December 31, 2014: | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | ($ in thousands) | | | | | | | Gross Unrealized | | | | Weighted Average | | Current Principal | | Unamortized Premium (Discount) | | Amortized Cost | | Gains | | Losses | | Fair Value | | Coupon | | Yield | | Life (Years)(1) | Agency RMBS: | | | | | | | | | | | | | | | | | | 15-year fixed rate mortgages | $ | 130,720 |
| | $ | 6,304 |
| | $ | 137,024 |
| | $ | 1,113 |
| | $ | (109 | ) | | $ | 138,028 |
| | 3.40% | | 2.46% | | 5.43 | 20-year fixed rate mortgages | 9,764 |
| | 577 |
| | 10,341 |
| | 227 |
| | — |
| | 10,568 |
| | 4.00% | | 3.04% | | 6.92 | 30-year fixed rate mortgages | 1,042,550 |
| | 61,089 |
| | 1,103,639 |
| | 20,379 |
| | (1,764 | ) | | 1,122,254 |
| | 4.09% | | 3.29% | | 8.48 | Adjustable rate mortgages | 41,710 |
| | 2,813 |
| | 44,523 |
| | 90 |
| | (330 | ) | | 44,283 |
| | 4.60% | | 3.08% | | 5.97 | Reverse mortgages | 31,412 |
| | 2,741 |
| | 34,153 |
| | 300 |
| | (28 | ) | | 34,425 |
| | 4.91% | | 2.56% | | 4.74 | Interest only securities | n/a | | n/a | | 10,780 |
| | 1,190 |
| | (726 | ) | | 11,244 |
| | 4.04% | | 11.82% | | 2.68 | Total Agency RMBS | 1,256,156 |
| | 73,524 |
| | 1,340,460 |
| | 23,299 |
| | (2,957 | ) | | 1,360,802 |
| | 4.05% | | 3.24% | | 7.54 | Non-Agency RMBS | 50,668 |
| | (20,377 | ) | | 30,291 |
| | 2,896 |
| | (686 | ) | | 32,501 |
| | 2.29% | | 10.76% | | 4.97 | Total RMBS | $ | 1,306,824 |
| | $ | 53,147 |
| | $ | 1,370,751 |
| | $ | 26,195 |
| | $ | (3,643 | ) | | $ | 1,393,303 |
| | 3.99% | | 3.41% | | 7.45 |
| | (1) | Average lives of RMBS are generally shorter than stated contractual maturities. Average lives are affected by the contractual maturities of the underlying mortgages, scheduled periodic payments of principal, and unscheduled prepayments of principal. |
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| Weighted Average Life Classifications [Table Text Block] |
By Estimated Weighted Average Life As of December 31, 2015: | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | ($ in thousands) | | Agency RMBS | | Agency Interest Only Securities | | Non-Agency RMBS | Estimated Weighted Average Life(1) | | Fair Value | | Amortized Cost | | Weighted Average Coupon | | Fair Value | | Amortized Cost | | Weighted Average Coupon | | Fair Value | | Amortized Cost | | Weighted Average Coupon | Less than three years | | $ | 30,054 |
| | $ | 30,227 |
| | 4.76 | % | | $ | 4,974 |
| | $ | 5,701 |
| | 3.55 | % | | $ | 2,558 |
| | $ | 1,543 |
| | 3.21 | % | Greater than three years and less than seven years | | 273,477 |
| | 273,107 |
| | 3.78 | % | | 2,784 |
| | 2,790 |
| | 4.97 | % | | 24,736 |
| | 25,478 |
| | 2.66 | % | Greater than seven years and less than eleven years | | 893,730 |
| | 891,112 |
| | 4.10 | % | | — |
| | — |
| | — | % | | 4,107 |
| | 3,374 |
| | 0.55 | % | Greater than eleven years | | 5,846 |
| | 5,883 |
| | 3.81 | % | | — |
| | — |
| | — | % | | — |
| | — |
| | — | % | Total | | $ | 1,203,107 |
| | $ | 1,200,329 |
| | 4.04 | % | | $ | 7,758 |
| | $ | 8,491 |
| | 3.82 | % | | $ | 31,401 |
| | $ | 30,395 |
| | 2.48 | % |
| | (1) | Average lives of RMBS are generally shorter than stated contractual maturities. |
As of December 31, 2014: | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | ($ in thousands) | | Agency RMBS | | Agency Interest Only Securities | | Non-Agency RMBS | Estimated Weighted Average Life(1) | | Fair Value | | Amortized Cost | | Weighted Average Coupon | | Fair Value | | Amortized Cost | | Weighted Average Coupon | | Fair Value | | Amortized Cost | | Weighted Average Coupon | Less than three years | | $ | 18,428 |
| | $ | 18,418 |
| | 5.13 | % | | $ | 5,197 |
| | $ | 5,563 |
| | 3.42 | % | | $ | 2,837 |
| | $ | 1,785 |
| | 3.02 | % | Greater than three years and less than seven years | | 410,759 |
| | 405,739 |
| | 4.12 | % | | 6,047 |
| | 5,217 |
| | 5.19 | % | | 17,660 |
| | 17,662 |
| | 2.63 | % | Greater than seven years and less than eleven years | | 920,371 |
| | 905,523 |
| | 4.00 | % | | — |
| | — |
| | — | % | | 12,004 |
| | 10,844 |
| | 1.28 | % | Total | | $ | 1,349,558 |
| | $ | 1,329,680 |
| | 4.05 | % | | $ | 11,244 |
| | $ | 10,780 |
| | 4.04 | % | | $ | 32,501 |
| | $ | 30,291 |
| | 2.29 | % |
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| Interest Income Components - Investments [Table Text Block] |
The following table reflects the components of interest income on the Company's RMBS for the years ended December 31, 2015, 2014, and 2013: | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Year Ended December 31, 2015 | | Year Ended
December 31, 2014 | | Year Ended
December 31, 2013 | ($ in thousands) | | Coupon Interest | | Net Amortization | | Interest Income | | Coupon Interest | | Net Amortization | | Interest Income | | Coupon Interest | | Net Amortization | | Interest
Income | Agency RMBS | | $ | 49,028 |
| | $ | (11,482 | ) | | $ | 37,546 |
| | $ | 52,755 |
| | $ | (9,112 | ) | | $ | 43,643 |
| | $ | 30,504 |
| | $ | (4,863 | ) | | $ | 25,641 |
| Non-Agency RMBS | | 1,153 |
| | 2,005 |
| | 3,158 |
| | 1,237 |
| | 1,930 |
| | 3,167 |
| | 1,185 |
| | 952 |
| | 2,137 |
| Total | | $ | 50,181 |
| | $ | (9,477 | ) | | $ | 40,704 |
| | $ | 53,992 |
| | $ | (7,182 | ) | | $ | 46,810 |
| | $ | 31,689 |
| | $ | (3,911 | ) | | $ | 27,778 |
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