The sum of the periodic adjustments of the differences between securities' face values and purchase prices that are charged against earnings. This is called accretion if the security was purchased at a discount and amortization if it was purchased at premium. As a noncash item, this element is an adjustment to net income when calculating cash provided by or used in operations using the indirect method.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

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Amount of operating interest income, including, but not limited to, amortization and accretion of premiums and discounts on securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1(e))
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The amount of other than temporary impairment losses on investments in debt and equity securities categorized as Available-for-sale which have been recognized in earnings during the period. Such impairment losses consist of other than temporary impairments (OTTI) on equity securities, credit losses on investments in debt securities, and when the entity intends to sell an impaired debt security or it is more likely than not that the entity will be required to sell the impaired debt security before recovery of its amortized cost basis.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 8A
-URI http://asc.fasb.org/extlink&oid=82896770&loc=SL6284422-111562

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount before accretion (amortization) of purchase discount (premium) of interest income on operating securities.

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Mortgage-Backed Securities and other securities (Details 6) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Mortgage-Backed Securities and other securities
Other than temporary impairment	$ 2,972	$ 7,225	$ 6,579	$ 6,097	$ 10,155	$ 4,978	$ 6,356	$ 10,797	$ 22,873	$ 32,286	$ 19,791
Components of interest income
Net (Premium Amortization/Amortization Basis) Discount Amortization									2,070	548	(5,086)
Interest Income	$ 34,878	$ 30,928	$ 30,055	$ 28,430	$ 35,764	$ 29,154	$ 29,220	$ 29,618	124,291	123,756	152,704
Mortgage-backed securities and other securities
Components of interest income
Coupon Interest									111,233	135,737	200,787
Net (Premium Amortization/Amortization Basis) Discount Amortization									(2,191)	(21,372)	(51,894)
Interest Income									109,042	114,365	148,893
Agency RMBS
Mortgage-Backed Securities and other securities
Other than temporary impairment									5,774	6,090	4,005
Components of interest income
Coupon Interest									38,108	70,467	119,789
Net (Premium Amortization/Amortization Basis) Discount Amortization									(13,058)	(24,836)	(48,119)
Interest Income									25,050	45,631	71,670
Agency CMBS
Components of interest income
Coupon Interest									40,064	2,619	3,600
Net (Premium Amortization/Amortization Basis) Discount Amortization									507	(1,701)	(2,102)
Interest Income									40,571	918	1,498
Non-Agency RMBS
Mortgage-Backed Securities and other securities
Other than temporary impairment									0	9,511	9,216
Components of interest income
Coupon Interest									5,602	35,221	44,473
Net (Premium Amortization/Amortization Basis) Discount Amortization									525	(5,243)	(8,008)
Interest Income									6,127	29,978	36,465
Non-Agency CMBS
Mortgage-Backed Securities and other securities
Other than temporary impairment									15,117	13,025	4,061
Components of interest income
Coupon Interest									19,179	24,893	26,562
Net (Premium Amortization/Amortization Basis) Discount Amortization									8,276	7,431	3,687
Interest Income									27,455	32,324	30,249
Other securities
Mortgage-Backed Securities and other securities
Other than temporary impairment									1,982	3,660	2,509
Components of interest income
Coupon Interest									8,280	2,537	6,363
Net (Premium Amortization/Amortization Basis) Discount Amortization									1,559	2,977	2,648
Interest Income									$ 9,839	$ 5,514	$ 9,011