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Mortgage-Backed Securities Interest Income Components (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Interest Income Components [Line Items]
Net Amortization			$ (8,165)	$ (6,025)	[1]
Interest income	$ 13,171	$ 12,867	40,677	36,078
Agency RMBS [Member]
Interest Income Components [Line Items]
Coupon Interest	16,744	16,880	50,341	43,373
Net Amortization	(4,029)	(4,646)	(11,485)	(8,983)
Interest income	12,715	12,234	38,856	34,390
Non-Agency RMBS [Member]
Interest Income Components [Line Items]
Coupon Interest	362	186	680	593
Net Amortization	44	172	282	445
Interest income	406	358	962	1,038
Residential Mortgage Backed Securities [Member]
Interest Income Components [Line Items]
Coupon Interest	17,106	17,066	51,021	43,966
Net Amortization	(3,985)	(4,474)	(11,203)	(8,538)
Interest income	$ 13,121	$ 12,592	$ 39,818	$ 35,428
[1] Conformed to current period presentation.

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- Definition

[Line Items] for Interest Income Components [Table]

+ References

No definition available.

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- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

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- Definition

Amount of the required periodic payments applied to interest.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
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