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Valuation Unobservable Input Reconciliation (Details) - Level 3 [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Agency RMBS [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 3,626	$ 2,525	$ 2,254	$ 12,347
Purchases	0	0	160	2,621
Proceeds from sales	0	0	0	0
Principal repayments	0	0	0	0
(Amortization)/accretion, net	(251)	(277)	(884)	(2,469)
Net realized gains (losses)	(11)	(106)	(177)	(180)
Change in net unrealized gains (losses)	62	(13)	536	(1,369)
Transfers
Transfers into level 3	1,598	777	2,219	0
Transfers out of level 3	(916)	(500)	0	(8,544)
Ending balance	4,108	2,406	4,108	2,406
Change in net unrealized gains (losses) for level 3 assets still held	200	(12)	700	(300)
Non-Agency RMBS [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	6,993	6,450	8,832	6,498
Purchases	0	2,508	0	4,324
Proceeds from sales	0	0	(3,638)	(2,866)
Principal repayments	(369)	(260)	(593)	(675)
(Amortization)/accretion, net	62	100	197	236
Net realized gains (losses)	0	4	1,254	184
Change in net unrealized gains (losses)	289	82	(660)	1,009
Transfers
Transfers into level 3	658	2,400	2,241	4,414
Transfers out of level 3	0	0	0	(1,840)
Ending balance	7,633	11,284	7,633	11,284
Change in net unrealized gains (losses) for level 3 assets still held	300	300	300	1,400
Residential Mortgage Backed Securities [Member]
Transfers
Transfers into level 3	2,300	3,200	$ 4,500	4,400
Transfers out of level 3	$ (900)	$ (500)		$ (10,400)

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- Definition

Fair Value, Measurements with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Amortized Premiums/Accreted Discounts, Net

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Fair Value, Measurements with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Principal Repayments

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- Definition

Amount of unrealized (holding) gain (loss) which is included in the statement of income (or changes in net assets) related to those assets still held at the reporting date for which fair value is measured on a recurring basis using significant unobservable inputs (Level 3).

+ References

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount of gain (loss) recognized in the income statement for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of gain (loss) recognized in other comprehensive income (loss) for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of sale of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of transfer of financial instrument classified as an asset into level 3 of the fair value hierarchy.

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Amount of transfers of financial instrument classified as an asset out of level 3 of the fair value hierarchy.

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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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