Investment in Securities (Summary of Investment Income) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Securities, Available-for-sale [Line Items]
Interest Income	$ 52,108	$ 36,016
Agency RMBS
Securities, Available-for-sale [Line Items]
Coupon Interest	20,912	12,190
Net Amortization	(8,844)	(4,628)
Interest Income	12,068	7,562
Non-Agency RMBS and CMBS
Securities, Available-for-sale [Line Items]
Coupon Interest	4,053	3,849
Net Amortization	713	547
Interest Income	4,766	4,396
CLOs
Securities, Available-for-sale [Line Items]
Coupon Interest	5,419	4,244
Net Amortization	(1,011)	65
Interest Income	4,408	4,309
Other Securities
Securities, Available-for-sale [Line Items]
Coupon Interest	2,925	1,593
Net Amortization	(1,045)	(562)
Interest Income	1,880	1,031
Securities Investment [Member]
Securities, Available-for-sale [Line Items]
Coupon Interest	33,309	21,876
Net Amortization	(10,187)	(4,578)
Interest Income	$ 23,122	$ 17,298

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://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=118932676&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.

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Amount before accretion (amortization) of purchase discount (premium) of interest income on nonoperating 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
-Subparagraph (SX 210.5-03.7(b))
-URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599

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