Mortgage-Backed Securities and other securities - OTTI and Interest Income (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Other than temporary impairment	$ 0	$ 0	$ 8,574
Depreciation, Amortization and Accretion, Net [Abstract]
Net (Premium Amortization/Amortization Basis) Discount Amortization	(1,540)	(5,141)	(7,398)
Interest income	164,071	178,028	217,264
Agency CMBS
Depreciation, Amortization and Accretion, Net [Abstract]
Coupon Interest	0	11,336	51,286
Net (Premium Amortization/Amortization Basis) Discount Amortization	0	(636)	(2,327)
Interest income	0	10,700	48,959
Agency RMBS
Debt Securities, Available-for-sale [Line Items]
Other than temporary impairment			74
Depreciation, Amortization and Accretion, Net [Abstract]
Coupon Interest	47	2,975	12,181
Net (Premium Amortization/Amortization Basis) Discount Amortization	(30)	(987)	(3,053)
Interest income	17	1,988	9,128
Non-Agency CMBS
Debt Securities, Available-for-sale [Line Items]
Other than temporary impairment			6,565
Depreciation, Amortization and Accretion, Net [Abstract]
Coupon Interest	9,874	15,331	14,178
Net (Premium Amortization/Amortization Basis) Discount Amortization	6,535	6,467	4,017
Interest income	16,409	21,798	18,195
Non-Agency RMBS
Debt Securities, Available-for-sale [Line Items]
Other than temporary impairment			1,331
Depreciation, Amortization and Accretion, Net [Abstract]
Coupon Interest	2,127	2,732	4,682
Net (Premium Amortization/Amortization Basis) Discount Amortization	(670)	(1,193)	(2,214)
Interest income	1,457	1,539	2,468
Other securities
Debt Securities, Available-for-sale [Line Items]
Other than temporary impairment			604
Depreciation, Amortization and Accretion, Net [Abstract]
Coupon Interest	4,685	8,263	11,633
Net (Premium Amortization/Amortization Basis) Discount Amortization	(1,574)	(4,781)	(6,472)
Interest income	3,111	3,482	5,161
Total mortgage-backed securities and other securities
Debt Securities, Available-for-sale [Line Items]
Other than temporary impairment			8,574
Depreciation, Amortization and Accretion, Net [Abstract]
Coupon Interest	16,733	40,637	93,960
Net (Premium Amortization/Amortization Basis) Discount Amortization	4,261	(1,130)	(10,049)
Interest income	$ 20,994	$ 39,507	$ 83,911

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.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
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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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-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
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Amount of other-than-temporary impairment (OTTI) on investment in debt security, recognized in earnings.

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-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 8A
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Amount before accretion (amortization) of purchase discount (premium) of interest income on operating securities.

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