Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash Flows from Operating Activities
Net income/(loss)	$ 1,568	$ 118,558	$ 63,683
Adjustments to reconcile net income/(loss) to net cash provided by (used in) operating activities:
Net amortization of premium	(4,031)	(4,596)	(9,569)
Net realized (gain)/loss	39,501	13,986	10,391
Unrealized (gain)/loss on real estate securities and loans, net	20,940	(45,529)	(2,673)
Unrealized (gain)/loss on derivative and other instruments, net	13,538	(19,813)	(8,613)
Property depreciation and amortization	2,336	0	0
Equity based compensation to affiliate	239	301	299
Equity based compensation expense	392	239	119
Income from investments in debt and equity of affiliates in excess of distributions received	(9,418)	(5,639)	(922)
Change in operating assets/liabilities:
Other assets	(857)	(3,752)	3,479
Other liabilities	13,824	5,099	(3,415)
Net cash provided by (used in) operating activities	78,032	58,854	52,779
Cash Flows from Investing Activities
Purchase of real estate securities	(2,138,411)	(2,225,724)	(563,568)
Purchase of residential mortgage loans	(205,043)	0	0
Purchase of commercial loans	(55,453)	(10,271)	(14,636)
Origination of commercial loans	0	0	(10,428)
Purchase of U.S. treasury securities	(249,659)	0	(358,418)
Purchase of single-family rental properties	(140,854)	0	0
Investments in debt and equity of affiliates	(62,479)	(28,168)	(33,127)
Purchase of excess mortgage servicing rights	(25,162)	(3,399)	0
Proceeds from sale of real estate securities	2,214,729	566,047	364,354
Proceeds from sale of residential mortgage loans	34,408	18,536	35,606
Proceeds from sales of U.S. treasury securities	249,227	0	588,220
Distributions received in excess of income from investments in debt and equity of affiliates	22,962	6,396	1,697
Principal repayments on real estate securities	487,519	518,047	495,645
Principal repayments on residential mortgage loans	4,704	6,597	3,250
Principal repayments on commercial loans	14,522	13,478	40,000
Net proceeds from (payment made on) reverse repurchase agreements	13,299	(1,980)	(22,634)
Net proceeds from (payment made on) sales of securities borrowed under reverse repurchase agreements	(12,732)	2,086	24,356
Net settlement of interest rate swaps and other instruments	10,435	6,224	(8,572)
Net settlement of TBAs	(233)	1,669	2,771
Proceeds from redemption of FHLBC Stock	0	0	8,014
Cash flows provided by (used in) other investing activities	(737)	4,058	1,378
Net cash provided by (used in) investing activities	161,042	(1,126,404)	553,908
Cash Flows from Financing Activities
Repurchase of common stock	0	0	(9,929)
Net proceeds from issuance of common stock	9,282	8,718	0
Deferred financing costs paid	(1,013)	0	0
Borrowings under financing arrangements	51,642,506	41,215,511	73,758,906
Borrowings under FHLBC advances	0	0	147,216
Repayments of financing arrangements	(51,789,674)	(40,112,384)	(73,892,590)
Repayments of FHLBC advances	0	0	(544,110)
Proceeds from transfer of loan participation	0	0	1,564
Repayments of loan participation	0	(1,800)	0
Net collateral received from (paid to) derivative counterparty	(201)	787	(940)
Net collateral received from (paid to) repurchase counterparty	292	(321)	322
Net collateral received from (paid to) FHLBC	0	0	250
Dividends paid on common stock	(55,254)	(55,730)	(53,309)
Dividends paid on preferred stock	(13,469)	(13,469)	(13,469)
Net cash provided by (used in) financing activities	(207,531)	1,041,312	(606,089)
Net change in cash and cash equivalents	31,543	(26,238)	598
Cash and cash equivalents, and restricted cash, Beginning of Year	52,815	79,053	78,455
Cash and cash equivalents, and restricted cash, End of Year	84,358	52,815	79,053
Supplemental disclosure of cash flow information:
Cash paid for interest on financing arrangements and FHLBC advances	63,180	40,106	32,477
Cash paid for income tax	1,394	1,738	1,587
Supplemental disclosure of non-cash financing and investing activities:
Principal repayments on real estate securities not yet received	0	734	1,124
Proceeds from mortgage loan sales not yet received	0	0	3,633
Common stock dividends declared but not paid	14,372	13,391	13,158
Repayments of financing arrangements not yet paid	0	0	770
Decrease of securitized debt	5,533	5,241	8,824
Transfer from residential mortgage loans to other assets	1,825	2,486	1,897
Transfer from investments in debt and equity of affiliates to CMBS	65,425	0	3,103
Transfer from financing arrangements to investments in debt and equity of affiliates	33,720	0	0
Transfer from non-agency to investments in debt and equity of affiliates	44,970	0	0
Transfer from other assets to investments in debt and equity of affiliates	$ 242	$ 0	$ 0