Condensed Consolidated Statements of Cash Flows - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net income (loss)	$ 1,474,767	$ 11,315,000
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Amortization/accretion of available-for-sale securities premiums and discounts, net	0	1,243,752
Amortization of collateralized loan obligations discounts, net	270,184	0
Amortization Of Offering Costs	(22,383)	0
Amortization of deferred financing costs	232,009	0
Realized (gain) loss on investments, net	709,439	2,848,007
Realized (gain) loss on derivative contracts, net	0	(2,792,794)
Unrealized (gain) loss on derivative contracts	0	(12,783,088)
Unrealized (gain) loss on mortgage servicing rights	379,998	(57,689)
Unrealized (gain) loss on multi-family loans held in securitization trusts	(694,339)	1,355,774
Unrealized (gain) loss on residential loans held in securitization trusts	0	255,403
Restricted stock compensation expense	3,773	4,804
Net change in:
Accrued interest receivable	(180,869)	100,083
Deferred offering costs	22,383	(7,617)
Other assets	(302,767)	143,759
Accrued interest payable	149,854	(291,435)
Deferred income	0	51,450
Fees and expenses payable to Manager	(128,564)	567,711
Other accounts payable and accrued expenses	583,418	(63,221)
Net cash provided by operating activities	2,496,903	1,889,899
Cash flows from investing activities:
Purchase of commercial mortgage loans held-for-investment	(64,612,349)	0
Proceeds from sales of available-for-sale securities	0	144,210,537
Net proceeds from derivative contracts	0	2,792,794
Principal payments from available-for-sale securities	0	36,468,741
Principal Payments From Retained Beneficial Interests	4,747,049	0
Principal payments from commercial mortgage loans held-for-investment	34,014,437	0
Investment related receivable	33,042,234	(136,340,151)
Due from broker	0	12,617,662
Net cash provided by investing activities	7,191,371	59,749,583
Cash flows from financing activities:
Proceeds from (costs for) issuance of common stock	0	7,310,584
Redemption of preferred stock	(40,250,000)	0
Dividends paid on common stock	(1,421,259)	(2,314,686)
Dividends paid on preferred stock	(521,114)	(880,509)
Proceeds from repurchase agreements - available-for-sale securities	0	4,064,474,000
Proceeds from secured term loan	40,250,000	0
Payment of deferred financing costs	(970,545)	0
Principal repayments of repurchase agreements - available-for-sale securities	0	(4,121,936,000)
Net cash (used in) financing activities	(2,912,918)	(53,346,611)
Net increase in cash, cash equivalents and restricted cash	6,775,356	8,292,871
Cash, cash equivalents and restricted cash, beginning of period	59,213,812	45,622,602
Cash, cash equivalents and restricted cash, end of period	65,989,168	53,915,473	$ 45,622,602
Supplemental disclosure of cash flow information
Cash paid for interest	4,965,785	5,242,972
Non-cash investing and financing activities information
Dividends declared but not paid at end of period	1,661,844	39,132
Net change in unrealized gain (loss) on available-for-sale securities	0	$ (10,865,347)
Consolidation of multi-family loans held in securitization trusts	0		1,111,092,392
Consolidation of residential loans held in securitization trusts	0		112,140,311
Consolidation of multi-family securitized debt obligations	0		1,090,753,067
Consolidation of residential securitized debt obligations	$ 0		$ 106,981,993