Consolidated Statement of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities
Net income	$ 62,515	$ 7,946
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of premiums	10,484	5,620
Accretion of discounts	(6,118)	(1,549)
Loan loss (benefit) provision	101	279
Net change in unrealized (gain) loss on investments held at fair value	(34,671)	11,130
Net realized losses	395	0
Vesting of stock-based compensation	1,485	292
Changes in operating assets and liabilities:
Accrued interest and dividends receivable	(1,362)	(4,477)
Accounts receivable and other assets	(363)	(749)
Accrued interest payable	2,735	1,201
Accounts payable, accrued expenses and other liabilities	2,025	1,341
Net cash provided by operating activities	37,226	21,034
Cash flows from investing activities
Proceeds from payments received on mortgage loans	42,130	5,237
Originations of bridge loan	(32,595)	0
Originations of loans, held-for-investment, net	(28,911)	(7,500)
Purchases of CMBS, at fair value	(36,874)	(40,200)
Sales of CMBS structured pass through certificates, at fair value	3,921	0
Net cash provided by (used in) investing activities	196,542	(110,112)
Cash flows from financing activities
Principal repayments on borrowings under secured financing agreements	(35,026)	(1,825)
Borrowings under master repurchase agreements	75,911	160,379
Principal repayments on borrowings under master repurchase agreements	(14,843)	(167)
Proceeds received from unsecured notes offering, net	72,684	0
Borrowings under bridge facility	0	86,000
Bridge Facility payments	0	(181,000)
Proceeds from the issuance of common stock	32,393	0
Redemption of redeemable noncontrolling interests in the OP	(32,393)	0
Repurchase of preferred stock	0	(8,571)
Repurchase of common stock	0	(1,716)
Payments for taxes related to net share settlement of stock-based compensation	(318)	0
Dividends paid to common stockholders	(9,811)	(5,367)
Dividends paid to preferred stockholders	(2,626)	0
Distributions to redeemable noncontrolling interests in the OP	(17,032)	(13,548)
Contributions from noncontrolling interests	0	11,783
Net cash provided by (used in) financing activities	(242,660)	107,042
Net increase (decrease) in cash, cash equivalents and restricted cash	(8,892)	17,964
Cash, cash equivalents and restricted cash, beginning of period	33,471	0
Cash, cash equivalents and restricted cash, end of period	24,579	17,964
Supplemental Disclosure of Cash Flow Information
Interest paid	18,755	16,499
Supplemental Disclosure of Noncash Investing and Financing Activities
Contributions from noncontrolling interests, including consolidation of the associated mortgage loans held in variable interest entities	0	2,797,735
Other assets acquired from contributions from noncontrolling interests	0	3,616
Assumed debt on contributions from noncontrolling interests, including consolidation of the associated bonds payable held in variable interest entities	0	(2,539,724)
Consolidation of mortgage loans and bonds payable held in variable interest entities	2,394,732	3,179,620
Due to brokers for securities purchased, not yet settled	2,188	0
Consolidation of noncontrolling interest in CMBS variable interest entities	7,069	0
Increase in dividends payable upon vesting of restricted stock units	180	121
Stock dividends received	0	1,254
Increase in dividends payable to preferred stockholders	874	874
Public Offering [Member]
Cash flows from financing activities
Proceeds from the issuance of common stock	51,385	91,488
Proceeds from the issuance of preferred stock	0	46,081
Private Placement [Member]
Cash flows from financing activities
Proceeds from the issuance of preferred stock	95	0
Variable Interest Entity, Primary Beneficiary [Member]
Cash flows from investing activities
Proceeds from payments received on mortgage loans	392,257	82,671
Purchases of CMBS, at fair value	(143,386)	(150,320)
Cash flows from financing activities
Distributions to bondholders of variable interest entities	$ (363,079)	$ (76,495)