Condensed Consolidated Statement of Cash Flows - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows provided by operating activities:
Net income		$ 18,377	$ 230,174	$ 219,986
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of discount/premium and PIK		(61,745)	(81,611)	(64,269)
Amortization of deferred financing costs		12,862	11,969	11,186
Equity-based compensation		16,815	15,897	8,809
Provision for loan losses and impairments, net	[1]	125,600	20,000	20,000
Foreign currency (gain) loss		(182)	3,768	29,617
Unrealized (gain) loss on derivative instruments		11,895	43,046	(29,345)
Loss on early extinguishment of debt		0	0	2,573
Realized loss on investments		47,632	12,513	0
Changes in operating assets and liabilities:
Proceeds received from PIK		0	16,469	75,652
Other assets		(4,667)	(4,472)	(10,198)
Accounts payable, accrued expenses and other liabilities		(1,703)	5,056	317
Payable to related party		(832)	626	1,636
Net cash provided by operating activities		164,052	273,435	265,964
Cash flows used in investing activities:
New funding of commercial mortgage loans		(463,940)	(2,526,384)	(1,849,100)
Add-on funding of commercial mortgage loans		(321,271)	(385,508)	(131,718)
New funding of subordinate loans and other lending assets		0	(493,017)	(220,809)
Add-on funding of subordinate loans and other lending assets		(91,447)	(30,549)	(149,238)
Proceeds received from the repayment and sale of commercial mortgage loans		662,688	1,428,535	675,140
Proceeds received from the repayment of subordinate loans and other lending assets		5,563	560,089	610,051
Origination and exit fees received on commercial mortgage loans, and subordinate loans and other lending assets, net		6,847	45,882	41,822
Increase (decrease) in collateral held related to derivative contracts, net		(14,160)	(34,160)	24,930
Net cash used in investing activities		(215,720)	(1,435,112)	(998,922)
Cash flows from financing activities:
Proceeds from issuance of common stock		0	315,158	275,879
Redemption of preferred stock		0	(172,500)	0
Repurchase of common stock		(127,994)	0	0
Payment of offering costs		0	(333)	(484)
Proceeds from secured debt arrangements		1,535,130	3,451,172	2,153,846
Repayments of secured debt arrangements		(1,242,317)	(2,273,750)	(1,580,343)
Repayments of senior secured term loan principal		(5,000)	(2,500)	0
Proceeds from issuance of senior secured term loan		0	497,500	0
Proceeds from participations sold		33,965	0	0
Proceeds from issuance of Notes		0	0	226,550
Exchanges of convertible senior notes		0	(704)	(40,461)
Payment of deferred financing costs		(11,115)	(13,688)	(15,337)
Other financing activities		(6,494)	(4,996)	0
Dividends on common stock		(237,751)	(269,232)	(227,217)
Dividends on preferred stock		(13,540)	(21,974)	(27,340)
Net cash (used in) provided by financing activities		(75,116)	1,504,153	765,093
Net increase in cash and cash equivalents		(126,784)	342,476	32,135
Cash and cash equivalents, beginning of period		452,282	109,806	77,671
Cash and cash equivalents, end of period		325,498	452,282	109,806
Supplemental disclosure of cash flow information:
Interest paid		129,812	133,469	97,880
Supplemental disclosure of non-cash financing activities:
Exchange of convertible senior notes for common stock		0	33,778	180,016
Dividend declared, not yet paid		52,768	74,771	69,033
Loan proceeds held by servicer		5,649	7,775	1,000
Deferred financing costs, not yet paid		2,596	5,193	0
Transfer of proceeds borrowed under secured credit facilities to Barclays Private Securitization		782,006	0	0
Restructuring of subordinate loan to commercial mortgage loan		68,500	0	0
Assumption of real estate owned, held for sale net of related debt from the foreclosure of a subordinate loan		$ 9,905	$ 0	$ 0

[1] Comprised of $118,019 of Specific CECL Allowance, $10,600 of General CECL Allowance, and a $3,019 reversal of a previously recorded impairment on an equity investment for the year ended December 31, 2020, respectively. For the years ended December 31, 2019 and 2018 the balance represents provision per loan losses as determined by the authoritative guidance at the time.