Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities
Net income	$ 307,393	$ 285,813	$ 217,968
Adjustments to reconcile net income to net cash provided by operating activities
Non-cash compensation expense	30,656	28,154	24,031
Amortization of deferred fees on loans and debt securities	(57,926)	(47,093)	(38,373)
Amortization of deferred financing costs and premiums/discount on debt obligations	32,016	28,097	21,988
Changes in assets and liabilities, net
Other assets	(7,355)	(23,352)	(4,632)
Other liabilities	(747)	18,383	6,479
Net cash provided by operating activities	304,037	290,002	227,461
Cash flows from investing activities
Origination and fundings of loans receivable	(6,890,249)	(7,890,051)	(3,598,166)
Principal collections and sales proceeds from loans receivable and debt securities	4,940,194	3,084,747	2,780,431
Loan contributed to securitization		512,002
Investment in debt securities held-to-maturity		(95,937)
Origination and exit fees received on loans receivable	66,558	104,408	55,441
Receipts under derivative financial instruments	49,673	47,527	6,453
Payments under derivative financial instruments	(6,524)	(18,475)	(20,870)
Collateral deposited under derivative agreements	(59,720)	(38,990)	(20,161)
Return of collateral deposited under derivative agreements	28,920	43,110	16,120
Net cash used in investing activities	(1,871,148)	(4,251,659)	(780,752)
Cash flows from financing activities
Borrowings under secured debt agreements	6,569,460	9,183,852	4,306,301
Repayments under secured debt agreements	(5,526,989)	(5,413,070)	(4,778,194)
Proceeds from issuance of collateralized loan obligations			817,500
Repayment of collateralized loan obligations	(102,478)
Proceeds from sale of loan participations	21,346	99,696	80,706
Repayment of loan participations	(115,874)	(85,875)	(381,310)
Net proceeds from issuance of secured term loan	748,414
Repayments of secured term loan	(3,122)
Payment of deferred financing costs	(39,370)	(25,006)	(27,465)
Contributions from non-controlling interests	51,418	9,315	12,165
Distributions to non-controlling interests	(41,629)	(5,907)	(6,162)
Net proceeds from issuance of convertible notes		214,775	394,632
Repayment of convertible notes		(219,232)
Net proceeds from issuance of class A common stock	372,337	476,420	391,558
Dividends paid on class A common stock	(320,961)	(277,260)	(234,989)
Net cash provided by financing activities	1,612,552	3,957,708	574,742
Net increase (decrease) in cash, cash equivalents, and restricted cash	45,441	(3,949)	21,451
Cash, cash equivalents, and restricted cash at beginning of year	105,662	102,518	75,567
Effects of currency translation on cash, cash equivalents, and restricted cash	(1,013)	7,093	5,500
Cash, cash equivalents, and restricted cash at end of year	150,090	105,662	102,518
Supplemental disclosure of cash flows information
Payments of interest	(425,801)	(318,919)	(206,966)
Receipts (payments) of income taxes	109	(554)	(296)
Supplemental disclosure of non-cash investing and financing activities
Dividends declared, not paid	(83,702)	(76,530)	(66,888)
Loan principal payments held by servicer, net	$ 49,584	$ 4,855	15,763
Consolidation of loans receivable of a VIE			500,000
Consolidation of securitized debt obligations of a VIE			$ (474,620)