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	$ 285,813	$ 217,968	$ 246,440
Adjustments to reconcile net income to net cash provided by operating activities
Non-cash compensation expense	28,154	24,031	21,899
Amortization of deferred fees on loans and debt securities	(47,093)	(38,373)	(40,345)
Amortization of deferred financing costs and premiums/discount on debt obligations	28,097	21,988	19,339
Gain on investments at fair value			(13,420)
Income from equity investment in unconsolidated subsidiary			(3,187)
Distributions of income from unconsolidated subsidiary			9,977
Changes in assets and liabilities, net
Other assets	(23,352)	(4,632)	6,069
Other liabilities	18,383	6,479	(10,120)
Net cash provided by operating activities	290,002	227,461	236,652
Cash flows from investing activities
Origination and fundings of loans receivable	(7,890,051)	(3,598,166)	(3,151,882)
Principal collections and sales proceeds from loans receivable	3,084,747	2,780,431	3,514,429
Loan contributed to securitization	512,002
Investment in debt securities held-to-maturity	(95,937)
Origination and exit fees received on loans receivable	104,408	55,441	44,697
Receipts under derivative financial instruments	47,527	6,453	41,573
Payments under derivative financial instruments	(18,475)	(20,870)	(14,730)
Return of collateral deposited under derivative agreements	43,110	16,120
Collateral deposited under derivative agreements	(38,990)	(20,161)
Net cash (used in) provided by investing activities	(4,251,659)	(780,752)	434,087
Cash flows from financing activities
Borrowings under secured debt agreements	9,183,852	4,306,301	3,185,933
Repayments under secured debt agreements	(5,413,070)	(4,778,194)	(3,534,803)
Proceeds from issuance of collateralized loan obligations		817,500
Proceeds from sale of loan participations	99,696	80,706	54,441
Repayment of loan participations	(85,875)	(381,310)	(136,000)
Payment of deferred financing costs	(25,006)	(27,465)	(15,350)
Contributions from non-controlling interests	9,315	12,165
Distributions to non-controlling interests	(5,907)	(6,162)	(21,070)
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	476,420	391,558	27
Dividends paid on class A common stock	(277,260)	(234,989)	(232,775)
Net cash provided by (used in) financing activities	3,957,708	574,742	(699,597)
Net (decrease) increase in cash, cash equivalents, and restricted cash	(3,949)	21,451	(28,858)
Cash, cash equivalents, and restricted cash at beginning of year	102,518	75,567	106,006
Effects of currency translation on cash, cash equivalents, and restricted cash	7,093	5,500	(1,581)
Cash, cash equivalents, and restricted cash at end of year	105,662	102,518	75,567
Supplemental disclosure of cash flows information
Payments of interest	(318,919)	(206,966)	(164,905)
Payments of income taxes	(554)	(296)	(286)
Supplemental disclosure of non-cash investing and financing activities
Dividends declared, not paid	(76,530)	(66,888)	(58,615)
Loan principal payments held by servicer, net	$ 4,855	15,763	$ 670
Consolidation of loans receivable of a VIE		500,000
Consolidation of securitized debt obligations of a VIE		$ (474,620)