Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Cash Flows from Operating Activities:
Net income	$ 92,799	$ 105,813	$ 318,886	$ 244,930
Adjustments to reconcile net income to net cash used in operating activities:
Amortization of deferred financing costs, premiums and discounts on secured financing agreements [and secured borrowings on transferred loans]			14,131	12,061
Amortization of discounts and deferred financing costs on senior notes			17,514	16,058
Accretion of net discount on investment securities			(11,669)	(11,967)
Accretion of net deferred loan fees and discounts			(27,014)	(38,809)
Share-based compensation			13,290	22,797
Share-based component of incentive fees			14,410	14,657
Change in fair value of fair value option investment securities	397	2,786	4,061	714
Change in fair value of consolidated VIEs			(59,160)	42,371
Change in fair value of servicing rights	4,867	14,283	21,301	33,213
Change in fair value of loans held-for-sale	(19,485)	(49,996)	(45,484)	(70,122)
Change in fair value of derivatives			62,463	3,360
Foreign currency (gain) loss, net			(28,211)	20,367
Gain on sale of investments and other assets			(17,004)	(165)
Impairment charges			1,099	711
Loan loss allowance, net	(171)	2,127	(3,170)	3,395
Depreciation and amortization			64,937	49,081
Earnings from unconsolidated entities	4,689	(4,305)	(27,763)	(12,849)
Distributions of earnings from unconsolidated entities			4,716	15,151
Bargain purchase gain				(8,406)
Loss on extinguishment of debt			5,916
Origination and purchase of loans held-for-sale, net of principal collections			(1,487,813)	(1,186,080)
Proceeds from sale of loans held-for-sale			987,828	1,123,512
Changes in operating assets and liabilities:
Related-party payable, net			(7,829)	(17,166)
Accrued and capitalized interest receivable, less purchased interest			(63,032)	(58,275)
Other assets			(12,198)	6,168
Accounts payable, accrued expenses and other liabilities			37,367	(3,537)
Net cash (used in) provided by operating activities			(222,428)	201,170
Cash Flows from Investing Activities:
Origination and purchase of loans held-for-investment			(2,195,258)	(1,583,628)
Proceeds from principal collections on loans			1,670,159	2,187,844
Proceeds from loans sold			37,079	236,433
Purchase of investment securities			(69,231)	(359,510)
Proceeds from sales of investment securities			11,134	3,799
Proceeds from principal collections on investment securities	123,644	22,772	209,903	70,316
Real estate business combinations, net of cash and restricted cash acquired			(18,194)	(91,186)
Proceeds from sale of properties			44,219
Purchases and additions to properties and other assets			(564,755)	(10,209)
Investment in unconsolidated entities			(20,544)	(3,870)
Distribution of capital from unconsolidated entities			3,858	15,026
Payments for purchase or termination of derivatives			(41,208)	(24,954)
Proceeds from termination of derivatives			23,686	37,652
Return of investment basis in purchased derivative asset			151	206
Net cash (used in) provided by investing activities			(909,001)	477,919
Cash Flows from Financing Activities:
Proceeds from borrowings			4,090,163	3,158,920
Principal repayments on and repurchases of borrowings			(2,724,179)	(3,138,534)
Payment of deferred financing costs			(17,038)	(17,799)
Proceeds from common stock issuances			541	299
Payment of equity offering costs			(647)
Payment of dividends			(376,061)	(343,670)
Contributions from non-controlling interests			105	10,417
Distributions to non-controlling interests			(7,519)	(5,400)
Purchase of treasury stock				(19,723)
Issuance of debt of consolidated VIEs			11,657	596
Repayment of debt of consolidated VIEs			(92,383)	(202,892)
Distributions of cash from consolidated VIEs			62,797	40,731
Net cash provided by (used in) financing activities			947,436	(517,055)
Net (decrease) increase in cash, cash equivalents and restricted cash			(183,993)	162,034
Cash, cash equivalents and restricted cash, beginning of period			650,755	391,884	$ 391,884
Effect of exchange rate changes on cash			1,674	(626)
Cash, cash equivalents and restricted cash, end of period	468,436	553,292	468,436	553,292	$ 650,755
Supplemental disclosure of cash flow information:
Cash paid for interest			177,604	146,011
Income taxes paid			7,722	3,038
Supplemental disclosure of non-cash investing and financing activities:
Dividends declared, but not yet paid	$ 125,638	$ 115,190	125,638	115,190
Consolidation of VIEs (VIE asset/liability additions)			2,092,516	19,118,645
Deconsolidation of VIEs (VIE asset/liability reductions)			2,244,267	5,404,305
Net assets acquired from consolidated VIEs			19,652	133,177
Fair value of assets acquired, net of cash and restricted cash			18,956	270,021
Fair value of liabilities assumed			$ 762	170,429
Unsettled investment securities sold				$ 14,926