Consolidated Statements of Cash Flows $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Cash Flows from Operating Activities:
Net income	$ 366,081	$ 536,935	$ 411,197
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Amortization of deferred financing costs, premiums and discounts on secured borrowings	40,131	36,088	27,832
Amortization of discounts and deferred financing costs on unsecured senior notes	7,939	7,760	11,785
Accretion of net discount on investment securities	(12,818)	(11,791)	(15,253)
Accretion of net deferred loan fees and discounts	(42,199)	(35,387)	(38,099)
Share-based compensation	31,241	36,155	22,758
Manager fees paid in stock	36,046	11,915	20,792
Change in fair value of investment securities	(5,393)	(833)	(10,345)
Change in fair value of consolidated VIEs	58,160	(67,798)	(17,408)
Change in fair value of servicing rights	3,715	3,640	10,202
Change in fair value of loans	(133,124)	(71,601)	(40,522)
Change in fair value of derivatives	88,544	11,441	(30,828)
Foreign currency (gain) loss, net	(42,395)	(17,582)	9,158
Gain on sale of investments and other assets	(7,310)	(188,028)	(59,044)
Impairment charges on properties and related intangibles		1,494	1,869
Credit loss provision, net	43,153	7,126	34,821
Depreciation and amortization	94,154	113,394	130,838
(Earnings) loss from unconsolidated entities	(37,317)	101,354	(10,540)
Distributions of earnings from unconsolidated entities	2,978	11,631	5,917
Loss on extinguishment of debt	3,654	19,270	5,808
Origination and purchase of loans held-for-sale, net of principal collections	(2,074,678)	(3,543,503)	(2,105,232)
Proceeds from sale of loans held-for-sale	2,802,118	3,177,640	2,246,989
Changes in operating assets and liabilities:
Related-party payable, net	(1,755)	(3,118)	1,674
Accrued and capitalized interest receivable, less purchased interest	(175,287)	(114,156)	(62,261)
Other assets	282	(29,787)	8,207
Accounts payable, accrued expenses and other liabilities	(372)	(5,458)	25,155
Net cash provided by (used in) operating activities	1,045,548	(13,199)	585,470
Cash Flows from Investing Activities:
Origination and purchase of loans held-for-investment	(3,133,196)	(5,473,399)	(4,428,891)
Proceeds from principal collections on loans	1,696,244	3,132,368	3,057,430
Proceeds from loans sold	504,231	1,141,411	835,849
Purchase and funding of investment securities	(22,408)	(98,258)	(492,400)
Proceeds from sales of investment securities	7,940	7,326	16,427
Proceeds from principal collections on investment securities	83,533	205,660	382,924
Infrastructure lending business combination			(2,158,553)
Proceeds from sales of real estate and related businesses, net of cash transferred	24,541	343,896	311,874
Purchases and additions to properties and other assets	(25,164)	(30,865)	(54,772)
Investment in unconsolidated entities	(3,133)	(18,055)	(3,100)
Proceeds from sale of interest in unconsolidated entities	10,313
Distribution of capital from unconsolidated entities	3,422	18,127	21,461
Payments for purchase or termination of derivatives	(74,801)	(42,835)	(29,581)
Proceeds from termination of derivatives	16,673	38,756	20,523
Net cash used in investing activities	(911,805)	(775,868)	(2,520,809)
Cash Flows from Financing Activities:
Proceeds from borrowings	7,100,563	10,167,339	9,412,715
Principal repayments on and repurchases of borrowings	(6,137,778)	(8,671,085)	(6,360,610)
Payment of deferred financing costs	(27,122)	(72,438)	(67,218)
Proceeds from common stock issuances	1,098	767	608
Payment of equity offering costs	(95)	(27)	(22)
Payment of dividends	(546,885)	(538,424)	(509,966)
Contributions from non-controlling interests	11,775	183,520	13,407
Distributions to non-controlling interests	(99,512)	(49,958)	(256,404)
Purchase of treasury stock	(33,828)		(12,090)
Issuance of debt of consolidated VIEs	187,494	184,540	102,474
Repayment of debt of consolidated VIEs	(522,348)	(373,155)	(410,453)
Distributions of cash from consolidated VIEs	79,921	45,642	92,283
Net cash provided by financing activities	13,283	876,721	2,004,724
Net increase in cash, cash equivalents and restricted cash	147,026	87,654	69,385
Cash, cash equivalents and restricted cash, beginning of year	574,031	487,865	418,273
Effect of exchange rate changes on cash	1,105	(1,488)	207
Cash, cash equivalents and restricted cash, end of year	722,162	574,031	487,865
Supplemental disclosure of cash flow information:
Cash paid for interest	379,949	481,483	337,605
Income taxes paid	11,369	11,284	10,900
Supplemental disclosure of non-cash investing and financing activities:
Dividends declared, but not yet paid	138,075	136,715	133,237
Consolidation of VIEs (VIE asset/liability additions)	4,665,636	10,368,817	9,885,200
Deconsolidation of VIEs (VIE asset/liability reductions)	32,270	377,071	1,649,485
Reclassification of loans held-for-investment to loans held-for-sale	749,995
Reclassification of loans held-for-sale to loans held-for-investment	104,327	340,948
Transfer of loans from VIE assets to loans held-for-sale upon redemption of a consolidated RMBS trust	176,614
Net assets acquired through control, foreclosure or conversion to equity interest	34,601	44,426
Loan principal collections temporarily held at master servicer	8,538	21,070
Redemption of Class A Units	(1,309)	440,966
Contribution of Woodstar II Portfolio net assets from non-controlling interests		360,049
Assets of Ireland real estate subsidiary sold, net of cash		75,525	271,243
Liabilities of Ireland real estate subsidiary sold		74,692
Settlement of 2019 Convertible Notes in shares	71,488	53,278
Settlement of loans transferred as secured borrowings		9,626
Lease liabilities arising from obtaining right-of-use assets		8,613	27,737
Net assets acquired from consolidated VIEs	$ 1,576	$ 2,877	416,626
Fair value of assets acquired, net of cash and restricted cash			2,167,652
Fair value of liabilities assumed			$ 9,099