Investments in unconsolidated equity method affiliates (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Nov. 30, 2021	Jul. 30, 2021	Aug. 31, 2020	Feb. 29, 2020
Schedule of Equity Method Investments [Line Items]
Interest income	$ 24,686	$ 19,629	$ 14,228	$ 12,119	$ 11,171	$ 9,717	$ 13,369	$ 40,268	$ 70,662	$ 74,525
Interest expense	10,698	7,197	5,294	4,061	4,004	4,357	8,613	19,971	27,250	36,945
Total Net Interest Income	13,988	12,432	8,934	8,058	7,167	5,360	4,756	20,297	43,412	37,580
Net interest component of interest rate swaps									(4,862)	731
Net realized gain/(loss)	6,822	(5,460)	4,374	(4,038)	661	(14,431)	(91,609)	(151,143)	1,698	(256,522)
Net unrealized gain/(loss)	3,704	29,461	9,685	19,849	16,754	21,465	100,179	(308,211)	62,699	(169,813)
Other income/(loss), net	0	0	0	37	47	(10)	(155)	1,652	37	1,534
Total Other Income/(Loss)	9,162	22,817	12,486	15,107	17,283	7,011	8,415	(456,779)	59,572	(424,070)
Other operating expenses	3,229	2,997	2,981	4,150	3,238	4,340	4,184	4,149	13,357	15,911
Net Income/(Loss)	10,865	34,579	15,493	43,249	40,991	20,046	3,061	(485,017)	104,186	(420,919)
Equity in earnings/(loss) from affiliates	$ (2,607)	$ 6,882	$ 1,278	$ 26,336	$ 21,942	$ 17,187	$ 3,434	$ (44,192)	31,889	$ (1,629)
Loan securitization, ownership interest						44.60%					40.90%	45.00%	45.00%	44.60%
ARC Home LLC
Schedule of Equity Method Investments [Line Items]
Equity in earnings/(loss) from affiliates									3,681
MATH
Schedule of Equity Method Investments [Line Items]
Equity in earnings/(loss) from affiliates									12,594
Land Related Financing
Schedule of Equity Method Investments [Line Items]
Equity in earnings/(loss) from affiliates									2,455
Other Investees
Schedule of Equity Method Investments [Line Items]
Equity in earnings/(loss) from affiliates									13,159
ARC Home LLC
Schedule of Equity Method Investments [Line Items]
Interest income									9,715
Interest expense									10,671
Total Net Interest Income									(956)
Net realized gain/(loss)									67,849
Net unrealized gain/(loss)									1,808
Other income/(loss), net									26,598
Total Other Income/(Loss)									96,255
Other operating expenses									73,115
Net Income/(Loss)									22,184
Net Income/(Loss) Attributable to Noncontrolling Preferred Interests									610
Net Income/(Loss)									$ 22,794
Loan securitization, ownership interest	44.60%				44.60%				44.60%	44.60%
MATH
Schedule of Equity Method Investments [Line Items]
Interest income									$ 14,562
Interest expense									4,437
Total Net Interest Income									10,125
Net realized gain/(loss)									(34,054)
Net unrealized gain/(loss)									54,474
Other income/(loss), net									0
Total Other Income/(Loss)									20,420
Other operating expenses									2,320
Net Income/(Loss)									28,225
Net Income/(Loss) Attributable to Noncontrolling Preferred Interests									0
Net Income/(Loss)									$ 28,225
Loan securitization, ownership interest	44.60%				44.60%				44.60%	44.60%
Land Related Financing
Schedule of Equity Method Investments [Line Items]
Interest income									$ 5,826
Interest expense									0
Total Net Interest Income									5,826
Net realized gain/(loss)									0
Net unrealized gain/(loss)									0
Other income/(loss), net									98
Total Other Income/(Loss)									98
Other operating expenses									815
Net Income/(Loss)									5,109
Net Income/(Loss) Attributable to Noncontrolling Preferred Interests									0
Net Income/(Loss)									5,109
Other
Schedule of Equity Method Investments [Line Items]
Interest income									46,406
Interest expense									2,904
Total Net Interest Income									43,502
Net realized gain/(loss)									10,255
Net unrealized gain/(loss)									(15,144)
Other income/(loss), net									1,487
Total Other Income/(Loss)									(3,402)
Other operating expenses									9,353
Net Income/(Loss)									30,747
Net Income/(Loss) Attributable to Noncontrolling Preferred Interests									0
Net Income/(Loss)									30,747
Equity Method Investment, Nonconsolidated Investee or Group of Investees
Schedule of Equity Method Investments [Line Items]
Interest income									76,509	$ 73,167
Interest expense									18,012	49,190
Total Net Interest Income									58,497	23,977
Net realized gain/(loss)									44,050	95,268
Net unrealized gain/(loss)									41,138	(151,514)
Other income/(loss), net									28,183	52,166
Total Other Income/(Loss)									113,371	(4,080)
Other operating expenses									85,603	79,416
Net Income/(Loss)									86,265	(59,519)
Net Income/(Loss) Attributable to Noncontrolling Preferred Interests									610	248
Net Income/(Loss)									$ 86,875	$ (59,271)