Interest income and interest expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Interest income
Total loans	$ 930,572	$ 634,426	$ 374,688
Total loans, held for sale, at fair value	2,899	8,590	6,826
Investments held to maturity	48	4,386
Preferred equity investments	7,854	10,445
Mortgage backed securities, at fair value	4,441	5,370	13,682
Total interest income	945,814	663,217	395,196
Interest expense
Secured borrowings	(194,423)	(127,388)	(56,519)
Paycheck Protection Program Liquidity Facility borrowings	(413)	(1,699)	(7,140)
Securitized debt obligations of consolidated VIEs	(405,013)	(185,047)	(82,249)
Guaranteed loan financing	(44,263)	(14,644)	(13,900)
Senior secured note	(17,539)	(17,503)	(15,472)
Convertible note	(5,418)	(8,752)	(8,752)
Corporate debt	(49,399)	(37,327)	(20,336)
Total interest expense	(716,468)	(392,360)	(204,368)
Net interest income before provision for loan losses	229,346	270,857	190,828
Bridge
Interest income
Total loans	654,670	414,308	148,038
Fixed rate
Interest income
Total loans	50,706	54,998	63,061
Total loans, held for sale, at fair value	2,279	7,581	2,556
Construction
Interest income
Total loans	93,483	28,234
Other
Interest income
Total loans	33,158	38,797	46,848
Total loans, held for sale, at fair value	620	1,009	4,270
Acquired SBA 7(a) loans
Interest income
Total loans	88,205	43,571	37,540
Paycheck Protection Program loans, at fair value
Interest income
Total loans	$ 10,350	$ 54,518	$ 79,201