Variable interest entities and securitization activities - Securitized Debt Obligations (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Variable interest entities
Current Principal Balance	$ 5,089,157	$ 2,145,133
Current principal balance of non-company sponsored securitized loans	30,600	63,100
Consolidated VIEs
Variable interest entities
Current Principal Balance	3,232,859	1,891,797
Carrying value	$ 3,183,711	$ 1,842,680
Weighted Average Rate	2.20%	3.30%
Waterfall Victoria Mortgage Trust 2011-SBC2
Variable interest entities
Current Principal Balance		$ 4,055
Carrying value		$ 4,055
Weighted Average Rate		5.50%
ReadyCap Lending Small Business Trust 2019-2
Variable interest entities
Current Principal Balance	$ 79,294	$ 103,030
Carrying value	$ 78,268	$ 101,468
Weighted Average Rate	2.60%	3.10%
Sutherland Commercial Mortgage Trust 2017-SBC6
Variable interest entities
Current Principal Balance	$ 16,729	$ 27,035
Carrying value	$ 16,471	$ 26,555
Weighted Average Rate	3.80%	3.60%
Sutherland Commercial Mortgage Trust 2018-SBC7
Variable interest entities
Current Principal Balance		$ 79,302
Carrying value		$ 78,168
Weighted Average Rate	4.70%	4.70%
Sutherland Commercial Mortgage Trust 2019-SBC8
Variable interest entities
Current Principal Balance	$ 145,351	$ 178,911
Carrying value	$ 143,153	$ 176,307
Weighted Average Rate	2.90%	2.90%
Sutherland Commercial Mortgage Trust 2020-SBC9
Variable interest entities
Current Principal Balance	$ 86,680	$ 131,729
Carrying value	$ 85,459	$ 129,014
Weighted Average Rate	4.10%	3.80%
Sutherland Commercial Mortgage Trust 2021-SBC10
Variable interest entities
Current Principal Balance	$ 159,745
Carrying value	$ 157,483
Weighted Average Rate	1.60%
ReadyCap Commercial Mortgage Trust 2014-1
Variable interest entities
Current Principal Balance	$ 6,770	$ 10,880
Carrying value	$ 6,756	$ 10,858
Weighted Average Rate	5.70%	5.80%
ReadyCap Commercial Mortgage Trust 2015-2
Variable interest entities
Current Principal Balance	$ 17,598	$ 45,075
Carrying value	$ 15,960	$ 35,183
Weighted Average Rate	5.10%	4.80%
ReadyCap Commercial Mortgage Trust 2016-3
Variable interest entities
Current Principal Balance	$ 19,106	$ 26,371
Carrying value	$ 18,285	$ 25,286
Weighted Average Rate	4.90%	4.70%
ReadyCap Commercial Mortgage Trust 2018-4
Variable interest entities
Current Principal Balance	$ 81,379	$ 94,273
Carrying value	$ 78,751	$ 91,098
Weighted Average Rate	4.10%	4.00%
ReadyCap Commercial Mortgage Trust 2019-5
Variable interest entities
Current Principal Balance	$ 150,547	$ 229,232
Carrying value	$ 143,204	$ 220,605
Weighted Average Rate	4.30%	4.20%
ReadyCap Commercial Mortgage Trust 2019-6
Variable interest entities
Current Principal Balance	$ 269,315	$ 359,266
Carrying value	$ 263,752	$ 348,773
Weighted Average Rate	3.20%	3.20%
Ready Capital Mortgage Financing 2018-FL2
Variable interest entities
Current Principal Balance		$ 48,979
Carrying value		$ 48,975
Weighted Average Rate	2.40%	2.40%
Ready Capital Mortgage Financing 2019-FL3
Variable interest entities
Current Principal Balance	$ 92,930	$ 229,440
Carrying value	$ 92,921	$ 227,950
Weighted Average Rate	1.60%	2.00%
Ready Capital Mortgage Financing 2020-FL4
Variable interest entities
Current Principal Balance	$ 304,157	$ 324,219
Carrying value	$ 300,832	$ 318,385
Weighted Average Rate	3.10%	3.10%
Ready Capital Mortgage Financing 2021-FL5
Variable interest entities
Current Principal Balance	$ 506,721
Carrying value	$ 501,697
Weighted Average Rate	1.50%
Ready Capital Mortgage Financing 2021-FL6
Variable interest entities
Current Principal Balance	$ 543,223
Carrying value	$ 536,270
Weighted Average Rate	1.30%
Ready Capital Mortgage Financing 2021-FL7
Variable interest entities
Current Principal Balance	$ 753,314
Carrying value	$ 744,449
Weighted Average Rate	1.60%