Variable interest entities and securitization activities - Securitized Debt Obligations (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Variable interest entities
Current Principal Balance	$ 1,976,068	$ 1,735,493
Current principal balance of non-company sponsored securitized loans	43,600	7,300
Consolidated VIEs
Variable interest entities
Current Principal Balance	2,137,096	1,845,886
Carrying value	$ 2,096,429	$ 1,807,883
Weighted Average Rate	3.40%	3.70%
Waterfall Victoria Mortgage Trust 2011-SBC2
Variable interest entities
Current Principal Balance	$ 5,858	$ 6,399
Carrying value	$ 5,858	$ 6,399
Weighted Average Rate	5.50%	5.50%
ReadyCap Lending Small Business Trust 2019-2
Variable interest entities
Current Principal Balance	$ 110,699	$ 131,032
Carrying value	$ 110,699	$ 129,007
Weighted Average Rate	3.50%	4.30%
Sutherland Commercial Mortgage Trust 2017-SBC6
Variable interest entities
Current Principal Balance	$ 35,387	$ 42,309
Carrying value	$ 34,758	$ 41,486
Weighted Average Rate	3.60%	3.40%
Sutherland Commercial Mortgage Trust 2018-SBC7
Variable interest entities
Current Principal Balance	$ 104,236	$ 138,235
Carrying value	$ 102,703	$ 136,212
Weighted Average Rate	4.70%	4.70%
Sutherland Commercial Mortgage Trust 2019-SBC8
Variable interest entities
Current Principal Balance	$ 200,821	$ 219,617
Carrying value	$ 198,135	$ 216,981
Weighted Average Rate	2.90%	2.90%
Sutherland Commercial Mortgage Trust 2020-SBC9
Variable interest entities
Current Principal Balance	$ 173,035
Carrying value	$ 169,925
Weighted Average Rate	4.00%
ReadyCap Commercial Mortgage Trust 2014-1
Variable interest entities
Current Principal Balance	$ 18,188	$ 18,626
Carrying value	$ 18,193	$ 18,632
Weighted Average Rate	5.80%	5.60%
ReadyCap Commercial Mortgage Trust 2015-2
Variable interest entities
Current Principal Balance	$ 48,066	$ 64,239
Carrying value	$ 45,706	$ 61,443
Weighted Average Rate	4.50%	4.50%
ReadyCap Commercial Mortgage Trust 2016-3
Variable interest entities
Current Principal Balance	$ 26,917	$ 32,269
Carrying value	$ 25,664	$ 30,777
Weighted Average Rate	3.60%	4.70%
ReadyCap Commercial Mortgage Trust 2018-4
Variable interest entities
Current Principal Balance	$ 96,969	$ 121,179
Carrying value	$ 93,501	$ 117,428
Weighted Average Rate	4.00%	3.90%
ReadyCap Commercial Mortgage Trust 2019-5
Variable interest entities
Current Principal Balance	$ 280,703	$ 309,296
Carrying value	$ 271,421	$ 299,273
Weighted Average Rate	4.10%	4.10%
ReadyCap Commercial Mortgage Trust 2019-6
Variable interest entities
Current Principal Balance	$ 375,057	$ 379,400
Carrying value	$ 368,091	$ 371,939
Weighted Average Rate	3.20%	3.20%
Ready Capital Mortgage Financing 2018-FL2
Variable interest entities
Current Principal Balance	$ 69,035	$ 115,381
Carrying value	$ 68,589	$ 114,057
Weighted Average Rate	2.80%	3.80%
Ready Capital Mortgage Financing 2019-FL3
Variable interest entities
Current Principal Balance	$ 267,904	$ 267,904
Carrying value	$ 265,376	$ 264,249
Weighted Average Rate	2.40%	3.50%
Ready Capital Mortgage Financing 2020-FL4
Variable interest entities
Current Principal Balance	$ 324,221
Carrying value	$ 317,810
Weighted Average Rate	3.10%