Investments in Servicing Related Assets, Geographic Concentration (Details)	Jun. 30, 2021	Dec. 31, 2020
Servicing Related Assets, Geographic Concentration [Abstract]
Outstanding unpaid principal balance	100.00%	100.00%
California [Member]
Servicing Related Assets, Geographic Concentration [Abstract]
Outstanding unpaid principal balance	11.90%	11.10%
Virginia [Member]
Servicing Related Assets, Geographic Concentration [Abstract]
Outstanding unpaid principal balance	9.50%	8.40%
New York [Member]
Servicing Related Assets, Geographic Concentration [Abstract]
Outstanding unpaid principal balance	8.90%	7.70%
Maryland [Member]
Servicing Related Assets, Geographic Concentration [Abstract]
Outstanding unpaid principal balance	7.20%	6.70%
Texas [Member]
Servicing Related Assets, Geographic Concentration [Abstract]
Outstanding unpaid principal balance	6.10%	5.80%
North Carolina [Member]
Servicing Related Assets, Geographic Concentration [Abstract]
Outstanding unpaid principal balance	5.90%	5.50%
All Other [Member]
Servicing Related Assets, Geographic Concentration [Abstract]
Outstanding unpaid principal balance	50.50%	54.80%