Investments in Servicing Related Assets, Geographic Concentration (Details)	Sep. 30, 2019	Dec. 31, 2018
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	12.50%	12.70%
Texas [Member]
Servicing Related Assets, Geographic Concentration [Abstract]
Outstanding unpaid principal balance	6.10%	6.40%
Maryland [Member]
Servicing Related Assets, Geographic Concentration [Abstract]
Outstanding unpaid principal balance	5.50%
Florida [Member]
Servicing Related Assets, Geographic Concentration [Abstract]
Outstanding unpaid principal balance	5.00%	5.10%
All Other [Member]
Servicing Related Assets, Geographic Concentration [Abstract]
Outstanding unpaid principal balance	70.90%	75.80%