Investments in Servicing Related Assets, Geographic Concentration (Details)	Dec. 31, 2018	Dec. 31, 2017
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	12.70%	13.70%
Texas [Member]
Servicing Related Assets, Geographic Concentration [Abstract]
Outstanding unpaid principal balance	6.40%
Florida [Member]
Servicing Related Assets, Geographic Concentration [Abstract]
Outstanding unpaid principal balance	5.10%	5.30%
New Jersey [Member]
Servicing Related Assets, Geographic Concentration [Abstract]
Outstanding unpaid principal balance		7.20%
All Other [Member]
Servicing Related Assets, Geographic Concentration [Abstract]
Outstanding unpaid principal balance	75.80%	73.80%