Distressed and Other Residential Mortgage Loans, Net - Delinquencies in Portfolio of Residential Mortgage Loans Held in Securitization Trusts (Details) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2019 USD ($) loan	Dec. 31, 2018 USD ($) loan
Financing Receivable, Past Due [Line Items]
Real estate owned through foreclosure, Number of Delinquent Loans \| loan	1
Real estate owned through foreclosure, Total Unpaid Principal \| $	$ 360
Real estate owned through foreclosure, % of Loan Portfolio	0.73%
90
Financing Receivable, Past Due [Line Items]
Number of Delinquent Loans \| loan	17	19
Total Unpaid Principal \| $	$ 10,289	$ 10,926
% of Loan Portfolio	20.92%	18.16%

Amount of financing receivable past due.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 55
-Paragraph 80
-URI http://asc.fasb.org/extlink&oid=118955255&loc=SL82922355-210448

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 14
-URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919253-210447

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7A
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953401-111524

Name:	us-gaap_FinancingReceivableRecordedInvestmentPastDue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant