Organization and Basis of Presentation (Details Textuals)	12 Months Ended
	Dec. 31, 2017 USD ($) payment
Organization And Basis Of Presentation [Line Items]
Number of payments made on RPL mortgage loans (at least)	5
Number of recent payments made on RPL mortgage loans	7
Principal balance of small balance commercial mortgage loans (up to) | $	$ 509,825,000
Number of payments made on NPL mortgage loans	3
Ownership percentage	5.00%
Percentage of outstanding OP units owned	96.80%
Percentage of outstanding OP owned by an unaffiliated holder	3.20%
Maximum
Organization And Basis Of Presentation [Line Items]
Principal balance of small balance commercial mortgage loans (up to) | $	$ 5,000,000
Thetis Asset Management
Organization And Basis Of Presentation [Line Items]
Ownership percentage	19.80%
AS Ajax E II LLC
Organization And Basis Of Presentation [Line Items]
Ownership percentage	53.10%
2017-D
Organization And Basis Of Presentation [Line Items]
Ownership interest in real estate trust, percentage	50.00%