Discontinued Operations - Summary of major components of assets and liabilities held for disposition (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Discontinued Operations
Net investment property		$ 32,778
Restricted escrows		3,274
Other assets		1,174
Total assets held for disposition	$ 37,000,000	37,226
Mortgages payable		30,642
Accounts payable and accrued expenses		19,069
Other liabilities		993
Total liabilities held for disposition	$ 49,600,000	$ 50,704