Real Estate Transactions (Details) ft² in Thousands, $ in Thousands	Mar. 31, 2017 USD ($) ft²
Liabilities of real estate assets held for sale
Unamortized deferred loan costs of note payable	$ 36
The ACS Center
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of property (in sq ft) | ft²	996
Real estate and other assets held for sale
Operating properties, net of accumulated depreciation of $73,525 in 2017	$ 33,459
Accounts receivable	1,028
Deferred rents receivable	8,913
Other assets	1,253
Total real estate and other assets held for sale	44,653
Liabilities of real estate assets held for sale
Note payable, net of unamortized deferred loan costs of $36 in 2017	126,962
Accounts payable and accrued expenses	2,340
Other liabilities	1,389
Total liabilities of real estate assets held for sale	130,691
Accumulated depreciation of operating properties	$ 73,525