Discontinued Operations - Discontinued operations balance sheet components (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Land	$ 84,383	$ 83,721
Buildings and improvements	145,690	144,543
Projects under construction	1,461	6,683
Total investments in properties	231,534	234,947
Less accumulated depreciation and depletion	28,871	28,394
Net investments in properties	202,663	206,553
Accounts receivable, net	919	564
Unrealized rents	548	53
Deferred costs	1,079	773
Assets of discontinued operations	32	3,224
Accounts payable and accrued liabilities	1,488	3,545
Deferred revenue	831	27
Tenant security deposits	334	53
Liabilities of discontinued operations	18	288
Discontinued Operations, Disposed of by Sale [Member]
Land	0	546
Buildings and improvements	0	3,315
Projects under construction	0	0
Total investments in properties	0	3,861
Less accumulated depreciation and depletion	0	2,374
Net investments in properties	0	1,487
Accounts receivable, net	32	910
Unrealized rents	0	473
Deferred costs	0	354
Assets of discontinued operations	32	3,224
Accounts payable and accrued liabilities	18	205
Deferred revenue	0	45
Tenant security deposits	0	38
Liabilities of discontinued operations	$ 18	$ 288