Schedule III (Consolidated) - Real Estate and Accumulated Depreciation - Reconciliation of Accumulated Depreciation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule III, Reconciliation of accumulated depreciation
Balance at beginning of the year	$ 71,752	$ 67,349	$ 64,069
Depreciation expense	6,018	6,245	6,002
Amounts retired or adjusted	(10,270)	(1,842)	(2,722)
Balance at the end of the year	$ 67,500	$ 71,752	$ 67,349