SCHEDULE III REAL ESTATE AND ACCUMULATED DEPRECIATION (Details 1) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of Real Estate
Balance at at beginning	$ 1,045,454	$ 982,827	$ 804,489
Additions
Acquisitions, improvements and construction	119,925	112,763	222,423
Deductions
Sale of real estate	(6,919)	(50,136)	(38,785)
Asset impairments			(5,300)
Balance at ending	1,158,460	1,045,454	982,827
Reconciliation of Accumulated Depreciation
Balance at at beginning	154,281	138,808	115,368
Additions
Depreciation	24,309	22,180	25,565
Deductions
Sale of real estate		(6,707)	(2,125)
Balance at ending	$ 178,590	$ 154,281	$ 138,808