Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Preferred stock, shares authorized	40,000,000	40,000,000
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares outstanding	11,873,139	11,833,573
Noncontrolling interest in consolidated partnership, redemption value	$ 925	$ 871
Series E Preferred Stock [Member]
Preferred stock, annual dividend rate	6.25%	6.25%
Preferred stock, shares authorized	925,000	925,000
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares outstanding	925,000	925,000
Preferred stock, liquidation preference	$ 9,395	$ 9,395