Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Liability for real estate additions due to Vornado	$ 124	$ 1,053
Development Fees [Member] | Vornado [Member]
Liability for real estate additions due to Vornado	$ 24	$ 92