Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Parent Company [Member]
Allowance for doubtful accounts receivable	$ 5,690	$ 5,295
Straight-line rent receivable allowance	3,688	1,365
Deferred costs accumulated amortization	82,277	76,823
Accumulated amortization of acquired lease intangible assets	53,878	45,639
Accumulated accretion of acquired lease intangible liabilities	$ 22,067	$ 17,555
Preferred stock, par value per share	$ 0.01	$ 0.01
Preferred stock, shares authorized	30,000,000	30,000,000
Preferred units of Series 6-7, units issued	13,000,000	13,000,000
Preferred units of Series 6-7, units outstanding	13,000,000	13,000,000
Preferred stock, liquidation preferences per share	$ 25	$ 25
Common stock, par value per share	$ 0.01	$ 0.01
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	104,492,738	97,212,638
Exchangeable operating partnership units aggregate redemption value	$ 11,947	$ 10,502
Treasury stock, shares held at cost	345,359	417,862
Partnership Interest [Member]
Allowance for doubtful accounts receivable	$ 5,534	$ 5,295
Straight-line rent receivable allowance	2,961	1,365
Deferred costs accumulated amortization	80,816	76,823
Accumulated amortization of acquired lease intangible assets	50,553	45,639
Accumulated accretion of acquired lease intangible liabilities	$ 20,240	$ 17,555
Preferred units of general partner par value per unit	$ 0.01	$ 0.01
Preferred units of Series 6-7, units issued	13,000,000	13,000,000
Preferred units of Series 6-7, units outstanding	13,000,000	13,000,000
Preferred stock, liquidation preferences per share	$ 25	$ 25
General partner units, outstanding	104,492,738	97,212,638
Limited partner units, outstanding	154,170	154,170