Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Parent Company [Member]
Allowance for doubtful accounts receivable	$ 14,790	$ 12,728
Deferred costs accumulated amortization	97,107	93,291
Accumulated amortization of acquired lease intangible assets	188,246	148,280
Accumulated accretion of acquired lease intangible liabilities	$ 75,179	$ 56,550
Preferred stock, par value per share	$ 0.01	$ 0.01
Preferred stock, shares authorized	30,000,000	30,000,000
Common stock, par value per share	$ 0.01	$ 0.01
Common stock, shares authorized	220,000,000	220,000,000
Common stock, shares issued	169,435,301	171,364,908
Exchangeable operating partnership units aggregate redemption value	$ 21,722	$ 24,206
Treasury stock, shares held at cost	381,258	366,628
Partnership Interest [Member]
Allowance for doubtful accounts receivable	$ 14,790	$ 12,728
Deferred costs accumulated amortization	97,107	93,291
Accumulated amortization of acquired lease intangible assets	188,246	148,280
Accumulated accretion of acquired lease intangible liabilities	$ 75,179	$ 56,550
Preferred units of general partner par value per unit	$ 0.01	$ 0.01
General partner units, outstanding	169,435,301	171,364,908
Limited partner units, outstanding	349,902	349,902