Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Parent Company [Member]
Allowance for doubtful accounts receivable	$ 13,945	$ 12,728
Deferred costs accumulated amortization	96,192	93,291
Accumulated amortization of acquired lease intangible assets	171,114	148,280
Accumulated accretion of acquired lease intangible liabilities	$ 68,123	$ 56,550
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	0	0
Preferred units of Series 6-7, units outstanding	0	0
Preferred stock, liquidation preferences per share	$ 0	$ 0
Common stock, par value per share	$ 0.01	$ 0.01
Common stock, shares authorized	220,000,000	220,000,000
Common stock, shares issued	169,408,781	171,364,908
Exchangeable operating partnership units aggregate redemption value	$ 20,634	$ 24,206
Treasury stock, shares held at cost	372,712	366,628
Partnership Interest [Member]
Allowance for doubtful accounts receivable	$ 13,945	$ 12,728
Deferred costs accumulated amortization	96,192	93,291
Accumulated amortization of acquired lease intangible assets	171,114	148,280
Accumulated accretion of acquired lease intangible liabilities	$ 68,123	$ 56,550
Preferred units of general partner par value per unit	$ 0.01	$ 0.01
Preferred units of Series 6-7, units issued	0	0
Preferred units of Series 6-7, units outstanding	0	0
Preferred stock, liquidation preferences per share	$ 0	$ 0
General partner units, outstanding	169,408,781	171,364,908
Limited partner units, outstanding	349,902	349,902