Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Allowance for doubtful accounts receivable	$ 3,922	$ 3,915
General partner units, outstanding	92,333,161.0	90,394,486.0
Limited Partners' Capital Account, Units Outstanding	165,796	177,164
Parent Company [Member]
Allowance for doubtful accounts receivable	3,922	3,915
Straight-line rent receivable allowance	547	870
Deferred costs accumulated amortization	73,231	69,224
Accumulated amortization of acquired lease intangible assets	25,591	19,148
Accumulated accretion of acquired lease intangible liabilities	10,102	6,636
Preferred stock, par value per share	$ 0.01	$ 0.01
Preferred stock, shares authorized	30,000,000	30,000,000
Preferred units of Series 3-5, units issued	13,000,000	13,000,000
Preferred units of Series 3-5, 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	92,333,161	90,394,486
Exchangeable operating partnership units aggregate redemption value	$ 7,676	$ 8,348
Treasury stock, shares held at cost	373,042	335,347
Partnership Interest [Member]
Limited Partners' Capital Account, Units Outstanding	165,796	177,164