Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Accounts receivable, allowance	$ 1,888	$ 1,576
Straight-line rent receivable, allowance	6,404	9,350
Deferred financing costs, accumulated amortization	39,553	37,016
Deferred leasing and other costs, accumulated amortization	305,316	394,049
Preferred shares, par value	$ 0.01	$ 0.01
Preferred shares, shares authorized	5,000,000	5,000,000
Preferred shares, shares issued	1,716,000	1,791,000
Preferred shares, shares outstanding	1,716,000	1,791,000
Common shares, par value	$ 0.01	$ 0.01
Common shares, shares authorized	400,000,000	400,000,000
Common shares, shares issued	328,480,000	326,399,000
Common shares, shares outstanding	328,480,000	326,399,000
Subsidiary of Common Parent [Member]
Accounts receivable, allowance	1,888	1,576
Straight-line rent receivable, allowance	6,404	9,350
Deferred financing costs, accumulated amortization	39,553	37,016
Deferred leasing and other costs, accumulated amortization	$ 305,316	$ 394,049
Common equity, General Partner Units issued	328,480,000	326,399,000
Common equity, General Partner Units outstanding	328,480,000	326,399,000
Preferred Units, Issued	1,716,000	1,791,000
Preferred Units, Outstanding	1,716,000	1,791,000
Limited Partner Units issued	4,387,000	4,387,000
Limited Partner Units outstanding	4,387,000	4,387,000