Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Other expense (income):
Provision for impairment	$ (866)	$ 0
Discontinued operations, net:
Gain (Loss) on Sale of Properties, Net of Applicable Income Taxes	12,868	803
Parent Company [Member]
Revenues:
Minimum rent	107,674	101,305
Percentage rent	1,703	1,808
Recoveries from tenants and other income	33,487	31,048
Management Fees Revenue	6,764	6,238
Total revenues	149,628	140,399
Operating expenses:
Depreciation and amortization	38,716	35,992
Operating and maintenance	22,685	21,172
General and administrative	16,299	16,378
Real estate taxes	15,870	15,131
Other operating expenses	2,306	1,166
Total operating expenses	95,876	89,839
Other expense (income):
Interest expense, net	24,142	26,633
Provision for impairment	1,666	0
Early extinguishment of debt	0	61
Marketable Securities, Gain (Loss), Excluding Other than Temporary Impairments	(155)	634
Total other expense	25,963	25,938
Income from operations before equity in income of investments in real estate partnerships	27,789	24,622
Equity in income of investments in real estate partnerships	12,920	5,567
Income from operations	40,709	30,189
Discontinued operations, net:
Gain (Loss) on Sale of Properties, Net of Applicable Income Taxes	12,868	803
Net income	53,577	30,992
Noncontrolling interests:
Exchangeable operating partnership units	(85)	(49)
Limited partners’ interests in consolidated partnerships	(349)	(503)
Income attributable to noncontrolling interests	(434)	(552)
Net income attributable to the Company	53,143	30,440
Preferred stock dividends	(5,266)	(5,266)
Net Income (Loss) Available to Common Stockholders, Basic	$ 47,877	$ 25,174
Income per common share/unit - basic:
Continuing operations (in dollars per share)	$ 0.49	$ 0.27
Income per common share/unit - diluted:
Continuing operations (in dollars per share)	$ 0.49	$ 0.27
Partnership Interest [Member]
Revenues:
Minimum rent	$ 107,674	$ 101,305
Percentage rent	1,703	1,808
Recoveries from tenants and other income	33,487	31,048
Management Fees Revenue	6,764	6,238
Total revenues	149,628	140,399
Operating expenses:
Depreciation and amortization	38,716	35,992
Operating and maintenance	22,685	21,172
General and administrative	16,299	16,378
Real estate taxes	15,870	15,131
Other operating expenses	2,306	1,166
Total operating expenses	95,876	89,839
Other expense (income):
Interest expense, net	24,142	26,633
Provision for impairment	1,666	0
Early extinguishment of debt	0	61
Marketable Securities, Gain (Loss), Excluding Other than Temporary Impairments	(155)	634
Total other expense	25,963	25,938
Income from operations before equity in income of investments in real estate partnerships	27,789	24,622
Equity in income of investments in real estate partnerships	12,920	5,567
Income from operations	40,709	30,189
Discontinued operations, net:
Gain (Loss) on Sale of Properties, Net of Applicable Income Taxes	12,868	803
Net income	53,577	30,992
Noncontrolling interests:
Limited partners’ interests in consolidated partnerships	(349)	(503)
Income attributable to noncontrolling interests	(349)	(503)
Net income attributable to the Company	53,228	30,489
Distributions Paid To Preferred Unit Holders	5,266	5,266
Net income attributable to common unit holders	$ 47,962	$ 25,223
Income per common share/unit - basic:
Continuing operations (in dollars per share)	$ 0.49	$ 0.27
Income per common share/unit - diluted:
Continuing operations (in dollars per share)	$ 0.49	$ 0.27