Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Other expense (income):
Provision for impairment	$ 0	$ 0	$ 1,666	$ 0
Discontinued operations, net:
Gain (Loss) on Sale of Properties, Net of Applicable Income Taxes	548	5,657	13,417	6,460
Parent Company [Member]
Revenues:
Minimum rent	109,945	102,390	217,619	203,695
Percentage rent	453	300	2,156	2,108
Recoveries from tenants and other income	35,874	32,431	69,362	63,479
Management Fees Revenue	6,140	6,008	12,904	12,246
Total revenues	152,412	141,129	302,041	281,528
Operating expenses:
Depreciation and amortization	40,299	36,225	79,015	72,218
Operating and maintenance	23,709	20,185	46,394	41,358
General and administrative	16,350	15,099	32,649	31,477
Real estate taxes	16,769	15,667	32,639	30,798
Other operating expenses	2,440	1,779	4,747	2,943
Total operating expenses	99,567	88,955	195,444	178,794
Other expense (income):
Interest expense, net	24,401	26,675	48,544	53,308
Provision for impairment	0	0	1,666	0
Early extinguishment of debt	0	0	0	61
Marketable Securities, Gain (Loss), Excluding Other than Temporary Impairments	602	367	446	1,000
Total other expense	23,799	26,308	49,764	52,247
Income from operations before equity in income of investments in real estate partnerships	29,046	25,866	56,833	50,487
Equity in income of investments in real estate partnerships	11,050	6,757	23,971	12,324
Income from operations	40,096	32,623	80,804	62,811
Discontinued operations, net:
Gain (Loss) on Sale of Properties, Net of Applicable Income Taxes	548	5,657	13,417	6,460
Net income	40,644	38,280	94,221	69,271
Noncontrolling interests:
Exchangeable operating partnership units	(64)	(61)	(150)	(110)
Limited partners’ interests in consolidated partnerships	(504)	(473)	(853)	(977)
Income attributable to noncontrolling interests	(568)	(534)	(1,003)	(1,087)
Net income attributable to the Company	40,076	37,746	93,218	68,184
Preferred stock dividends	(5,266)	(5,266)	(10,531)	(10,531)
Net Income (Loss) Available to Common Stockholders, Basic	$ 34,810	$ 32,480	$ 82,687	$ 57,653
Income per common share/unit - basic:
Continuing operations (in dollars per share)	$ 0.36	$ 0.35	$ 0.85	$ 0.61
Income per common share/unit - diluted:
Continuing operations (in dollars per share)	$ 0.35	$ 0.34	$ 0.84	$ 0.61
Partnership Interest [Member]
Revenues:
Minimum rent	$ 109,945	$ 102,390	$ 217,619	$ 203,695
Percentage rent	453	300	2,156	2,108
Recoveries from tenants and other income	35,874	32,431	69,362	63,479
Management Fees Revenue	6,140	6,008	12,904	12,246
Total revenues	152,412	141,129	302,041	281,528
Operating expenses:
Depreciation and amortization	40,299	36,225	79,015	72,218
Operating and maintenance	23,709	20,185	46,394	41,358
General and administrative	16,350	15,099	32,649	31,477
Real estate taxes	16,769	15,667	32,639	30,798
Other operating expenses	2,440	1,779	4,747	2,943
Total operating expenses	99,567	88,955	195,444	178,794
Other expense (income):
Interest expense, net	24,401	26,675	48,544	53,308
Provision for impairment	0	0	1,666	0
Early extinguishment of debt	0	0	0	61
Marketable Securities, Gain (Loss), Excluding Other than Temporary Impairments	602	367	446	1,000
Total other expense	23,799	26,308	49,764	52,247
Income from operations before equity in income of investments in real estate partnerships	29,046	25,866	56,833	50,487
Equity in income of investments in real estate partnerships	11,050	6,757	23,971	12,324
Income from operations	40,096	32,623	80,804	62,811
Discontinued operations, net:
Gain (Loss) on Sale of Properties, Net of Applicable Income Taxes	548	5,657	13,417	6,460
Net income	40,644	38,280	94,221	69,271
Noncontrolling interests:
Limited partners’ interests in consolidated partnerships	(504)	(473)	(853)	(977)
Income attributable to noncontrolling interests	(504)	(473)	(853)	(977)
Net income attributable to the Company	40,140	37,807	93,368	68,294
Distributions Paid To Preferred Unit Holders	5,266	5,266	10,531	10,531
Net income attributable to common unit holders	$ 34,874	$ 32,541	$ 82,837	$ 57,763
Income per common share/unit - basic:
Continuing operations (in dollars per share)	$ 0.36	$ 0.35	$ 0.85	$ 0.61
Income per common share/unit - diluted:
Continuing operations (in dollars per share)	$ 0.35	$ 0.34	$ 0.84	$ 0.61