Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues:
Lease income	$ 1,094,301	$ 1,083,770	$ 950,186
Other property income	9,201	8,711	7,982
Management, transaction, and other fees	29,636	28,494	26,158
Total revenues	1,133,138	1,120,975	984,326
Operating expenses:
Depreciation and amortization	374,283	359,688	334,201
Operating and maintenance	169,909	168,034	143,990
General and administrative	74,984	65,491	67,624
Real estate taxes	136,236	137,856	109,723
Other operating expenses	7,814	9,737	89,225
Total operating expenses	763,226	740,806	744,763
Other expense (income):
Interest expense, net	151,264	148,456	132,629
Provision for impairment, net of tax	54,174	38,437	0
Gain on sale of real estate, net of tax	(24,242)	(28,343)	(27,432)
Early extinguishment of debt	11,982	11,172	12,449
Net investment (income) loss	(5,568)	1,096	(3,985)
Total other expense (income)	187,610	170,818	113,661
Income from operations before equity in income of investments in real estate partnerships and income taxes	182,302	209,351	125,902
Equity in income of investments in real estate partnerships (note 4)	60,956	42,974	43,341
Deferred income tax benefit of taxable REIT subsidiary	0	0	(9,737)
Net income	243,258	252,325	178,980
Noncontrolling interests:
Exchangeable operating partnership units	(634)	(525)	(388)
Limited partners’ interests in consolidated partnerships	(3,194)	(2,673)	(2,515)
Income attributable to noncontrolling interests	(3,828)	(3,198)	(2,903)
Net income attributable to the Company	239,430	249,127	176,077
Net income attributable to the Company	239,430	249,127	176,077
Preferred stock dividends and issuance costs			(16,128)
Net income attributable to common stockholders	$ 239,430	$ 249,127	$ 159,949
Income per common share - basic (note 15)	$ 1.43	$ 1.47	$ 1.00
Income per common share - diluted (note 15)	$ 1.43	$ 1.46	$ 1.00
Income from operations before equity in income of investments in real estate partnerships and income taxes	$ 182,302	$ 209,351	$ 125,902
Deferred income tax benefit of taxable REIT subsidiary	1,245	522	(9,647)
Partnership Interest [Member]
Revenues:
Lease income	1,094,301	1,083,770	950,186
Other property income	9,201	8,711	7,982
Management, transaction, and other fees	29,636	28,494	26,158
Total revenues	1,133,138	1,120,975	984,326
Operating expenses:
Depreciation and amortization	374,283	359,688	334,201
Operating and maintenance	169,909	168,034	143,990
General and administrative	74,984	65,491	67,624
Real estate taxes	136,236	137,856	109,723
Other operating expenses	7,814	9,737	89,225
Total operating expenses	763,226	740,806	744,763
Other expense (income):
Interest expense, net	151,264	148,456	132,629
Provision for impairment, net of tax	54,174	38,437	0
Gain on sale of real estate, net of tax	(24,242)	(28,343)	(27,432)
Early extinguishment of debt	11,982	11,172	12,449
Net investment (income) loss	(5,568)	1,096	(3,985)
Total other expense (income)	187,610	170,818	113,661
Income from operations before equity in income of investments in real estate partnerships and income taxes	182,302	209,351	125,902
Equity in income of investments in real estate partnerships (note 4)	60,956	42,974	43,341
Net income	243,258	252,325	178,980
Noncontrolling interests:
Limited partners’ interests in consolidated partnerships	(3,194)	(2,673)	(2,515)
Income attributable to noncontrolling interests	(3,194)	(2,673)	(2,515)
Net income attributable to the Company	240,064	249,652	176,465
Net income attributable to the Company	240,064	249,652	176,465
Income from operations before equity in income of investments in real estate partnerships and income taxes	182,302	209,351	125,902
Deferred income tax benefit of taxable REIT subsidiary			(9,737)
Preferred unit distributions and issuance costs			(16,128)
Net income attributable to common unit holders	$ 240,064	$ 249,652	$ 160,337
Income per common unit - basic (note 15):	$ 1.43	$ 1.47	$ 1.00
Income per common unit - diluted (note 15):	$ 1.43	$ 1.46	$ 1.00