Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenues:
Lease income	$ 272,143	$ 268,948	$ 815,682	$ 808,661
Other property income	2,780	2,408	6,956	6,755
Management, transaction, and other fees	7,353	6,954	21,768	20,999
Total revenues	282,276	278,310	844,406	836,415
Operating expenses:
Depreciation and amortization	91,856	89,183	282,639	266,812
Operating and maintenance	41,695	40,557	125,092	124,924
General and administrative	16,705	17,564	56,722	51,947
Real estate taxes	33,601	35,129	101,263	97,096
Other operating expenses	1,819	2,045	4,486	6,476
Total operating expenses	185,676	184,478	570,202	547,255
Other expense (income):
Interest expense, net	38,253	36,618	113,178	111,477
Provision for impairment, net of tax	(14)	855	12,099	29,443
Gain on sale of real estate, net of tax	(887)	(3,228)	(17,819)	(4,448)
Early extinguishment of debt	1,391		11,982	11,172
Net investment income	(370)	(923)	(3,690)	(1,524)
Total other expense (income)	38,373	33,322	115,750	146,120
Income from operations before equity in income of investments in real estate partnerships	58,227	60,510	158,454	143,040
Equity in (loss) income of investments in real estate partnerships	(283)	10,024	43,673	29,548
Net income	57,944	70,534	202,127	172,588
Noncontrolling interests:
Exchangeable operating partnership units	(157)	(147)	(456)	(358)
Limited partners’ interests in consolidated partnerships	(822)	(665)	(2,532)	(2,008)
Income attributable to noncontrolling interests	(979)	(812)	(2,988)	(2,366)
Net income attributable to common stockholders	$ 56,965	$ 69,722	$ 199,139	$ 170,222
Income per common share - basic	$ 0.34	$ 0.41	$ 1.19	$ 1.00
Income per common share - diluted	$ 0.34	$ 0.41	$ 1.19	$ 1.00
Partnership Interest [Member]
Revenues:
Lease income	$ 272,143	$ 268,948	$ 815,682	$ 808,661
Other property income	2,780	2,408	6,956	6,755
Management, transaction, and other fees	7,353	6,954	21,768	20,999
Total revenues	282,276	278,310	844,406	836,415
Operating expenses:
Depreciation and amortization	91,856	89,183	282,639	266,812
Operating and maintenance	41,695	40,557	125,092	124,924
General and administrative	16,705	17,564	56,722	51,947
Real estate taxes	33,601	35,129	101,263	97,096
Other operating expenses	1,819	2,045	4,486	6,476
Total operating expenses	185,676	184,478	570,202	547,255
Other expense (income):
Interest expense, net	38,253	36,618	113,178	111,477
Provision for impairment, net of tax	(14)	855	12,099	29,443
Gain on sale of real estate, net of tax	(887)	(3,228)	(17,819)	(4,448)
Early extinguishment of debt	1,391		11,982	11,172
Net investment income	(370)	(923)	(3,690)	(1,524)
Total other expense (income)	38,373	33,322	115,750	146,120
Income from operations before equity in income of investments in real estate partnerships	58,227	60,510	158,454	143,040
Equity in (loss) income of investments in real estate partnerships	(283)	10,024	43,673	29,548
Net income	57,944	70,534	202,127	172,588
Noncontrolling interests:
Limited partners’ interests in consolidated partnerships	(822)	(665)	(2,532)	(2,008)
Income attributable to noncontrolling interests	(822)	(665)	(2,532)	(2,008)
Net income attributable to common unit holders	$ 57,122	$ 69,869	$ 199,595	$ 170,580
Income per common unit - basic	$ 0.34	$ 0.41	$ 1.19	$ 1.00
Income per common unit - diluted	$ 0.34	$ 0.41	$ 1.19	$ 1.00