Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenues:
Lease income	$ 266,236	$ 272,203	$ 543,539	$ 539,713
Other property income	2,194	2,322	4,176	4,347
Management, transaction, and other fees	7,442	6,887	14,415	14,045
Total revenues	275,872	281,412	562,130	558,105
Operating expenses:
Depreciation and amortization	93,589	89,105	190,783	177,629
Operating and maintenance	42,759	41,851	83,397	84,367
General and administrative	18,717	16,776	40,017	34,382
Real estate taxes	33,506	31,541	67,661	61,967
Other operating expenses	1,533	2,799	2,667	4,432
Total operating expenses	190,104	182,072	384,525	362,777
Other expense (income):
Interest expense, net	37,173	38,074	74,925	74,859
Provision for impairment, net of tax	10,441	12,533	12,113	28,587
Gain on sale of real estate, net of tax	(442)	(1,123)	(16,932)	(1,219)
Early extinguishment of debt		11,010	10,591	11,172
Net investment income	(966)	(569)	(3,320)	(602)
Total other expense (income)	46,206	59,925	77,377	112,797
Income from operations before equity in income of investments in real estate partnerships	39,562	39,415	100,228	82,531
Equity in income of investments in real estate partnerships	13,128	9,174	43,955	19,523
Net income	52,690	48,589	144,183	102,054
Noncontrolling interests:
Exchangeable operating partnership units	(109)	(100)	(299)	(212)
Limited partners’ interests in consolidated partnerships	(853)	(648)	(1,710)	(1,342)
Income attributable to noncontrolling interests	(962)	(748)	(2,009)	(1,554)
Net income attributable to common stockholders	$ 51,728	$ 47,841	$ 142,174	$ 100,500
Income per common share - basic	$ 0.31	$ 0.28	$ 0.85	$ 0.59
Income per common share - diluted	$ 0.31	$ 0.28	$ 0.85	$ 0.59
Partnership Interest [Member]
Revenues:
Lease income	$ 266,236	$ 272,203	$ 543,539	$ 539,713
Other property income	2,194	2,322	4,176	4,347
Management, transaction, and other fees	7,442	6,887	14,415	14,045
Total revenues	275,872	281,412	562,130	558,105
Operating expenses:
Depreciation and amortization	93,589	89,105	190,783	177,629
Operating and maintenance	42,759	41,851	83,397	84,367
General and administrative	18,717	16,776	40,017	34,382
Real estate taxes	33,506	31,541	67,661	61,967
Other operating expenses	1,533	2,799	2,667	4,432
Total operating expenses	190,104	182,072	384,525	362,777
Other expense (income):
Interest expense, net	37,173	38,074	74,925	74,859
Provision for impairment, net of tax	10,441	12,533	12,113	28,587
Gain on sale of real estate, net of tax	(442)	(1,123)	(16,932)	(1,219)
Early extinguishment of debt		11,010	10,591	11,172
Net investment income	(966)	(569)	(3,320)	(602)
Total other expense (income)	46,206	59,925	77,377	112,797
Income from operations before equity in income of investments in real estate partnerships	39,562	39,415	100,228	82,531
Equity in income of investments in real estate partnerships	13,128	9,174	43,955	19,523
Net income	52,690	48,589	144,183	102,054
Noncontrolling interests:
Limited partners’ interests in consolidated partnerships	(853)	(648)	(1,710)	(1,342)
Income attributable to noncontrolling interests	(853)	(648)	(1,710)	(1,342)
Net income attributable to common unit holders	$ 51,837	$ 47,941	$ 142,473	$ 100,712
Income per common unit - basic	$ 0.31	$ 0.28	$ 0.85	$ 0.59
Income per common unit - diluted	$ 0.31	$ 0.28	$ 0.85	$ 0.59