Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues		$ 1,164,762	$ 1,200,834	$ 1,170,792
Operating expenses
Rent		(10,929)	(11,145)	(10,993)
Real estate taxes		(153,336)	(157,196)	(146,615)
Operating and maintenance		(164,294)	(169,552)	(171,416)
General and administrative		(87,797)	(91,690)	(86,796)
Provision for doubtful accounts		(6,253)	(5,630)	(5,563)
Impairment charges	[1],[2]	79,207	67,331	93,266
Depreciation and amortization		(310,380)	(360,811)	(355,320)
Total operating expenses		(812,196)	(863,355)	(869,969)
Gain on sale of operating properties/change in control of interests		229,840	93,538	92,823
Operating income		582,406	431,017	393,646
Other income/(expense)
Other income, net		13,041	2,559	5,425
Interest expense		(183,339)	(191,956)	(192,549)
Early extinguishment of debt charges		(12,762)	(1,753)	(45,674)
Income before income taxes, net, equity in income of joint ventures, net, gain on change in control of joint venture interests and equity in income from other real estate investments, net		399,346	239,867	160,848
(Provision)/benefit for income taxes, net		(1,600)	880	(78,583)
Equity in income		71,617	60,763	218,714
Gain on change in control of joint venture interests			71,160	57,386
Net income		498,463	439,671	386,138
Net income attributable to noncontrolling interests		(668)	(13,596)	(7,288)
Net income attributable to the Company		497,795	426,075	378,850
Preferred stock redemption charges			(7,014)
Preferred dividends		(58,191)	(46,600)	(46,220)
Net income available to the Company's common shareholders		$ 439,604	$ 372,461	$ 332,630
Per common share:
Basic (in dollars per share)		$ 1.02	$ 0.87	$ 0.79
Diluted (in dollars per share)		$ 1.02	$ 0.87	$ 0.79
Weighted average shares:
-Basic (in shares)		420,641	423,614	418,402
-Diluted (in shares)	[3]	421,379	424,019	419,709
Joint Ventures [Member]
Other income/(expense)
Equity in income		$ 71,617	$ 60,763	$ 218,714
Other Real Estate Investments [Member]
Other income/(expense)
Equity in income		29,100	67,001	27,773
Revenues from Rental Properties [Member]
Revenues		882,345	912,670	893,365
Reimbursement Income [Member]
Revenues		246,381	247,563	239,015
Other Rental Property Income [Member]
Revenues		20,877	23,552	20,021
Management and Other Fee Incomes [Member]
Revenues		$ 15,159	$ 17,049	$ 18,391

[1] During 2016, the Company recognized aggregate impairment charges of $93.3 million, before an income tax benefit of $21.1 million and noncontrolling interests of $0.4 million, primarily related to sale of certain operating properties and certain properties maintained in the Company's TRS for which the hold period was re-evaluated in connection with the Merger (see Footnote 21 of the Notes to Consolidated Financial Statements for additional disclosure) and adjustments to property carrying values in connection with the Company's efforts to market certain properties and management's assessment as to the likelihood and timing of such potential transactions and the anticipated hold period for such properties.

[2] See Footnote 15 of the Notes to Consolidated Financial Statements for additional disclosure on fair value

[3] The effect of the assumed conversion of certain convertible units had an anti-dilutive effect upon the calculation of Income from continuing operations per share. Accordingly, the impact of such conversions has not been included in the determination of diluted earnings per share calculations. Additionally, there were 1.3 million, 3.1 million and 3.5 million stock options that were not dilutive as of December 31, 2018, 2017 and 2016, respectively.