Consolidated Statement of Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Preferred Stock	Common Stock	Additional Paid-In-Capital	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Noncontrolling Interests	Series I Preferred Stock Preferred Stock
Beginning Balance at Dec. 31, 2017	$ 6,589,454	$ 221,932	$ 939	$ 4,968,338	$ (124,049)	$ 18,604	$ 1,139,329	$ 364,361
Beginning Balance (in shares) at Dec. 31, 2017			92,803
Adjusted Balance at Dec. 31, 2017	7,159,978		$ 939	4,968,338	(124,049)	18,604	1,709,853	364,361	$ 221,932
Increase (Decrease) in Stockholders' Equity
Net income	105,702						105,504	198
Other comprehensive loss	9,969					9,969
Preferred dividends	(3,738)						(3,738)
DRSPP proceeds (in shares)			1
DRSPP proceeds	42			42
Reallocation of noncontrolling interest in the Operating Partnership	3,645						3,645
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings (in shares)			(19)
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings	3,102			3,102
Repurchases of common stock (in shares)			(3,654)
Repurchases of common stock	(354,744)		$ (37)	(195,617)			159,090
Proceeds from stock options exercised (in shares)			4
Proceeds from stock options exercised	729			729
Contributions to consolidated joint venture interests	157							157
Deconsolidation of partially owned entity	(314,596)							(314,596)
Cash distributions to noncontrolling interests	(276)							(276)
Cash distributions declared (per common share, none of which represented a return of capital for federal income tax purposes)	(72,341)						(72,341)
Ending Balance at Mar. 31, 2018	6,537,629	221,932	$ 902	4,776,594	(124,049)	28,573	1,583,833	49,844
Ending Balance (in shares) at Mar. 31, 2018			89,135
Beginning Balance at Dec. 31, 2017	6,589,454	221,932	$ 939	4,968,338	(124,049)	18,604	1,139,329	364,361
Beginning Balance (in shares) at Dec. 31, 2017			92,803
Adjusted Balance at Dec. 31, 2017	7,159,978		$ 939	4,968,338	(124,049)	18,604	1,709,853	364,361	221,932
Increase (Decrease) in Stockholders' Equity
Preferred dividends	(7,475)
Ending Balance at Jun. 30, 2018	6,242,056	221,932	$ 868	4,601,608	(124,049)	32,622	1,457,835	51,240
Ending Balance (in shares) at Jun. 30, 2018			85,725
Beginning Balance at Dec. 31, 2017	6,589,454	221,932	$ 939	4,968,338	(124,049)	18,604	1,139,329	364,361
Beginning Balance (in shares) at Dec. 31, 2017			92,803
Adjusted Balance at Dec. 31, 2017	7,159,978		$ 939	4,968,338	(124,049)	18,604	1,709,853	364,361	221,932
Ending Balance at Dec. 31, 2018	5,947,855		$ 847	4,508,685	(124,049)	15,108	1,278,998	46,334	221,932
Ending Balance (in shares) at Dec. 31, 2018			83,684
Beginning Balance at Mar. 31, 2018	6,537,629	221,932	$ 902	4,776,594	(124,049)	28,573	1,583,833	49,844
Beginning Balance (in shares) at Mar. 31, 2018			89,135
Increase (Decrease) in Stockholders' Equity
Net income	107,466						107,293	173
Other comprehensive loss	4,049					4,049
Preferred dividends	(3,737)						(3,737)
DRSPP proceeds (in shares)			0
DRSPP proceeds	22			22
Conversion of units of the Operating Partnership to common stock (in shares)			15
Conversion of units in the Operating Partnership for common stock	1,560			1,560
Reallocation of noncontrolling interest in the Operating Partnership	(8,138)						(8,138)
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings (in shares)			(1)
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings	4,988			4,988
Repurchases of common stock (in shares)			(3,479)
Repurchases of common stock	(338,347)		$ (35)	(186,463)			151,849
Proceeds from stock options exercised (in shares)			55
Proceeds from stock options exercised	4,908		$ 1	4,907
Contributions to consolidated joint venture interests	1,671							1,671
Deconsolidation of partially owned entity	0							0
Cash distributions to noncontrolling interests	(448)							(448)
Cash distributions declared (per common share, none of which represented a return of capital for federal income tax purposes)	(69,567)						(69,567)
Ending Balance at Jun. 30, 2018	6,242,056	221,932	$ 868	4,601,608	(124,049)	32,622	1,457,835	51,240
Ending Balance (in shares) at Jun. 30, 2018			85,725
Beginning Balance at Dec. 31, 2018	5,947,855		$ 847	4,508,685	(124,049)	15,108	1,278,998	46,334	221,932
Beginning Balance (in shares) at Dec. 31, 2018			83,684
Increase (Decrease) in Stockholders' Equity
Net income	47,767						47,530	237
Acquisition of subsidiary interest from noncontrolling interest	0
Other comprehensive loss	(19,113)					(19,113)
Preferred dividends	(3,738)						(3,738)
DRSPP proceeds (in shares)			1
DRSPP proceeds	47			47
Conversion of units of the Operating Partnership to common stock (in shares)			5
Conversion of units in the Operating Partnership for common stock	446			446
Reallocation of noncontrolling interest in the Operating Partnership	(28,932)						(28,932)
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings (in shares)			(20)
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings	4,835			4,835
Repurchases of common stock (in shares)			(398)
Repurchases of common stock	(34,243)		$ (4)	(21,432)			(12,807)
Contributions to consolidated joint venture interests	161							161
Cash distributions to noncontrolling interests	(208)							(208)
Cash distributions declared (per common share, none of which represented a return of capital for federal income tax purposes)	(70,554)						(70,554)
Ending Balance at Mar. 31, 2019	5,844,323		$ 843	4,492,581	(124,049)	(4,005)	1,210,497	46,524	221,932
Ending Balance (in shares) at Mar. 31, 2019			83,272
Beginning Balance at Dec. 31, 2018	5,947,855		$ 847	4,508,685	(124,049)	15,108	1,278,998	46,334	221,932
Beginning Balance (in shares) at Dec. 31, 2018			83,684
Increase (Decrease) in Stockholders' Equity
Preferred dividends	(7,475)
Ending Balance at Jun. 30, 2019	5,879,501	221,932	$ 835	4,451,209	(124,049)	(28,395)	1,288,390	69,579
Ending Balance (in shares) at Jun. 30, 2019			82,410
Beginning Balance at Mar. 31, 2019	5,844,323		$ 843	4,492,581	(124,049)	(4,005)	1,210,497	46,524	$ 221,932
Beginning Balance (in shares) at Mar. 31, 2019			83,272
Increase (Decrease) in Stockholders' Equity
Net income	162,702						164,840	(2,138)
Acquisition of subsidiary interest from noncontrolling interest	(25,791)			(515)				(25,276)
Other comprehensive loss	(24,390)					(24,390)
Preferred dividends	(3,737)						(3,737)
DRSPP proceeds (in shares)			2
DRSPP proceeds	216			216
Conversion of units of the Operating Partnership to common stock (in shares)
Conversion of units in the Operating Partnership for common stock	0
Reallocation of noncontrolling interest in the Operating Partnership	14,904						14,904
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings (in shares)			3
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings	5,698			5,698
Repurchases of common stock (in shares)			(867)
Repurchases of common stock	(75,070)		$ (8)	(46,771)			(28,291)
Contributions to consolidated joint venture interests	50,532							50,532
Deconsolidation of partially owned entity	0
Cash distributions to noncontrolling interests	(63)							(63)
Cash distributions declared (per common share, none of which represented a return of capital for federal income tax purposes)	(69,823)						(69,823)
Ending Balance at Jun. 30, 2019	$ 5,879,501	$ 221,932	$ 835	$ 4,451,209	$ (124,049)	$ (28,395)	$ 1,288,390	$ 69,579
Ending Balance (in shares) at Jun. 30, 2019			82,410