Condensed Consolidated Statements of Changes in Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Parent [Member]	Noncontrolling Interest [Member]	Total
Balance at Dec. 31, 2017	$ (754,375)	$ (344)	$ 41	$ 4,256	$ 6,152,764	$ 5,402,342	$ 127,903	$ 5,530,245
Balance (in shares) at Dec. 31, 2017			41	425,646
Contributions from noncontrolling interests	0	0	$ 0	$ 0	0	0	109	109
Net income	409,634	0	0	0	0	409,634	882	410,516
Change in unrealized value on interest rate swap								344
Redeemable noncontrolling interests income	0	0	0	0	0	0	(279)	(279)
Dividends declared to common and preferred shares	(398,605)	0	0	0	0	(398,605)	0	(398,605)
Distributions to noncontrolling interests	0	0	0	0	0	0	(2,373)	(2,373)
Issuance of common stock	0	0	$ 0	$ 11	(11)	0	0	0
Issuance of common stock (in shares)			0	1,101
Surrender of restricted common stock	0	0	$ 0	$ (2)	(4,288)	(4,290)	0	(4,290)
Surrender of restricted common stock (in shares)			0	(291)
Exercise of common stock options	0	0	$ 0	$ 0	487	487	0	487
Exercise of common stock options (in shares)			0	35
Amortization of equity awards	0	0	$ 0	$ 0	13,065	13,065	0	13,065
Adjustment of redeemable noncontrolling interests to estimated fair value					(3,918)	(3,918)		(3,918)
Change in unrealized loss on interest rate swap	0	344	0	0	0	344	0	344
Repurchase of common stock	0	0	$ 0	$ (51)	(75,075)	(75,126)	0	(75,126)
Repurchase of common stock (in shares)			0	(5,100)
Issuance of preferred stock	0	0	$ 2	$ 0	33,112	33,114	0	33,114
Issuance of preferred stock (in shares)			2	0
Acquisition/deconsolidation of noncontrolling interests	0	0	$ 0	$ 0	1,203	1,203	(48,395)	(47,192)
Balance at Sep. 30, 2018	(743,346)	0	$ 43	$ 4,214	6,117,339	5,378,250	77,847	5,456,097
Balance (in shares) at Sep. 30, 2018			43	421,391
Balance at Jun. 30, 2018	(710,981)	72	$ 43	$ 4,214	6,117,862	5,411,210	77,768	5,488,978
Balance (in shares) at Jun. 30, 2018			43	421,388
Contributions from noncontrolling interests	0	0	$ 0	$ 0	0	0	109	109
Net income	100,158	0	0	0	0	100,158	567	100,725
Change in unrealized value on interest rate swap	0	(72)	0	0	0	(72)	0	(72)
Redeemable noncontrolling interests income	0	0	0	0	0	0	(94)	(94)
Dividends declared to common and preferred shares	(132,523)	0	0	0	0	(132,523)	0	(132,523)
Distributions to noncontrolling interests	0	0	0	0	0	0	(503)	(503)
Issuance of common stock	0	0	$ 0	$ 0	0	0	0	0
Issuance of common stock (in shares)			0	26
Surrender of restricted common stock	0	0	$ 0	$ 0	(798)	(798)	0	(798)
Surrender of restricted common stock (in shares)			0	(55)
Exercise of common stock options	0	0	$ 0	$ 0	457	457	0	457
Exercise of common stock options (in shares)			0	32
Amortization of equity awards	0	0	$ 0	$ 0	3,736	3,736	0	3,736
Adjustment of redeemable noncontrolling interests to estimated fair value	0	0	0	0	(3,918)	(3,918)	0	(3,918)
Balance at Sep. 30, 2018	(743,346)	0	$ 43	$ 4,214	6,117,339	5,378,250	77,847	5,456,097
Balance (in shares) at Sep. 30, 2018			43	421,391
Balance at Dec. 31, 2018	(787,707)	0	$ 43	$ 4,214	6,117,254	5,333,804	77,249	5,411,053
Balance (in shares) at Dec. 31, 2018			43	421,389
Net income	301,186	0	$ 0	$ 0	0	301,186	2,332	303,518
Change in unrealized value on interest rate swap								0
Redeemable noncontrolling interests income	0	0	0	0	0	0	(279)	(279)
Dividends declared to common and preferred shares	(397,220)	0	0	0	0	(397,220)	0	(397,220)
Distributions to noncontrolling interests	0	0	0	0	0	0	(3,499)	(3,499)
Issuance of common stock	0	0	$ 0	$ 8	(8)	0	0	0
Issuance of common stock (in shares)			0	838
Surrender of restricted common stock	0	0	$ 0	$ (2)	(3,946)	(3,948)	0	(3,948)
Surrender of restricted common stock (in shares)			0	(236)
Exercise of common stock options	0	0	$ 0	$ 2	3,349	3,351	0	3,351
Exercise of common stock options (in shares)			0	239
Amortization of equity awards	0	0	$ 0	$ 0	14,219	14,219	0	14,219
Redemption of preferred stock	0	0	$ (14)	$ 0	(349,986)	(350,000)	0	(350,000)
Redemption of preferred stock (in shares)			(14)	0
Acquisition/deconsolidation of noncontrolling interests	0	0	$ 0	$ 0	489	489	(3,215)	(2,726)
Balance at Sep. 30, 2019	(883,741)	0	$ 29	$ 4,222	5,781,371	4,901,881	72,588	4,974,469
Balance (in shares) at Sep. 30, 2019			29	422,230
Balance at Jun. 30, 2019	(835,934)	0	$ 43	$ 4,221	6,125,572	5,293,902	73,559	5,367,461
Balance (in shares) at Jun. 30, 2019			43	422,094
Net income	83,990	0	$ 0	$ 0	0	83,990	1,463	85,453
Change in unrealized value on interest rate swap								0
Redeemable noncontrolling interests income	0	0	0	0	0	0	(94)	(94)
Dividends declared to common and preferred shares	(131,797)	0	0	0	0	(131,797)	0	(131,797)
Distributions to noncontrolling interests	0	0	0	0	0	0	(2,340)	(2,340)
Issuance of common stock	0	0	$ 0	$ 0	0	0	0	0
Issuance of common stock (in shares)			0	52
Surrender of restricted common stock	0	0	$ 0	$ 0	(259)	(259)	0	(259)
Surrender of restricted common stock (in shares)			0	(14)
Exercise of common stock options	0	0	$ 0	$ 1	1,539	1,540	0	1,540
Exercise of common stock options (in shares)			0	98
Amortization of equity awards	0	0	$ 0	$ 0	4,505	4,505	0	4,505
Redemption of preferred stock	0	0	$ (14)	$ 0	(349,986)	(350,000)	0	(350,000)
Redemption of preferred stock (in shares)			(14)	0
Balance at Sep. 30, 2019	$ (883,741)	$ 0	$ 29	$ 4,222	$ 5,781,371	$ 4,901,881	$ 72,588	$ 4,974,469
Balance (in shares) at Sep. 30, 2019			29	422,230