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
Net income	309,476	0	$ 0	$ 0	0	309,476	315	309,791
Change in unrealized loss on interest rate swap	0	416	0	0	0	416	0	416
Redeemable noncontrolling interests income	0	0	0	0	0	0	(185)	(185)
Dividends declared to common and preferred shares	(266,082)	0	0	0	0	(266,082)	0	(266,082)
Distributions to noncontrolling interests	0	0	0	0	0	0	(1,870)	(1,870)
Repurchase of common stock	0	0	$ 0	$ (51)	(75,075)	(75,126)	0	(75,126)
Repurchase of common stock (in shares)			0	(5,100)
Surrender of restricted stock	0	0	$ 0	$ (2)	(3,490)	(3,492)	0	(3,492)
Surrender of restricted stock (in shares)			0	(236)
Amortization of equity awards	0	0	$ 0	$ 0	9,329	9,329	0	9,329
Issuance of common stock	0	0	$ 0	$ 11	(11)	0	0	0
Issuance of common stock (in shares)			0	1,075
Exercise of common stock options	0	0	$ 0	$ 0	30	30	0	30
Exercise of common stock options (in shares)			0	3
Acquisition/deconsolidation of noncontrolling interests	0	0	$ 0	$ 0	1,203	1,203	(48,395)	(47,192)
Issuance of preferred stock	0	0	$ 2	$ 0	33,112	33,114	0	33,114
Issuance of preferred stock (in shares)			2	0
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
Balance at Mar. 31, 2018	(743,845)	(66)	$ 43	$ 4,249	6,164,185	5,424,566	77,836	5,502,402
Balance (in shares) at Mar. 31, 2018			43	424,900
Net income	165,386	0	$ 0	$ 0	0	165,386	423	165,809
Change in unrealized loss on interest rate swap	0	138	0	0	0	138	0	138
Redeemable noncontrolling interests income	0	0	0	0	0	0	(93)	(93)
Dividends declared to common and preferred shares	(132,522)	0	0	0	0	(132,522)	0	(132,522)
Distributions to noncontrolling interests	0	0	0	0	0	0	(398)	(398)
Repurchase of common stock	0	0	$ 0	$ (35)	(50,815)	(50,850)	0	(50,850)
Repurchase of common stock (in shares)			0	(3,500)
Surrender of restricted stock	0	0	$ 0	$ 0	(118)	(118)	0	(118)
Surrender of restricted stock (in shares)			0	(12)
Amortization of equity awards	0	0	$ 0	$ 0	4,610	4,610	0	4,610
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
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	217,196	0	$ 0	$ 0	0	217,196	869	218,065
Redeemable noncontrolling interests income	0	0	0	0	0	0	(185)	(185)
Dividends declared to common and preferred shares	(265,423)	0	0	0	0	(265,423)	0	(265,423)
Distributions to noncontrolling interests	0	0	0	0	0	0	(1,159)	(1,159)
Surrender of restricted stock	0	0	$ 0	$ (2)	(3,687)	(3,689)	0	(3,689)
Surrender of restricted stock (in shares)			0	(223)
Amortization of equity awards	0	0	$ 0	$ 0	9,714	9,714	0	9,714
Issuance of common stock	0	0	$ 0	$ 8	(8)	0	0	0
Issuance of common stock (in shares)			0	786
Exercise of common stock options	0	0	$ 0	$ 1	1,810	1,811	0	1,811
Exercise of common stock options (in shares)			0	142
Acquisition/deconsolidation of noncontrolling interests	0	0	$ 0	$ 0	489	489	(3,215)	(2,726)
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
Balance at Mar. 31, 2019	(804,241)	0	$ 43	$ 4,220	6,119,855	5,319,877	76,981	5,396,858
Balance (in shares) at Mar. 31, 2019			43	422,037
Net income	101,027	0	$ 0	$ 0	0	101,027	360	101,387
Redeemable noncontrolling interests income	0	0	0	0	0	0	(93)	(93)
Dividends declared to common and preferred shares	(132,720)	0	0	0	0	(132,720)	0	(132,720)
Distributions to noncontrolling interests	0	0	0	0	0	0	(474)	(474)
Surrender of restricted stock	0	0	$ 0	$ 0	(437)	(437)	0	(437)
Surrender of restricted stock (in shares)			0	(36)
Amortization of equity awards	0	0	$ 0	$ 0	4,536	4,536	0	4,536
Issuance of common stock	0	0	$ 0	$ 0	0	0	0	0
Issuance of common stock (in shares)			0	3
Exercise of common stock options	0	0	$ 0	$ 1	1,129	1,130	0	1,130
Exercise of common stock options (in shares)			0	90
Acquisition/deconsolidation of noncontrolling interests	0	0	$ 0	$ 0	489	489	(3,215)	(2,726)
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