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	144,090					144,090	(108)	143,982
Change in unrealized loss on interest rate swap		278				278		278
Redeemable noncontrolling interests income							(92)	(92)
Dividends declared to common and preferred shares	(133,560)					(133,560)		(133,560)
Distributions to noncontrolling interests							(1,472)	(1,472)
Issuance of common stock				$ 11	(11)
Issuance of common stock (in shares)				1,075
Repurchase of common stock				$ (16)	(24,260)	(24,276)		(24,276)
Repurchase of common stock (in shares)				(1,600)
Surrender of restricted stock				$ (2)	(3,372)	(3,374)		(3,374)
Surrender of restricted stock (in shares)				(224)
Exercise of common stock options					30	30		30
Exercise of common stock options (in shares)				3
Amortization of equity awards					4,719	4,719		4,719
Issuance of preferred stock			$ 2		33,112	33,114		33,114
Issuance of preferred stock (in shares)			2
Acquisition/deconsolidation of noncontrolling interests					1,203	1,203	(48,395)	(47,192)
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
Balance at Dec. 31, 2018	(787,707)		$ 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	116,169					116,169	509	116,678
Redeemable noncontrolling interests income							(92)	(92)
Dividends declared to common and preferred shares	(132,703)					(132,703)		(132,703)
Distributions to noncontrolling interests							(685)	(685)
Issuance of common stock				$ 8	(8)
Issuance of common stock (in shares)				783
Surrender of restricted stock				$ (2)	(3,250)	(3,252)		(3,252)
Surrender of restricted stock (in shares)				(187)
Exercise of common stock options					681	681		681
Exercise of common stock options (in shares)				52
Amortization of equity awards					5,178	5,178		5,178
Balance at Mar. 31, 2019	$ (804,241)		$ 43	$ 4,220	$ 6,119,855	$ 5,319,877	$ 76,981	$ 5,396,858
Balance (in shares) at Mar. 31, 2019			43	422,037