Consolidated Statements of Changes in Equity - USD ($) $ 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, 2015		$ (572,335)	$ 5,588		$ 32	$ 4,134	$ 5,608,881	$ 5,046,300	$ 135,651	$ 5,181,951
Balance (in shares) at Dec. 31, 2015					32,000	413,431,000
Contributions/deemed contributions from noncontrolling interests									16,667	16,667
Net income		378,850						378,850	7,288	386,138
Change in unrealized gains/losses related to available-for-sale securities			8					8		8
Change in unrealized value on interest rate swaps			451					451		451
Change in foreign currency translation adjustment			(281)					(281)		(281)
Redeemable noncontrolling interests income									(4,349)	(4,349)
Dividends declared to common and preferred shares		(483,382)						(483,382)		(483,382)
Distributions to noncontrolling interests									(8,522)	(8,522)
Issuance of common stock						$ 107	286,314	286,421		286,421
Depositary Shares Issued (in shares)						10,711,000
Surrender of restricted stock						$ (3)	(7,005)	(7,008)		(7,008)
Surrender of restricted stock (in shares)						(276,000)
Exercise of common stock options						$ 12	21,048	21,060		$ 21,060
Exercise of common stock options (in shares)						1,168,000				1,167,819
Amortization of equity awards							13,720	13,720		$ 13,720
Balance at Dec. 31, 2016		(676,867)	5,766		$ 32	$ 4,250	5,922,958	5,256,139	146,735	$ 5,402,874
Repurchase of common stock (in shares)										(257,477)
Balance (in shares) at Dec. 31, 2016					32,000	425,034,000
Contributions/deemed contributions from noncontrolling interests									48,877	$ 48,877
Net income		426,075						426,075	13,596	439,671
Change in unrealized gains/losses related to available-for-sale securities			(1,542)					(1,542)		(1,542)
Change in unrealized value on interest rate swaps			631					631		631
Change in foreign currency translation adjustment			(6,335)					(6,335)		(6,335)
Redeemable noncontrolling interests income									(1,297)	(1,297)
Dividends declared to common and preferred shares		(510,545)						(510,545)		(510,545)
Distributions to noncontrolling interests									(13,995)	(13,995)
Issuance of common stock						$ 8	(8)
Depositary Shares Issued (in shares)						776,000
Surrender of restricted stock						$ (2)	(5,697)	(5,699)		(5,699)
Surrender of restricted stock (in shares)						(248,000)
Exercise of common stock options							1,526	1,526		$ 1,526
Exercise of common stock options (in shares)						84,000				83,863
Amortization of equity awards							18,983	18,983		$ 18,983
Issuance of preferred stock					$ 18		439,401	439,419		439,419
Issuance of preferred stock (in shares)					18,000
Redemption of preferred stock					$ (9)		(224,991)	(225,000)		(225,000)
Redemption of preferred stock (in shares)					(9,000)
Redemption/conversion of noncontrolling interests							592	592	(66,013)	(65,421)
Balance at Dec. 31, 2017		(761,337)	(1,480)		$ 41	$ 4,256	6,152,764	5,394,244	127,903	$ 5,522,147
Repurchase of common stock (in shares)										(232,304)
Balance (in shares) at Dec. 31, 2017					41,000	425,646,000
Adoption of accounting policy | Accounting Standards Update 2017-05 [Member]	[1]	8,098						8,098		$ 8,098
Adoption of accounting policy | Accounting Standards Update 2016-01 [Member]	[1]	(1,136)	1,136
Contributions/deemed contributions from noncontrolling interests									109	109
Net income		497,795						497,795	668	498,463
Change in unrealized gains/losses related to available-for-sale securities
Change in unrealized value on interest rate swaps			344					344		344
Redeemable noncontrolling interests income									(373)	(373)
Dividends declared to common and preferred shares		(531,127)						(531,127)		(531,127)
Distributions to noncontrolling interests									(2,663)	(2,663)
Issuance of common stock						$ 11	(11)
Depositary Shares Issued (in shares)						1,101,000
Surrender of restricted stock						$ (3)	(4,357)	(4,360)		(4,360)
Surrender of restricted stock (in shares)						(300,000)
Exercise of common stock options						$ 1	591	592		$ 592
Exercise of common stock options (in shares)						42,000				42,259
Amortization of equity awards							16,548	16,548		$ 16,548
Issuance of preferred stock					$ 2		33,112	33,114		33,114
Issuance of preferred stock (in shares)					2,000
Balance at Dec. 31, 2018		(787,707)			$ 43	$ 4,214	6,117,254	5,333,804	77,249	5,411,053
Balance at Dec. 31, 2017		(754,375)	(344)	[2]	41	4,256	6,152,764	5,402,342	127,903	5,530,245
Repurchase of common stock						$ (51)	(75,075)	(75,126)		$ (75,126)
Repurchase of common stock (in shares)						(5,100,000)				(278,566)
Acquisition/deconsolidation of noncontrolling interests							1,203	1,203	(48,395)	$ (47,192)
Adjustment of redeemable noncontrolling interests to estimated fair value							$ (7,521)	$ (7,521)		$ (7,521)
Balance (in shares) at Dec. 31, 2018					43,000	421,389,000

[1] Represents the impact of change in accounting principles for its respective Accounting Standard Updates ("ASU"). See Footnote 1 of the Notes to Consolidated Financial Statements for additional disclosure.

[2] Represents the balance as adjusted for the impact of change in accounting principles for ASU 2016-01. See Footnote 1 of the Notes to the Consolidated Financial Statements for additional disclosure.