Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Class A Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Accumulated Deficit [Member]	Stockholders' Equity [Member]	Non-Controlling Interests [Member]
Balance at Dec. 31, 2015	$ 2,505,731	$ 937	$ 3,070,200	$ (32,758)	$ (545,791)	$ 2,492,588	$ 13,143
Shares of class A common stock issued, net	8	8				8
Restricted class A common stock earned	19,045		19,045			19,045
Dividends reinvested	27		377		(350)	27
Deferred directors' compensation	375		375			375
Other comprehensive income (loss)	(23,444)			(23,444)		(23,444)
Net income	246,440				238,297	238,297	8,143
Dividends declared on common stock, $2.48 per share	(233,293)				(233,293)	(233,293)
Distributions to non-controlling interests	(21,286)						(21,286)
Balance at Dec. 31, 2016	2,493,603	945	3,089,997	(56,202)	(541,137)	2,493,603
Shares of class A common stock issued, net	391,568	134	391,434			391,568
Restricted class A common stock earned	23,584		23,584			23,584
Issuance of convertible notes	964		964			964
Dividends reinvested	44		444		(400)	44
Deferred directors' compensation	438		438			438
Other comprehensive income (loss)	26,496			26,496		26,496
Net income	217,968				217,631	217,631	337
Dividends declared on common stock, $2.48 per share	(243,262)				(243,262)	(243,262)
Contributions from non-controlling interests	12,165						12,165
Distributions to non-controlling interests	(6,162)						(6,162)
Balance at Dec. 31, 2017	2,917,406	1,079	3,506,861	(29,706)	(567,168)	2,911,066	6,340
Shares of class A common stock issued, net	476,430	155	476,275			476,430
Restricted class A common stock earned	27,644		27,644			27,644
Issuance of convertible notes	1,462		1,462			1,462
Conversion of convertible notes	(46,720)		(46,720)			(46,720)
Dividends reinvested	53		518		(465)	53
Deferred directors' compensation	500		500			500
Other comprehensive income (loss)	(4,516)			(4,516)		(4,516)
Net income	285,813				285,078	285,078	735
Dividends declared on common stock, $2.48 per share	(286,873)				(286,873)	(286,873)
Contributions from non-controlling interests	9,315						9,315
Distributions to non-controlling interests	(5,907)						(5,907)
Balance at Dec. 31, 2018	$ 3,374,607	$ 1,234	$ 3,966,540	$ (34,222)	$ (569,428)	$ 3,364,124	$ 10,483