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, 2016	$ 2,493,603	$ 945	$ 3,089,997	$ (56,202)	$ (541,137)	$ 2,493,603
Shares of class A common stock issued, net	3	3				3
Restricted class A common stock earned	17,493		17,493			17,493
Issuance of convertible notes	964		964			964
Dividends reinvested	31		327		(296)	31
Deferred directors' compensation	313		313			313
Other comprehensive income	23,840			23,840		23,840
Net income	159,829				159,741	159,741	$ 88
Dividends declared on common stock	(176,374)				(176,374)	(176,374)
Contributions to non-controlling interests	6,090						6,090
Balance at Sep. 30, 2017	2,525,792	948	3,109,094	(32,362)	(558,066)	2,519,614	6,178
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	369,790	118	369,672			369,790
Restricted class A common stock earned	20,110		20,110			20,110
Issuance of convertible notes	1,462		1,462			1,462
Conversion of convertible notes	(20)		(20)			(20)
Dividends reinvested	39		381		(342)	39
Deferred directors' compensation	375		375			375
Other comprehensive income	(3,143)			(3,143)		(3,143)
Net income	211,917				211,436	211,436	481
Dividends declared on common stock	(210,343)				(210,343)	(210,343)
Contributions from non-controlling interests	4,500						4,500
Distributions to non-controlling interests	(4,100)						(4,100)
Balance at Sep. 30, 2018	$ 3,307,993	$ 1,197	$ 3,898,841	$ (32,849)	$ (566,417)	$ 3,300,772	$ 7,221