Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]	Stockholders' Equity [Member]	Non-Controlling Interests [Member]	Class A Common Stock [Member] Common Stock [Member]
Balance at Dec. 31, 2014	$ 1,500,886	$ 2,027,404	$ (15,024)	$ (547,592)	$ 1,465,371	$ 35,515	$ 583
Shares of class A common stock issued, net	1,029,557	1,029,208			1,029,557		349
Restricted class A common stock earned	6,504	6,504			6,504
Dividends reinvested	7	125		(118)	7
Deferred directors' compensation	188	188			188
Other comprehensive loss	(4,308)		(4,308)		(4,308)
Net income	78,512			64,679	64,679	13,833
Dividends declared on common stock	(78,874)			(78,874)	(78,874)
Distributions to non-controlling interests	(36,985)					(36,985)
Balance at Jun. 30, 2015	2,495,487	3,063,429	(19,332)	(561,905)	2,483,124	12,363	932
Balance at Dec. 31, 2015	2,505,731	3,070,200	(32,758)	(545,791)	2,492,588	13,143	937
Shares of class A common stock issued, net	2				2		2
Restricted class A common stock earned	9,335	9,335			9,335
Dividends reinvested	13	180		(167)	13
Deferred directors' compensation	188	188			188
Other comprehensive loss	(9,385)		(9,385)		(9,385)
Net income	126,649			120,128	120,128	6,521
Dividends declared on common stock	(116,452)			(116,452)	(116,452)
Distributions to non-controlling interests	(6,987)					(6,987)
Balance at Jun. 30, 2016	$ 2,509,094	$ 3,079,903	$ (42,143)	$ (542,282)	$ 2,496,417	$ 12,677	$ 939