Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Income (loss) [Member]	Accumulated Deficit [Member]	Stockholders' Equity [Member]	Non-Controlling Interests [Member]	Class A Common Stock [Member] Common Stock [Member]
Balance at Dec. 31, 2013	$ 756,750	$ 1,252,986	$ 798	$ (536,170)	$ 717,909	$ 38,841	$ 295
Shares of class A common stock issued, net	763,407	763,123			763,407		284
Restricted class A common stock earned	5,552	5,554			5,552		(2)
Dividends reinvested		149		(149)
Deferred directors' compensation	281	281			281
Other comprehensive loss	(7,003)		(7,003)		(7,003)
Net income	75,157			68,555	68,555	6,602
Dividends declared on common stock	(70,962)			(70,962)	(70,962)
Distributions to non-controlling interests	(13,323)					(13,323)
Balance at Sep. 30, 2014	1,509,859	2,022,093	(6,205)	(538,726)	1,477,739	32,120	577
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	1,029,535	1,029,186			1,029,535		349
Restricted class A common stock earned	9,599	9,599			9,599
Dividends reinvested	13	192		(179)	13
Deferred directors' compensation	281	281			281
Other comprehensive loss	(12,564)		(12,564)		(12,564)
Net income	146,288			131,564	131,564	14,724
Dividends declared on common stock	(136,674)			(136,674)	(136,674)
Distributions to non-controlling interests	(37,202)					(37,202)
Balance at Sep. 30, 2015	$ 2,500,162	$ 3,066,662	$ (27,588)	$ (552,881)	$ 2,487,125	$ 13,037	$ 932