CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Series D	Series E	Cumulative Preferred Distributions	Common Stock	Cumulative Common Distributions	Additional Paid-in Capital	Cumulative Net Income	Cumulative Other Comprehensive Income (Loss)	Noncontrolling Interest in Consolidated Subsidiary
Net income (loss)	$ (156,967)							$ (177,060)		$ 20,093
Balance at Dec. 31, 2012	3,501,468	$ 368,270	$ 265,391	$ (529,367)	$ 838	$ (2,972,569)	$ 3,585,400	2,386,900	$ 565	396,040
Balance (in shares) at Dec. 31, 2012		15,180,000	11,000,000		83,804,068
Comprehensive income (loss):
Unrealized loss on derivative instrument	4,918								4,918
Foreign currency translation adjustments	(43,718)								(43,718)
Equity in unrealized income of an investee	(132)								(96)	(36)
Total comprehensive income (loss)	(195,899)
Issuance of shares, net	626,809				$ 345		626,506			(42)
Issuance of shares, net (in shares)					34,500,000
Share grants	1,821				$ 1		1,536			284
Share grants (in shares)					82,850
Adjustments to noncontrolling interest resulting from changes in ownership of a subsidiary	0						32			(32)
Distributions	(169,169)			(44,604)		(109,702)
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	(14,863)
Deconsolidation of a subsidiary	(401,444)									(401,444)
Balance at Dec. 31, 2013	3,363,586	$ 368,270	$ 265,391	(573,971)	$ 1,184	(3,082,271)	4,213,474	2,209,840	(38,331)	0
Balance (in shares) at Dec. 31, 2013		15,180,000	11,000,000		118,386,918
Net income (loss)	24,012							24,012		0
Comprehensive income (loss):
Unrealized loss on derivative instrument	7,407								7,407
Foreign currency translation adjustments	(22,270)								(22,270)
Equity in unrealized income of an investee	(22)								(22)	0
Total comprehensive income (loss)	9,127
Issuance of shares, net	2,402				$ 0		2,402			0
Issuance of shares, net (in shares)					90,135
Share grants	6,160				$ 8		6,152
Share grants (in shares)					717,727
Distributions	(61,692)			(32,095)		(29,597)
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	0
Redemption of shares	0	$ (249,004)		(16,205)	$ 104		265,105
Redemption of shares (in shares)		10,264,503			10,412,499
Balance at Dec. 31, 2014	$ 3,319,583	$ 119,266	$ 265,391	(622,271)	$ 1,296	(3,111,868)	4,487,133	2,233,852	(53,216)	0
Balance (in shares) at Dec. 31, 2014	129,607,279	4,915,497	11,000,000		129,607,279
Net income (loss)	$ 99,857							99,857		0
Comprehensive income (loss):
Unrealized loss on derivative instrument	612								612
Foreign currency translation adjustments	48,917								48,917
Equity in unrealized income of an investee	0
Total comprehensive income (loss)	149,386
Issuance of shares, net	0				$ 0		0			0
Stock Repurchased During Period, Shares					(3,410,300)
Stock Repurchased During Period, Value	(87,983)				$ (35)		(87,948)
Issuance of shares, net (in shares)					0
Share grants	15,425				$ 2		15,423
Share grants (in shares)					152,791
Distributions	(27,924)			(27,924)		0
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	0
Redemption of shares	0	$ (3)		0	$ 0		3
Redemption of shares (in shares)		301			144
Balance at Dec. 31, 2015	$ 3,368,487	$ 119,263	$ 265,391	$ (650,195)	$ 1,263	$ (3,111,868)	$ 4,414,611	$ 2,333,709	$ (3,687)	$ 0
Balance (in shares) at Dec. 31, 2015	126,349,914	4,915,196	11,000,000		126,349,914