Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013		Dec. 31, 2013
Summary of Net Property Operations Income by Segment
Rental income	$ 92,975		$ 91,620		$ 283,157		$ 277,936
Straight line adjustment	930		1,763		3,143		4,526
Tenant recovery income	15,055		16,669		50,396		53,459
Other property income	1,819		2,114		6,766		5,501
Lodging income	231,044		156,670		696,587		446,791
Total income	341,823		268,836		1,040,049		788,213
Operating expenses	197,375		143,713		585,393		411,686
Net operating income	144,448		125,123		454,656		376,527
Non allocated expenses	(100,563)	[1]	(88,389)	[2]	(288,003)	[2]	(264,998)	[2]
Other income and expenses	1,418	[3]	(29,747)	[3]	(57,253)	[3]	(85,380)	[3]
Equity in loss of unconsolidated entities	(2,089)	[4]	(2,471)	[4]	4,843	[5]	5,005	[5]
Provision for asset impairment	(2,337)	[6]	(39,942)	[7]	(80,281)	[8]	(225,009)	[9]
Net income (loss) from continuing operations	40,877		(35,426)		33,962		(193,855)
Net income from discontinued operations	11,683		272,967		158,577		403,136
Less: net income attributable to noncontrolling interests	(8)		(8)		(16)		(16)
Net income attributable to Company	52,552		237,533		192,523		209,265
Total assets	8,281,773				8,281,773				9,662,464
Real Estate Assets, Net	6,021,773	[10]			6,021,773	[10]
Non-Segmented Assets	2,260,000	[11]			2,260,000	[11]
Capital Expenditures					41,124
Retail [Member]
Summary of Net Property Operations Income by Segment
Rental income	50,671		51,180		152,971		162,977
Straight line adjustment	1,579		1,038		3,942		4,380
Tenant recovery income	14,064		15,108		45,433		48,801
Other property income	663		1,271		3,467		3,196
Total income	66,977		68,597		205,813		219,354
Operating expenses	21,630		21,691		65,872		69,529
Net operating income	45,347		46,906		139,941		149,825
Provision for asset impairment			(11,723)				(21,179)
Provision for asset impairment, properties affected			3				4
Real Estate Assets, Net	2,084,705				2,084,705
Capital Expenditures					12,865
Lodging [Member]
Summary of Net Property Operations Income by Segment
Rental income	0		0		0		0
Straight line adjustment	0		0		0		0
Tenant recovery income	0		0		0		0
Other property income	0		0		0		0
Lodging income	231,044		156,670		696,587		446,791
Total income	231,044		156,670		696,587		446,791
Operating expenses	160,534		110,264		481,025		311,931
Net operating income	70,510		46,406		215,562		134,860
Provision for asset impairment	(1,667)	[6]	(26,175)		(4,665)		(26,175)
Provision for asset impairment, properties affected	1		2		2		2
Real Estate Assets, Net	2,616,032				2,616,032
Capital Expenditures					26,388
Student Housing [Member]
Summary of Net Property Operations Income by Segment
Rental income	17,587		15,022		51,896		38,360
Straight line adjustment	17		154		193		261
Tenant recovery income	134		114		400		347
Other property income	1,119		768		3,119		2,009
Total income	18,857		16,058		55,608		40,977
Operating expenses	11,564		7,360		25,636		17,138
Net operating income	7,293		8,698		29,972		23,839
Real Estate Assets, Net	622,158				622,158
Capital Expenditures					231
Non Core [Member]
Summary of Net Property Operations Income by Segment
Rental income	24,717		25,418		78,290		76,599
Straight line adjustment	(666)		571		(992)		(115)
Tenant recovery income	857		1,447		4,563		4,311
Other property income	37		75		180		296
Total income	24,945		27,511		82,041		81,091
Operating expenses	3,647		4,398		12,860		13,088
Net operating income	21,298		23,113		69,181		68,003
Provision for asset impairment	(670)	[6]	(2,044)		(75,616)		(177,655)
Provision for asset impairment, properties affected	1		4		5		11
Real Estate Assets, Net	698,878				698,878
Capital Expenditures					$ 1,640

[1] Non-allocated expenses consists of general and administrative expenses and depreciation and amortization.

[2] Non-allocated expenses consists of general and administrative expenses, Business Manager management fee and depreciation and amortization.

[3] Other income and expenses consists of gain on sale of investment properties, interest and dividend income, interest expense, other income, realized gain on sale of marketable securities, net, and income tax expense.

[4] Equity in loss of unconsolidated entities includes the gain, (loss) and (impairment) of investment in unconsolidated entities.

[5] Equity in earnings of unconsolidated entities includes the gain, (loss) and (impairment) of investment in unconsolidated entities.

[6] Total provision for asset impairment included $1,667 related to one lodging property and $670 related to one non-core property.

[7] Total provision for asset impairment included $26,175 related to two lodging properties, $11,723 related to three retail properties and $2,044 related to four non-core properties.

[8] Total provision for asset impairment included $4,665 related to two lodging properties and $75,616 related to five non-core properties.

[9] Total provision for asset impairment included $26,175 related to two lodging properties, $21,179 related to four retail properties and $177,655 related to eleven non-core properties.

[10] Real estate assets includes intangible assets, net of amortization.

[11] Construction in progress is included as non-segmented assets.