SCHEDULE III REAL ESTATE AND ACCUMULATED DEPRECIATION - Analysis of Carrying Amount of Real Estate Properties and Accumulated Depreciation (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			12 Months Ended
	Dec. 31, 2014	Jun. 30, 2014	Sep. 30, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Real Estate Properties
Balance at the beginning of the year				$ 5,537,165	$ 7,829,409	$ 7,244,232
Additions				70,963	231,485	1,041,655
Loss on asset impairment	(167,100)	(22,700)	(124,300)	(191,490)	(384,141)	(242,497)
Deconsolidation of SIR					(1,446,781)
Properties reclassified to discontinued operations					(552,024)	(174,562)
Properties reclassified to continuing operations				341,024
Disposals				(29,219)	(140,783)	(39,419)
Balance at the end of the year	5,728,443			5,728,443	5,537,165	7,829,409
Accumulated Depreciation
Balance at the beginning of the year				895,059	1,007,606	934,170
Additions				164,815	176,777	188,220
Loss on asset impairment				(6,423)	(185,795)	(73,865)
Deconsolidation of SIR					(56,023)
Properties reclassified to discontinued operations					(15,471)	(10,521)
Properties reclassified to continuing operations				5,724
Disposals				(28,730)	(32,035)	(30,398)
Balance at the end of the year	$ 1,030,445			$ 1,030,445	$ 895,059	$ 1,007,606