Discontinued Operations (Details 1) - Disposal Groups Including Discontinued Operations Name [Domain] - USD ($)	3 Months Ended			6 Months Ended
	Jun. 30, 2015	Mar. 31, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Disposal Group Including Discontinued Operation Unclassified Balance Sheet Disclosures Abstract
Real Estate, Net	$ 27,205,000			$ 27,205,000		$ 2,028,677,000
Other Assets	7,686,000			7,686,000		209,797,000
Assets related to discontinued operations	34,891,000			34,891,000		2,238,474,000
Mortgages Payable	0			0		1,288,535,000
Other Liabilities (primarily deferred revenue in 2014)	12,611,000			12,611,000		222,827,000
Liabilities related to discontinued operations	12,611,000			12,611,000		$ 1,511,362,000
(Loss) income from discontinued operations:
Total revenues	1,573,000		$ 96,157,000	21,531,000	$ 202,720,000
Total expenses	2,020,000		65,879,000	15,393,000	141,904,000
Income from discontinued operations before gain on sale of real estate	(447,000)		30,278,000	6,138,000	60,816,000
Transaction related costs	(327,000)		(3,016,000)	(22,972,000)	(3,515,000)
Net gain on sale of lease position in Geary Street, CA	0		0	21,376,000	0
Net gains on sale of real estate	0	$ 3,675,000	0	10,867,000	0
Impairment losses	0		0	(256,000)	(20,842,000)
Pretax (loss) income from discontinued operations	(774,000)		27,262,000	15,153,000	36,459,000
Income tax expense	0		(319,000)	(86,000)	(1,050,000)
(Loss) income from Discontinued Operations	(774,000)		26,943,000	15,067,000	35,409,000
Cash flows related to discontinued Operations:
Cash flows from operating activities, discontinued operations				(35,738,000)	55,065,000
Cash flows from investing activities, discontinued operations				310,069,000	(59,141,000)
Other Segment [Member]
(Loss) income from discontinued operations:
(Loss) income from Discontinued Operations	$ (774,000)		$ 21,024,000	$ 15,067,000	$ 23,623,000