Dispositions (Details 1) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Dispositions [Abstract]
Real Estate, Net	$ 3,111		$ 3,111		$ 29,561
Other Assets	5,567		5,567		7,459
Assets related to discontinued operations	8,678		8,678		37,020
Other Liabilities	8,104		8,104		12,470
Liabilities related to discontinued operations	8,104		8,104		$ 12,470
Income (loss) from discontinued operations:
Total revenues	947	$ 1,983	2,129	$ 22,279
Total expenses	682	2,020	1,148	15,393
Income (loss) from discontinued operations before gain on sale of real estate	265	(37)	981	6,886
Net gains on sale of real estate	2,210	0	2,210	10,867
UE spin off transaction related costs	0	(327)	0	(22,972)
Net gain on sale of lease position in Geary Street, CA	0	0	0	21,376
Impairment losses	0	0	0	(256)
Pretax income from discontinued operations	2,475	(364)	3,191	15,901
Income tax expense	0	0	0	(86)
Income (loss) from discontinued operations	2,475	(364)	3,191	15,815
Cash flows related to discontinued Operations:
Cash flows from operating activities			(4,685)	(35,738)
Cash flows from investing activities			0	310,069
Washington DC Segment [Member]
Income (loss) from discontinued operations:
Income (loss) from discontinued operations	0	0	0	0
New York Segment [Member]
Income (loss) from discontinued operations:
Income (loss) from discontinued operations	$ 0	$ 0	$ 0	$ 0