Real Estate and Other Assets Held For Sale and Discontinued Operations (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
Assets, held for sale [Abstract]
Land held for development	$ 989		$ 989		$ 0
Net real estate assets	989		989		0
Prepaid expenses and other assets	43		43		0
Real estate and other assets, net, held for sale	1,032		1,032		0
Discontinued operations [Abstract]
Rental and other revenues	0	5,277	0	18,537
Operating expenses:
Rental property and other expenses	0	2,312	0	7,178
Depreciation and amortization	0	1,451	0	5,506
Total operating expenses	0	3,763	0	12,684
Income from discontinued operations	0	1,514	0	5,853
Impairment of real estate assets	0	0	0	(2,194)
Net gains on disposition of discontinued operations	0	37,946	384	52,353
Total discontinued operations	$ 0	$ 39,460	$ 384	$ 56,012
Raleigh, NC Office Properties Disposition (9/2014) [Member]
Operating expenses:
Number of land parcels included in real estate and other assets, net, held for sale	2		2