Real Estate Properties (Details) (USD $)	0 Months Ended	1 Months Ended		3 Months Ended		6 Months Ended
	Jun. 27, 2014	Mar. 31, 2014	Jan. 31, 2013 property	Jun. 30, 2014 property sqft	Jun. 30, 2013 sqft	Jun. 30, 2014 property sqft	Jun. 30, 2013 sqft
Real estate properties information
Real estate improvements						$ 47,000,000
Number of Real Estate Properties Held for Sale				0		0
Number of Properties Sold			3
Number of buildings sold			18
Impairment Loss	2,400,000			(2,072,000)	(4,589,000)	(2,360,000)	(8,535,000)
Loss on early extinguishment of debt	3,300,000			(3,345,000)		(3,345,000)
Property square feet				42,920,000	68,263,000	42,920,000	68,263,000
Reversal of loss on asset impairment		4,800,000
CBD
Real estate properties information
Number of Properties Sold	1
Number of buildings sold	2
Number of Real Estate Properties Held for Use		2
Number of Buildings Held for Use		2
Suburban property
Real estate properties information
Number of Properties Sold	13
Number of buildings sold	41
Number of Real Estate Properties Held for Use		29
Number of Buildings Held for Use		65
CBD and suburban properties
Real estate properties information
Property square feet, sold	2,784,098
Aggregate sale price of properties sold, excluding closing costs	$ 215,900,000
Property square feet		5,641,450