Annual report pursuant to Section 13 and 15(d)

Fair Value Measurements (Details 3)

v3.3.1.900
Fair Value Measurements (Details 3)
$ in Thousands
 12 Months Ended
Dec. 31, 2015
USD ($)
Dec. 31, 2014
USD ($)
Dec. 31, 2013
USD ($)
Property
Fair value of impaired properties and other assets      
Impairment losses $ 23,289 $ 1,416 $ 5,857
Exit costs included in impairment losses in connection with dispositions 0 0 979
Fair value measurement on a recurring basis [Member]      
Fair value of impaired properties and other assets      
Assets 5,816 6,156  
Fair value measurement on a nonrecurring basis [Member]      
Fair value of impaired properties and other assets      
Exit costs included in impairment losses in connection with dispositions     419
Fair value measurement on a nonrecurring basis [Member] | Discontinued Operations [Member]      
Fair value of impaired properties and other assets      
Impairment losses     15,200
Real Estate Investment Properties, Net [Member] | Fair value measurement on a nonrecurring basis [Member]      
Fair value of impaired properties and other assets      
Impairment losses 23,500 $ 1,400  
Assets 13,850    
Real Estate Investment Properties, Net [Member] | Fair value measurement on a nonrecurring basis [Member] | Significant Unobservable Inputs (Level 3) [Member]      
Fair value of impaired properties and other assets      
Assets 13,850    
Real Estate Investment Properties, Net [Member] | Fair value measurement on a nonrecurring basis [Member] | Indicative Bids [Member] | Significant Unobservable Inputs (Level 3) [Member]      
Fair value of impaired properties and other assets      
Assets 24,423    
Real Estate Investment Properties, Net [Member] | Fair value measurement on a nonrecurring basis [Member] | Comparable Sales Price [Member] | Significant Unobservable Inputs (Level 3) [Member]      
Fair value of impaired properties and other assets      
Assets 10,850    
Real Estate Investment Properties, Net [Member] | Fair value measurement on a nonrecurring basis [Member] | Colorado Springs [Member]      
Fair value of impaired properties and other assets      
Impairment losses 12,800    
Real Estate Investment Properties, Net [Member] | Fair value measurement on a nonrecurring basis [Member] | Aberdeen, Maryland [Member]      
Fair value of impaired properties and other assets      
Impairment losses 6,600    
Real Estate Investment Properties, Net [Member] | Fair value measurement on a nonrecurring basis [Member] | White Marsh, Maryland [Member]      
Fair value of impaired properties and other assets      
Impairment losses 2,600    
Real Estate Investment Properties, Net [Member] | Fair value measurement on a nonrecurring basis [Member] | Land controlled for future development [Member] | Northern Virginia [Member]      
Fair value of impaired properties and other assets      
Impairment losses 1,300    
Assets Held-for-sale, Net [Member] | Fair value measurement on a nonrecurring basis [Member]      
Fair value of impaired properties and other assets      
Assets 21,423    
Assets Held-for-sale, Net [Member] | Fair value measurement on a nonrecurring basis [Member] | Significant Unobservable Inputs (Level 3) [Member]      
Fair value of impaired properties and other assets      
Assets $ 21,423    
Property Conveyances [Member] | Fair value measurement on a nonrecurring basis [Member]      
Fair value of impaired properties and other assets      
Impairment losses     11,000
Exit costs included in impairment losses in connection with dispositions     560
Other Properties with Shortened Holding Periods [Member] | Fair value measurement on a nonrecurring basis [Member] | White Marsh, Maryland [Member]      
Fair value of impaired properties and other assets      
Impairment losses     $ 5,900
Number of properties, shortened holding period | Property     2