Annual report pursuant to Section 13 and 15(d)

Significant Accounting Policies (Narrative) (Details)

v3.3.1.900
Significant Accounting Policies (Narrative) (Details) - USD ($)
 3 Months Ended 12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Jan. 06, 2016
Jan. 06, 2015
Dec. 31, 2012
Significant Accounting Policies [Line Items]                
Capitalized development and construction salaries and other related costs     $ 4,200,000 $ 3,100,000 $ 4,400,000      
Construction, tenant improvement, and development in-progress $ 88,700,000 $ 62,800,000 $ 88,700,000 62,800,000        
Maximum period after cessation of major construction activity that projects are considered complete     1 year          
Threshold of investment value for discontinuation of equity method accounting 0   $ 0          
Amortization of deferred financing costs     3,790,000 3,274,000 3,172,000      
Loss from early extinguishment of debt   $ (582,000)   (582,000) (156,000)      
Write off of unamortized deferred financing costs       12,000 156,000      
Deferred leasing costs     3,521,000 $ 3,840,000 $ 4,223,000      
Deferred tax asset $ 22,400,000   22,400,000          
Income taxes, material adjustment amount     $ 0          
Common stock, shares outstanding 89,583,950 89,076,578 89,583,950 89,076,578     88,866,652  
Common units outstanding 10,516,844 11,083,876 10,516,844 11,083,876 11,864,775   11,083,876 12,141,836
Distributions payable, record date Jan. 06, 2016 Jan. 06, 2015            
Distributions payable, approved date Dec. 08, 2015 Dec. 09, 2014            
Common stock dividends and common unit distributions per share $ 0.15 $ 0.15            
Dividends paid per common share     $ 0.60 $ 0.90 $ 1.50      
Dividends paid, percent representing ordinary income     90.00% 77.00% 53.00%      
Dividends paid, percent representing return of capital to shareholders       23.00% 33.00%      
Dividends paid, percent representing capital gain     10.00%   14.00%      
Restricted stock expense     $ 2,219,000 $ 8,139,000 $ 2,387,000      
Distributions payable, pay date Jan. 15, 2016 Jan. 14, 2015            
Difference between other comprehensive income and net income     0 0 $ 0      
Accumulated other comprehensive income $ 0 $ 0 $ 0 0        
Executive Officer [Member]                
Significant Accounting Policies [Line Items]                
Restricted stock expense       $ 5,824,000        
Subsequent Event [Member]                
Significant Accounting Policies [Line Items]                
Common stock, shares outstanding           89,584,008    
Common units outstanding           10,516,844