Quarterly report pursuant to Section 13 or 15(d)

Significant Accounting Policies (Narrative) (Details)

v3.7.0.1
Significant Accounting Policies (Narrative) (Details) - USD ($)
 3 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2017
Dec. 31, 2016
Jun. 30, 2016
Jun. 30, 2017
Jun. 30, 2016
Dec. 31, 2016
Jul. 06, 2017
Jan. 05, 2017
Significant Accounting Policies [Line Items]                
Capitalized development and construction salaries and other related costs $ 600,000   $ 800,000 $ 1,200,000 $ 1,300,000      
Construction, tenant improvement, and development in-progress 390,700,000 $ 361,100,000   $ 390,700,000   $ 361,100,000    
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 1,175,000   1,180,000 2,278,000 2,349,000      
Loss from extinguishment of debt, net       (239,000) 12,420,000      
Write off of unamortized deferred financing costs 0   0 239,000 0      
Deferred leasing costs 946,000   870,000 1,988,000 1,650,000      
Deferred tax asset $ 16,600,000     16,600,000        
Income taxes, material adjustment amount       $ 0        
Common stock, shares outstanding 89,913,919 89,696,713   89,913,919   89,696,713   89,696,824
Common units outstanding 10,438,855 10,488,105   10,438,855   10,488,105   10,488,105
LTIP units outstanding 1,230,877 657,373   1,230,877   657,373   657,373
Distributions payable, record date       Jul. 06, 2017   Jan. 05, 2017    
Distributions payable, approved date   Dec. 13, 2016   Jun. 09, 2017        
Common stock dividends and common unit distributions per share   $ 0.15   $ 0.20        
Restricted stock expense $ 2,046,000   $ 1,469,000 $ 3,099,000 $ 2,253,000      
Distributions payable, pay date   Jan. 13, 2017   Jul. 14, 2017        
Subsequent Event [Member]                
Significant Accounting Policies [Line Items]                
Common stock, shares outstanding             89,913,978  
Common units outstanding             10,438,855  
LTIP units outstanding             1,230,877