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Equity (Details 2) - USD ($)
 3 Months Ended 9 Months Ended
Sep. 30, 2019
Sep. 30, 2019
Sep. 30, 2018
Dec. 31, 2018
Class of Stock [Line Items]        
Common stock, shares authorized (in shares) 280,000,000 280,000,000   280,000,000
Preferred stock, shares authorized (in shares) 50,000,000 50,000,000   50,000,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period   81,626    
Common stock issued through the dividend reinvestment plan (in shares)   1,594 1,713  
Number of shares of stock grants withheld (in shares)   83,602 67,963  
Stock Issued During Period, Shares, Employee Stock Purchase Plans   7,156    
Stock issued during period, shares, share-based compensation, forfeited (in shares)   1,730    
Issuance of common stock, net   $ 207,789,000 $ 1,224,000  
Continuous Equity Programs CEP IV and CEP V [Member]        
Class of Stock [Line Items]        
Stock Issued During Period, Shares, New Issues   994,634    
Continuous Equity Program CEP IV        
Class of Stock [Line Items]        
Stock Issued During Period, Shares, New Issues   755,054    
Maximum value of shares of common stock that can be sold (in dollars) $ 1,000,000,000 $ 1,000,000,000    
Shares Issued, Weighted Average Price Per Share   $ 198.26    
Issuance of common stock, net 0 $ 147,450,000    
Continuous Equity Program CEP V [Member]        
Class of Stock [Line Items]        
Stock Issued During Period, Shares, New Issues   239,580    
Maximum value of shares of common stock that can be sold (in dollars) 1,000,000,000 $ 1,000,000,000    
Shares Issued, Weighted Average Price Per Share   $ 208.70    
Issuance of common stock, net   $ 49,250,000    
Common stock value, remaining to be authorized under continuous equity program $ 950,000,000 $ 950,000,000    
Forward Contract Indexed to Issuer's Equity, Shares   947,868    
Forward Contract Indexed to Issuer's Equity, Approximate Net Proceeds   $ 198,000,000    
Maximum | Continuous Equity Program CEP IV        
Class of Stock [Line Items]        
Percentage of compensation received by sales agent   2.00%    
Maximum | Continuous Equity Program CEP V [Member]        
Class of Stock [Line Items]        
Percentage of compensation received by sales agent   1.50%    
Restricted Stock and Restricted Stock Converted From Performance Shares        
Class of Stock [Line Items]        
Equity instruments granted (in shares)   150,359 187,010  
Deferred Compensation, Share-based Payments [Member] | Non Employee Director        
Class of Stock [Line Items]        
Equity instruments granted (in shares)   1,838