Annual report pursuant to Section 13 and 15(d)

Unsecured Lines of Credit Payable - Narrative (Details)

v3.19.3.a.u2
Unsecured Lines of Credit Payable - Narrative (Details)
3 Months Ended 12 Months Ended
Mar. 31, 2018
USD ($)
extension_option
Dec. 31, 2019
USD ($)
arrangement
Dec. 31, 2018
USD ($)
Mar. 29, 2018
USD ($)
arrangement
Dec. 31, 2017
USD ($)
Jul. 22, 2016
USD ($)
arrangement
Sep. 15, 2015
USD ($)
arrangement
Line of Credit Facility [Line Items]              
Revolving credit facility borrowing capacity   $ 700,000,000 $ 700,000,000   $ 600,000,000    
One-month LIBOR (percent)   1.70%          
U.S. Covered Terrorism Losses, Percent   0.85          
Insurance provider covered terrorism loss (percent)   0.10          
Aggregate insured losses from all insurers in covered terrorism metric   $ 100,000,000,000          
Interest Rate Swap              
Line of Credit Facility [Line Items]              
Derivative notional amount   $ 600,000,000          
Credit Agreement 2018              
Line of Credit Facility [Line Items]              
Credit agreement, aggregate maximum borrowing capacity including accordion feature $ 1,500,000,000            
2015 Term Loan | Interest Rate Swap              
Line of Credit Facility [Line Items]              
Number of interest rate swaps | arrangement   2         2
Derivative notional amount   $ 150,000,000         $ 150,000,000.0
Derivative fixed interest rate (percent)             2.72%
2016 Term Loan | Interest Rate Swap              
Line of Credit Facility [Line Items]              
Number of interest rate swaps | arrangement           2  
Derivative notional amount           $ 150,000,000.0  
Derivative fixed interest rate (percent)           2.86%  
2018 Term Loan              
Line of Credit Facility [Line Items]              
Debt instrument face amount       $ 250,000,000.0      
2018 Term Loan | Interest Rate Swap              
Line of Credit Facility [Line Items]              
Derivative fixed interest rate (percent)       2.87%      
2018 Term Loan A | Interest Rate Swap              
Line of Credit Facility [Line Items]              
Derivative notional amount $ 150,000,000.0 150,000,000   $ 150,000,000.0      
Derivative fixed interest rate (percent) 2.31%     2.31%      
2018 Term Loan B              
Line of Credit Facility [Line Items]              
Debt instrument face amount       $ 100,000,000.0      
2018 Term Loan B | Interest Rate Swap              
Line of Credit Facility [Line Items]              
Number of interest rate swaps | arrangement       4      
Derivative notional amount $ 100,000,000.0 $ 100,000,000   $ 100,000,000.0      
Derivative fixed interest rate (percent) 3.71%     3.71%      
Term Loan | 2015 Term Loan              
Line of Credit Facility [Line Items]              
Debt instrument face amount $ 150,000,000.0            
Debt instrument term (in years)   5 years 6 months          
Effective interest rate (percent)   2.70%          
Term Loan | 2015 Term Loan | LIBOR              
Line of Credit Facility [Line Items]              
Basis spread on variable rate (percent)   1.10%          
Term Loan | 2016 Term Loan              
Line of Credit Facility [Line Items]              
Debt instrument face amount         150,000,000.0    
Term Loan | 2018 Term Loan              
Line of Credit Facility [Line Items]              
Debt instrument face amount 250,000,000.0            
Effective interest rate (percent)   2.87%          
Proceeds from issuance of debt 100,000,000.0            
Term Loan | 2018 Term Loan | LIBOR | Minimum              
Line of Credit Facility [Line Items]              
Basis spread on variable rate (percent)   0.85%          
Term Loan | 2018 Term Loan | LIBOR | Maximum              
Line of Credit Facility [Line Items]              
Basis spread on variable rate (percent)   1.75%          
Term Loan | 2018 Term Loan | Base Rate | Minimum              
Line of Credit Facility [Line Items]              
Basis spread on variable rate (percent)   0.00%          
Term Loan | 2018 Term Loan | Base Rate | Maximum              
Line of Credit Facility [Line Items]              
Basis spread on variable rate (percent)   0.75%          
Revolving Credit Facility              
Line of Credit Facility [Line Items]              
Revolving credit facility borrowing capacity $ 700,000,000.0 $ 700,000,000     $ 600,000,000.0    
Debt instrument term (in years) 4 years            
Number of extensions allowed | extension_option 2            
Term of allowable extension (in years) 6 months            
Commitment fee (percent)   0.20%          
Revolving Credit Facility | Minimum              
Line of Credit Facility [Line Items]              
Commitment fee (percent)   0.10%          
Revolving Credit Facility | Maximum              
Line of Credit Facility [Line Items]              
Commitment fee (percent)   0.30%          
Revolving Credit Facility | LIBOR              
Line of Credit Facility [Line Items]              
Basis spread on variable rate (percent)   1.00%          
Base rate component, spread on variable rate (percent)   1.00%          
Revolving Credit Facility | LIBOR | Minimum              
Line of Credit Facility [Line Items]              
Basis spread on variable rate (percent)   0.775%          
Revolving Credit Facility | LIBOR | Maximum              
Line of Credit Facility [Line Items]              
Basis spread on variable rate (percent)   1.55%          
Revolving Credit Facility | Base Rate | Minimum              
Line of Credit Facility [Line Items]              
Basis spread on variable rate (percent)   0.00%          
Revolving Credit Facility | Base Rate | Maximum              
Line of Credit Facility [Line Items]              
Basis spread on variable rate (percent)   0.55%          
Revolving Credit Facility | Federal Funds Rate              
Line of Credit Facility [Line Items]              
Base rate component, spread on variable rate (percent)   0.50%