Quarterly report pursuant to Section 13 or 15(d)

Unsecured Line of Credit and Term Notes - Additional Information (Detail)

v3.4.0.3
Unsecured Line of Credit and Term Notes - Additional Information (Detail) - USD ($)
3 Months Ended 12 Months Ended
Apr. 08, 2014
Mar. 31, 2016
Mar. 31, 2015
Dec. 31, 2011
Jan. 31, 2016
Dec. 31, 2015
Unsecured Line Of Credit And Term Notes [Line Items]            
Unsecured term note   $ 750,000,000       $ 750,000,000
Debt issuance costs   3,200,000 $ 3,400,000      
Revolving Credit Facility [Member]            
Unsecured Line Of Credit And Term Notes [Line Items]            
Revolving credit limit   $ 500,000,000     $ 300,000,000  
Maturity on June 4, 2020 [Member]            
Unsecured Line Of Credit And Term Notes [Line Items]            
Basis spread over LIBOR   1.15%        
Unsecured term note   $ 325,000,000        
Maturity on December 10, 2019 [Member]            
Unsecured Line Of Credit And Term Notes [Line Items]            
Basis spread over LIBOR   1.10%        
Facility fee   0.15%        
Interest rate, line of credit facility   1.53%       1.72%
Amount available on unsecured line of credit   $ 359,000,000        
Line of credit facility, expiration date   Dec. 10, 2019        
Maturity in April, 2024 [Member]            
Unsecured Line Of Credit And Term Notes [Line Items]            
Line of credit facility, expiration date   Apr. 08, 2024        
Additional secured term note $ 175,000,000          
Term note stated interest rate   4.533%        
Increase in interest rate on term loan   6.283%        
Repayment of Lines of Credit $ 115,000,000          
Maturity in August 2021 [Member]            
Unsecured Line Of Credit And Term Notes [Line Items]            
Line of credit facility, expiration date   Aug. 05, 2021        
Additional secured term note       $ 100,000,000    
Term note stated interest rate       5.54%    
Increase in interest rate on term loan       7.29%    
Maturity in April 2016 [Member]            
Unsecured Line Of Credit And Term Notes [Line Items]            
Unsecured term note   $ 150,000,000        
Line of credit facility, expiration date   Apr. 26, 2016        
Term note stated interest rate   6.38%        
Increase in interest rate on term loan   8.13%