Quarterly report pursuant to Section 13 or 15(d)

Unsecured Line of Credit and Term Notes - Borrowings Outstanding on Unsecured Line of Credit and Term Notes (Detail)

v3.10.0.1
Unsecured Line of Credit and Term Notes - Borrowings Outstanding on Unsecured Line of Credit and Term Notes (Detail) - USD ($)
$ in Thousands
Sep. 30, 2018
Dec. 31, 2017
Unsecured Line Of Credit And Term Notes [Line Items]    
Revolving line of credit borrowings $ 128,000 $ 105,000
Total term note principal balance outstanding 1,625,000 1,625,000
Less: unamortized debt issuance costs (9,913) (10,962)
Less: unamortized senior term note discount (4,539) (4,949)
Term notes payable 1,610,548 1,609,089
Term Note Due June 4, 2020 [Member]    
Unsecured Line Of Credit And Term Notes [Line Items]    
Total term note principal balance outstanding 100,000 100,000
Term Note Due August 5, 2021 [Member]    
Unsecured Line Of Credit And Term Notes [Line Items]    
Total term note principal balance outstanding 100,000 100,000
Term Note Due April 8, 2024 [Member]    
Unsecured Line Of Credit And Term Notes [Line Items]    
Total term note principal balance outstanding 175,000 175,000
Senior Term Note Due July 1, 2026 [Member]    
Unsecured Line Of Credit And Term Notes [Line Items]    
Total term note principal balance outstanding 600,000 600,000
Senior Term Note Due December 15, 2027 [Member]    
Unsecured Line Of Credit And Term Notes [Line Items]    
Total term note principal balance outstanding 450,000 450,000
Term Note Due July 21, 2028 [Member]    
Unsecured Line Of Credit And Term Notes [Line Items]    
Total term note principal balance outstanding $ 200,000 $ 200,000