Financing Activity - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Debt Instrument [Line Items]
Line of Credit Facility, Description	We have entered into four credit agreements (collectively, as amended, the “Credit Agreements”), as further discussed in our Annual Report on Form 10-K for the year ended December 31, 2017: (1) the 2013 Revolving Facility, (2) the 2014 7-Year Term Loan, (3) the 2014 5-Year Term Loan, and (4) the 2015 5-Year Term Loan. The 2014 7-Year Term Loan, the 2014 5-Year Term Loan and the 2015 5-Year Term Loan are collectively referred to as the “Term Loans.”
Term Loan Borrowing	$ 550,000,000
Maximum Unsecured Borrowing Amount Under Unencumbered Debt Yield Covenant	189,700,000
Sales Per Square Foot	500
Long-term Debt	$ 547,949,000		$ 547,758,000
Line of Credit Facility, Commitment Fee Percentage	0.25%
Minimum [Member]
Debt Instrument [Line Items]
Capitalization Rates	6.50%
Maximum [Member]
Debt Instrument [Line Items]
Capitalization Rates	7.50%
2013 Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Letters of Credit Outstanding, Amount	$ 15,800,000
Interest Expense, Debt, Excluding Amortization	365,000	$ 764,000
Non-cash amortization of deferred financing fees	200,000	199,000
Term Loans [Member]
Debt Instrument [Line Items]
Interest Expense, Debt, Excluding Amortization	4,286,000	2,835,000
Non-cash amortization of deferred financing fees	191,000	$ 187,000
Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt Issuance Costs, Line of Credit Arrangements, Net	$ 2,100,000