Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013 Store Customer	Jun. 30, 2012	Jun. 30, 2013 Store Customer	Jun. 30, 2012	Dec. 31, 2012
Significant Accounting Policies [Line Items]
Number of Shopping centers	33		33
Number of tenants	2		2
Allowance for doubtful accounts receivables	$ 1,000,000		$ 1,000,000		$ 1,200,000
Construction in progress	6,165,000		6,165,000		2,267,000
Deferred debt costs, net	8,342,000		8,342,000		7,713,000
Accumulated amortization deferred leasing cost	4,100,000		4,100,000		3,800,000
Deferred leasing costs, net	24,757,000		24,757,000		26,102,000
Accumulated amortization deferred leasing cost	16,500,000		16,500,000		16,200,000
Amortization expense deferred leasing cost			3,200,000	2,800,000
Interest expensed capitalized	34,000	4,000	34,000	3,600
Depreciation and amortization expense			25,600,000	16,800,000
Repairs and maintenance expense			4,900,000	4,600,000
Increase in depreciation expense			8,800,000
Shares credited to directors' deferred fee accounts			221,852
Percentage of ownership in Operating Partnership			74.60%
Minimum
Significant Accounting Policies [Line Items]
Accounts receivable, net representing rental income accrued	35,700,000		35,700,000		34,400,000
Allowance for doubtful accounts receivables representing rental income accrued	243,000		243,000		220,000
Two Thousand Seven | Stock Options
Significant Accounting Policies [Line Items]
Antidilutive securities, stock options issued	92,500
Two Thousand Eight | Stock Options
Significant Accounting Policies [Line Items]
Antidilutive securities, stock options issued			25,000
Building | Minimum
Significant Accounting Policies [Line Items]
Estimated useful life			35 years
Building | Maximum
Significant Accounting Policies [Line Items]
Estimated useful life			50 years
Building Improvements | Maximum
Significant Accounting Policies [Line Items]
Estimated useful life			20 years
Van Ness Square
Significant Accounting Policies [Line Items]
Construction in progress	4,900,000		4,900,000
Additional depreciation expense as a result of reduction in estimated useful life			$ 8,000,000
Estimated remaining useful life			4 months
Giant Food
Significant Accounting Policies [Line Items]
Number of Shopping centers			10
Percentage of total revenue			4.90%
Safeway
Significant Accounting Policies [Line Items]
Number of Shopping centers			8
Percentage of total revenue			2.70%