Rental Revenues of Reportable Segments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Segment Reporting Information [Line Items]
Minimum rents									$ 51,252		$ 48,113		$ 46,916
Percentage rents									330		333		397
Other									5,938		5,990		5,265
Rental revenues	14,992	14,899	14,231	13,398	14,122	13,318	13,609	13,387	57,520		54,436		52,578
Office real estate
Segment Reporting Information [Line Items]
Minimum rents									24,415		24,101		23,324
Percentage rents									104	[1]	109	[1]	107	[1]
Other									1,275	[2]	1,605	[2]	1,249	[2]
Rental revenues									25,794		25,815		24,680
Retail real estate
Segment Reporting Information [Line Items]
Minimum rents									18,473		17,753		16,930
Percentage rents									121	[1]	121	[1]	129	[1]
Other									3,161	[2]	3,290	[2]	3,046	[2]
Rental revenues									21,755		21,164		20,105
Multifamily residential real estate
Segment Reporting Information [Line Items]
Minimum rents									8,364		6,259		6,662
Percentage rents									105	[1]	103	[1]	161	[1]
Other									1,502	[2]	1,095	[2]	970	[2]
Rental revenues									$ 9,971		$ 7,457		$ 7,793

[1] Percentage rents are based on tenants' sales.

[2] Other rental revenue includes cost reimbursements for real estate taxes, property insurance and common area maintenance as well as termination fees.