Operating Leases - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2012 State Property
Operating Leased Assets [Line Items]
Number of leased properties	23
Number of states where retail, office and mixed-use properties are located	5
Years, minimum term range of office and retail leases	3 years
Years, maximum term range of office and retail leases	10 years
Months, minimum term of apartment leases	7 months
Months, maximum term of apartment leases	15 months
Retail Or Office
Operating Leased Assets [Line Items]
Number of leased properties	837
Residential Property
Operating Leased Assets [Line Items]
Number of leased properties	780