Useful Lives of Related Real Estates and Other Assets (Detail)	12 Months Ended
	Dec. 31, 2012
Building and Building Improvements
Property, Plant and Equipment [Line Items]
Weighted average useful lives of related real estate and other assets	37 years 4 months 24 days
Tenant Lease Intangibles
Property, Plant and Equipment [Line Items]
Weighted average useful lives of related real estate and other assets	15 years 8 months 12 days
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Weighted average useful lives of related real estate and other assets	21 years 10 months 24 days
Furniture, Equipment And Other
Property, Plant and Equipment [Line Items]
Weighted average useful lives of related real estate and other assets	9 years 6 months