Summary of Significant Accounting Policies - Weighted Average Useful Lives of Related Real Estate and Other Assets (Detail)	12 Months Ended
	Dec. 31, 2014
Buildings and improvements [Member]
Property, Plant and Equipment [Line Items]
Weighted average useful lives of related real estate and other assets	37 years 10 months 24 days
Tenant lease intangibles [Member]
Property, Plant and Equipment [Line Items]
Weighted average useful lives of related real estate and other assets	17 years 10 months 24 days
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Weighted average useful lives of related real estate and other assets	22 years 3 months 18 days
Furniture, equipment and other [Member]
Property, Plant and Equipment [Line Items]
Weighted average useful lives of related real estate and other assets	6 years 6 months