Investment in Real Estate Properties - Additional Information (Detail) (Consolidated Properties [Member])	Sep. 30, 2014 sqft Building	Dec. 31, 2013 Building sqft
Consolidated Properties [Member]
Real Estate Properties [Line Items]
Number of buildings owned	283	296
Square feet of industrial buildings	57,600,000	57,200,000

The number of real estate properties owned as of the balance sheet date.

No definition available.

Name:	us-gaap_NumberOfRealEstateProperties
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant