Investment in Real Estate - Quantitative Information About Level 3 Fair Value Measurements (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014 sqft Property	Sep. 30, 2013 Unobservable Inputs (Level 3) Contracted Price sqft Property
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value of industrial property		$ 6,875	[1]
Number of industrial properties	638	1
Gross leasable area (GLA) of industrial properties	63,300,000	500,000

[1] The fair value for the property was based upon the value of a third party purchase contract, which was subject to our corroboration for reasonableness.