Investment in Real Estate - Fair Value Measurements on Non-Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Fair Value Assets Measured On Nonrecurring Basis [Line Items]
Long-lived Assets Sold Impairment	$ (1,605)	$ (1,194)	[1]
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Assets Measured On Nonrecurring Basis [Line Items]
Long-lived Asssets Held for Sale	0	0	[1]
Significant Other Observable Inputs (Level 2)
Fair Value Assets Measured On Nonrecurring Basis [Line Items]
Long-lived Asssets Held for Sale	0	0	[1]
Unobservable Inputs (Level 3)
Fair Value Assets Measured On Nonrecurring Basis [Line Items]
Long-lived Asssets Held for Sale	6,993	24,069	[1]
Fair Value, Measurements, Nonrecurring [Member]
Fair Value Assets Measured On Nonrecurring Basis [Line Items]
Long-lived Asssets Held for Sale	$ 6,993	$ 24,069	[1]

[1] Excludes industrial properties for which impairment of $52 was recorded during the six months ended June 30, 2012 since the related assets are recorded at carrying value, which is lower than estimated fair value at June 30, 2012.