Investment in Real Estate - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 Property sqft	Sep. 30, 2013 Property	Dec. 31, 2013 Property
Real Estate Investment Property, Net [Abstract]
Number of industrial properties acquired			3
Gross leasable area (GLA) of industrial properties acquired			500,000
Purchase price of acquisitions			$ 52,882
Number of industrial properties sold			20
Gross leasable area (GLA) of industrial properties sold			1,000,000
Proceeds from sale of industrial properties			59,011
Gain on sale of real estate			14,483	16,203
Number of sold industrial properties included in discontinued operations			20	19	67
Number of industrial properties held for sale			2
Gross leasable area (GLA) of industrial properties held for sale			200,000
Impairment of real estate			0	2,652
Impairment of real estate included in discontinued operations	$ 0	$ 0	$ 0	$ 1,605