Commitment and Contingencies - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 Property sqft Buildings	Dec. 31, 2011	Dec. 31, 2010
Commitments And Contingencies [Line Items]
Number of leased properties granting the tenants options to purchase the property	7
Letter of credit and performance bonds in the aggregate amount	$ 9,546
Development of industrial buildings	3
Development of industrial buildings in Square feet	1,500,000
Estimated construction cost	107,723
Estimated construction cost to be funded	45,793
Operating and ground lease expense	$ 1,565	$ 1,955	$ 3,047