Building Improvement Program and Agreement to Extend Lease - Additional Information (Detail) (USD $)	Dec. 31, 2012	Oct. 15, 2009	Dec. 31, 2004	Dec. 31, 1999	Oct. 15, 2009 Line of Credit [Member]	Dec. 31, 2012 Forecast [Member]	Dec. 31, 2012 Maximum [Member]	Dec. 31, 2006 Maximum [Member]
Real Estate Activity [Line Items]
Building improvement program costs			$ 31,400,000	$ 12,200,000		$ 82,300,000		$ 82,300,000
Debt instrument amount		42,910,000			21,000,000		63,900,000
Actual improvement Cost	$ 51,677,946