Term Loan - Additional Information (Detail) (USD $)	9 Months Ended				1 Months Ended
	Oct. 08, 2011	Oct. 06, 2012	Jul. 21, 2012	Dec. 31, 2011	May 20, 2011 Term Loans	Oct. 06, 2012 Term Loans	Dec. 31, 2011 Term Loans	May 20, 2011 Term Loans Base Rate Loans Minimum	May 20, 2011 Term Loans Base Rate Loans Maximum	May 20, 2011 Term Loans Eurodollar Loans Minimum	May 20, 2011 Term Loans Eurodollar Loans Maximum
Debt Instrument [Line Items]
Basis spread on variable rate					0.50%			0.00%	1.375%	0.875%	2.375%
Term loan borrowed amount		$ 150,000,000	$ 20,000,000		$ 150,000,000
Term loan maturity date					Aug. 01, 2013
Annual amortization of principal balance for first year					10.00%
Annual amortization of principal balance for second year					10.00%
Annual amortization of principal balance for third year					15.00%
Annual amortization of principal balance for fourth year					20.00%
Annual amortization of principal balance for fifth year					45.00%
Additional financing costs	2,108,000				100,000
Unamortized financing costs					800,000
Amounts outstanding under term loan		$ 67,500,000		$ 90,000,000		$ 67,500,000	$ 90,000,000