Revolving Credit Facility - Additional Information (Detail) (USD $)	9 Months Ended		1 Months Ended		3 Months Ended	9 Months Ended		9 Months Ended				10 Months Ended	9 Months Ended	10 Months Ended
	Sep. 30, 2012	Oct. 02, 2011	Mar. 03, 2011 Secured Revolving Credit Facility [Member]	Dec. 21, 2011 Revolving Credit Facility [Member]	Sep. 30, 2012 Revolving Credit Facility [Member]	Sep. 30, 2012 Revolving Credit Facility [Member]	Oct. 31, 2012 Revolving Credit Facility [Member]	Sep. 30, 2012 Revolving Credit Facility [Member] Minimum	Sep. 30, 2012 Revolving Credit Facility [Member] Maximum	Sep. 30, 2012 Second Quarter Of 2012	Sep. 30, 2012 Third Quarter Of 2012	Oct. 31, 2012 Fourth Quarter Of 2012 [Member]	Sep. 30, 2012 Subsequent Quarters	Oct. 31, 2012 Subsequent Quarters	Sep. 30, 2012 Libor Plus Applicable Margin Revolving Credit Facility [Member] Minimum	Sep. 30, 2012 Libor Plus Applicable Margin Revolving Credit Facility [Member] Maximum	Sep. 30, 2012 Bank's Prime Rate, Less Applicable Margin Revolving Credit Facility [Member] Minimum	Sep. 30, 2012 Bank's Prime Rate, Less Applicable Margin Revolving Credit Facility [Member] Maximum
Line of Credit Facility [Line Items]
Maturity period			3 years
Maximum amount available under the Revolving Facility			$ 100,000,000	$ 150,000,000	$ 150,000,000	$ 150,000,000	$ 100,000,000
Maturity date			Mar. 03, 2014	Dec. 31, 2014
Current borrowing capacity					24,600,000	24,600,000
Borrowings under the Revolving Facility					80,000,000	80,000,000
Letter of credit outstanding					3,100,000	3,100,000
Variable interest rate								1.25%	1.75%						1.25%	1.75%	0.25%	1.00%
Weighted average interest rate					2.23%	2.25%
Repayments of Long-term Debt	32,000,000	34,700,000			20,000,000	32,000,000
Proceeds from issuance of debt	27,000,000	111,700,000			15,000,000	27,000,000
Increase of interest rate on all obligations under the revolving facility in the event of default						2.00%
Fee on the maximum amount available to be drawn under each letter of credit								0.60%	1.00%
Percentage of fee to be paid on unused portion of the New Facility								0.15%	0.25%
Maximum funded debt to EBITDA						2.5
Asset coverage ratio					1	1
Minimum adjusted EBITDA allowed for the trailing twelve months										$ 25,000,000	$ 35,000,000	$ 40,000,000	$ 45,000,000	$ 45,000,000