Quarterly report pursuant to Section 13 or 15(d)

Line of Credit - Additional Information (Detail)

v2.4.0.6
Line of Credit - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
 3 Months Ended 1 Months Ended
Mar. 31, 2013
Mar. 31, 2013
Minimum
Oct. 29, 2012
Ninth Amended and restated
Oct. 29, 2012
Eleventh Amendment
Line of Credit Facility [Line Items]        
Revolving credit facility, maximum borrowing capacity     $ 60 $ 80
Revolving credit facility, expiration date     Dec. 31, 2013 Dec. 31, 2014
Revolving credit facility, interest rate description Amounts borrowed under our revolving line of credit bear interest, at our option, at either the prime lending rate established by JPMorgan Chase Bank, N.A. or LIBOR plus 1.5 percent      
Revolving credit facility, interest rate above LIBOR 1.50%      
Revolving credit facility, unused annual commitment fee 0.25%      
Revolving credit facility, amount outstanding 10.0      
Total outstanding letters of credit 46.8      
Revolving credit facility, unused portion 23.2      
Line of credit covenant, current ratio   1.25    
Line of credit covenant, debt to net worth   0.5    
Line of credit covenant, Earnings before interest, taxes, depreciation and amortization (EBITDA) to interest expense ratio 4.0      
Line of credit covenant, minimum net worth required $ 242.6