Quarterly report pursuant to Section 13 or 15(d)

Debt (Details Textual)

v2.4.0.6
Debt (Details Textual) (USD $)
In Millions, unless otherwise specified
9 Months Ended 12 Months Ended
Sep. 30, 2012
Dec. 31, 2011
Line of Credit Facility [Line Items]    
Interest rate descriptions   Three month LIBOR plus 1.00%
Issuance of letters of credit outstanding, amount 10.0  
Revolving line of credit facility, maximum   150.0
Debt (Textual) [Abstract]    
Revolving line of credit outstanding 25.0 50.3
Unamortized debt issuance costs 1.0 1.3
Accrued and unpaid interest due and payable, date   Dec. 30, 2015
Revolving Credit Facility [Member]
   
Line of Credit Facility [Line Items]    
Revolving line of credit facility, maximum 125.0  
Sublimit of Letters of Credit [Member]
   
Line of Credit Facility [Line Items]    
Sublimit for issuance of letters of credit   10.0
Maximum [Member]
   
Line of Credit Facility [Line Items]    
Basis spread on interest rate 2.50%  
Minimum [Member]
   
Line of Credit Facility [Line Items]    
Basis spread on interest rate 2.00%  
LIBOR [Member]
   
Line of Credit Facility [Line Items]    
Interest rate descriptions The terms of the amendment, the LIBOR rate margin ranges from 2.00% to 2.50%, based on the company’s senior leverage ratio 2.50% — 3.00% plus LIBOR
Basis spread on interest rate   1.00%
LIBOR [Member] | Maximum [Member]
   
Line of Credit Facility [Line Items]    
Basis spread on interest rate   3.00%
LIBOR [Member] | Minimum [Member]
   
Line of Credit Facility [Line Items]    
Basis spread on interest rate   2.50%
Wells Fargo's prime rate [Member]
   
Line of Credit Facility [Line Items]    
Interest rate descriptions   0.00% — 0.25% plus Wells Fargo’s prime rate
Wells Fargo's prime rate [Member] | Maximum [Member]
   
Line of Credit Facility [Line Items]    
Basis spread on interest rate   0.25%
Wells Fargo's prime rate [Member] | Minimum [Member]
   
Line of Credit Facility [Line Items]    
Basis spread on interest rate   0.00%
Federal funds rate [Member]
   
Line of Credit Facility [Line Items]    
Interest rate descriptions   The federal funds rate plus 0.50%
Basis spread on interest rate   0.50%