Annual report pursuant to Section 13 and 15(d)

Debt (Detail)

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Debt (Detail) (USD $)
12 Months Ended 12 Months Ended 1 Months Ended 12 Months Ended 1 Months Ended 12 Months Ended
Dec. 31, 2012
Dec. 31, 2013
Dec. 31, 2013
Federal Funds Rate
Dec. 31, 2013
LIBOR
Sep. 30, 2012
LIBOR
Minimum
Dec. 31, 2013
LIBOR
Minimum
Sep. 30, 2012
LIBOR
Maximum
Dec. 31, 2013
LIBOR
Maximum
Dec. 31, 2013
Wells Fargo's prime rate
Minimum
Dec. 31, 2013
Wells Fargo's prime rate
Maximum
Dec. 31, 2013
Revolving Credit Facility
Dec. 31, 2013
Standby Letters of Credit
Line of Credit Facility [Line Items]                        
Line of credit facility                     $ 150,000,000  
Sub limit for issuance of letters of credit                       10,000,000
Basis spread on interest rate     0.50% 1.00% 2.00% 2.50% 2.50% 3.00% 0.00% 0.25%    
Principal together with accrued and unpaid interest due and payable, date Dec. 30, 2015                      
Revolving line of credit facility borrowed 10,000,000 0                    
Revolving line of credit facility, available borrowing capacity   150,000,000                    
Issuance of letters of credit outstanding, amount   10,000,000                    
Unamortized debt issuance costs $ 800,000 $ 300,000