Debt (Additional Information) (Details) (USD $)
 3 Months Ended 1 Months Ended 0 Months Ended 3 Months Ended 0 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Jul. 31, 2011
Jul. 13, 2011
Dec. 31, 2012
Jan. 22, 2015
Dec. 31, 2014
Sep. 30, 2014
Jun. 30, 2014
Dec. 31, 2011
Nov. 23, 2010
Jul. 31, 2013
Debt Instrument [Line Items]                        
Credit agreement, maximum borrowing capacity                     $ 165,000,000.0  
Revolving credit outstanding borrowings 0     100,000,000     0          
FCCR covenant limit 1.75 1.75         1.75 1.75 1.75      
Actual leverage ratio 1.51                      
Actual FCCR 2.36 2.69         2.58 2.70 2.65      
Capitalized debt issuance costs         100,000         700,000 1,600,000  
Amortization expense, debt issue costs 100,000 100,000                    
Capitalized debt issuance costs, net 600,000                      
Repayment of debt principal 5,065,000 3,826,000                    
LIBOR in Effect at Period End 0.1875%                      
Interest rate spread over variable rate (percent) 1.75%                      
Irrevocable standby letters of credit 1,400,000                      
Option to buy out capital lease, year 2013                      
Capital lease, expiration date 2021                      
Capital lease obligation 5,900,000                      
Amortization expense related to the capital lease 100,000 100,000                    
Capital lease accumulated depreciation 1,700,000           1,600,000          
Interest expense on outstanding debt 800,000 500,000                    
Unused commitment fee   100,000                    
Interest expense on capital lease 100,000 100,000                    
Credit Agreement [Member]                        
Debt Instrument [Line Items]                        
Variable rate lower range basis spread       0.75%                
Variable rate higher range basis spread       1.50%                
Line of credit, interest rate description     The base reference rate is the greater of the prime rate; federal funds effective rate plus 50 basis points; and adjusted LIBOR plus 100 basis points.                  
Credit Agreement [Member] | Maximum [Member]                        
Debt Instrument [Line Items]                        
Leverage ratio 3                      
FCCR covenant limit 1.75                      
Interest Rate Swap [Member]                        
Debt Instrument [Line Items]                        
Fair value of interest rate swap liability 300,000                      
Bank Term Loan [Member]                        
Debt Instrument [Line Items]                        
Revolving credit outstanding borrowings 125,000,000                      
Term loan debt 55,000,000                      
Interest rate swap derivative, percentage of debt hedged (percent)                       65.00%
Bank Term Loan [Member] | Cash Flow Hedging [Member]                        
Debt Instrument [Line Items]                        
Interest rate swap derivative, percentage of debt hedged (percent)                       65.00%
Bank Term Loan [Member] | One Month LIBOR [Member]                        
Debt Instrument [Line Items]                        
Interest rate spread over variable rate (percent) 1.75%                      
Amended Credit Facility [Member]                        
Debt Instrument [Line Items]                        
Credit agreement, maximum borrowing capacity       265,000,000                
Credit agreement, agreement period       5 years                
Reduction in interest costs       0.25%                
Revolving credit outstanding borrowings 125,000,000                      
Payments commencement date     Sep. 30, 2011                  
Repayment of debt principal 5,000,000       3,800,000              
Required payment on debt obligation within the next 12 months 42,500,000                      
Amended Credit Facility [Member] | Minimum [Member]                        
Debt Instrument [Line Items]                        
Unused commitment fee percentage     0.20%                  
Amended Credit Facility [Member] | Maximum [Member]                        
Debt Instrument [Line Items]                        
Unused commitment fee percentage     0.35%                  
Amended Credit Facility [Member] | Federal Funds Rate [Member]                        
Debt Instrument [Line Items]                        
Variable rate lower range basis spread       0.50%                
Amended Credit Facility [Member] | One Month LIBOR [Member]                        
Debt Instrument [Line Items]                        
Variable rate higher range basis spread       1.00%                
Amended Credit Facility [Member] | Bank Term Loan [Member]                        
Debt Instrument [Line Items]                        
Credit agreement, maximum borrowing capacity       100,000,000.0                
Eurocurrency loans [Member] | Credit Agreement [Member]                        
Debt Instrument [Line Items]                        
Line of credit, LIBOR rate, minimum spread       1.75%                
Line of credit, LIBOR rate, maximum spread       2.50%                
Revolving Credit Facility [Member] | Arlon [Member]                        
Debt Instrument [Line Items]                        
Proceeds from line of credit $ 125,000,000         $ 125,000,000