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Derivatives - Narrative (Details)
3 Months Ended 9 Months Ended
Sep. 30, 2017
USD ($)
Jul. 01, 2017
USD ($)
Oct. 01, 2016
USD ($)
Sep. 30, 2017
USD ($)
Oct. 01, 2016
USD ($)
Jan. 16, 2015
USD ($)
Forward Currency-Exchange Contracts [Abstract]            
Recognized gains (losses) $ 109,000   $ (120,000) $ (1,384,000) $ (556,000)  
NII FPG [Member]            
Forward Currency-Exchange Contracts [Abstract]            
Recognized gains (losses)   $ (1,754,000)        
Interest Rate Swap Agreement [Member]            
Interest Rate Swaps [Abstract]            
Rate of effectiveness of interest rate swap agreement (in hundredths)       100.00%    
Maximum consolidated leverage ratio       3.5    
Minimum consolidated interest coverage ratio       3    
Unrealized gain on derivatives       $ 65,000    
Foreign Exchange Forward [Member]            
Forward Currency-Exchange Contracts [Abstract]            
Maximum period over which entity manages its level of exposure of risk       12 months    
Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member] | Swap Agreement 2015 [Member]            
Interest Rate Swaps [Abstract]            
Derivative, notional amount           $ 10,000,000
Fixed rate of interest (in hundredths)           1.50%