Quarterly report pursuant to Section 13 or 15(d)

Basis of Presentation (Details)

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Basis of Presentation (Details) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2018
Apr. 01, 2017
Jan. 01, 2018
Dec. 31, 2017
Business Acquisition [Line Items]        
Research and development, design and related engineering $ 28,900 $ 22,900    
Capitalized precontract cost 8,400      
Adoption of ASU 2018-02 1,400      
ACCUMULATED OTHER COMPREHENSIVE LOSS        
Business Acquisition [Line Items]        
Adoption of ASU 2018-02 (1,373)      
RETAINED EARNINGS        
Business Acquisition [Line Items]        
Adoption of ASU 2018-02 1,373      
Accounting Standards Update 2014-09 | RETAINED EARNINGS        
Business Acquisition [Line Items]        
Adoption of ASU 2014-09     $ 3,300 $ 3,268
Selling, General and Administrative Expenses | Accounting Standards Update 2017-07        
Business Acquisition [Line Items]        
Other net periodic benefit costs 500 400    
Other Expense | Accounting Standards Update 2017-07        
Business Acquisition [Line Items]        
Other net periodic benefit costs $ (500) $ (400)