Revenue - Revenue by Customer (Details) - USD ($)
$ in Thousands
3 Months Ended
Apr. 03, 2020
Mar. 29, 2019
Disaggregation of Revenue [Line Items]    
Total revenue $ 351,734 $ 325,906
Army    
Disaggregation of Revenue [Line Items]    
Total revenue 247,555 226,692
Air Force    
Disaggregation of Revenue [Line Items]    
Total revenue 73,341 67,931
Navy    
Disaggregation of Revenue [Line Items]    
Total revenue 15,237 15,088
Other    
Disaggregation of Revenue [Line Items]    
Total revenue $ 15,601 $ 16,195