Revenue - Revenue by Customer (Details) - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended
Oct. 02, 2020
Sep. 27, 2019
Oct. 02, 2020
Sep. 27, 2019
Disaggregation of Revenue [Line Items]        
Total revenue $ 352,415 $ 359,873 $ 1,040,212 $ 1,017,368
Army        
Disaggregation of Revenue [Line Items]        
Total revenue $ 236,267 245,817 711,173 $ 698,377
Revenue, percent change (3.90%)     1.80%
Air Force        
Disaggregation of Revenue [Line Items]        
Total revenue $ 79,425 86,576 231,088 $ 227,100
Revenue, percent change (8.30%)     1.80%
Navy        
Disaggregation of Revenue [Line Items]        
Total revenue $ 18,785 13,344 48,564 $ 45,227
Revenue, percent change 40.80%     7.40%
Other        
Disaggregation of Revenue [Line Items]        
Total revenue $ 17,938 $ 14,136 $ 49,387 $ 46,664
Revenue, percent change 26.90%     5.80%