| Summary of Contract Assets and Liabilities | The following table presents the beginning and ending balances of contract assets and contract liabilities during the three months ended April 3, 2021: 
|  |  |  |  |  |  |  |  |  |  |  |  |  
| (In thousands) |  | Contract Assets | Contract Liabilities |  
| Beginning Balance, January 1, 2021 |  | $ | 17,697 |  | $ | 28,641 |  |  
| Ending Balance, April 3, 2021 |  | $ | 25,510 |  | $ | 31,285 |  |  | 
| Disaggregation of Revenue | The following table presents our revenue disaggregated by Market Segments as follows: 
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
|  |  | Three Months Ended |  |  |  
| (In thousands) |  | April 3, 2021 |  | March 28, 2020 |  |  |  |  |  
| Aerospace Segment |  |  |  |  |  |  |  |  |  
| Commercial Transport |  | $ | 38,208 |  |  | $ | 102,775 |  |  |  |  |  |  
| Military |  | 20,982 |  |  | 18,113 |  |  |  |  |  |  
| Business Jet |  | 14,028 |  |  | 15,006 |  |  |  |  |  |  
| Other |  | 8,198 |  |  | 5,176 |  |  |  |  |  |  
| Aerospace Total |  | 81,416 |  |  | 141,070 |  |  |  |  |  |  
|  |  |  |  |  |  |  |  |  |  
| Test Systems Segment |  |  |  |  |  |  |  |  |  
| Semiconductor |  | — |  |  | 1,634 |  |  |  |  |  |  
| Aerospace & Defense |  | 24,441 |  |  | 14,880 |  |  |  |  |  |  
| Test Systems Total |  | 24,441 |  |  | 16,514 |  |  |  |  |  |  
|  |  |  |  |  |  |  |  |  |  
| Total |  | $ | 105,857 |  |  | $ | 157,584 |  |  |  |  |  | The following table presents our revenue disaggregated by Product Lines as follows: 
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
|  |  | Three Months Ended |  |  |  
| (In thousands) |  | April 3, 2021 |  | March 28, 2020 |  |  |  |  |  
| Aerospace Segment |  |  |  |  |  |  |  |  |  
| Electrical Power & Motion |  | $ | 29,344 |  |  | $ | 69,456 |  |  |  |  |  |  
| Lighting & Safety |  | 27,100 |  |  | 37,922 |  |  |  |  |  |  
| Avionics |  | 14,843 |  |  | 22,143 |  |  |  |  |  |  
| Systems Certification |  | 878 |  |  | 3,331 |  |  |  |  |  |  
| Structures |  | 1,053 |  |  | 3,042 |  |  |  |  |  |  
| Other |  | 8,198 |  |  | 5,176 |  |  |  |  |  |  
| Aerospace Total |  | 81,416 |  |  | 141,070 |  |  |  |  |  |  
|  |  |  |  |  |  |  |  |  |  
| Test Systems |  | 24,441 |  |  | 16,514 |  |  |  |  |  |  
|  |  |  |  |  |  |  |  |  |  
| Total |  | $ | 105,857 |  |  | $ | 157,584 |  |  |  |  |  |  |