Summary of Significant Accounting Policies - Disaggregated Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2020	Sep. 28, 2019	Sep. 26, 2020	Sep. 28, 2019
Disaggregation of Revenue [Line Items]
Revenue	$ 150,371	$ 181,101	$ 471,155	$ 534,162
Electronic Systems
Disaggregation of Revenue [Line Items]
Revenue	103,470	90,588	293,540	264,045
Structural Systems
Disaggregation of Revenue [Line Items]
Revenue	46,901	90,513	177,615	270,117
Military and space
Disaggregation of Revenue [Line Items]
Revenue	113,859	80,487	307,479	231,635
Military and space | Electronic Systems
Disaggregation of Revenue [Line Items]
Revenue	82,175	59,081	223,692	176,813
Military and space | Structural Systems
Disaggregation of Revenue [Line Items]
Revenue	31,684	21,406	83,787	54,822
Commercial aerospace
Disaggregation of Revenue [Line Items]
Revenue	26,020	88,922	130,948	269,080
Commercial aerospace | Electronic Systems
Disaggregation of Revenue [Line Items]
Revenue	10,803	19,815	37,120	53,785
Commercial aerospace | Structural Systems
Disaggregation of Revenue [Line Items]
Revenue	15,217	69,107	93,828	215,295
Industrial
Disaggregation of Revenue [Line Items]
Revenue	10,492	11,692	32,728	33,447
Industrial | Electronic Systems
Disaggregation of Revenue [Line Items]
Revenue	$ 10,492	$ 11,692	$ 32,728	$ 33,447