Organization and Significant Accounting Policies - Revenue by Category (Details)	3 Months Ended
	Jul. 27, 2019 USD ($) contract	Jul. 28, 2018 USD ($)
Disaggregation of revenue
Number of active contracts | contract	1
Contract Liability
Disaggregation of revenue
Revenue	$ 830,000	$ 1,548,000
Domestic
Disaggregation of revenue
Revenue	38,808,000	35,352,000
International
Disaggregation of revenue
Revenue	48,103,000	42,691,000
U.S. government
Disaggregation of revenue
Revenue	49,134,000	35,908,000
Non-U.S. government
Disaggregation of revenue
Revenue	37,777,000	42,135,000
FFP
Disaggregation of revenue
Revenue	67,944,000	58,003,000
CPFF
Disaggregation of revenue
Revenue	18,264,000	19,983,000
T&M
Disaggregation of revenue
Revenue	703,000	57,000
Small UAS
Disaggregation of revenue
Revenue	66,745,000	41,216,000
TMS
Disaggregation of revenue
Revenue	5,587,000	22,766,000
HAPS
Disaggregation of revenue
Revenue	12,335,000	11,563,000
Other
Disaggregation of revenue
Revenue	$ 2,244,000	$ 2,498,000