Basis of Presentation and Summary of Significant Accounting Policies - Certain Risks and Concentrations (Details)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Customer concentration risk | Distributor To The U.S. Navy | Revenue
Concentration Risk [Line Items]
Concentration risk (less than for geographic concentration risk)	19.00%	67.00%	33.00%	52.00%
Customer concentration risk | Distributor To The U.S. Navy | Accounts receivable
Concentration Risk [Line Items]
Concentration risk (less than for geographic concentration risk)			12.00%		28.00%
Customer concentration risk | Shipbuilder For U.S. Navy | Revenue
Concentration Risk [Line Items]
Concentration risk (less than for geographic concentration risk)	17.00%		10.00%
Customer concentration risk | Shipbuilder For U.S. Navy | Accounts receivable
Concentration Risk [Line Items]
Concentration risk (less than for geographic concentration risk)			27.00%		21.00%
Customer concentration risk | Regional Commercial Lighting Retrofit Company | Revenue
Concentration Risk [Line Items]
Concentration risk (less than for geographic concentration risk)	27.00%	12.00%	17.00%	14.00%
Customer concentration risk | Regional Commercial Lighting Retrofit Company | Accounts receivable
Concentration Risk [Line Items]
Concentration risk (less than for geographic concentration risk)			34.00%
Customer concentration risk | Distributor To The U.S. Navy Combined With Sales To Shipbuilders | Revenue
Concentration Risk [Line Items]
Concentration risk (less than for geographic concentration risk)	36.00%	68.00%	43.00%	58.00%
Supplier concentration risk | Offshore Supplier | Accounts Payable
Concentration Risk [Line Items]
Concentration risk (less than for geographic concentration risk)			63.00%		44.00%
Supplier concentration risk | Offshore Supplier | Total Expenditures
Concentration Risk [Line Items]
Concentration risk (less than for geographic concentration risk)	19.00%	25.00%	30.00%	19.00%
Supplier concentration risk | Domestic Supplier | Total Expenditures
Concentration Risk [Line Items]
Concentration risk (less than for geographic concentration risk)		20.00%		14.00%
Geographic concentration risk | Revenue | Countries outside of the United States
Concentration Risk [Line Items]
Concentration risk (less than for geographic concentration risk)	1.00%	0.00%	1.00%	0.00%