Summary of Significant Accounting Policies - Concentrations (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Percentage of employees under collective bargaining agreements	8.00%
Net Sales | U.S. government | Customer Concentration Risk
Segment Reporting Information [Line Items]
Risk percentage	96.00%	96.00%	94.00%
Net Sales | Non U.S. government customers | Customer Concentration Risk
Segment Reporting Information [Line Items]
Risk percentage	4.00%	4.00%	6.00%
Net Sales | RS-25 program | Customer Concentration Risk
Segment Reporting Information [Line Items]
Risk percentage	18.00%	17.00%	14.00%
Net Sales | Standard Missile program | Customer Concentration Risk
Segment Reporting Information [Line Items]
Risk percentage	13.00%	13.00%	13.00%
Net Sales | THAAD program | Customer Concentration Risk
Segment Reporting Information [Line Items]
Risk percentage	11.00%	10.00%	11.00%
Net Sales | PAC-3 program | Customer Concentration Risk
Segment Reporting Information [Line Items]
Risk percentage	10.00%	10.00%	8.00%
Net Sales | Lockheed Martin | Customer Concentration Risk
Segment Reporting Information [Line Items]
Risk percentage	34.00%	33.00%	30.00%
Net Sales | NASA | Customer Concentration Risk
Segment Reporting Information [Line Items]
Risk percentage	21.00%	21.00%	18.00%
Net Sales | Raytheon | Customer Concentration Risk
Segment Reporting Information [Line Items]
Risk percentage	17.00%	17.00%	19.00%
Net Sales | ULA | Customer Concentration Risk
Segment Reporting Information [Line Items]
Risk percentage		10.00%	17.00%
Accounts Receivable | Lockheed Martin | Customer Concentration Risk
Segment Reporting Information [Line Items]
Risk percentage	21.00%	26.00%
Accounts Receivable | NASA | Customer Concentration Risk
Segment Reporting Information [Line Items]
Risk percentage		14.00%
Accounts Receivable | Raytheon | Customer Concentration Risk
Segment Reporting Information [Line Items]
Risk percentage	20.00%	21.00%
Accounts Receivable | The Boeing Company | Customer Concentration Risk
Segment Reporting Information [Line Items]
Risk percentage	16.00%	18.00%