Major Customers and Concentrations of Credit Risk - Receivables from Customers (Details) - Customer Concentration Risk - Accounts Receivable	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Boeing
Concentration Risk [Line Items]
Concentration percentage	4.80%	5.90%
Lockheed Martin
Concentration Risk [Line Items]
Concentration percentage	2.40%	1.30%
Northrop
Concentration Risk [Line Items]
Concentration percentage	12.30%	6.50%
Raytheon
Concentration Risk [Line Items]
Concentration percentage	15.00%	6.70%
Spirit
Concentration Risk [Line Items]
Concentration percentage	1.10%	2.00%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9054-108599

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
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-URI http://asc.fasb.org/extlink&oid=121572278&loc=d3e13531-108611

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6404-108592

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