Nature of Business and Basis of Presentation - Narrative (Details) - segment	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2020
Concentration Risk [Line Items]
Number of reportable segments		1
Customer concentration risk \| Direct Company Sales \| General Motors Company
Concentration Risk [Line Items]
Concentration risk (percentage)	7.00%	7.00%
Labor force concentration risk \| Workforce Subject to Collective Bargaining Arrangements \| Collective Bargaining Arrangements Expiring August 2022
Concentration Risk [Line Items]
Concentration risk (percentage)		38.00%
Labor force concentration risk \| Workforce Subject to Collective Bargaining Arrangements \| Collective Bargaining Arrangements Expiring February 2023
Concentration Risk [Line Items]
Concentration risk (percentage)		6.00%

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
-SubTopic 10
-Section 50
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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
-Publisher FASB
-Name Accounting Standards Codification
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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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