Summary of Significant Accounting Policies - Relationship with Former Parent and Related Entities (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Trinity Industries, Inc. [Member]
Sales to Trinity businesses	$ 160.3	$ 148.3
Purchases from Trinity businesses	44.5	53.2
Corporate Segment
Corporate overhead costs	$ 26.0	$ 39.3

Indirect cost incurred related to good produced and service rendered.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
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Direct costs arising from transactions with related parties who are not affiliates or joint Ventures. These costs are categorized as cost of goods sold.

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-Paragraph 2
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Amount of revenue, fees and commissions earned from transactions between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, for example, but not limited to, pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 220
-Section S99
-Paragraph 1
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