Operating Segments - Summarized Segment Financial Information (Parenthetical) (Details) - Forty-Vehicle Ferry $ in Millions	3 Months Ended
Mar. 31, 2020 Vechicle	Mar. 31, 2019 USD ($) Vechicle
Segment Reporting Information [Line Items]
Revenue reclassified between the Shipyard and Fabrication & Services segments \| $		$ 0.8
Number of vehicle ferry projects \| Vechicle	2	2

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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