Commitments and Contingencies - Narrative (Details) $ in Millions |
Sep. 30, 2018
USD ($)
vessel
|
Mar. 31, 2018
USD ($)
vessel
|
|---|---|---|
| Loss Contingencies [Line Items] | ||
| Number of multi-purpose service vessels | 2 | |
| Balance sheet exposure | $ | $ 12.5 | |
| U.S. Navy [Member] | ||
| Loss Contingencies [Line Items] | ||
| Number of towing, salvage and rescue vessels | 1 | |
| Construction in progress | $ | $ 63.6 | |
| Number of additional vessels | 7 |
| X | ||||||||||
- Definition Construction In Progress, Number Of Additional Vessels1 No definition available.
|
| X | ||||||||||
- Definition Construction In Progress, Number Of Multi-Purpose Service Vessels No definition available.
|
| X | ||||||||||
- Definition Construction In Progress, Number Of Towing, Salvage, And Rescue Ship Vessels No definition available.
|
| X | ||||||||||
- Definition Amount of structure or a modification to a structure under construction. Includes recently completed structures or modifications to structures that have not been placed into service. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition 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. No definition available.
|
| X | ||||||||||
- Definition Reflects the estimated amount of loss from the specified contingency as of the balance sheet date. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Details
|