RELATED PARTY TRANSACTIONS - Trade Receivables (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Related Party Transaction [Line Items]
Total accounts receivable	$ 35.1	$ 38.0
Equinor ASA | Director
Related Party Transaction [Line Items]
Total accounts receivable	0.0	24.1
Dofcon Navegacao | Equity Method Investee
Related Party Transaction [Line Items]
Total accounts receivable	23.4	4.2
Techdof Brasil AS | Equity Method Investee
Related Party Transaction [Line Items]
Total accounts receivable	9.2	8.0
Others | Other Affiliates
Related Party Transaction [Line Items]
Total accounts receivable	$ 2.5	$ 1.7