Income Taxes Income Tax Reconciliation Nondeductible Expense Uncertain Tax Position (Details) - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018
Income Tax Disclosure [Abstract]
IncomeTaxReconciliationNondeductibleExpenseUncertainTaxPosition	$ 2.3	$ 1.3
Income Tax ReconciliationValuation Allowance	$ 1.5

Amount of increase (decrease) to previously recorded tax expense for uncertain tax positions.

No definition available.

Name:	oii_IncomeTaxReconciliationNondeductibleExpenseUncertainTaxPosition
Namespace Prefix:	oii_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration