Accrued Liabilities - CARES Act (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Accrued Liabilities, Current [Abstract]
CARES Act deferred payroll taxes, total		$ 7.6
CARES Act deferred payroll taxes paid	$ 3.8
CARES Act deferred payroll taxes, current	$ 3.8

Carrying value, as of the balance sheet date, of the current portion of obligations incurred and payable for payroll taxes deferred as provided for under the Coronavirus Aid, Relief, and Economic Security Act ("CARES Act").

No definition available.

Name:	orn_DeferredPayrollTaxesCaresActCurrent
Namespace Prefix:	orn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant