Debt - Financial covenants (Details)	3 Months Ended
Dec. 31, 2022	Sep. 30, 2022
Debt Disclosure [Abstract]
Covenant compliance, Leverage Ratio, maximum		3.00
Covenant compliance, Fixed Charge Coverage Ratio, minimum	1.25
Consolidated leverage ratio		2.88

Financial measurement that compares the amount of capital that comes in the form of debt or assess the entity's ability to meet its financial obligations.

No definition available.

Name:	orn_DebtInstrumentCovenantComplianceLeverageRatio
Namespace Prefix:	orn_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration