Other Long-Term Liabilities - Sale-Leaseback (Details) - Failed Sale Leaseback $ in Millions	Sep. 27, 2019 USD ($) Options
Failed Sale Leaseback
Sale price of properties sold	$ 19.1
Lease term	15 years
Annual rent	$ 1.5
Annual percentage rent increase	2.00%
Number of consecutive options to extend term \| Options	2
Term of available options	10 years

The annual percentage rent increase per terms of the failed sale leaseback arrangement.

No definition available.

Name:	orn_FailedSaleLeasebackArrangementAnnualRentIncreasePercent
Namespace Prefix:	orn_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The yearly payments due under a failed sale leaseback arrangement entered into in connection with the transaction involving the sale of property to another party and the lease of the property back to the seller.

+ References

No definition available.

+ Details

Name:	orn_FailedSaleLeasebackArrangementAnnualRentalPayments
Namespace Prefix:	orn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Term of failed sale leaseback arrangement.

+ References

No definition available.

+ Details

Name:	orn_FailedSaleLeasebackArrangementLeaseTermOfContract
Namespace Prefix:	orn_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Term of available options under failed sale leaseback arrangement.

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No definition available.

+ Details

Name:	orn_FailedSaleLeasebackArrangementLeaseTermOfOptions
Namespace Prefix:	orn_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of consecutive options to extend the term available under a failed sale leaseback arrangement.

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No definition available.

+ Details

Name:	orn_FailedSaleLeasebackArrangementNumberOfExtensionOptions
Namespace Prefix:	orn_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of cash inflow before closing and debt issuance costs received by a seller-lessee in a failed sale-leaseback recognized in financing activities.

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No definition available.

+ Details

Name:	orn_FailedSaleLeasebackTransactionGrossProceedsFinancingActivities
Namespace Prefix:	orn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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.

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No definition available.

+ Details

Name:	us-gaap_SaleLeasebackTransactionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_SaleLeasebackTransactionDescriptionAxis=orn_FailedSaleLeasebackMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: