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

Amount of obligations related to failed sale leaseback arrangement that will be paid after one year.

No definition available.

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

n/a

No definition available.

Name:	orn_OtherLongTermLiabilitiesAbstract
Namespace Prefix:	orn_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Carrying value as of the balance sheet date of obligations incurred through that date and due beyond one year (or beyond one operating cycle if longer) to insurance entities to mitigate potential loss from various risks or to satisfy a promise to provide certain coverages to employees.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.24)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Name:	us-gaap_AccruedInsuranceNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Aggregate carrying value as of the balance sheet date of the liabilities for all deferred compensation arrangements payable beyond one year (or the operating cycle, if longer).

No definition available.

Name:	us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of liabilities classified as other, due after one year or the normal operating cycle, if longer.