Represents the amount accrued by the entity related to the achievement of a development milestone.

No definition available.

Name:	omth_LicenseAgreementAmountAccruedOnAchievementOfDevelopmentMilestone
Namespace Prefix:	omth_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the amount accrued by the entity as a result of the successful completion of its Phase III clinical trial.

+ References

No definition available.

+ Details

Name:	omth_LicenseAgreementAmountAccruedOnSuccessfulCompletionOfClinicalTrial
Namespace Prefix:	omth_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the amount of payments made by the entity as of the balance sheet date as a result of the successful completion of development milestones.

+ References

No definition available.

+ Details

Name:	omth_LicenseAgreementPaymentsMadeOnSuccessfulCompletionOfDevelopmentMilestones
Namespace Prefix:	omth_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the percentage reduction in royalty payable upon certain specified events.

+ References

No definition available.

+ Details

Name:	omth_LicenseAgreementPercentageReductionInRoyaltyPayableUponCertainSpecifiedEvents
Namespace Prefix:	omth_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the period of commercial sales of the product for which the entity is required to pay royalty on net sales of product under the license agreement.

+ References

No definition available.

+ Details

Name:	omth_LicenseAgreementPeriodOfCommercialSalesForWhichRoyaltyPayableOnNetSales
Namespace Prefix:	omth_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the amount of potential developmental and regulatory milestones payments to be paid by the entity under the license agreement.

+ References

No definition available.

+ Details

Name:	omth_LicenseAgreementPotentialDevelopmentAndRegulatoryMilestonePaymentsToBePaidByEntity
Namespace Prefix:	omth_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the percentage of net sales of the product payable as royalty by the entity for a specified period under the license agreement.

+ References

No definition available.

+ Details

Name:	omth_LicenseAgreementRoyaltyPayableOnNetSalesPercentage
Namespace Prefix:	omth_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the period after regulatory approval for the entity's product, within which if the entity does not commercialize its product, the agreement is cancellable by the entity under the terms of the supply agreement.

+ References

No definition available.

+ Details

Name:	omth_SupplyAgreementCancellationTermsCommercializationPeriodPostRegulatoryApprovalForProductAfterWhichAgreementIsCancellable
Namespace Prefix:	omth_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the capacity of a manufacturing facility.

+ References

No definition available.

+ Details

Name:	omth_SupplyAgreementConstructionOfManufacturingFacilityCapacity
Namespace Prefix:	omth_
Data Type:	num:massItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the cost of construction of manufacturing facility under the terms of the supply agreement.

+ References

No definition available.

+ Details

Name:	omth_SupplyAgreementConstructionOfManufacturingFacilityCost
Namespace Prefix:	omth_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represents the amount of payments made for cost of construction of manufacturing facility under the terms of the supply agreement.

+ References

No definition available.

+ Details

Name:	omth_SupplyAgreementConstructionOfManufacturingFacilityCostPaymentsMade
Namespace Prefix:	omth_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the one-time payment upon completion of FDA inspection of the site required to be made under the supply agreement.

+ References

No definition available.

+ Details

Name:	omth_SupplyAgreementOneTimePaymentUponCompletionOfFDASiteInspection
Namespace Prefix:	omth_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the one-time payment upon shipment into commerce of the first commercial product required to be made under the supply agreement.

+ References

No definition available.

+ Details

Name:	omth_SupplyAgreementOneTimePaymentUponShipmentIntoCommerceOfFirstCommercialProduct
Namespace Prefix:	omth_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

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

- Definition

Gross amount, at the balance sheet date, of long-lived assets under construction that include construction costs to date on capital projects that have not been completed and assets being constructed that are not ready to be placed into service.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 12

-Paragraph 5

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

+ Details

Name:	us-gaap_ConstructionInProgressGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Licenses and Supply Agreement (Details) (USD $)			0 Months Ended			3 Months Ended				1 Months Ended			1 Months Ended
Licenses and Supply Agreement (Details) (USD $)	Mar. 31, 2013 License agreement with Chrysalis	Dec. 31, 2012 License agreement with Chrysalis	Nov. 13, 2009 License agreement with Chrysalis Epanova and treatment of patients with very high triglycerides	Nov. 13, 2009 License agreement with Chrysalis Epanova and treatment of patients with high triglycerides	Nov. 13, 2009 License agreement with Chrysalis Epanova and the treatment of atrial fibrillation, heart failure or cardiovascular indications for patients with type II diabetes	Mar. 31, 2013 License agreement with Chrysalis Epanova	Mar. 31, 2013 License agreement with Chrysalis Epanova Minimum	Mar. 31, 2013 License agreement with Chrysalis Epanova Maximum	Dec. 31, 2012 License agreement with Chrysalis Amendment No.9	Mar. 31, 2012 Supply agreement with Ocean Nutrition Canada Limited	Mar. 31, 2012 Supply agreement with BioVectra Inc. Epanova t	Mar. 31, 2013 Supply agreement with BioVectra Inc. Epanova	Mar. 31, 2012 Supply agreement with BioVectra Inc. Epanova Maximum	Feb. 28, 2013 Long-term exclusive supply agreement Epanova Maximum
Licenses and supply agreement
Potential developmental and regulatory milestones payments to be paid			$ 9,500,000	$ 15,000,000	$ 10,000,000
Amount paid as a result of the successful completion of a development milestone	400,000
Amount accrued as a result of the successful completion of the Phase III clinical trial		2,000,000
Period of commercial sales for which royalty payable on net sales						15 years
Royalty on net sales of product (as a percent)							7.00%	12.00%
Percentage reduction in royalty rates payable								50.00%
Amount accrued related to the achievement of a development milestone									2,000,000
One-time payment upon completion of FDA inspection of the site										1,000,000
One-time payment upon shipment into commerce of the first commercial product										500,000
Capacity of manufacturing facility											100
Cost of construction of manufacturing facility													5,000,000
Cost of construction of manufacturing facility paid												3,100,000
Capitalized construction in progress												$ 1,400,000
Commercialization period post regulatory approval														12 months