Represents the base annual rent the lessee is obligated to pay on a lease per month.

No definition available.

Name:	ovas_LeaseBaseAnnualRentPerMonth
Namespace Prefix:	ovas_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represents the percentage of annual increase in the base annual rent the lessee is obligated to pay on an operating lease.

+ References

No definition available.

+ Details

Name:	ovas_PercentageOfAnnualIncreaseInLeaseBaseAnnualRent
Namespace Prefix:	ovas_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the percentage of annual increase in the sublease base annual rent the lessee is obligated to pay on an operating lease.

+ References

No definition available.

+ Details

Name:	ovas_PercentageOfAnnualIncreaseInSubleaseBaseAnnualRent
Namespace Prefix:	ovas_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the sublease base annual rent the lessee is obligated to pay on the lease per month.

+ References

No definition available.

+ Details

Name:	ovas_SubleaseBaseAnnualRentPerMonth
Namespace Prefix:	ovas_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of rent expense incurred for leased assets, including but not limited to, furniture and equipment, that is not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

+ References

No definition available.

+ Details

Name:	us-gaap_LeaseAndRentalExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Term of the lessee's leasing arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_LesseeLeasingArrangementsOperatingLeasesTermOfContract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Net rentable area for properties owned.

+ References

No definition available.

+ Details

Name:	us-gaap_NetRentableArea
Namespace Prefix:	us-gaap_
Data Type:	num:areaItemType
Balance Type:	na
Period Type:	instant

- Details

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

- Definition

Amount of required minimum rental payments for leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 10

-Section 55

-Paragraph 40

-Subparagraph (Note 3)

-URI http://asc.fasb.org/extlink&oid=6584154&loc=d3e38371-112697

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 20

-Section 50

-Paragraph 2

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6453985&loc=d3e41502-112717

+ Details

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

- Details

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

- Definition

Amount of required minimum rental payments maturing in the next fiscal year following the latest fiscal year for operating leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

+ Details

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

- Definition

Amount of required minimum rental payments maturing in the third fiscal year following the latest fiscal year for operating leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

+ Details

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

- Definition

Amount of required minimum rental payments maturing in the second fiscal year following the latest fiscal year for operating leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

+ Details

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

- Details

Name:	us-gaap_TypeOfArrangementAxis=ovas_LeaseAgreementsTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TypeOfArrangementAxis=ovas_SubleaseAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TypeOfArrangementAxis=us-gaap_LeaseAgreementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Commitments and Contingencies (Details) (USD $)	12 Months Ended			0 Months Ended	1 Months Ended
Commitments and Contingencies (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	May 01, 2012	Jun. 30, 2014	May 31, 2012
Future minimum lease payments
Rent expense	$ 600,000us-gaap_LeaseAndRentalExpense	$ 400,000us-gaap_LeaseAndRentalExpense	$ 200,000us-gaap_LeaseAndRentalExpense
Lease agreement
Commitments and contingencies
Period of lease				60 months
Area of lease (in square feet)	6,000
Base annual rent per month	22,000
Annual increase in base annual rent (as a percent)	3.00%
Future minimum lease payments
2015	646,000
2016	292,000
2017	173,000
Total	1,111,000
Lease Agreements Two
Commitments and contingencies
Period of lease					17 months 15 days
Area of lease (in square feet)	5,800
Base annual rent per month	27,272
Annual increase in sublease base annual rent (as a percent)	1.80%
Sublease agreement
Commitments and contingencies
Period of lease						24 months
Area of lease (in square feet)	1,900
Sublease base annual rent per month	$ 4,000
Annual increase in sublease base annual rent (as a percent)	3.00%