Represents the number of principal stockholders of the entity for which the entity's chief executive officer serves as a general partner.

No definition available.

+ Details

Name:	ovas_NumberOfPrincipalStockholdersForWhichChiefExecutiveOfficerServesAsAGeneralPartner
Namespace Prefix:	ovas_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the number of principal stockholders of the entity from whom the entity has leased office space.

+ References

No definition available.

+ Details

Name:	ovas_NumberOfPrincipalStockholdersFromWhomEntityHasLeasedOfficeSpace
Namespace Prefix:	ovas_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Details

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

- Details

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

- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(2)(iii)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Gross number of share options (or share units) granted during the period.

+ References

No definition available.

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=us-gaap_ChiefExecutiveOfficerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Related Party Transactions (Details)	1 Months Ended
Related Party Transactions (Details)	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2012	Dec. 31, 2011 item
Related Party Transactions
Number of principal stockholders for which chief executive officer serves as a general partner	1
Number of principal stockholders from whom the entity has leased office space				1
CEO \| Stock option
Related Party Transactions
Granted (in shares)	200,000	500,000	339,313
CEO \| Restricted stock units
Related Party Transactions
Granted (in shares)	54,078		192,308