Related Party Transactions (Details)	Jun. 30, 2012 item	Dec. 31, 2011 item
Related Party Transactions
Number of principal stockholders for which chief executive officer serves as a general partner	1	1
Number of principal stockholders from whom the entity has leased office space		1

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.

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