ORGANIZATION AND BASIS OF PRESENTATION (Details)	Mar. 31, 2013 foreign_country
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Exploratory and development interests in foreign countries (in number of foreign countries)	2

Represents the number of foreign countries in which the entity has exploratory and development interests.

No definition available.

Name:	fst_ExploratoryAndDevelopmentInterestsInForeignCountriesNumber
Namespace Prefix:	fst_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant