Commitments and Contingencies (Detail Textuals) (USD $)	Dec. 31, 2012
Commitments and Contingencies Disclosure [Abstract]
Maximum estimated additional liabilities of future medical benefits and severance compensation	$ 1,400,000

This element represents maximum estimated additional liabilities of future medical benefits and severance compensation.

No definition available.

Name:	svt_MaximumEstimatedAdditionalLiabilitiesOfFutureMedicalBenefitsAndSeveranceCompensation
Namespace Prefix:	svt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant