Related Party Transaction (Detail Textuals) (Aero Metal Products, Inc. (AMP), USD $)	Dec. 31, 2009
Aero Metal Products, Inc. (AMP)
Related Party Transaction [Line Items]
Real property lease agreement, annual rental expenses	$ 60,000

Total amount of annual capital lease rental payments to related party.

No definition available.

Name:	svt_CapitalLeaseTransactionAnnualRentalPaymentsToRelatedParty
Namespace Prefix:	svt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant