Name:	svt_CurrentFederalTaxExpenseBenefitDiscontinuingOperation
Namespace Prefix:	svt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	svt_CurrentIncomeTaxExpenseBenefitDiscontinuingOperationsAbstract
Namespace Prefix:	svt_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The component of income tax expense for the period representing amounts of income taxes paid or payable (or refundable) for the period for all income tax obligations as determined by applying the provisions of relevant enacted tax laws to relevant amounts of taxable Income or Loss from discontinuing operations.

No definition available.

Name:	svt_CurrentIncomeTaxExpenseBenefitDiscontinuingOperationTotal
Namespace Prefix:	svt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The component of income tax expense for the period representing amounts paid or payable (or refundable) as determined by applying the provisions of enacted state and local tax law to relevant amounts of taxable Income or Loss from discontinuing operations.

No definition available.

Name:	svt_CurrentStateAndLocalTaxExpenseBenefitDiscontinuingOperation
Namespace Prefix:	svt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The component of total income tax expense for the period comprised of the increase (decrease) during the period in the entity's domestic deferred tax assets and liabilities attributable to discontinuing operations as determined by applying the provisions of the federally enacted tax law.

No definition available.

Name:	svt_DeferredFederalIncomeTaxExpenseBenefitDiscontinuingOperations
Namespace Prefix:	svt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	svt_DeferredIncomeTaxExpenseBenefitDiscontinuingOperationsAbstract
Namespace Prefix:	svt_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The component of income tax expense for the period representing the increase (decrease) in the entity's deferred tax assets and liabilities pertaining to discontinuing operations.

No definition available.

Name:	svt_DeferredIncomeTaxExpenseBenefitDiscontinuingOperationsTotal
Namespace Prefix:	svt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The component of total income tax expense for the period comprised of the increase (decrease) in the entity's state and local deferred tax assets and liabilities attributable to discontinuing operations as determined by applying the provisions of the applicable enacted tax laws.

No definition available.

Name:	svt_DeferredStateAndLocalIncomeTaxExpenseBenefitDiscontinuingOperations
Namespace Prefix:	svt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The sum of the current income tax expense or benefit and the deferred income tax expense or benefit pertaining to discontinuing operations.

No definition available.