Long-Term Debt (Detail Textuals ) (USD $)	9 Months Ended
Sep. 30, 2014
ATG
Debt Instrument [Line Items]
Adding up long term financing for existing capital projects	$ 2,000,000
CPG
Debt Instrument [Line Items]
Adding up long term financing for existing capital projects	2,000,000
Line of credit
Debt Instrument [Line Items]
Unsecured line of credit	2,000,000
Unsecured line of credit remaining	1,000,000
Interest rate	3.25%
Industrial Development Revenue Bonds \| Letter of credit from bank
Debt Instrument [Line Items]
Annual sinking fund payments, commenced on December 1, 2000 through 2013	170,000
Final sinking fund payment due December 1, 2014	$ 2,620,000
Percentage of annual fee of secured amount	1.00%
Percentage of annual fee of principal amount outstanding	0.25%
Interest rate	0.29%

Represents the information about refinance additional payment.

No definition available.

Name:	svt_FinalSinkingFundPaymentAdditional
Namespace Prefix:	svt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the amount to be paid into a fund, which is used to retire the debt instrument.

+ References

No definition available.

+ Details

Name:	svt_FinalSinkingFundPaymentDue
Namespace Prefix:	svt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the percentage of annual fee of principal amount outstanding.

+ References

No definition available.

+ Details

Name:	svt_PercentageOfAnnualFeeOfPrincipalAmountOutstanding
Namespace Prefix:	svt_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the percentage of annual fee of secured amount.

+ References

No definition available.

+ Details

Name:	svt_PercentageOfAnnualFeeOfSecuredAmount
Namespace Prefix:	svt_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateEffectivePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount paid into a fund, which is used to retire the debt instrument.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

+ Details

Name:	us-gaap_DebtInstrumentSinkingFundPayment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant