Payment made related to obligation excluding interest.

No definition available.

Name:	sli_PaymentMadeRelatedToObligationExcludingInterest
Namespace Prefix:	sli_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Percentage of stand by commission.

+ References

No definition available.

+ Details

Name:	sli_PercentageOfStandByCommissionFee
Namespace Prefix:	sli_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Standby and commercial letter of credit sublimit.

+ References

No definition available.

+ Details

Name:	sli_StandbyAndCommercialLetterOfCreditSublimit
Namespace Prefix:	sli_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

Subline for loans funded to be made available to the acquired entity.

+ References

No definition available.

+ Details

Name:	sli_SubLineForLoansFunded
Namespace Prefix:	sli_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- 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 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

Reference 2: 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

+ Details

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

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.16)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.16)

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 20, 22

-Article 5

+ Details

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

- Definition

The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

+ Details

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

- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityExpirationDate1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Period remaining on line of credit facility before it terminates, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityExpirationPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
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

+ 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

- Definition

Amount of long-term debt, after unamortized discount or premium, scheduled to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

+ Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=sli_TwoThousandTwelveCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=sli_PncBankNationalAssociationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=sli_StandbyLettersOfCreditDueMayTwentyEightTwoThousandSixteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_BaseRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=sli_FederalFundsOpenRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=sli_DailyLiborRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=sli_SixthAmendmentToTwoThousandTwelveCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Debt - Additional Information (Detail) - USD ($)		9 Months Ended
Debt - Additional Information (Detail) - USD ($)	Aug. 09, 2012	Sep. 30, 2015	Jul. 24, 2015	Jun. 01, 2015	Dec. 31, 2014	May. 28, 2013
Line of Credit Facility [Line Items]
Debt outstanding		$ 13,500,000			$ 0
2012 Credit Facility [Member]
Line of Credit Facility [Line Items]
Maximum borrowings		$ 40,000,000
Maturity date of expiration		Aug. 09, 2016
Credit availability under Credit Facility		$ 26,044,000			39,527,000
Balance under the Credit Facility		$ 13,500,000			$ 0
2012 Credit Facility [Member] \| PNC Bank, National Association (PNC Bank) [Member]
Line of Credit Facility [Line Items]
Maximum borrowings	$ 40,000,000
Maximum borrowings under certain conditions	70,000,000
Standby and commercial letter of credit sublimit	$ 10,700,000
Maturity date of expiration		Aug. 09, 2016
Letter of credit, expiration period from the date of closing	1 year
Interest rate		1.47%
2012 Credit Facility [Member] \| PNC Bank, National Association (PNC Bank) [Member] \| Minimum [Member]
Line of Credit Facility [Line Items]
Standby and commercial letter of credit sublimit	$ 5,000,000
2012 Credit Facility [Member] \| PNC Bank, National Association (PNC Bank) [Member] \| Maximum [Member]
Line of Credit Facility [Line Items]
Standby and commercial letter of credit sublimit	$ 25,000,000
2012 Credit Facility [Member] \| Standby Letters of Credit Due June 10, 2016 [Member]
Line of Credit Facility [Line Items]
Maturity date of expiration		Jun. 10, 2016
Balance of letter of credit under Credit Facility		$ 4,282,000				$ 8,564,000
Annual commitment fee		0.125%
Standby commission		1.00%
Payment related to obligation excluding interest				$ 2,141,000
2012 Credit Facility [Member] \| London Interbank Offered Rate (LIBOR) [Member] \| PNC Bank, National Association (PNC Bank) [Member] \| Minimum [Member]
Line of Credit Facility [Line Items]
Margin rate range		1.25%
2012 Credit Facility [Member] \| London Interbank Offered Rate (LIBOR) [Member] \| PNC Bank, National Association (PNC Bank) [Member] \| Maximum [Member]
Line of Credit Facility [Line Items]
Margin rate range		2.00%
2012 Credit Facility [Member] \| Base Rate [Member] \| PNC Bank, National Association (PNC Bank) [Member] \| Minimum [Member]
Line of Credit Facility [Line Items]
Margin rate range		0.25%
2012 Credit Facility [Member] \| Base Rate [Member] \| PNC Bank, National Association (PNC Bank) [Member] \| Maximum [Member]
Line of Credit Facility [Line Items]
Margin rate range		1.00%
2012 Credit Facility [Member] \| Federal Funds Open Rate [Member] \| PNC Bank, National Association (PNC Bank) [Member] \| Maximum [Member]
Line of Credit Facility [Line Items]
Margin rate range		0.50%
2012 Credit Facility [Member] \| Daily Libor Rate [Member] \| PNC Bank, National Association (PNC Bank) [Member] \| Maximum [Member]
Line of Credit Facility [Line Items]
Margin rate range		1.00%
Sixth Amendment to 2012 Credit Facility [Member]
Line of Credit Facility [Line Items]
Subline for loans funded for acquired entity			$ 4,000,000