Credit Facilities and Long Term Debt (Details) - Group f Financial Institutions [Member] - Secured Revolving Credit Facility [Member] $ in Millions	6 Months Ended
Jun. 30, 2016 USD ($)
Line of Credit Facility [Line Items]
Secured revolving credit agreement, maximum borrowing capacity	$ 125.0
Line of credit facility optional maximum borrowing capacity subject to conditions	$ 200.0
Credit facility, maturing date	Oct. 31, 2016
Eligible collateral under the credit facility	$ 44.4
Availability under line of credit	38.9
Total outstanding letters of credit	5.5
Outstanding borrowings	$ 0.0
Maximum [Member]
Line of Credit Facility [Line Items]
Percentage of eligible accounts receivable for borrowings	85.00%
Percentage of qualified inventories for borrowings	40.00%

Refers to the amount of eligible collateral letters of credit, based on borrowing base availability.

No definition available.

Name:	syx_EligibleCollateralUnderTheCreditFacility
Namespace Prefix:	syx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The optional borrowing capacity subject to conditions 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

No definition available.

+ Details

Name:	syx_LineOfCreditFacilityOptionalBorrowingCapacitySubjectToConditions
Namespace Prefix:	syx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Refers to the amount of outstanding advances.

+ References

No definition available.

+ Details

Name:	syx_OutstandingAdvances
Namespace Prefix:	syx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The percentage of eligible accounts receivable for borrowings under the agreement.

+ References

No definition available.

+ Details

Name:	syx_PercentageOfEligibleAccountsReceivableForBorrowings
Namespace Prefix:	syx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The percentage of qualified inventories for borrowings under the agreement.

+ References

No definition available.

+ Details

Name:	syx_PercentageOfQualifiedInventoriesForBorrowings
Namespace Prefix:	syx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- 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

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

+ 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

+ Details

Name:	us-gaap_LineOfCreditFacilityExpirationDate1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
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

- Details

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

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
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: