Number Of Directors That Resigned

No definition available.

Name:	syx_NumberOfDirectorsThatResigned
Namespace Prefix:	syx_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of equity compensation plans during the period.

+ References

No definition available.

+ Details

Name:	syx_NumberOfEquityCompensationPlans
Namespace Prefix:	syx_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of units expected to vest on an annual basis under the plan.

+ References

No definition available.

+ Details

Name:	syx_NumberOfUnitsVestingAnnually
Namespace Prefix:	syx_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Number Of Units Vesting Immediately

+ References

No definition available.

+ Details

Name:	syx_NumberOfUnitsVestingImmediately
Namespace Prefix:	syx_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- References

No definition available.

+ Details

Name:	syx_RestrictedStockAndRestrictedStockUnitsAbstract
Namespace Prefix:	syx_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Share Based Compensation, Acceleration Of Stock Options

+ References

No definition available.

+ Details

Name:	syx_ShareBasedCompensationAccelerationOfStockOptionsDueToSaleOfBusiness
Namespace Prefix:	syx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Number of equal installments in which non-performance award vests.

+ References

No definition available.

+ Details

Name:	syx_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfVestingInstallments
Namespace Prefix:	syx_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Share-based Compensation Arrangement By Share-based Payment Award, Stock Plan Offering Period

+ References

No definition available.

+ Details

Name:	syx_SharebasedCompensationArrangementBySharebasedPaymentAwardStockPlanOfferingPeriod
Namespace Prefix:	syx_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Stock Issued During Period, Shares, Employee Stock Purchase Plans, Maximum Shares Available To Purchase, Per Employee

+ References

No definition available.

+ Details

Name:	syx_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlansMaximumSharesAvailableToPurchasePerEmployee
Namespace Prefix:	syx_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5047-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.F)
-URI http://asc.fasb.org/extlink&oid=115993241&loc=d3e301413-122809

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

+ Details

Name:	us-gaap_AllocatedShareBasedCompensationExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Aggregate number of common shares reserved for future issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.29)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_CommonStockCapitalSharesReservedForFutureIssuance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Unrecognized cost of unvested options awarded to employees as compensation.

+ References

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

+ References

+ Details

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

- Definition

The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

+ Details

Name:	us-gaap_ShareBasedCompensation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

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

- Definition

The highest quantity of shares an employee can purchase under the plan per period.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumNumberOfSharesPerEmployee
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of equity instruments other than options outstanding, including both vested and non-vested instruments.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(ii)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(i)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Number of options outstanding, including both vested and non-vested options.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

+ References

+ Details

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Purchase price of common stock expressed as a percentage of its fair value.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_EmployeeStockOptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=syx_EuropeanTechnologyProductsSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=syx_NorthAmericanTechnologyProductsSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_RestrictedStockUnitsRSUMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TitleOfIndividualAxis=syx_KeyEmployeeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardDateAxis=syx_GrantDateNovember2011Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementLocationAxis=us-gaap_SellingGeneralAndAdministrativeExpensesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardDateAxis=syx_GrantDateFebruary2016Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TitleOfIndividualAxis=syx_TwoKeyEmployeesFirstGrantMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TitleOfIndividualAxis=us-gaap_DirectorMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=syx_LongTermStockIncentivePlanAsAmended1999PlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=syx_LongTermStockIncentivePlan2010PlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardDateAxis=syx_GrantDateAugust2010Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=syx_A2018EmployeeStockPurchasePlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_EmployeeStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementOperatingActivitiesSegmentAxis=us-gaap_SegmentDiscontinuedOperationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementOperatingActivitiesSegmentAxis=us-gaap_SegmentContinuingOperationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

SHAREHOLDERS' EQUITY - Narrative (Details) $ in Millions	1 Months Ended						2 Months Ended	3 Months Ended	12 Months Ended
SHAREHOLDERS' EQUITY - Narrative (Details) $ in Millions	Dec. 31, 2018 USD ($) plan shares	Oct. 31, 2018 Installment shares	Feb. 29, 2016 Installment shares	Jul. 31, 2015 Installment shares	Nov. 30, 2011 Installment shares	Aug. 31, 2010 Installment shares	Nov. 30, 2017 Installment shares	Mar. 31, 2012 Installment shares	Dec. 31, 2018 USD ($) plan shares	Dec. 31, 2017 USD ($) director shares	Dec. 31, 2016 USD ($) shares	Apr. 30, 2018 shares	Oct. 31, 2017 Installment shares	Dec. 31, 2015 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of compensation plans \| plan	2								2
Share based compensation cost \| $									$ 0.9	$ 1.6	$ 1.6
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options outstanding (in shares)	596,148								596,148	1,001,300	1,410,250			954,625
Share based compensation cost \| $									$ 0.3	$ 1.1	$ 0.7
Share based compensation cost, future income tax benefits \| $									0.1	0.2	0.3
Total intrinsic value of options exercised \| $									9.5	1.3	0.0
Unrecognized compensation costs, unvested stock options \| $	$ 0.5								$ 0.5
Weighted average period of recognition									1 year 9 months
Total fair value of stock options vested \| $									$ 1.2	0.9	0.6
Employee Stock Option \| ETG
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation cost \| $									0.4	0.0	0.1
Acceleration of stock options due to sale of business \| $									0.3
Employee Stock Option \| NATG
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation cost \| $											0.0
Restricted Stock Units (RSUs) \| Key Employee \| Granted November 2011 \| Selling, General and Administrative Expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation cost \| $									0.2	0.1	0.1
Restricted Stock Units (RSUs) \| Key Employee \| Grant February 2016 \| Selling, General and Administrative Expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation cost \| $									$ 0.1	0.2	0.5
Restricted Stock and Restricted Stock Units [Abstract]
Unvested, will accelerate and vest (in shares)	16,666								16,666
Restricted Stock Units (RSUs) \| Two Key Employees \| Selling, General and Administrative Expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation cost \| $									$ 0.1	0.1	0.1
Restricted Stock Units (RSUs) \| Director \| Selling, General and Administrative Expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation cost \| $									$ 0.1	$ (0.1)	0.1
1999 Long-term Stock Incentive Plan, as amended
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for issuance (in shares)	7,500,000								7,500,000
Number of shares granted per calendar year in total, maximum (in shares)									3,000,000
1999 Long-term Stock Incentive Plan, as amended \| Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted per calendar year in total, maximum (in shares)									1,500,000
Number of options outstanding (in shares)	50,000								50,000
2010 Long-term Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for issuance (in shares)	7,500,000								7,500,000
2010 Long-term Stock Incentive Plan \| Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted per calendar year in total, maximum (in shares)									1,500,000
Number of options outstanding (in shares)	546,148								546,148
2010 Long-term Stock Incentive Plan \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock outstanding (in shares)	132,484								132,484
2010 Long-term Stock Incentive Plan \| Restricted Stock Units (RSUs) \| Key Employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation cost \| $									$ 0.0		0.0
Restricted Stock and Restricted Stock Units [Abstract]
RSU's granted (in shares)		5,117	100,000	23,620	100,000		53,288
Number of vesting installments \| Installment		4	3	4	10								2
Number of units vesting annually (in shares)				5,905	10,000		49,600
Unvested, will accelerate and vest (in shares)					30,000
Number of units vesting immediately												1,844	1,844
Number of directors that resigned during period \| director										2
2010 Long-term Stock Incentive Plan \| Restricted Stock Units (RSUs) \| Key Employee \| Granted August 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation cost \| $									$ 0.1	$ 0.1	$ 0.1
Restricted Stock and Restricted Stock Units [Abstract]
RSU's granted (in shares)						175,000
Number of vesting installments \| Installment						10
Number of units vesting annually (in shares)						17,500
Unvested, will accelerate and vest (in shares)						35,000
2010 Long-term Stock Incentive Plan \| Restricted Stock Units (RSUs) \| Two Key Employees
Restricted Stock and Restricted Stock Units [Abstract]
RSU's granted (in shares)								50,000
Number of vesting installments \| Installment								10
Number of units vesting annually (in shares)								5,000
2018 Employee Stock Purchase Plan \| Employee Stock
Restricted Stock and Restricted Stock Units [Abstract]
Employee stock purchase plan, shares issued (in shares)	500,000								500,000
Share-based Compensation Arrangement By Share-based Payment Award, Stock Plan Offering Period	6 months
Employee stock purchase plan, maximum shares available to purchase (in shares)	10,000
Employee stock purchase plan, purchase price of stock, percent	85.00%
2018 Employee Stock Purchase Plan \| Employee Stock \| Selling, General and Administrative Expenses
Restricted Stock and Restricted Stock Units [Abstract]
Allocated Share-based Compensation Expense \| $									$ 0.1
Maximum \| 2010 Long-term Stock Incentive Plan \| Restricted Stock Units (RSUs) \| Key Employee
Restricted Stock and Restricted Stock Units [Abstract]
Number of vesting installments \| Installment							3
Discontinued Operations \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation cost \| $									1.5
Discontinued Operations \| 2010 Long-term Stock Incentive Plan \| Restricted Stock Units (RSUs) \| Key Employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation cost \| $									1.5	$ 0.1
Continuing Operations \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation cost \| $									0.8
Continuing Operations \| 2010 Long-term Stock Incentive Plan \| Restricted Stock Units (RSUs) \| Key Employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation cost \| $									$ 0.0