Legal Proceedings (Details)	Sep. 30, 2017 state
Commitments and Contingencies Disclosure [Abstract]
Number of states seeking recovery of unclaimed property	17

The number of states being audited and seeking recovery of unclaimed property.

No definition available.

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