Legal Proceedings (Details)	Mar. 31, 2021 state
Commitments and Contingencies Disclosure [Abstract]
Number of states seeking recovery of unclaimed property	27
Number of states requesting payment	19

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