Recent Accounting Pronouncements (Details Textual)	Jan. 02, 2018 USD ($)
New Accounting Pronouncement or Change in Accounting Principle, Assets And Liabilities	$ 0

The amount of assets and liabilities regarding new accounting policy and change in accounting principle.

No definition available.

Name:	sga_NewAccountingPronouncementOrChangeInAccountingPrincipleAssetsAndLiabilities
Namespace Prefix:	sga_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant