Stockholders' Equity (Details) (USD $) In Millions, unless otherwise specified	Jul. 14, 2009
Equity [Abstract]
Shelf registration statement maximum amount of securities authorized for issuance	$ 200

Shelf Registration Statement Maximum Amount Of securities Authorized For Issuance

No definition available.

Name:	hgg_ShelfRegistrationStatementMaximumAmountOfSecuritiesAuthorizedForIssuance
Namespace Prefix:	hgg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant