Document and Entity Information - USD ($)	12 Months Ended
	Jan. 01, 2016	Mar. 10, 2016	Jul. 03, 2015
Document and Entity Information [Abstract]
Entity Registrant Name	HACKETT GROUP, INC.
Entity Central Index Key	0001057379
Document Type	10-K
Document Period End Date	Jan. 01, 2016
Amendment Flag	false
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--01-01
Entity Filer Category	Accelerated Filer
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 310,389,146
Entity Common Stock, Shares Outstanding		30,157,675