Document and Entity Information (USD $)	3 Months Ended
	Sep. 30, 2012	Nov. 07, 2012
Document and Entity Information
Entity Registrant Name	Great Southern Bancorp Inc
Document Type	10-Q
Document Period End Date	Sep. 30, 2012
Amendment Flag	false
Entity Central Index Key	0000854560
Current Fiscal Year End Date	--12-31
Entity Common Stock, Shares Outstanding		13,590,950
Entity Public Float	$ 192,585,174
Entity Filer Category	Accelerated Filer
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	No
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	Q3