Document and Entity Information - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Mar. 01, 2018	Jun. 30, 2017
Details
Registrant Name	GREAT SOUTHERN BANCORP, INC.
Registrant CIK	0000854560
SEC Form	10-K
Period End date	Dec. 31, 2017
Fiscal Year End	--12-31
Trading Symbol	GSBC
Tax Identification Number (TIN)	431524856
Number of common stock shares outstanding		14,109,837
Public Float			$ 392,225,119
Filer Category	Accelerated Filer
Current with reporting	Yes
Voluntary filer	No
Well-known Seasoned Issuer	No
Amendment Flag	false
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY
Entity Incorporation, State Country Name	Maryland
Entity Address, Address Line One	1451 E. Battlefield
Entity Address, City or Town	Springfield
Entity Address, State or Province	Missouri
Entity Address, Postal Zip Code	65804
City Area Code	417
Local Phone Number	887-4400

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