Note 27: Condensed Parent Company Statements: Condensed Statement of Comprehensive Income -- Great Southern Bancorp, Inc. (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Unrealized Appreciation (Depreciation) on Available for Sale Securities, Net	$ (478)	$ (2,363)	$ (1,321)
Statements of Comprehensive Income | Parent Company
Net Income Parent Company	51,564	45,342	46,502
Unrealized Appreciation (Depreciation) on Available for Sale Securities, Net	0	(158)	400
Reclassification adjustment for gains included in net income	0	(1,742)	0
Change in Fair Value of Cash Flow Hedge, Net	161	87	(50)
Comprehensive Income of subsidiaries	(478)	(2,293)	(1,722)
Comprehensive Income parent	$ 51,247	$ 41,236	$ 45,130