Note 5: Investment Securities: Unrealized Gain (Loss) on Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Unrealized Losses and Estimated Fair Value
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 86,443	$ 104,460
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(989)	(1,509)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	86,443	104,460
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(989)	(1,509)
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	86,443	102,296
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(989)	(1,501)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	86,443	102,296
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ (989)	(1,501)
US States and Political Subdivisions Debt Securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		2,164
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		(8)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		2,164
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		$ (8)