Note 5: Investment Securities: Unrealized Gain (Loss) on Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		$ 104,460
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		(1,509)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		104,460
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		(1,509)
Unrealized Losses and Estimated Fair Value
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 84,613
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(971)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	84,613
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(971)
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	84,118	102,296
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(965)	(1,501)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	84,118	102,296
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(965)	(1,501)
US States and Political Subdivisions Debt Securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	495	2,164
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(6)	(8)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	495	2,164
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ (6)	$ (8)