Note 2: Investments in Securities: Unrealized Gain (Loss) on Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Total Unrealized Losses and Estimated Fair Value
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 104,460	$ 64,927
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	(1,509)	(567)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		10,291
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss		(254)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	104,460	75,218
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	(1,509)	(821)
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	102,296	45,146
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	(1,501)	(348)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		9,382
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss		(253)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	102,296	54,528
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	(1,501)	(601)
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, Aggregate Loss	(8)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		909
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss		(1)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	2,164	909
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	$ (8)	(1)
US Government Agencies Debt Securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		19,781
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss		(219)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		19,781
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss		$ (219)