Note 2: Investments in Securities: Unrealized Gain (Loss) on Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 11,255	$ 33,862
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(82)	(384)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	74,186	55,845
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(2,489)	(1,254)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	85,441	89,707
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(2,571)	(1,638)
Collateralized Mortgage Obligations
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	9,725
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(14)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	9,725
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(14)
US States and Political Subdivisions Debt Securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	511	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	511	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	0	0
Unrealized Losses, Fair Value, Time in Continuous Unrealized Loss Position
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	21,491	33,862
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(96)	(384)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	74,186	55,845
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(2,489)	(1,254)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	95,677	89,707
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ (2,585)	$ (1,638)