Note 4. Investment Securities: Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value (Details) $ in Thousands	Sep. 30, 2016 USD ($)	Dec. 31, 2015 USD ($)
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	$ 86,145	$ 210,357
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	691	3,709
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	68,729	91,565
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	2,150	4,512
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	154,874	301,922
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 2,841	$ 8,221
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year	39	99
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year	28	31
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	67	130
Corporate Debt Securities
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	$ 24,023	$ 101,903
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	225	2,559
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	30,032	55,217
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	1,206	3,309
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	54,055	157,120
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	1,431	5,868
US Treasury Securities
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	18,229	19,809
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	26	64
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	18,229	19,809
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	26	64
US Government-sponsored Enterprises Debt Securities
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value		6,539
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		128
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	10,160	4,997
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	222	126
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	10,160	11,536
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	222	254
US States and Political Subdivisions Debt Securities
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	38,919	68,898
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	363	780
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	24,875	31,351
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	621	1,077
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	63,794	100,249
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	984	1,857
Foreign Government Debt
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	3,666	484
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	58	6
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	3,666	484
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	58	6
Redeemable Preferred Stock
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value		3,749
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	3,662
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	101
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	3,662	3,749
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	101	14
Debt Securities
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	84,837	204,249
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	672	3,565
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	68,729	91,565
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	2,150	4,512
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	153,566	295,814
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	2,822	8,077
Nonredeemable Preferred Stock
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	1,308	1,324
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	19	2
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,308	1,324
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	19	2
Equity Securities
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	1,308	6,108
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	19	144
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,308	6,108
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 19	144
Residential Mortgage Backed Securities Member
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value		2,867
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		14
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		2,867
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		14
COMMON STOCK, AMOUNT
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value		4,784
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		142
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		4,784
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		$ 142