Note 3. Investment Securities: Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value (Details) $ in Thousands	Jun. 30, 2015 USD ($)	Dec. 31, 2014 USD ($)
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	$ 397,970	$ 161,904
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	4,945	2,540
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	77,818	161,489
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	3,315	3,736
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	475,788	323,393
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 8,260	$ 6,276
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year	80	70
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year	26	46
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	106	116
Corporate Debt Securities
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	$ 98,506	$ 77,868
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	3,527	1,473
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	32,146	69,498
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	1,729	1,841
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	130,652	147,366
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	5,256	3,314
Residential Mortgage Backed Securities Member
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	2,030	2,062
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	19	16
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		1,562
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		6
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	2,030	3,624
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	19	22
US Treasury Securities
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	196,800
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	25
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	196,800
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	25
US Government-sponsored Enterprises Debt Securities
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	7,853
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	30
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	3,133	9,581
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	34	86
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	10,986	9,581
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	64	86
US States and Political Subdivisions Debt Securities
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	87,890	58,819
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1,081	744
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	42,539	67,318
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	1,552	1,642
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	130,429	126,137
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	2,633	2,386
Debt Securities
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	393,079	159,897
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	4,682	2,404
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	77,818	161,141
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	3,315	3,725
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	470,897	321,038
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	7,997	6,129
COMMON STOCK
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	4,891	2,007
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	263	136
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		348
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		11
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	4,891	2,355
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	263	147
Equity Securities
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	4,891	2,007
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	263	136
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		348
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		11
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	4,891	2,355
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 263	147
Commercial Mortgage Backed Securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		953
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		22
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		953
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		22
Foreign Government Debt
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value		21,148
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		171
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		12,229
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		128
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		33,377
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		$ 299