Note 4. Investment Securities: Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Table Text Block] (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	$ 363,155	$ 130,045
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	12,888	1,683
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	31,152	22,199
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	1,716	814
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	394,307	152,244
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	14,604	2,497
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year	113	45
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year	15	23
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	128	68
Domestic Corporate Debt Securities
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	153,179	61,386
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	6,403	953
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	4,721
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	330
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	157,900	61,386
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	6,733	953
Commercial Mortgage Backed Securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	571	570
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	404	405
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	571	570
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	404	405
US Treasury Securities
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	17,385	5,667
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	268	2
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	17,385	5,667
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	268	2
US Government Agencies Debt Securities
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	118
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	1
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	118
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	1
US Government-sponsored Enterprises Debt Securities
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	15,453	6,162
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	92	40
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	5,648	2,784
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	177	27
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	21,101	8,946
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	269	67
US States and Political Subdivisions Debt Securities
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	145,939	53,036
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	4,406	657
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	20,212	17,707
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	805	338
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	166,151	70,743
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	5,211	995
Foreign Government Debt
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	27,446
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	1,591
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	27,446
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	1,591
Redeemable Preferred Stock
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	3,635
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	127
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	3,635
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	127
Residential Mortgage Backed Securities Member
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value		2,416
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss		21
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		1,138
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss		44
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		3,554
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss		65
Debt Securities
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value		128,667
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss		1,673
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		22,199
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss		814
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		150,866
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss		2,487
Nonredeemable Preferred Stock
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value		1,378
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss		10
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		1,378
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss		$ 10