Note 4. Investment Securities: Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Table Text Block] (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	$ 320,853	$ 130,045
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	13,119	1,683
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	34,752	22,199
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	1,979	814
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	355,605	152,244
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	15,098	2,497
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year	109	45
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year	16	23
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	125	68
Domestic Corporate Debt Securities
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	142,526	61,386
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	6,169	953
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	4,684
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	344
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	147,210	61,386
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	6,513	953
Commercial Mortgage Backed Securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	572	570
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	403	405
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	572	570
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	403	405
US Treasury Securities
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	4,127	5,667
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	71	2
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	4,127	5,667
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	71	2
US Government-sponsored Enterprises Debt Securities
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	3,574	6,162
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	91	40
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	5,482	2,784
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	208	27
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	9,056	8,946
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	299	67
US States and Political Subdivisions Debt Securities
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	139,702	53,036
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	4,801	657
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	22,687	17,707
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	898	338
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	162,389	70,743
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	5,699	995
Foreign Government Debt
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	26,215
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	1,684
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	1,327
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	126
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	27,542
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	1,810
Redeemable Preferred Stock
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	3,471
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	292
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	3,471
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	292
Debt Securities
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	319,615	128,667
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	13,108	1,673
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	34,752	22,199
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	1,979	814
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	354,367	150,866
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	15,087	2,487
Nonredeemable Preferred Stock
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	1,238	1,378
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	11	10
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,238	1,378
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	11	10
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