Note 4. Investment Securities: Schedule of Unrealized Loss on Investments (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	$ 157,846	$ 130,045
Available for sale Securities Continuous Unrealized Loss Position Less Than 12 Months Aggregate Losses2	1,968	1,683
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value	28,587	22,199
Available for sale Securities Continuous Unrealized Loss Position 12 Months Or Longer Aggregate Losses2	947	814
Available For Sale Securities Continuous Unrealized Loss Position Fair Value	186,433	152,244
Available for sale Securities Continuous Unrealized Loss Position Aggregate Losses2	2,915	2,497
Available For Sale Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions Less Than 12 Months	53	45
Available For Sale Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions More Than 12 Months	17	23
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	70	68
Corporate Debt Securities
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	88,143	61,386
Available for sale Securities Continuous Unrealized Loss Position Less Than 12 Months Aggregate Losses2	1,147	953
Available For Sale Securities Continuous Unrealized Loss Position Fair Value	88,143	61,386
Available for sale Securities Continuous Unrealized Loss Position Aggregate Losses2	1,147	953
Residential Mortgage Backed Securities Member
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	2,089	2,416
Available for sale Securities Continuous Unrealized Loss Position Less Than 12 Months Aggregate Losses2	19	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 Losses2		44
Available For Sale Securities Continuous Unrealized Loss Position Fair Value	2,089	3,554
Available for sale Securities Continuous Unrealized Loss Position Aggregate Losses2	19	65
Commercial Mortgage Backed Securities
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value	576	570
Available for sale Securities Continuous Unrealized Loss Position 12 Months Or Longer Aggregate Losses2	399	405
Available For Sale Securities Continuous Unrealized Loss Position Fair Value	576	570
Available for sale Securities Continuous Unrealized Loss Position Aggregate Losses2	399	405
US Treasury Securities
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	7,004	5,667
Available for sale Securities Continuous Unrealized Loss Position Less Than 12 Months Aggregate Losses2	18	2
Available For Sale Securities Continuous Unrealized Loss Position Fair Value	7,004	5,667
Available for sale Securities Continuous Unrealized Loss Position Aggregate Losses2	18	2
US Government-sponsored Enterprises Debt Securities
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	1,416	6,162
Available for sale Securities Continuous Unrealized Loss Position Less Than 12 Months Aggregate Losses2	65	40
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value	5,894	2,784
Available for sale Securities Continuous Unrealized Loss Position 12 Months Or Longer Aggregate Losses2	70	27
Available For Sale Securities Continuous Unrealized Loss Position Fair Value	7,310	8,946
Available for sale Securities Continuous Unrealized Loss Position Aggregate Losses2	135	67
US States and Political Subdivisions Debt Securities
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	42,289	53,036
Available for sale Securities Continuous Unrealized Loss Position Less Than 12 Months Aggregate Losses2	460	657
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value	22,117	17,707
Available for sale Securities Continuous Unrealized Loss Position 12 Months Or Longer Aggregate Losses2	478	338
Available For Sale Securities Continuous Unrealized Loss Position Fair Value	64,406	70,743
Available for sale Securities Continuous Unrealized Loss Position Aggregate Losses2	938	995
Foreign Government Debt
Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value	16,905
Available for sale Securities Continuous Unrealized Loss Position Less Than 12 Months Aggregate Losses2	259
Available For Sale Securities Continuous Unrealized Loss Position Fair Value	16,905
Available for sale Securities Continuous Unrealized Loss Position Aggregate Losses2	259
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 Losses2		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 Losses2		814
Available For Sale Securities Continuous Unrealized Loss Position Fair Value		150,866
Available for sale Securities Continuous Unrealized Loss Position Aggregate Losses2		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 Losses2		10
Available For Sale Securities Continuous Unrealized Loss Position Fair Value		1,378
Available for sale Securities Continuous Unrealized Loss Position Aggregate Losses2		$ 10