Note 5. Employee Benefit Plans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost on benefit obligation	$ 18,871	$ 17,589
Expected return on plan assets	(23,327)	(22,657)
Amortization of actuarial loss	2,475	4,650
Amortization of prior-service costs (credits)	404	418
Net periodic benefit expense (income)	(1,577)	0
Non Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost on benefit obligation	862	804
Expected return on plan assets	0	0
Amortization of actuarial loss	219	279
Amortization of prior-service costs (credits)	1	1
Net periodic benefit expense (income)	1,082	1,084
Postretirement Medical Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	271	429
Interest cost on benefit obligation	672	891
Amortization of actuarial loss	(657)	0
Amortization of prior-service costs (credits)	(716)	(263)
Net periodic benefit expense (income)	$ (430)	$ 1,057