Note 7. Employee Benefit Plans (Detail) - Net Periodic Pension Cost (Income) Three Months Ended September 30 (USD $) In Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Pension Benefits [Member]
Service cost	$ 969	$ 551	$ 2,908	$ 1,652
Interest cost	1,028	931	3,085	2,793
Expected return on plan assets	(1,370)	(1,261)	(4,111)	(3,781)
Amortization of prior service cost	101	151	302	452
Amortization of net (gain) loss	220	217	660	650
Net periodic benefit cost	948	589	2,844	1,766
Other Benefits [Member]
Service cost	14	11	41	34
Interest cost	19	18	58	55
Expected return on plan assets	(22)
Amortization of prior service cost	55	14	33	40
Amortization of net (gain) loss	(32)	(12)	(32)	(35)
Net periodic benefit cost	$ 34	$ 31	$ 100	$ 94